toolboy's Corner: Ryobi 40v Batteries



Several years ago Ryobi introduced a 40v line of batteries and tools. Similar to their 18v line of batteries and tools, all of the these batteries and tools are interchangeable. Or at least that seems to have been the idea. In reality this isn't 100% true -- certain 40v batteries actually CANNOT be used with certain 40v tools, and this will be discussed later.

Model Appearance Weight (measured) Ah/Wh Rating # Cells / Cell Configuration Features Comments
OP4015, OP4015A ?? oz / ???g (measured) 1.5Ah / 54 Wh Ten 18650 1.5Ah cells / 10S1P SMALLER than other batteries because it uses just TEN cells!
OP40201 ?? oz / ???g (measured) 2.0Ah / 72 Wh Ten 18650 2.0Ah cells / 10S1P SMALLER than other batteries because it uses just TEN cells!
OP4026, OP40261 ?? oz / ???g (measured) 2.6Ah / 94 Wh Twenty 18650 1.3Ah cells / 10S2P  
OP4030, OP40301 ?? oz / ???g (measured) 3.0Ah / 108 Wh Twenty 18650 1.5Ah cells / 10S2P  
OP4040, OP40401 ?? oz / ???g (measured) 4.0Ah / 144 Wh Twenty 18650 2.0Ah cells / 10S2P  
OP4050, OP40501 ?? oz / ???g (measured) 5.0Ah / 180 Wh Twenty 18650 2.5Ah cells / 10S2P  
OP40601 ?? oz / ???g (measured) 6.0Ah / 216 Wh Twenty 18650 3.0Ah cells / 10S2P  
OP40602 ?? oz / ???g (measured) 6.0Ah / 216 Wh Thirty 18650 2.0Ah cells / 10S3P LARGER than other batteries because it uses THIRTY cells!
OP40752 ?? oz / ???g (measured) 7.5Ah / 270 Wh Thirty 18650 2.5Ah cells / 10S3P LARGER than other batteries because it uses THIRTY cells!
OP40902 (no image) ?? oz / ???g (measured) 9.0Ah / 324 Wh ??? Not released (yet), but mentioned in the manual!
OP40122 (no image) ?? oz / ???g (measured) 12.0Ah / 432 Wh ??? Not released (yet), but mentioned in the manual!


Are Ryobi's 40v batteries really 40v?

If you're familiar with Ryobi's ONE+ line of 18v tools, you might know that the 18v Li-Ion batteries contain five 18650 cells in series. Each 18650 cell has a nominal voltage rating of 3.6v, so five in series yields 5x3.6v= 18v. The claimed 40v can't be divided equally with 3.6v cells, so something is awry. It seems far more likely that Ryobi simply doubled the number of cells from their 18v batteries, or ten cells in series. That would mean the 40v batteries are really 10x3.6v = 36v. I've disassembled several 40v batteries and I can confirm that they contain ten cells in series (or parallel strings of ten cells) so yes, they're really 36v batteries.

Why would Ryobi call these 40v batteries instead of 36v batteries?

I'm suspect this was a marketing decision, and that Ryobi execs believed that "40v" would sell better than "36v". To be clear, calling these batteries and tools "40v" is not technically wrong. The cells inside have an operating voltage range of about 2.7v-4.2v, and ten are placed in series, so the operating voltage range of the battery is 27v-42v. IMHO calling these batteries 36v would be the "most correct" choice, but technically any value in the range of 27v-42 could be considered correct.

Many manufacturers do or have done this sort of thing. Part of the reason for this may have to do with cell chemistries. At one time the most popular cell chemistries were Nickel Cadmium (NiCD) or Nickel Metal Hydride (NiMH). The nominal cell voltage for these chemistries is 1.2v, so battery pack voltages had to be a multiple of 1.2v Popular tool lines used batteries rated 9.6v, 12v, 14.4v, 18v, 19.2v, etc. When manufacturers started using Li-Ion cells (nominal cell voltage 3.6v) the voltages didn't always align well. The 18v lines were fine, as 15 1.2v NiCD Sub-C cells have the same nominal voltage as five 3.6v 18650 Li-Ion cells. But the 19.2v batteries which used 16 1.2v NiCD cells couldn't be achieved directly with Li-Ion cells, so manufacturers used five 3.6v 18650 cells (18v) and called the batteries 19.2v anyways.

The newer Lithium Polymer (LiPO) cells have a nominal voltage of 3.2v, so if/when these get integrated into existing tool lines manufacturers will have to decide how to do their rounding. For a 40v battery that's 40v/3.2v = 12.5 cells, or for 36v that's 11.25 cells. I bet they'll choose 12 cells so the actual nominal voltage will be 38.4v.

The appearance of Ryobi 40v batteries has changed over time

The appearance of the same capacity Ryobi 40v batteries may be slightly different depending on when they was manufactured. The earlier revisions of Ryobi 40v batteries typically lacked a prominent indication of the battery capacity on the label. For some 40v batteries the labeling can be seen as "upright" when the battery's contacts are on top, and for others the label is upright when the contacts are on bottom. For a short while some 40v batteries were given labels which were more white (or silver?) than the typical neon green. Here are examples of different styles for the same battery models:
Ryobi OP4026
2.6Ah

No prominent AH rating

Big Ah rating on label
Ryobi OP40401
4.0Ah

Upright w/contacts down

Upright w/contacts up
Ryobi OP4050
5.0Ah

Green style

White style


Which 40v batteries are compatible with my 40v tools and chargers?

Broadly speaking, all 40v batteries are compatible with all 40v tools and chargers. However, some of the newest "tall" batteries may not physically fit in certain older tools. Also, I've found that the OP406A rapid charger simply won't charge certain older, lower capacity batteries.

The most recent of Ryobi's 40v batteries are taller than previous models, probably because they contain THIRTY cells whereas the older batteries contained only TWENTY. As a result, these batteries will not fit any tool which was molded to fit completely around the back of the 40v battery. "Tall" batteries such as the 7.5Ah OP40752 and the 6.0Ah OP40602 will not fit into these tools: Humorously, the ad for the 7.5Ah battery on The Home Depot's website includes a generic video which pitches the 40v system and which depicts two tools which are incompatible with the 7.5Ah battery due to the battery's extended height! Look carefully at the video for the mower at about 0:05 and the chainsaw around 0:20.

I do own a Ryobi OP406A Rapid Charger and batteries with capacities ranging from 2.6Ah to 6.0Ah. I've found that the OP406A simply refuses to charge the 2.6Ah batteries, but YMMV. This is fine by me, because IMHO the charge rate of the OP406A charger is so high that IMHO it shouldn't be used with batteries smaller than 6.0Ah anyways.

Do the serial numbers mean anything?

Yes! All Ryobi 40v batteries (and tools) are stamped with a serial number which includes a date code. The date code indicates when the battery was manufactured. The serial number begins with two letters which I presume identify the factory. The next four digits are the year and week of manufacture, respectively.

Examples:
EU20026N080123 = "20" for 2020 and "02" for week 2
EU18304D230001 = 2018, week 30 = July, 2018

All Ryobi 40v batteries and tools have a 2D barcode on the label which is encoded with the manufacturer part #, serial number, and model #. Here's an example: "130302037DG9|EU20026N080123|OP40601". This barcode indicates manufacturer part # 130302037DG9, serial # EU20026N080123, model # OP40601. The "EU2002" in the serial # indicates that this battery was manufactured in the 2nd week of 2020, or between 06-Jan-2020 and 12-Jan-2020.

Please view the 18bv batteries page for good information on Li-Ion battery purchase selection and storage as this information is also relevant to Ryobi's 40v batteries.

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Last revised 05-Feb-2021
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