toolboy's Corner: Ryobi 18v Charger Testing #2

This page represents additional testing performed on Ryobi chargers. I'm hoping to determine a predictable way to predict the length of time required to recharge a given fully discharged Ryobi battery on a given Ryobi charger. Testing with a P102 battery on various Ryobi chargers suggests that we must first know the ACTUAL capacity of a given battery, not just the rated capacity, in order to give a close estimate. Without knowing the ACTUAL capacity of a battery we can only estimate the maximum amount of time required, which may be significantly longer than the actual time needed.

I'll concentrate on testing with the more popular battery sizes and charger models. I'm thinking the 4Ah P108, 3Ah P191, 6Ah P192, and the 9Ah P194 batteries and the P117 and P118B chargers will be of the most interest. But I'll I may extend the testing to other combinations of batteries and chargers as time permits. Given the length of time needed to perform each test, I'll strive to perform one or two tests per day and update this page with results as I go.

4Ah P108 Battery

I have a P108 battery available for testing whose date code begins with CS1835, meaning that it was manufactured in the 35th week of 2018. It's currently the 52nd week of 2019, so the age of this battery is 69 weeks, or about 1 year and 4 months old. I'll begin by charging on a P117 then measuring capacity on my CBA and repeating until consecutive capacity readings are within 3%. In so doing, I've noticed that my datalogger indicates that about 3% more energy is dumped into the battery pack while charging than is measured as available by the CBA. For example, on one cycle the datalogger measures 3,868mA "Current In" and 3,750mA "Current Out", a difference of 3.15%. I did expect some loss due to heat and other factors, but for some reason I expected a greater loss than 3%. Here is the final charge cycle:

4Ah P108 Battery on Ryobi P117 Charger

Charger	P117 (85W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	1:26:05 (5,165 sec)
Current In	3.801A
Average charge rate	A
Measured Capacity	3.708Ah / 66.7Wh

4Ah P108 Battery on Ryobi P117 "30 Minute Charger"

The "30 Minute Charger" claim is just a cruel joke when charging a 4Ah/72Wh P108 battery. The charger is rated for 85W input. So if we use a P117 to completely recharge a fully depleted P108 battery whose ACTUAL capacity was the same at its rated capacity, and this charger was capable of charging this battery with 100% efficiency (hah!) the time required would be 72Wh/85W = 0.85 hours or 50:49. From previous experiences with this I know the actual time needed will be closer 1.5 hrs. For this charge cycle I used my modified datalogger with the 10x current readings. Here's how the charging went with our P108 whose ACTUAL capacity has been measured at 3.708Ah / 66.7Wh / 92.7% of rated capacity:

4Ah P108 Battery on Ryobi P117 Charger

Charger	P117 (85W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	1:25:31 (5,131 sec)
Current In	3.974A
Average charge rate	A
Measured Capacity	Ah / Wh

I made additional notes during the charge cycle to compare the datalogger's current readings with my multimeter. Here is what I recorded:

Clock Time (hh:mm)	Current / Datalogger (Amps x10)	Current / Multimeter (Amps)	Voltage / Datalogger (Volts)
10:38	30.2	2.909	17.44
10:41	30.4	2.918	17.76
10:52	30.5	2.932	18.23
11:21	30.7	2.944	18.99
11:34	30.7	2.946	19.62
11:40	30.7	2.947	20.00

The readings above show a consistent difference in current measurements between the modded datalogger and multimeter of 0.12A. So to create the graph above I not only divided all current readings by ten, but I subtracted that 0.12A. The total charge time was 01:25:31 and the Current In was 3.9743A.

4Ah P108 Battery on Ryobi P118B Charger

Charger	P118B (60W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	02:05:17 (7,517 sec)
Current In	4.0104A
Average charge rate	1.856A
Measured Capacity	3.734Ah / 66.55Wh

I monitored the current out on the multimeter vs the datalogger and, aside from the regular dips, the datalogger measured 20.5A and the multimeter measured 1.974 during the entire CC phase.

Calibrated Datalogger

Well I'll be! I discovered that it's possible to calibrate my datalogger! I've just calibrated the modified probe to match the current readings on my multimeter (though current is still 10X), so moving forward I shouldn't need to adjust the graphs with an offset, the division by 10 will do.

I also made another interesting observation while performing the calibration. I happened to be charging a battery which was nearly at a full charge, so the P117 charger I was using was in the CV mode. What I happened to observe was that the charge current was not decreasing smoothly, it was actually moving in steps! This can be seen in the graphs, but I had been thinking that the steps were an artifact of the resolution of the probe (and perhaps that was at least partially true with the original probe). But with the modded probe and especially while looking at my multimeter I could see that during the CV phase the charge current drops by about 50mA at a time, holds for a while, then drops by another 50mA. I'll try to catch the end of a future cycle so I can monitor exactly how the cycle ends with the multimeter.

4Ah P108 Battery on Ryobi P118 Charger

Charger	P118 (50W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	02:14:11 (8,051 sec)
Current In	3.8474A
Average charge rate	1.734A
Measured Capacity	Ah / Wh

I watched carefully as the charge cycle came to an end and compared the current readings on the datalogger with the multimeter. The multimeter has one more digit of precision than the datalogger, but when rounded the multimeter and the datalogger matched spot on.

4Ah P108 Battery on Ryobi P119 Trickle Charger

Charger	P119 (7W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	18:10:53 (65,453 sec)
Current In	4.1422A
Average charge rate	0.223A
Measured Capacity	3.618Ah / 64.28Wh

The spikes occurred almost exactly on the hour every hour and lasted for about a second each.

4Ah P108 Battery on Ryobi P131 In-Vehicle Charger

Charger	P131 In-Vehicle (12v DC @ 6A)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	1:42:40 (6,160 sec)
Current In	3.8319A
Average charge rate	2.261A
Measured Capacity	3.707Ah / 66.37Wh

The label on the P131 lists the input as 12V DC at 6A and the output as 18V DC at 3A. I'm using the +12v rail of a 430W ATX power supply as the 12v DC power source as described on the original Charger Testing web page.

Based on a previous experience, I watched as the voltage approached 21v to see how the lights behaved. I also left the battery on the charger for an hour after the green light came on indicating a full charge. What I observed is that the green light came on steady when it was supposed to -- when the CV mode charging was complete. During that extra hour on the charger, the output remained at 0.0, exactly as it is supposed to. I have no idea why my first experience was so different, but this time the behavior was more like other CC/CV chargers.

The only oddity of this charge cycle is erratic charge current, as seen by the "wide" curve for current. The recorded data shows consecutive current readings which vary by as much as 60mA! And that's with a sampling rate of 4 points per second! Here's eight consecutive current readings from 92 to 93 seconds in: 2.44, 2.37, 2.47, 2.51, 2.51, 2.45, 2.45, 2.42. That's just plain bizarre.

4Ah P108 Battery on Ryobi P135 Charger

Charger	P135 (85W)
Battery	P108 (rated 4Ah / 72Wh)
Total Charge Time	1:34:18 (5,658 sec)
Current In	3.9022A
Average charge rate	2.506A
Measured Capacity	3.790Ah / 67.77Wh

6Ah P193 Battery

I have a P193 battery available for testing whose date code begins with CS1805, meaning that it was manufactured in the 5th week of 2018. It's currently the 1st week of 2020, so the age of this battery is 99 weeks, or about 1 year and 11 months old. As with the other batteries, I'll first determine the capacity by repeated charge/discharge cycles with a P117/CBA until consecutive CBA readings are within 3%. Here is the final charge cycle:

6Ah P193 Battery on Ryobi P117 "30 Minute" Charger

Charger	P117 (85W)
Battery	P193 (rated 6Ah / 108Wh)
Total Charge Time	2:13:52 ( sec)
Current In	5.6127A
Average charge rate	2.541A
Measured Capacity	5.282Ah / 94.09Wh

6Ah P193 Battery on Ryobi P118B Charger

Charger	P118B (60W)
Battery	P193 (rated 6Ah / 108Wh)
Total Charge Time	03:35:31 (12,931 sec)
Current In	5.6195A
Average charge rate	1.577A
Measured Capacity	5.414Ah / 97.14Wh

6Ah P193 Battery on Ryobi P118 Charger

Charger	P118 (50W)
Battery	P193 (rated 6Ah / 108Wh)
Total Charge Time	03:35:21 (12,921 sec)
Current In	5.6816A
Average charge rate	1.596A
Measured Capacity	5.238Ah / 93.46Wh

6Ah P193 Battery on Ryobi P135 Charger

Charger	P135 (85W)
Battery	P193 (rated 6Ah / 108Wh)
Total Charge Time	02:22:19 (8,539 sec)
Current In	5.5885A
Average charge rate	2.378A
Measured Capacity	5.419Ah / 97.43Wh

9Ah P194 Battery

The P194 I have selected for testing has a date code of CS1829, meaning that it was manufactured in the 29th week of 2018. The battery was therefore about 77 weeks old at the time of testing (1 year and 6 months).

One of the first things I noticed in the results is that the "mA Out" reading on my data probe must be stored as a 16-bit integer. That's my guess because this value ramps up to 65535 then goes to zero, where it stays for the remainder of the test. So to extrapolate this value I calculated the "next" value as the previous value + Amps/3600/4*10000. I compared derived values with recorded values for the 0-65535 range where the data probe has values, and found that the extrapolated values were very accurate, varying by no more than +/- 0.4mA for all 65K values. The total charge time was 3:17:53 and the extrapolated Current In was 8.7524A. The average charge current was 2.664A.

9Ah P194 Battery on Ryobi P118 Charger

Charger	P118 (50W)
Battery	P194 (rated 9Ah / 162Wh)
Total Charge Time	05:23:03 (19,383 sec)
Current In	8.7958A (extrapolated)
Average charge rate	1.640A
Measured Capacity	8.207Ah / 146.8Wh

9Ah P194 Battery on Ryobi P118B Charger

Charger	P118B (60W)
Battery	P194 (rated 9Ah / 162Wh)
Total Charge Time	04:50:46 (17,446 sec)
Current In	8.7544A (extrapolated)
Average charge rate	1.813A
Measured Capacity	8.426Ah / 151.4Wh

9Ah P194 Battery on Ryobi P135 Charger

Charger	P135 (85W)
Battery	P194 (rated 9Ah / 162Wh)
Total Charge Time	03:34:27 (12,867 sec)
Current In	8.7043A (extrapolated)
Average charge rate	2.459A
Measured Capacity	8.203Ah / 146.6Wh

9Ah P194 Battery on Ryobi P119 Trickle Charger

Charger	P119 (7W)
Battery	P194 (rated 9Ah / 162Wh)
Total Charge Time	43:58:47 (71,927 sec)
Current In	9.7536A (extrapolated)
Average charge rate	0.223A
Measured Capacity	8.407Ah / 150.58Wh

As with other large batteries, the P119 Trickle Charger was unable to start a charge cycle on the P194. I used a P117 for several seconds, until the datalogger indicated 10mA had been delivered into the battery. The P119 was still unable to start a charge cycle, so again I used the P117 to deliver another 10mA. The P119 was then able to start its charge cycle. As always with the P119, we see spikes occurring almost exactly on the hour every hour and lasting for about a second each. Yes, with a 44 hour charge cycle, we see 43 spikes.

9Ah P194 Battery on Ryobi P131 In-Vehicle Charger

Charger	P131 In-Vehicle (12v DC @ 6A)
Battery	P194 (rated 9Ah / 162Wh)
Total Charge Time	( sec)
Current In	A
Average charge rate	A
Measured Capacity	Ah / Wh

2Ah P190 Battery

The P190 battery I am using for testing has a date code indicating that it's 50 weeks old. Testing reveals that this battery has an ACTUAL capacity of 1.815Ah / 32.38 Wh.

2Ah P190 Battery on Ryobi P117 "30 Minute" Charger

Charger	P117 "30 Minute" Charger (85W)
Battery	P190 (rated 2Ah / 36Wh)
Total Charge Time	47:41 (2,861 sec)
Current In	A
Average charge rate	2.364A
Measured Capacity	1.840Ah / 33.02Wh

2Ah P190 Battery on Ryobi P118B Charger

Charger	P118B Charger (60W)
Battery	P190 (rated 2Ah / 36Wh)
Total Charge Time	1:10:47 (4,247 sec)
Current In	1.8822A
Average charge rate	1.609A
Measured Capacity	1.812Ah / 32.5Wh

At this point I decided to evaluate whether or not to continue testing this P190. It's performing reasonably well at over 90% rated capacity, but just look at the discharge curves:

The test equipment is configured to end the test when the voltage reaches 14v, which it did. However it's clear that the battery's internal self-protection cutoff circuit is set too high. The battery dis-engaged early at around 16.25V when it should have continued to at least 14v. I've done a quick analysis and I've concluded that when these batteries hit 16.25v they have less than 3-4% usable energy remaining. So technically this battery is faulty because all of its energy is not available for use. But the loss is small and it's doubtful that anyone would have noticed this fault without using a battery analyzer. Frankly, this battery is likely to outlive its non-faulty counterparts because it is less likely to be overly discharged. I'll continue with testing this battery.

2Ah P190 Battery on Ryobi P118 Charger

Charger	P118 Charger (50W)
Battery	P190 (rated 2Ah / 36Wh)
Total Charge Time	1:11:55 (4,306 sec)
Current In	1.8955A
Average charge rate	1.590A
Measured Capacity	1.841Ah / 32.46Wh

2Ah P190 Battery on Ryobi P119 Trickle Charger

Charger	P119 Trickle Charger (7W)
Battery	P190 (rated 2Ah / 36Wh)
Total Charge Time	08:46:31 (31,591 sec)
Current In	1.9908A
Average charge rate	0.221A
Measured Capacity	1.776Ah / 31.70Wh

3Ah P191 Battery

The P191 battery I am using for testing has a date code indicating that it's 31 weeks old. Testing reveals that this battery has an ACTUAL capacity of 2.875Ah / 51.99Wh.

3Ah P191 Battery on Ryobi P117 "30 Minute" Charger

Charger	P117 "30 Minute" Charger (85W)
Battery	P191 (rated 3Ah / 54Wh)
Total Charge Time	1:07:59 (4,079 sec)
Current In	2.9631A
Average charge rate	2.642A
Measured Capacity	2.905Ah / 52.79Wh

3Ah P191 Battery on Ryobi P118B Charger

Charger	P118B Charger (60W)
Battery	P191 (rated 3Ah / 54Wh)
Total Charge Time	1:45:13 (6,313 sec)
Current In	3.0057A
Average charge rate	1.729A
Measured Capacity	2.971Ah / 53.83Wh

3Ah P191 Battery on Ryobi P118 Charger

Charger	P118 Charger (50W)
Battery	P191 (rated 3Ah / 54Wh)
Total Charge Time	1:48:25 (6,505 sec)
Current In	3.0210A
Average charge rate	1.685A
Measured Capacity	2.916Ah / 52.97Wh

3Ah P191 Battery on Ryobi P119 Trickle Charger

Charger	P119 Trickle Charger (7W)
Battery	P191 (rated 3Ah / 54Wh)
Total Charge Time	15:17:47 (55,067 sec)
Current In	3.4854A
Average charge rate	0.221A
Measured Capacity	2.894Ah / 52.37Wh

2.6Ah P105 Battery

The P105 battery I am using for testing has a date code indicating that it's 35 weeks old. Testing reveals that this battery has an ACTUAL capacity of Ah / Wh.

2.6Ah P105 Battery on Ryobi P117 "30 Minute" Charger

Charger	P117 "30 Minute" Charger (85W)
Battery	P105 (rated 2.6Ah / 48Wh)
Total Charge Time	1:02:29 (3,749 sec)
Current In	2.4737A
Average charge rate	2.398A
Measured Capacity	2.438Ah / 43.55Wh

2.6Ah P105 Battery on Ryobi P118B Charger

Charger	P118B Charger (60W)
Battery	P105 (rated 2.6Ah / 48Wh)
Total Charge Time	1:34:04 (5,644 sec)
Current In	2.4724A
Average charge rate	1.590A
Measured Capacity	2.432Ah / 43.47Wh

2.6Ah P105 Battery on Ryobi P118 Charger

Charger	P118 Charger (50W)
Battery	P105 (rated 2.6Ah / 48Wh)
Total Charge Time	1:36:43 (5,803 sec)
Current In	2.4971A
Average charge rate	1.563A
Measured Capacity	2.458Ah / 44.00Wh

2.6Ah P105 Battery on Ryobi P119 Trickle Charger

Charger	P119 (7W)
Battery	P105 (rated 2.6Ah / 48Wh)
Total Charge Time	11:08:20 (40,100 sec)
Current In	2.560A
Average charge rate	0.224A
Measured Capacity	2.380Ah / 42.14Wh

1.5Ah P107 Battery

The only P107 battery I own is 246 weeks old (almost 5 years). Its ACTUAL capacity tests consistently at 1.02Ah, or 68% of its 1.5Ah rated capacity. I'll continue using it, but that performance level is not good enough to be representative of P107 performance.

1.3Ah P103 Battery

I own a couple of P103 batteries which are 598 weeks old (11.5 years), but I'm not sure why. I just tested these and one has an ACTUAL capacity of 0.12Ah (9% rated capacity) and the other's ACTUAL capacity is 0.734Ah (57% rated capacity). These would not be suitable to represent P103 performance.

It has occurred to me that it might be nice to provide a single graph of the charging time for a given battery on each of Ryobi's chargers. What I found was that if I overload all information on the same graph, the result was simply too busy to be useful. I made separate plots of just voltage vs Time and Amps vs. Time, but even these lack visual appeal. So I created a plot of Current In vs Time. I think we have a winner!

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Last revised 07-Apr-2022
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