toolboy's Corner: Ryobi 18v Lithium+ HP Technology

By now you've probably seen that Ryobi has released new batteries dubbed "LITHIUM+ HP Technology". These batteries come in 3Ah, 4Ah, 6Ah. and 9Ah sizes (Models P191, P192, P193 and P194, respectively). These new batteries sport additional contacts at the base and rear of the battery pack's stem. Ryobi calls this "HP Technology", and claims that "HP Technology communicates with brushless tools to maximize performance in all applications, allowing users to make faster cuts, drive larger screws, utilize bigger drill bits, and more." This is really two separate claims. The first claim is that "HP Technology communicates with brushless tools" and the second claim I'll condense into "Brushless tools work harder with HP Technology".

HP Technology "communicates with brushless tools"

Really? The technology "communicates" with brushless tools"? I find this claim highly suspect.

I can't help but wonder what sort of communication the battery will send to a brushless tool to make it work harder. Will it say "I'm a battery with HP Technology, so work harder now!" or will it say "HP Technology here. Let 'er rip!", or even "Release the Kraken!"? Maybe it will be more like a cheerleader: "Yay Ryobi!", "Gimme an R! Gimme a Y!...", or "Strawberry shortcake, huckleberry pie! Make my Ryobi drill drive, drive, drive!". Or perhaps the message will sound more like a foul-mouthed drill sergeant: "Make that cut faster, you maggot!".

I suppose my aversion to this claim really is with the term "communicates". When I think of digital communication, I think of discrete message(s) originating at a sending device and terminating at a receiving device. Historically this has been done by transitioning the signal voltage on a wire between "high" and "low" states. Two wires are required to send a digital signal -- one signal wire and one ground reference wire from which one measures the state (the signal voltage) on the signal wire. The receiver interprets these highs and lows into 1s and 0s and translate the sequence of digits into a message. The pace at which the transitions occur can be described as the baud rate, and when only two signal states are possible this is also known as the bit rate. A modulator/demodulator (MODEM) is at the heart of this type of communication.

When I see the exterior of the new Ryobi batteries with HP Technology, I see exactly two new contacts as compared with previous models. So the HP Technology must work entirely from these two contacts, and the "communication" must occur via these contacts. But there's really no message to send. The battery and tool will work as hard as the operator pushes them no matter what message(s) are communicated between the two.

What is far more likely is that those extra contacts on the Lithium+ HP batteries are additional paths to the positive and negative power outputs, just like those on the stem of the battery pack. So why would having two extra contacts matter? I believe the answer has everything to do with the losses associated with transmitting power over wires. It's a fact that when power is transferred through a wire, some of that power is lost during transmission. For direct currect (DC) power such as is the case here my guess is that the portion of the power loss which can be attributed to the resistance of the wire (e.g., conversion of energy into heat) is so large as to render all other sources of power loss negligible. If we know the voltage and current sourced by a battery and the length, gauge, and metallurgy of the transmission wires, we can calculate the power loss over the wires and the voltage drop at the far end of those wires. Several online tools are available to help with this.

I've not yet pulled apart a Ryobi battery with HP Technology, but I know that in a 4Ah model P108 battery the wires connecting the internal circuit board to the contacts in the step of the battery pack are about 4" long, 16 AWG, and they look like copper. If we assume that a Ryobi battery is delivering 18v, we can estimate the voltage drop for various tools. I've measured the current draw of a P3210 fan on LO at 0.2A, a P704 flashlight at 0.6A, a P716 spotlight at 2.4A, a P2108 leaf blower at 11.2A, and a P3150 heat gun at 14.5A. Using the voltage drop calculator at calculator.net, I calculate the voltage drop for these devices to be 0.00053v/fan, 0.0016v/flashlight, 0.0064v/spotlight, 0.03/leaf blower, and 0.39v/heat gun. So the heat gun is the tool with the highest current draw, and even when it's drawing 14.5A @ 18v the tool actually sees 17.961v @ 14.5A, a loss of 0.22%. (Calculator settings: wire material Copper, size 16 AWG, Voltage 18v, Phase DC, # conductors single set, distance .333 ft, load current as stated.) That's hardly anything -- certainly not enough to warrant spending the time to develop a way to safely deliver MORE energy.

So let's think of this in another way. How much current can these battery packs safely deliver? The cells inside these battery packs are rated by the manufacturer to safely sustain a discharge rate of 10C, or 10x each cell's Ah rating. The 3Ah P191 contains two strings of cells in parallel, so the cells must each be rated 1.5Ah. With a 10C discharge rate that's 15A per string x2 = 30A continuous. In a similar way, it can be seen that the maximum continuous current draw for the 4Ah P192 is 40A, for the 6Ah P193 it is 60A and it is 90A for the 9Ah P194. NOW we're starting to talk about some serious current. Back to the voltage drop calculator, I find that with a 90A draw at 18v the voltage drop is just 0.24v of a pair of 4" 16AWG copper wires, or a 1.34% loss. That's still not enough for concern. How long will the Ryobi battery be able to deliver this kind of current? At a discharge rate of 10C the run time will be 1/10 of an hour, or 6 minutes. (Actually the run time will be shorter than 6 minutes once Peukert's Law is considered.) But this analysis considers the amount of current which can be drawn *safely*, as per manufacturer specs.

Can the electric motors found in these hand tools actually draw 10C or more? I'm reminded of something I observed years ago. I had been using my P203 drill with a P103 battery to raise and lower the jacks located on the corners of my travel trailer. But one of the jacks had become slightly rusty and bent. The drill slowed down as the jack extended and raised the trailer, and it cut off abruptly before reaching the point where I wanted it to stop. I tried a different P103 battery and again the power cut. So I tried a P104 battery, and this time I had no trouble extending the jack to the point I wanted it to go. I used my Watts Up meter to measure the current draw and found that it exceeded the 50A scale when the P104 battery was used to finish the job. Based on the previous paragraph the 2.4Ah P104 battery should be able to safely deliver a continuous 24A, yet it was delivering over twice that in a short burst. The 1.3Ah P103 should be able to safely deliver a continuous 13A, and the internal circuit engaged to protect the cells sometime before 50A, or 4x the safe rating.

I haven't mentioned it until now, but a quick web search will reveal that tables exist which provide the maximum recommended current handling capacity for a given gauge of wire and intended purpose (called its ampacity). Looking at the table, I find that the maximum recommended ampacity for a 16 AWG wire is 22 Amps. Huh?!! We just determined that the cells in the 3Ah/4Ah/6Ah/9Ah HP battery packs are capable of safely delivering a continuous 30A/40A/60A/90A, respectively. These all exceed the safety rating for the 16 AWG wires inside the battery packs which connect the cells to the terminal places in the battery's stem. So how is this safe?!

Well not only is the reference table conservative, it is likely giving the maximum continuous amperage which can be sustained continuously without melting the insulation off the wire. There's no indication of how long this will take. So according to the table, if we overload an 16AWG wire with a continuous 25 Amps, the wire will start to warm up thanks to the energy loss which is converted into heat. Some of that heat will radiate from the wire. But because we have exceeded the maximum 22 Amp rating we know that the wire cannot radiate the heat fast enough. The wire will continue to get hotter and hotter until it reaches a temperature where the insulation melts off. It's possible that in time the wire itself will actually melt. If the ampacity of a wire is exceeded by a small amount, this entire process may take hours. But the more greatly the ampacity rating is exceeded the faster this process goes. If you've ever witnessed someone accidentally connecting a benchtop jumper wire (typical 20 AWG) between the + and - terminals of a car battery you know that this entire process can occur in a second or two and cause a flash fire with the insulation.

Back to the Ryobi batteries. According to my experiments the most power-hungry tool which draws a continuous load is the P3150 heat gun, which can draw 16A. This is well below the 22A rating for 16 AWG wire, so we see no safety concerns regarding the selection of 16 AWG wire inside the Ryobi batteries for this high current draw continuous-load tool. What about the instantaneous loads? I'll speculate our worst case scenario to be the 9Ah battery delivering 4x the safe rating of current, or 4x90A = 360A. That's a LOT of juice over 16 AWG wires, plenty enough to melt the insulation and probably enough to melt the wire itself. But how long would this take? The answer to this will not be found in a table somewhere on the web. We'd need to determine this ourselves by conducting a very dangerous MythBusters-type experiment. Could be fun, but I'll pass for now. Instead I'll point out that the circuit board inside the Ryobi batteries is designed to disengage the batteries when overloaded. How long will it allow the battery to deliver 360A? I don't know but my guess is less than one second.

So what does all of this have to do with having the HP Technology in the battery communicate with the brushless tools? Nothing. The extra contacts are not for "communication", they're just extra + and - terminals, with a length of zero inches of power-robbing 16 AWG wire to connect the battery with the tool. Zero inches means zero voltage drop across that length, so a slightly higher voltage gets to the tool. These terminals aren't needed in tools which never draw more than 22A -- which means pretty much every 18v tool Ryobi makes except for the saws, drills, belt sander and angle grinder. But for those tools which require a short burst of energy -- like saws and drills -- the extra contacts can deliver that current. Overall a tool with the extra contacts may feel snappier or more energetic when paired with a battery having HP Technology because these batteries are capable of delivering a short burst of energy greater that the batteries without the extra contacts. This means that when the electric motors in these tools get bogged down by a load, they not only have more energy available to maintain speed through the load but they can get a greater momentary burst of energy to regain speed after the load passes. And with a slightly higher voltage, the electric motor should spin slightly faster.

Brushless tools work harder with HP Technology

I find the rest of the original claim (essentially that a brushless tool will work harder) very easy to believe, at least for the three larger capacity batteries. For the smallest 3Ah P191 battery, I'm not so sure. Why?

Let's compare a 3A P191 battery with HP Technology with a 4Ah P108 battery without the HP Technology. As discussed before, the 3Ah P191 battery can safely deliver 30A of continuous current, and it's likely that it can deliver a spike current of up to 4X this rating or 120A. Following this same logic, the 4Ah P108 battery can deliver 40A of continuous current or a spike of 160A. Also as discussed before, the extra contacts simply eliminate the 4" of 16AWG wires which connect the internal circuit board to the terminals in the stem of the battery. So, using the extra contacts the 3A P191 can theoretically deliver a burst of 18v @ 120A or 2,160W of energy. The 4A P108 can theoretically deliver a burst of 18V @ 160A, or 2,880W. But the P108 must deliver that energy through four inches of 16 AWG wires, and according to the voltage drop calculator at calculator.net this means a voltage drop of 0.43v. So the tool will actually be able to consume 160A @ 17.57v, or 2,811W. So does the tool work harder with the 3A P191's higher voltage and lower current spike, or the 4A P108's lower voltage and higher current spike? I'm not certain how to devise a controlled and objective test to answer this question.

All of the other Ryobi batteries which have the HP Technology are the same or greater capacity than the P108. No matter which of these batteries we choose to compare against the P108, we'll find that the P108 delivers "less" due to the 4 inches of 16 AWG wire which the energy from the P104 must traverse.

Bottom Line: Does the HP Technology really make a performance difference?

I've seen YouTube videos which depict a Ryobi brushless tool performing some task with a P104 battery, then the P104 battery is swapped for a P194 and the task is performed again. The tool performs better with the P194, thus proving that the HP Technology is for real! Makes sense, right? Well, not necessarily.

First of all, did the author of the video make an effort to determine the energy in those two batteries prior to conducting the test? No, I don't mean to ask if they we both fully charged before doing the test. I'll assume that everyone is sensible enough to realize that the electric motor in an 18v tool will spin faster/perform better when powered by a fully charged battery as compared to being powered by the same battery after it has been discharged by any amount. Therefore fully charged batteries are necessary in order to minimize the bias due to battery charge level. By "determining the energy in the batteries" I mean to ask if the amount of energy that each battery can deliver has been quantitated. This is important, because a "new" battery can deliver noticeably and measurably more energy than an "old" battery. A new P108 battery may deliver 95% of its rated 4.0Ah/72Wh of energy, but a 3-year-old P108 may deliver only 75% of its rated energy. In this case if the "old" P108 battery is compared against a "new" P194 battery it starts off with a 20% disadvantage.

So let's say we minimize the age bias by selecting a new P108 battery and a new P194 battery. We still need to objectively measure the energy in both batteries. When this is complete we need to recharge and measure the energy a second time. Repeat until consecutive measurements are the same (e.g., within 3%). IMHO if both batteries are shown to have 95% or better of their rated capacity, then we have minimized the battery bias due to age and usage.

So now we can shoot our video which compares the P108 and P194 batteries at work in our brushless tool. Which battery do you think will cause the tool to be peppier? We don't need to shoot the video, we already know that the P194 will win thus proving the HP Technology. So how do we know this without even conducting the test?

Think about it. The P108 is rated 4Ah and as determined previously can deliver 40A continuously or an estimated energy burst of 160A. The P194 is rated 9Ah and can deliver 90A continuously or an estimated burst of 360A. Let's face it, the ratings for the P194 greatly exceed those of the P108. The P194 hardly breaks a sweat to defeat the P108 with or withut the HP Technology.

So how do we conduct an objective test to determine if the HP Technology actually makes a difference? To be objective, we'd need to devise a test which compares the performance of a tool using a battery with the HP Technology against that same tool using that same battery with the HP Technology disabled. But how can we disable the HP Technology without destroying the battery? Well let's see, the HP Technology is implemented via those two contacts on the back of the battery. So it seems like the easist solution would be to conduct a test with those contacts covered up and compare against the same test with those terminals exposed. Or we could compare the 4Ah P108 (no HP Technology) with the 4Ah P192 (HP Technology). My guess is that the difference in tool performance between these two tests will be very small, perhaps even small enough that the average person could not tell which was which.

So will a brushless circular saw cut through thick, damp plywood better with a 9.0Ah P194 "HP Technology" battery than it will with a 4.0Ah P108 non-"HP Technology" battery? You bet it will, assuming that both batteries are fully charged and performing like new. But it's not the "HP Technology" that makes this possible. What makes this possible is the fifteen 3Ah cells in the P194 as compared to the ten 2.0Ah cells in the P108.

Will a brushless circular saw cut through thick, damp plywood better with a 3.0Ah P191 "HP Technology" battery than it will with a 4.0Ah P108 non-"HP Technology" battery? I seriously doubt it, assuming that both batteries are fully charged and performing like new.

What if a 4.0Ah P192 "HP Technology" battery was put head-to-head against a 4.0Ah P108 non-"HP Technology" battery? My expectation is that a dynamometer MIGHT indicate bettter performance with the P192, but that the average person could not tell. Again, this is assuming that both batteries are fully charged and performing like new.

How about a comparison between the 3.0Ah P191 "HP Technology" battery and the compact 3.0Ah P195 "HP Technology" battery (assuming fully charged and new-like performance for each)? These batteries have the same 3.0Ah rating, and they both have the "HP Technology", but the P195 is smaller and lighter than the P191. The functional difference in the batteries is the cells which are used. The P191 has two strings of 1.5Ah 18650 cells in parallel, and the P195 has one string of 3.0Ah 21700 cells. In the past I've found that two strings of cells are better than one (give the same total Ah rating), but that was when all cells were 18650s. The 21700 cells have 47% more volume per cell than the 18650s, which is a lot more surface area to work with when delivering energy to the tool. My prediction is that when like new, there will be very little difference when comparing performance between the P191 and P195, but I won't be surprised to find that as they age the P191 starts to perform slightly better (i.e., two strings of cells are better than one). I will try to test this at some point.

HP Technology Discharge Anomaly

I've observed an interesting anomaly in all of the batteries I've tested which feature "HP Technology", models P191, P192, P193, and P194.

First let me say that my process to test a battery is to fully charge it, then fully discharge it on a computerized battery analyzer (CBA), then fully recharge it. The CBA tests the battery by discharging it with a fixed current level of 4.5 Amps. The CBA samples the voltage of the pack and graphs a plot of the voltage readings taken at a rate of 1 Hz (1 point per second). The voltage on a new and fully charged new pack starts at around 21v and lowers as the pack is discharged. The test concludes when the pack reaches 14v. The CBA then displays the amount of energy the pack was able to deliver (in mAh or Wh) and indicates a Pass/Fail status based on whether or not the pack was able reach or exceed 85% of the pack's rated energy. The 4.5A draw, 14v cutoff, and the 85% Pass/Fail point are all setpoints which I've configured within the CBA software.

Prior to the release of batteries featuring "HP Technology", I would connect a pack to the CBA and hit the start button, and the CBA system would require no further interaction until the test had concluded with the pack fully discharged to 14v. For a "good" P108 battery rated at 4Ah I'd expect this test to take about 48 minutes. (4Ah rated)/(4.5A draw) = .88 hrs or 53 min, though most new batteries test in the range of 85%-95% rated capacity or around 45-50 min.

But the batteries with HP Technology are unable to perform this test without intervention. Every single battery having the HP Technology which I've tested has encountered sudden voltage drops at two different levels during the discharge. One drop occurs around 17.8v, and the second drop occurs about 2.2v below the first drop. For example, a new and fully charged P194 is connected to the CBA for testing and the test proceeds for about 50 minutes with the pack voltage slowly dropping until the pack voltage reaches 18.001v. At this point the pack disengages the load, the battery voltage drops offscale (below 14v), and because the voltage has crossed the lower boundary the CBA ends the test. The battery has delivered only about half of its rated energy, so the test is assigned a status of "fail". But the pack is still half full of energy, so a second CBA test is started immediately. The voltage starts at around 18v and slowly lowers to 15.689v, at which point the pack once again disengages the load, the voltage drops offscale and the test ends. This time the battery has delivered about a third of its total rated energy, or about 83% total. So with about 17% of battery energy remaining a third CBA test is started. The voltage slowly drops until the lower limit of 14v is reached. This third time the battery has delivered about 10% of its rated energy, or 93% total. Testing concludes.
P194 Testing on CBA


In the graph above one can see that three separate tests were required in order to test each battery. I've obscured the actual serial numbers of each battery, but I've left the date code visble. These battery tests were conducted from 5-Dec-2019 to 8-Dec-2019, or week 49 of 2019. The three newer batteries were 45 weeks old (~10 months) and the older battery was 84 weeks old (1yr and ~7 months) and yet they all tested favorably. Battery #1 delivered 4.58Ah+3.00Ah+1.01Ah = 8.59Ah, or 95.4% of it's rated 9.0Ah capacity. Battery #2 achieved 8.55Ah / 95.0%, and battery #3 was 8.48 / 94.2%. Battery #4, while 9 months older than the other three, still tested at 8.18Ah or 90.9% of it's rated capacity. Bear in mind that I only tested each of these batteries ONCE, and Li-Ion batteries typically test better on their 2nd cycle and better still on their 3rd cycle afer having sat idle for an extended period of time, as would be the case here. I wouldn't be a bit surprised to find that each could deliver better than 98% of rated capacity if tested after three cycles.

UPDATE 24-Jan-2020: I did some fiddling with the CBA configuration to see if I could capture a full discharge curve in one test. I did this by lowering the cutoff voltage setting -- when the measured voltage goes below this level, the test stops. My concern with lowering this setting is that the CBA could potentially over-discharge the cells in the pack, which could result in "killing" the battery as can be done so easily with the model P102. (I have dedicated an entire page to this phenomenon with the P102.) I ran several tests on P191 batteries and decreased the cutoff voltage by 1v each time. The test concluded at the first voltage drop when the cutoff voltage was set to 13v, 12v, and 11v. But when set to 10v, I observed that the voltage actually dropped to about 10.7v, not zero! The battery was not actually disengaged from the load as I has suspected. For about five seconds the voltage remained at about 10.7v and during this time the current dropped to about 1.5A then ramped back up to over 5A. The CBA must have been making adjustments during that time to try and maintain a steady current draw of 4A as it had been configured to do. After those five seconds, the voltage jumped back to where it was before the dropout occurred and the test plodded along as before. However the test concluded when the second voltage drop occurred. So I tried again with a cutff voltage setting of 9v, and then the test was able to get past both the first and the second voltage drops. Again for about five seconds, the second voltage drop hovered around 9.3v before jumping back to over 15v. I've now revised all of my CBA test configurations for HP Technology batteries with a 9v cutoff voltage. Here's a graph which includes two P191 batteries tested with a 14v cutoff (3 curves) and twi P191 tested with a 9v cutoff (single curve):
P191 Testing on CBA


These spikes can be seen in the discharge curves created while operating tools. Evidently the battery pack re-engages the pack after each of these predictable disconnections. See the graphs below which highlight this behavior. The first graph is the discharge curve for a P193 6.0Ah Lithium+ battery with HP Technology, and the second graph is a close up of 9 seconds from the first graph. I conducted this test by holding the trigger switch "ON" with a bar clamp, then I left the room for lunch and I did not return until well after the test was complete.
According to the raw data, the 6.0Ah battery ran the tool for a total of 22:33. For about six minutes, the tool draws 16-16.5 Amps while the voltage slowly drops from about 18.5v to 17.5v. At 6:05 the voltage and current both drop to zero, then the current spikes offscale and the voltage pops back (to about 17v). The discharge for for both current and voltage are approximately linear for about ten minutes, with current dropping from 16.5A-13.5A and voltage dropping from about 17.5v-16v. Once again at 16:02, the voltage and current both drop to zero, then the current spikes offscale and the voltage pops back (to about 16v). The discharge for for both current and voltage are approximately linear for about five minutes, with current dropping from 13.5A-11A and voltage dropping from about 16v-9v. We see a third dropout around 20:48, with a recovery shortly thereafter. For the remaining 90 seconds, the current and voltage decrease at an increasing rate.


The data for all three dropouts are similar. The dropout is NOT momentary. I count 22 points recorded from when the current dropped from 15.1A until it spiked back up from zero. At 4pts/sec, that's an interruption of 5.5 seconds (+/- one half second). I also counted 22 data points at each of the other two dropouts (15:59 and 20:43), so this interval is regular.

I hope you noticed the big current spike when the tool restarted! Prior to the dropout, the datalogger was recording 17.01v@15.1A, and after the dropout the datalogger recorded 17.81v@16.3A. The first data point recorded when the tool came back "on" from 0v@0A is 15.94v@31.6A, which is followed by another 15.94v@31.6A, then 17.81v@17.7A, then 17.81v@16.3A. The datalogger clearly captured a current spike to restart the tool's electric motor! The spike lasted for about a half a second.

Prior to the second dropout, the datalogger was recording 15.34v@12.8A, and afterwards this was 16.1v@13.8A. The current boost is captured as 9.03v@17.6A, 15.75v@23.8A, then 16.1v@14.5A. The second spike was about a half second.

Prior to the third dropout, the datalogger was recording 13.53v@10.5A, and afterwards this was 14.31v@11.5A. The current boost is captured as 7.09v@23.3A, 13.85v@18.2A, then 1431v@11.9A. The third spike was also about a half second.

You may be wondering why in the second graph the voltage and current don't drop immediately to zero. Several data points are recorded which show the voltage and current are dropping to zero. Did the battery turn off slowly rather than immediately? No, I suspect that the battery did cut itself off instantly. But at that instant the electric motor inside the leaf blower was still rotating. That rotational energy was converted into electrical energy by the tool's DC motor, which is what the datalogger recorded.

I've tried to come up with tools/scenarios where this behavior would be particularly dangerous or undesirable, but so far I've been able to come up with just a few. Let's face it, if you're running a fan and power is disconnected and then reconnected after five seconds, you might not even notice. If this happened while operating a drill, saw, leaf blower, or most any other tool, you'd probably release the trigger and examine the tool for a moment. You'd probably press the power level button on the battery once or twice, or remove the battery from the tool then re-insert it. All of this will likely take longer than five seconds, which is long enough that the battery will have reset itself and be ready to get back to work. It's a little puzzling, but no big deal. But this could be a real hassle if the tool you're using happens to be a light, a radio, or an AC inverter. Most of the Ryobi radios and lights have electronic ON/OFF switches, and so does the AC Inverter. So your device will turn OFF with the interruption and it won't automatically turn back ON afterwards. Imagine your surprise when you go back to the light, radio, or AC Inverter and find that it has turned itself OFF. You check the battery's power meter only to find that it has lots of energy left, and your tool turns back ON when you hit the power button. You're likely to suspect that the tool is faulty when in fact it's the battery that caused the interruption.

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Last revised 24-Jan-2020
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