toolboy's Corner: Ryobi 18v Batteries



Over time the 18v battery packs have increased in performance and decreased in weight. All of these packs are interchangeable, meaning that any of these packs can be used with any of the Ryobi 18v tools, including the old blue/yellow and the new neon green
Model Chemistry Appearance Weight (measured) mAh Rating
Wh Rating		 % Power compared to P100 Battery Height
and Features		 Comments
130224007, 130256001, 1322401, 1322705, 1323303, 1400672 Nickel Cadmium 1lb 15oz
880g
(measured)		 1500mAh
27Wh?		 88%
  • Full-height
  • Predates "One+" designation
P100 Nickel Cadmium 1lb 15oz
880g
(measured)		 1500mAh ..or 1700mAh??
27Wh ...or 31Wh??		 100%
  • Full-height (2.213 in)
  • The "standard" battery pack against which the Lithium Ion packs were originally compared
  • P100 Manual (143KB)
P102 Lithium Ion 15.4oz
430g
(measured)		 1300mAh
(But more like 1200mAh)
24Wh 		70.6%
  • Half-height (1.350 in)
  • Battery label indicates 24Wh -- same as the "old" P103 batteries
  • Click Here for information dedicated to the P102
  • P102/105 Manual (1,406KB)
P103 Lithium Ion 1lb 1oz
480g
(measured)		 1300mAh or 1500mAh
24Wh or 28Wh		 76%
or 88%
  • Half-height (1.402 in)
  • Smaller than all other packs at 1-7/16" tall "battery" portion, as compared to 2 3/16" "battery" portion on all other packs
  • Measured weight is 45% less than P100, as claimed. 1-(480/880) = 45.45%
  • Actual power is 1300mAh, which is 23.53% LESS than P100, not 40% more than P100 as claimed!
  • Update 29-Aug-2012! Originally 1.3Ah, but changed to 1.5Ah 17th week of 2012 (CS1217)
  • P103/104 Manual (884KB)
P104 Lithium Ion 1lb 11oz
770g
(measured)		 2400mAh or 2600mAh
45Wh, 46Wh, or 48Wh		 141%
or 153%
  • Full-height (2.137 in)
  • On-board fuel gauge
  • Measured weight is 12.5% less than P100, not as much as the 20% claimed. 1-(770/880) = 12.5%
  • Update 29-Apr-2010! Originally 2.4Ah, but changed to 2.6Ah 48th week of 2009 (CS0948)
  • P103/104 Manual (884KB)
P105 Lithium Ion 1lb 8.44oz
693g
(measured)		 2400mAh
45Wh or 48Wh		 141%
  • Full-height (2.104 in)
  • Battery label says 45wh (same as an original P104)
  • P102/105Manual (1,406KB)
P107 Lithium Ion 1lb 0.2oz
460g
(measured)		 1500mAh
28Wh		 88%
  • Half-height (1.371 in)
  • On-board fuel gauge
  • Extreme weather performance
P108 Lithium Ion 1lb 9.2oz
720g
(measured)		 4000mAh
72Wh		 235%
  • Full-height (2.092 in)
  • On-board fuel gauge
  • Extreme weather performance
P189 Lithium Ion   1500mAh
27Wh		 88%
  • Half-height
P190 Lithium Ion 15.6 oz
445g
(measured)		 2000mAh
36Wh		 118%
  • Half-height (1.352 in)
P191 Lithium Ion  
760g
(measured)		 3000mAh
54Wh		 176%
  • Full height
  • On-board fuel gauge
  • "Lithium+ HP"
  • DOES have the two extra "Lithium+ HP" contacts in the back at the base of the battery stem
  • P191 Manual (1,002KB)
P192 Lithium Ion   4000mAh
72Wh		 235%
  • Full-height, and a bit taller than previous full-height batteries
  • On-board fuel gauge
  • "Lithium+ HP"
  • DOES have the two extra "Lithium+ HP" contacts in the back at the base of the battery stem
  • P192 Manual (1,002KB)
P193 Lithium Ion  
930g
(measured)		 6000mAh
108Wh		 353%
  • Full-Height Plus: 1/2 inch taller than most full-height batteries
  • On-board fuel gauge
  • "Lithium+ HP"
  • DOES have the two extra "Lithium+ HP" contacts in the back at the base of the battery stem
  • Battery Height: 2.575 in
  • P193 Manual (1,723KB)
P194 Lithium Ion 2lb 10.0 oz
1190g
(measured)		 9000mAh
162Wh		 529%
  • Full-Height and a half!
    Battery is one inch taller than most full-height batteries
  • On-board fuel gauge
  • "Lithium+ HP"
  • DOES have the two extra "Lithium+ HP" contacts in the back at the base of the battery stem
  • Battery Height: 2.968 in
  • P194 Manual (1,322KB)
P195 Lithium Ion   3000mAh
54Wh
 176%
  • Half-height battery, but taller than most half-height batteries
  • On-board fuel gauge
  • "Lithium+ HP"
  • Ryobi's first 18v battery pack to contain the larger 21700 cells
  • P195 Manual (966KB)
P197 Lithium Ion 1lb 10.4 oz
750g
(measured)		 4000mAh
72Wh		 235%
  • Full-height
  • On-board fuel gauge
PBP002 Lithium Ion   1500mAh
27Wh		 88%
  • Half-height
  • On-board fuel gauge
PBP003 Lithium Ion   2000mAh
37Wh		 118%
  • Half-height
  • On-board fuel gauge
  • "Lithium HIGH PERFORMANCE"
  • DOES have the two extra "Lithium+ HP" contacts in the back at the base of the battery stem
  • PBP003 Manual (1,813KB)
PBP004 Lithium Ion   4000mAh
72Wh		 236%
  • Full-height
  • On-board fuel gauge
PBP005 Lithium Ion   4000mAh
72Wh		 236%
  • Full-height
  • On-board fuel gauge
PBP006 Lithium Ion   2000mAh
36Wh		 118%
  • Half-height
  • On-board fuel gauge
PBP007 Lithium Ion 1lb 11.0 oz
765g
(measured)		 6000mAh
108Wh		 353%
  • Full-height (2.047 in)
    and NOT taller than other full-height batteries!
  • On-board fuel gauge
NOTE: Ryobi also sells batteries in kits of two or more: P101 = 2x P100, P106 = 2x P103, P109 = 2x P107, P122 = 2x P108, P145 = 2x P197, P170 = 2x P102, P161 = 2x P190, P161-6 = 6x P190, P161-10 = 10x P190, P162 = 2x P191, P162-6 = 6x P191, P162-10 = 10x P191, P164 = 2x P193, P164-P168 = 2x P193 + 2x P194, P168 = 2x P194, P181 = 4x P102, P184 = 2x P105, P185 = 3x P105, P192-2 = 2x P192, P192-6 = 6x P192, P19590 = 1x P190 + 1x P195, PBP2003 = 2x PBP003, PBP2004 = 2x PBP004, PBP2006 = 2x PBP006, and PBP2007 = 2x PBP007

Battery Height Measurements

In the above table I've included a measurement of battery height. What does this mean? All Ryobi 18v batteries must have the same size and shape where the stem plugs into a tool or charger. But the part that sticks out, where most or all of the cells in the battery pack are located, can vary in size. All of the measurements were made with my Mitutoyo Caliper, which I picked up from Master Gauge & Tool. See the images below to see how I've defined Battery Width, Stem Height, Battery Length, and Battery Height.
Stem Height: 2.070 in
Battery Width: 2.977 in
Battery Length: 5.354 in
Battery Height: Varies


Battery Contacts

Each Ryobi 18v battery has three or more exposed metal contacts. In this section I'll arbitrarily assign a left and right side to the battery, number each contact, and describe their purpose.
  1. Located at the top and left side of the stem, the contact labeled "-" is the negative contact.
  2. Located at the top and front of the stem, this contact is used only by chargers.
    It's a safety feature which monitors the temperature of cells and interrupts the charge cycle if the cells become too warm.
    This contact may also aid in determining if Li-Ion batteries are too cold to be charged (unconfirmed).
  3. Located at the top and right side of the stem, the contact labeled "+" is the positive contact.
    #1 and #3 are located at the top and opposite sides of the stem.
    These two are used to transfer power into (charge) or out of the battery (powering a tool).
  4. Located in front of the battery stem at its base and in front of the "platform", just left of center.
    This contact exists only on Li-Ion chemistry batteries, and is used only by the charger
  5. Located in front of the battery stem at its base and in front of the "platform", just right of center.
    This contact exists only on certain first generation Li-Ion batteries such as the P103.
    This contact serves no purpose, which is probably why its existence was so short lived.
  6. Located at the back of the battery at the base of the stem.
  7. Located at the back of the battery at the base of the stem.
    Only the batteries (and tools) advertised as having "Lithium+ HP" Technology have these last two contacts.


Note that the Ryobi "ONE+ HP 18v Brushless Cordless Compact" series of batteries and tools do NOT have contacts #6 and #7, therefore this series of batteries and tools lack the "Lithium+ HP" technology. Yes, it is very confusing to use such similar names ("HP" vs "Lithium+ HP") to describe different features. A critic might suggest that this was done deliberately. I'll point out that the original "Lithium+ HP" claims included a greater use range for temperature, water resistance, improved tool performance (presumably via those two new contacts #6 and #7), and possibly other benefits. The newer "HP" may simply include many or all of the "Lithium+ HP" benefits except for those gained by the extra contacts. I sure don't know.



What's the deal with batteries marketed by Ryobi as Lithium Ion, Lithium+, Lithium+ HP, and Lithium Ion HIGH PERFORMANCE

In 2007, Ryobi manufactured their first 18v battery based on Lithium Ion chemistry, the 2.4Ah model P104. The following year they started manufacturing the "compact" 1.3Ah model P103. As of March 2022, Ryobi has offered 19 different models of Lithium Ion 18v batteries which could be arranged into four groups based on Ryobi's description. The above list includes only those batteries sold in North America. Ryobi has sold a number of different 18v batteries internationally, including compact 2.5Ah models (e.g., RB18L25) and full size 5Ah models (e.g., RB1850C, RBB18L50C).

So what do some of the features in the table at the top of this page actually mean?

mAh Rating

A battery pack's mAh rating is an indication of how much power the pack has. In general, the larger the number the longer the battery can be operated before a recharge is needed. Unfortunately, many factors influence how long a battery will last after a fresh charge, including battery age, number of times the pack has been recharged already, temperature, the tool used, and other factors.

Just to give some sort of not-too-unrealistic and tangible comparison, let's say we compare how long each battery pack might theoretically operate a P704 flashlight if in new condition and operating in optimal conditions. For the sake of argument, let's say a P704 flashlight bulb draws a steady 600mA of current (=0.6A) until the battery pack is depleted. In this case, I'd expect the P100 battery to operate the flashlight for 1700mAh/600mAh= 2.8 hours. The P102 and P103 would last 1300mAh/600mAh = 2.2 hours, the P107 would last 1500mAh/600mAh= 2.5 hours, the P104 and P105 would last 2400mAh/600mAh= 4 hours, and the P108 would last 4000mAh/600mAh= 6.7 hours

Wh Rating

Some of Ryobi's battery packs have an energy rating on the label, expressed in "Wh" or Watt-hours. In its simplest terms, Watt-hours is an expression of Voltage x Current. This is a more precise measure of the amount of energy in a battery packs than milliamp-hours (mAh), as it takes into account both voltage level and current draw during the discharge of the battery.

So a typical 18 volt, 1.3Ah P103 battery could be described as having 18v x 1.3A = 23.4Wh. The first battery I saw with a Wh rating was the P103, and it was rated 24Wh, so that seems about right. Here's a list of Wh ratings I've seen:

NiCD (15 Sub-C cells x 1.2v = 18v) Li-Ion (5 18650 cells x 3.6v = 18v) Li-Ion (5 21700 cells x 3.6v = 18v) Li-Ion (10 18650 cells total, 2 parallel strings of [5 cells x 3.6v = 18v]) Li-Ion (15 18650 cells total, 3 parallel strings of [5 cells x 3.6v = 18v]

Holds charge 4X longer and reduces the need to recharge during long periods of non-use

This refers to the Lithium Ion chemistry's low self-discharge rate as compared to that of Nickel Cadmium. Say what??

Have you ever charged a NiCad pack, then put the charged pack on the shelf for a few weeks or months before you needed it? If so I bet you noticed that the pack was not fully charged when you went to use it. That's because Nickel Cadmium cells lose charge over time just sitting idle. So do Lithium Ion cells, but the rate of loss is 4X slower. So after sitting for a month or two unused a NiCad pack may seem nearly discharged while a Lithium Ion pack may still seem nearly fully charged.

Which batteries are compatible with my tools?

As far as I can tell, any 18v Ryobi battery will work with any 18v Ryobi tool. See the photos below to see each of the four battery types plugged into an old drill. Note that I took the photos below back in 2012. I could add photos showing newer tools and newer batteries, but rest assured that all 18v batteries are compatible with all 18v tools.



I should point out that certain Ryobi tools intended for use in wet environments include a latchable cover with watertight seal. Some of these tools predate the release of the extra-tall P194 9Ah battery. I've not had the opportunity to examine all of these wet-use tools, so it's possible that one or more of these older tools is incompatible with the P194 battery simply because the battery is too tall to fit under the watertight battery cover. I own an Arctic Cove model MBF018 misting fan (from 2015) which is designed for use with Ryobi 18v batteries and the watertight cover on this unit is too small to close over a P194. I also own a Ryobi model RY120350 Pressure Washer (from 2020) and the battery cover on this unit is large enough for a P194.

Exactly what make of 18650 cells are in Ryobi 18v batteries?

I've personally cracked open several different models of Ryobi 18v batteries and each has contained quality Samsung or LG cells. I've read that Ryobi has also used Sony VTC4 and VTC6 cells in some batteries, and I believe these Sony cells to be quality cells. However, I've found this post on Reddit which indicates that Ryobi started switching from Japanese cells to Chinese cells in 2020 or possibly as early as late 2019. The article offers detailed information on which cells are in which of the newest Ryobi battery models. I cannot confirm or deny the information reported on Reddit, though I suspect it to be credible. The Reddit posting indicates that the newer cells are from Chinese manufactureres EVE energy and TenPower. I have no experience with the cells from these companies. The EVE website lists two "Power Cell" models in the 18650 size: ICR18650/15P = 3.6v, 1.5Ah, 30A discharge; ICR18650/20P = 3.6v, 2.0Ah, 20A discharge. The TenPower website also indicates two 18650 cells: 15SG = 3.6v, 1.5Ah, 30A discharge; 20SG = 3.6v, 2.0Ah, 30A discharge. One takeaway from the Reddit article is that Ryobi's HIGH PERFORMANCE batteries (PBP003/2Ah, PBP004/4Ah, PBP007/6Ah) contain Japanese Sony VTC6 cells whereas Ryobi's "standard" line of batteries contain Chinese EVE or TenPower cells (PBP002/1.5Ah, PBP005/4Ah, PBP006/2Ah). Also let's not forget that the P195 3A battery is the only 18v battery to contains 21700 cells, and these are apparently Samsung 30T cells.

Do the serial numbers mean anything?

Yes! All Ryobi batteries (and tools) are stamped with a date code, and newer batteries have a serial number. The date code indicates when the battery was manufactured. The first two digits are the year and the second two are the week of manufacture. Some batteries may have one or two letters before the four numbers, not sure what they mean but my guess is the site of the factory.

Examples:
0903 = "09" for 2009 and "03" for week 3
G0734 = 2007, week 34
CS0850 = 2008, week 50
CS12374N420709 = 2012, week 37 = Sep 2012


In 2012 Ryobi started printing a 2D barcode on each label which is encoded with the manufacturer part #, serial number, and model #. Here's an example: "130429231|CS18173N410796|P102". The barcode indicates manufacturer part # 130429231, serial # CS18173N410796, model # P102. The "CS1817" in the serial # indicates that this battery was manufactured in the 17th week of 2018, or between 23-Apr-2018 and 29-Apr-2018.

I want to buy NEW batteries, but everything in the store is at least 3 months old! What's up with that?

It's perfectly normal to visit The Home Depot, check date codes, and find that everything on the shelves was manufactured several months ago. Why? Let's not forget that Ryobi tools are manufactured in China. They're sent to the USA via boat, whose transit time can be a couple of months. While I have no knowledge of the actual process, I might expect additional delays. For example, the Ryobi factory probably manufactures a tool or kit in a "run" which lasts for several weeks. The items manufactured in the first week(s) may sit around until enough product has been produced to make a full shipment. Additional delays are likely at the shipping ports in China and in the USA, and of course some time is required for distribution. Tools manufactured for a special event sale (Memorial Day, Father's Day, Black Friday) may be held a little longer so they appear on shelves on the day that these sales begin. Without making a heroic effort, I doubt that new Ryobi tools can reach the shelves of The Home Depot in less than 2 months from the date of manufacture. Based on my personal observations I'd say that 3 months (or more) is typical for the factory-to-shelf process.

Hey! I just bought some new batteries and the date code says they're 9 months old! Is that a problem?

Not necessarily. These batteries are designed to sit on the shelf for months before sale. I have no hard data to support this, but I suspect that "new" batteries up to a year old or more are still 100% fine. Even still, when I go to The Home Depot I always check the serial numbers printed on the tool package before I buy (especially if the package contains batteries) and I'll always select the newest ones. Ryobi ships all batteries with a low charge, and all batteries self-discharge over time. When the voltage on Lithium Ion cells gets too low the cell begins to deteriorate. This phenomena doesn't really occur to NiCad batteries. NiCad packs are very resistant to problems when sitting on the shelf with a low charge for a long time. NiCad packs that are 18 months old or older may test lower than expected on the first cycle, but after 3-4 cycles they should recover back to like-new performance. Lithium Ion packs DO NOT like to sit idle on the shelf with a low charge for a long time! After 9 months or more on the shelf in the store or warehouse the deterioration of Lithium Ion cells can begin. That's why I would avoid purchasing a Lithium Ion battery that's more than 9 months old.

Update 13-Apr-2010: Beware of new old stock P104 batteries! I've found that "new" P104 batteries taken from old kits (more than a year old) are often dead or operate at a greatly reduced capacity. I recommend avoiding the purchase of kits containing P104 batteries that are more than a year old. Batteries with a date code between and including 0821 to 0832 have had an especially high DOA rate. If you do purchase new old stock P104s, test them immediately using the "flashlight test" or other means to ensure that they are operating properly. Exchange or return the batteries if they're not OK!

Update 12-Jul-2010:
Last week I received some CS1018 batteries (1st week of May, 2010?), These are the most recent date codes I've seen. The behavior of the built-in tester has now changed a bit. Ryobi has now built a 2-3 second delay into the formerly momentary check-while-you-hold-the-button device. So press the button for just a moment and it stays lit for 2-3 seconds for you to read it. Not a big deal, but it's clear that Ryobi are continually changing their products.

The batteries in my new kit take a charge. Should I assume that they're all OK?

Absolutely not! The kit may have been new, and the batteries may take a charge, but that DOES NOT MEAN that your batteries are working as they should. I have purchased literally hundreds of Ryobi kits containing batteries, and I can tell you from experience that "New" does NOT necessarily mean that the batteries are in good working order, even if they take a charge! ALWAYS test your batteries soon after you open your kit! The sooner you test them, the greater the chance that you will be allowed to return/exchange your kit should you find a problem.

The easiest way to test your batteries is to fully charge them, then fully discharge them at a controlled, slow rate. A battery's capacity can be estimated from the length of time that it takes to discharge. The "Flashlight Test" is easy and accurate:


 A battery's capacity in mAh is 10x a flashlight's run time in minutes. 



(See the Battery Rebuilds, etc. page for a more detailed description of how to do this. Note that this applies to the older flashlights with an INCANDESCENT bulb!)

I've found that the P104 is the battery most likely to have problems. This is especially true if the kit is more than 9 months old. It's unusual to find a bad P103 at all, and downright rare to find a bad P103 or P104 in a kit that's less than 6 months old (though it does happen). I would immediately return a Lithium Ion pack that tests below 80% capacity of its first charge. (At HD it's far easier to exchange a whole kit than it is to get a single battery from a kit exchanged, which is why I test batteries FIRST, remove the tools only after the batteries have tested good.)

If you buy a kit containing P104 batteries that's more than a year old, you should expect problems. Period. When you open the kit I suspect that the batteries may or may not take a charge. If they do, I'd expect their capacity to test below 50%. I know that Ryobi discounts discontinued tool kits when they're about a year old, and I suspect that Ryobi (and other makers who do the same) count on consumers not realizing that the batteries are no longer good. Let's face it, if the battery takes a charge and comes from a "new" kit, then the average consumer will think that it must be good, right? Wrong. I further suspect that some of the negative reviews given by first-time buyers of cordless tools who mention poor battery life and performance are actually consumers who purchased a kit containing bad batteries, and because they have no "new" reference packs to compare against they don't realize that this is what has happened.

As above, kits over a year old containing P103 batteries are also likely to have batteries which can no longer operate at full capacity. Case in point: I recently purchased two P542 chainsaw kits, each containing a P103 battery that was 70 weeks old. The batteries would not test over 900mAh even after several cycles. Otherwise they were fine. These old stock batteries will never operate above 70% of their rated capacity. An uninformed consumer who purchases such a kit may simply think that this is the best a P103 can do.

The story with NiCad batteries is not the same as with Lithium Ions. New old stock NiCad packs seem to show a diminished power at first, but recover well after a few cycles. For example, I received two new old stock P100s recently that were 86 weeks old(!!). After the first charge they tested just under 1000mAh, but the discharge curves did not contain the telltale stairstep of bad cells. So I cycled them and retested, getting about 1200mAh the second time. I decide to go once more and got about 1360mAh. A few more cycles and they'll be fine.

Is there a "Quick Check" I can do in-store to see if the batteries in an old, discounted kit are still OK?

Maybe, and this would work only for Lithium Ion batteries (not P100). Open the kit and press the battery tester on each battery. If it lights up to any color at all, the pack is probably OK. Carry a P150 Fuel Gauge with you into The Home Depot and use it to test batteries without a fuel gauge (e.g., P102, P103, P105, etc.).

Why would this be an adequate "Quick Check"? I have a theory that I haven't quite proved yet, but well here goes. We know that the irreparable damage occurs to Lithium Ion cells only after the cell voltage has self-discharged below a certain threshold. And we know that the pack's self-protection circuit kicks in and disconnects the cells before the cells have discharged below this lower threshold voltage. So my theory is that if a pack can light up a battery tester, then the cells must not have discharged below the lower threshold yet, and must therefore still be "good". The pack could still be faulty (e.g., one cell has died while the others are OK enough to light the tester, or bad circuit board). But if the tester won't light up at all, the pack almost assuredly has problems and you should either pass up on the deal altogether or be prepared to return later with the faulty battery for an exchange.

How should I store my batteries when they're not in use?

This is the subject of much debate. I offer my opinions below based on my understanding and experience. YMMV

All Batteries
Keep them plugged into an IntelliPort Charger all the time, such as the P114, P115, P116, P117, or P126 SuperCharger. The IntelliPort Chargers are designed to keep batteries at a full charge without ever overcharging. If you don't have an IntelliPort charger, or (like me) have more batteries than chargers, then read on. DO NOT leave your battery connected to a charger while the charger is unplugged -- when unplugged the charger will actually discharge and potentially damage a battery pack.

It's also VERY important to keep your charger inside the house and NOT in the garage. This is because the charger will refuse to charge the battery if the ambient temperature is too high or too low. When the temperature is too high or too low, the charger's IntelliPort feature won't work and the charger can actually drain a battery that's plugged into it (possibly killing it) rather than maintain it. If you must keep your charger in the garage, then be certain to unplug your batteries once it's fully charged and set them aside. Ryobi manuals indicate that ambient temperatures must be between 50 and 100 degrees Fahrenheit for proper operation, and most garages will go outside of this range at some time during the year. (Note: I keep a P125 SuperCharger in my garage, and I use it year 'round. But I don't leave batteries plugged into it for long after they've reached a full charge.)

NiCads (P100):
NiCad batteries will degrade in performance if left idle for a long time with a charge on them. That's because dendrites form across the plates when in the presence of a charge. These dendrites are like little jumper wires that short out a cell. This phenomenon is often observed as "memory effect". One can usually "burn off" an accumulation of dendrites by putting a huge charge across the plates of a cell. Some folks advocate momentarily connecting a pack to a large voltage source to burn off dendrites. This does work, but also decreases the overall capacity of each cell each time it's done because it also leaves holes in the plate surface area (where each dendrite had been located) and cell capacity is a function of the total surface area of the cell. To avoid a buildup of dendrites, once can completely drain a NiCad cell and then short it out and store it in a cool, dry place to prevent a charge buildup. This works. Unfortunately this applies to the storage of single cells and does not translate well into the storage of a multi-cell pack such as the P100. In a multi-cell pack it's very difficult to ensure that every cell in the pack has been completely discharged, and simply discharging a pack is sure to result in the "reversing" of several cells as the pack's overall charge reaches zero. Cell reversing is generally more harmful than dendrites, so avoid this if possible. What does this mean for NiCad battery storage? Unfortunately not much, but I thought I mention it all so folks could get an understanding of what's going on in a NiCad pack like the P100.

The best advice I can give on NiCad pack storage would be to fully charge them before putting them away for storage. Then store them in a cool (55F to 75F) and dry place. I would further recommend that you discharge then recharge them ONCE PER MONTH. Mark your calendar if you need to. An idle pack will develop dendrites over time, so the best way to avoid this is to USE THEM periodically. I recommend using a flashlight, just plug the battery in and leave it on until the battery is depleted, then charge the battery and put it back into storage. It's a pain, but NiCads really don't like to be left alone for extended periods of time.

Lithium Ions (P102, P103, P104, P105, P107, P108, P189, P190, P191, etc.):
Lithium Ion packs degrade in performance when the charge on a cells goes out of the service range. This range is about 2.8 volts to 4.2 volts. Ryobi packs have five cells (P103) or five pairs of cells (P104) in series, for a safe voltage range of 14v to 21v. Sitting idle, packs can only discharge (slowly) so the best way to store these packs is to give them a full charge before storage. If left with a full charge, it should take more than a year before a Lithium pack will self-discharge enough to drop below 2.8v on a cell! I'd still recommend topping off the charge on an idle pack periodically (once every 6-12 months?) but there's no need to discharge them first like with the NiCads.

Update 02-Jun-2013:
I've changed my opinion somewhat on how to use and store Lithium Ion batteries, based on the results of studies carried out by Battery University. Of the various results, one can see that the number of cycles a battery can deliver can be increased significantly by not fully charging or discharging the cells, and by not storing the cells at extreme temperatures. I'm talking 2x, 3x, 4x or more times as many cycles per battery! Battery University reports that for maximum longevity, batteries in long-term storage should be kept at a 40% charge. This is difficult to achieve with the available tools, since a Ryobi charger will bring a pack to 100% charge. The older chargers will trickle charge packs when they reach a full charge, keeping them at 100% charge continuously and which will decrease the pack's recoverable capacity (by 20%/year?). But an IntelliPort charger stops charging when a pack reaches a full charge, allowing the pack to self-discharge a bit. After a period of time the charger "wakes up", checks the battery, and tops it off. This behavior is actually quite beneficial to the longevity of the battery. But it still keeps packs near a full charge, which is not ideal.

If you're really serious about the longevity of your Lithium Ion batteries, then you should actively monitor your use of them. Try to avoid fully charging and discharging them. If you have a battery with a meter (or a P150 pocket meter), try to stop using your battery when you're down the last bar. And don't allow the battery to reach a full charge -- pull it off the charger when the fourth bar gets illuminated. Finally, avoid exposing your battery to extreme temperatures. Keep your batteries stored in your house, not in your vehicle or in the garage (which can get very hot or very cold).

Of course, for many of us the advice in the preceding paragraph will be very difficult to follow. To simplify: swap the battery you're using more often to avoid fully discharging any of them, get an IntelliPort charger or quickly remove your batteries from older chargers once the charge is complete, and always try to keep your batteries in the house (even if you keep the rest of your tools in the truck or garage).

Which battery pack do you recommend?

First of all, I recommend having two or more packs and a one hour charger if you're doing anything that drains a pack before you're done with the job. Then you can swap packs, put the drained pack on the charger, and get back to work.

I find that I usually reach for a compact battery when I want to use a flashlight, radio, or a drill for a quick job. I use a full-height battery with the reciprocating saw, canister vac, and yard tools. If you'll have just one or two batteries, get the best deal you can on full-height Lithium Ion batteries. The full-height batteries contain two strings of cells and will deliver a better bang-for-the-buck than compact batteries which contain a single string of cells. Most homeowners will not benefit from paying extra for "better" batteries, but read the discussion below for details.

Unfortunately, purchasing a single battery is typically the most expensive option. One can generally get a better deal on batteries by purchasing a tool kit which includes one or more batteries (plus tools). Ryobi places different tool kits on sale regularly, and Ryobi sales often include a 2-for-1 deal on 4Ah batteries or a deal where one purchases a battery kit and receives one "free" bare tool.

PBP007 6Ah HIGH PERFORMANCE Battery
In the Spring of 2022 I purchased a couple of PBP007 batteries on sale for $139 and I'm very pleased with them. These full-height 6Ah batteries are the same physical size and weigh about the same as 4Ah batteries but have 50% more available energy. (The PBP007 at 765g/27.0oz is 6.25%/45g/1.8oz heavier than the lightest of the 4Ah batteries, the P108 at 720g/25.2oz). Sure, the 9Ah P194 batteries have even more energy per pack, but the P194 are much larger and much heavier. (The P194 at 1190g/42.0oz is 65%/470g/16.8oz heavier than the 4Ah P108 and 56%/425g/15.0oz heavier than the 6Ah PBP007.) The larger size of the P194 makes it more difficult to reach around the back of one with one hand to press both clips and release from a tool. The PBP007 is easily my favorite 18v battery, and as of this writing they're on sale two for $119 -- that's $10/Ah or $0.55/Wh.

I've made the switch to Lithium Ion. Any reason to keep using NiCads?

This question/answer is quite old. Ryobi NiCad batteries have been discontinued for more than a decade now. If you still have and use a genuine Ryobi NiCad battery (like the P100) it's hard to imagine that it has much life remaining. It's probably time to replace it. My original response was:

Well, there's no reason to throw out good batteries, period. But actually, yes, there might be some very good reasons to continue using NiCads. If you work in a very cold environment, NiCads might be a better choice than Lithium Ions because you can recharge them when cold. Lithium Ions will not take a charge if too cold. If you need to push your tools to the limit with maximum torque, then NiCads may be the best choice for you. That's right, if you need every bit of torque from your drill as it slowly crawls that spade bit through wet lumber, NiCads are for you. Why? It's because the Lithium Ions contain an internal protection circuit that cuts them off when pushed to the limit like this. NiCads do NOT have such a circuit, so you can push them as hard as you need to.

Should I pay extra for "better" batteries?

As described above, Ryobi sells (or has sold) numerous models of 18v Lithium Ion batteries. The "standard" models are described as "Lithium", and these are typically the least expensive per capacity. The "better" batteries are described as "Lithium+", "Lithium+ HP", and "Lithium HIGH PERFORMANCE", and these typically are more expensive than the "Lithium" batteries at the same capacity. So should I spend more to get the "better" batteries? That all depends on what you'll be doing and what tool(s) you'll be using.

The "better" batteries boast better performance at lower temperatures. So if you work in below-freezing temperatures, then getting "better" batteries might be beneficial.

The "better" batteries can be beneficial to tools which demand high current, and especially to those which require short burst of power. Think saws, drills, and impact wrenches. Tools which have the two additional contacts in the battery stem are designed to take advantage of the "better" batteries which have the matching contacts on the back side of the battery stem (see contacts #6 and #7 as described earlier).

I suspect that most homeowners do not have a need for the "better" batteries. Even if the "better" batteries mean better performance, does a typical homeowner need that? I mean, let's say that a homeowner needs to make some cuts with a saw and that each cut can be made using a "regular" battery in 60 seconds. Let's also suppose that using the "regular" battery the saw stalls twice during each cut, and that the battery will be depleted after 20 cuts. Perhaps a "better" battery of the same capacity can make the same cut in 40 seconds without stalling and 25% more cuts can be made (this is a guess). A homeowner may need to make only ten such cuts, and if so then either battery will last for the entire job and the "better" battery would save (10 cuts)(20 sec/cut) = about 3 minutes on the total job. This is probably not a big deal for the homeowner, but this could become substantial over time for someone who is cutting all day long.

Some tools require a relatively high current but don't require bursts of energy. Think about leaf blowers. These tools draw a high current to reach operating speed. Then the need for current decreases as the tool must simply maintain that operating speed. A saw or drill might bog down when the blade or bit encounters additional friction (e.g., a knot or damper section of the wood) thus increasing the current demand to maintain operating speed. But the amount of friction a leaf blower encounters doesn't typically change much once operating speed has been reached. Therefore the performance benefit of "better" batteries is likely minimal for a leaf blower. For a leaf blower, a larger capacity battery would probably be a better investment. If you simply want to extend the run time of your leaf blower, I'd suggest investing in a larger standard "Lithium" battery and don't pay extra for a "better" battery. However, it would be reasonable to consider the cost per Ah in your decision making process. (BTW, yes, technically friction can increase for a leaf blower due to conditions such as a blocked intake/output or use of the "turbo" mode.)

For example, say your leaf blower operates for 11 minutes when powered by your 2Ah compact "Lithium" battery, and you need to increase your run time to at least 30 minutes to meet your need. You find that you could buy (A) one 4Ah "Lithium" battery for $79, (B) one 9Ah "Lithium+ HP" battery for $139, or (C) two 4Ah "Lithium+ HIGH PERFORMANCE" batteries for $159. Your tool is a leaf blower so you shouldn't really care whether your batteries are "Lithium", "Lithium+ HP", or "Lithium+ HIGH PERFORMANCE". Let's consider the cost per Ah. Option (A) is $79/(4Ah x 1) = $19.75/Ah. Option (B) is $159/(9Ah x 1) = $17.67/Ah. Option (C) is $169/(4Ah x 2) = $21.13/Ah. The best price per Ah in this example is the single 9Ah battery. You could reasonably expect that your run time would increase from 11 minutes to (9Ah/2Ah * 11 min) = 49.5 minutes. Of course, the 4Ah battery would require the least total investment, and with this battery you could expect your run time to double to 22 minutes. So your original 2Ah battery plus a new 4Ah battery should mean a total run time of 33 minutes, which exceeds your desired goal of 30 minutes. Don't forget that Ryobi tools regularly go on sale, so if you don't need the new battery right now you might want to wait and monitor the sales ads. A 2-pack of "Lithium" 4Ah batteries can typically be found on sale for $99 or less several times per year (YMMV). I've read online discussions where posters have indicated that it's a good time to buy when the price point reaches "$10/Ah" or less (e.g., two 4Ah batteries for $79 would be $79/(4Ahx2)= $9.88/Ah).

I don't measure 18 volts across my Ryobi 18v battery terminal. What's up with that?

One could measure the voltage of older Ryobi 18v batteries by placing a voltmeter across the output terminals. This gave an indication of the battery's charge level, much like the P150 Fuel Gauge.

But in 2012 and starting with the P107 and P108 batteries (marketed as "Lithium+") this was no longer true. On all current Ryobi 18v battteries, the voltage at the terminals remains low until a load is detected. When used with most tools, you'll never notice the difference. But if you use a radio or other extremely low current drain tool (e.g., a radio) you may find that the tool doesn't come on when you press the power button. The quick fix is to press the battery's power level meter first, which briefly "wakes up" the battery.

I've found that with my new PBP007 6Ah batteries I can use a voltmeter without having to press the power level meter, so it appears that Ryobi does periodically change their internal board designs.

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Last revised 10-Aug-2022
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