I just bought a new SMC True Spec Premium 85A/90C 4600 mah battery and was doing my "baseline" reading of the battery. I'm OCD. I do a baseline reading of the battery and then do the same after 10 full cycles to track how the battery degrades over time and use. The numbers that you will see WILL NOT be the same as whatever other charger/discharger you use since it seems that manufacturers have their own methods to determine internal resistance (IR). So this is the way that I charge/discharge batteries and I'm sure everyone else has their opinion of what's right for them. I wanted to share quantitatively what it looks like using my equipment.

Charger = Team Orion set at 10 Amps
Discharger = Duratrax ICE at 10 Amps (It's the only one that I know so far that discharges at the full 10 Amps)

Baseline
SMC 4600 85C
mAh: 4612 mah
IR: 27 mOhms
Avg V: 7.45 V

REVTECH 4500 100C
mAh: 4500 mah (weird it came out exact)
IR: 21 mOhms
Avg V: 7.51 V

Ultimate 6000 90C
mAh: 6030 mah
IR: 13 mOhms
Avg V: 7.55 V

Current State of Old Batteries
REVTECH 4500 100C after 30 cycles
mAh: 3621 mah (lost around 900 mah over 30 cycles)
IR: 34 mOhms
Avg V: 7.25 V

Ultimate 6000 90C after 20 cycles
mAh: 5021mah (lost 1000 mah over 20 cycles)
IR: 16 mOhms
Avg V: 7.51 V

So what does this tell me? It tells me that both SMC and REVTECH are not as good as the Turnigy Ultimates. The SMC brand new has an IR that is much higher than the Ultimate even at 20 cycles or the REVTECH. The voltage of the Ultimate is also higher even at 20 cycles.

I paid $33 + $12 shipping for the SMC. Running the car, it does feel "flat" like the REVTECH when compared to the older Ultimate pack. Go figure. Would it get better in time? I'll let you know... But right now, I'm not buying anymore SMC's until I get more data.

Prior to me doing the baselines, I also ran Turnigy Nano-Tech which gave me 18 and 20 IR. But I didn't include them in the above since I didn't have a true baseline for them. I also ran Thunder Powers which gave me 34 IR after about 80 cycles (I don't have an accurate # of cycles for them).

Again, I'm just sharing my results and I have no affiliation with any of these companies. I'm just being OCD with a natural curiosity about these things. I'm sure others can have differing results. But these are mine.

Edit: I got sucked into the marketing and bought the brand spankin new Reedy Zappers. This was $80 shipped from Reedy directly.... go figure... here were the results:

Reedy Zappers 4800 110C 7.6V HV (charged to 8.4V)
mAh: 4099 mah
IR: 17 mOhms
Avg V: 7.51 V

Reedy Zappers 4800 110C 7.6V HV (charged to 8.6V)
mAh: 4466 mah
IR: 17 mOhms
Avg V: 7.56 V

Am I cynical for actually expecting that the mah will fall short? Honestly, I didn't think it would fall THAT short. We're talking 15% short when charged to 8.4V and 7% short when charged to 8.6V. I hope that this will improve after 10 cycles. But we'll see.

I would have thought that the average voltage would be higher. But, of course, it was not much. I highly doubt I would notice a 0.02 or 0.07 V difference when compared to the Ultimate Shorty.

Resistance wise, it looks just about as good as the cheaper batteries. As always, the proof will be in the pudding. I'll let you know once I get it on the track.

Love me some Turnigy batteries, you can never go wrong with Nano-Tech's and Ultimates are even better. I get more life out of them than I ever have with "name brand" batteries.

I have tried,
Orion: good, low resistance
Gens ace, slightly better, low resistance
LRP, terrible, very high resistance
and
Turnigy Ultimate, the best, very low resistance.

My experiences are from new and after about 6 Months of running once to twice a week. My experience is that the higher the price the worse the battery was.
Go Figure.

I think it's nice that your IR readings are correlating what I would expect on paper. What I like to do is multiply the capacity times the C rating to get "relative amps" rA and the testing I've done over the years has proved to me that the pack with the highest rA typically performs the best under load:





Also notice that in this particular case that you're comparing apples to oranges because you're not comparing identical capacity and C ratings between packs... but I agree when it comes down to the bottom line on what you're spending in the comparison that it becomes justifiable for the comparison.

I don't know what you have done for your packs to lose capacity that early in their life.

Protek recommends that you don't discharge below 50% for the first 5 cycles. Also, that the first 5 cycles are not really high C rates. I follow that advice, and notice my batteries don't puff or lose any capacity until 100+ cycles.

Additionally, a 10A charge/discharge cycle is not going to do anything to stress the battery enough for your ir numbers to mean anything. If you start cycling at 40A you would see way different IR numbers.

You may have been involved in the hobby for 40+ years, but it sounds like you have been doing it wrong for a while.

Dude, if you read the post, the objective is for me to get comparative numbers using the same type of test. Sorry if you don't like it or agree. Ideally, one would discharge the batteries at the same exact amp rating as the load found while running the car. The numbers may not mean anything to you, but it does to me especially when the "road test" confirms them.

And as for your last comment, I'm sure I've forgotten more than what you currently think you know.

Funny that you wrote that as I was wondering the same thing. I actually have an Ultimate 4600 and Graphene 4600 both 90C coming in shortly and I'll run the same test.

I've done enough data logging to know a 40 amp cycle is more strenuous than a run in my stock buggy. The point of cycling packs like that is to heat them up to lower IR and increase performance. My packs show .9 to 1.2 mOhms when close to done charging.

It is great that you want to track performance, and ir is a good indication of pack health. I have pushed several batteries "beyond" their limit. So far the Protek 3600mah LiHV batteries have endured my punishment the best.

I have been racing rc cars for 25+ years. My fastest lap with my 17.5 2wd is about .5 second off the fastest mod 2wd lap times at my home track. I am also going to school for mechanical engineering. My 2wd buggy has $1000+ in development parts on it. It was a 4.0 before the 4.0 was available to the public. I still have upgrades that I haven't had time to finish making.

Half a second off a mod car is pretty much what is at the limit of a stock buggy. At least according to the people I talk with about toy cars. One of these people has won the Reedy Race Open class, so I trust what he says.

You could probably use a light bulb bank to increase your discharge capacity. You're smart enough to figure out how many bulbs you need to get the discharge rate to match the discharge rate of your car driving around on track.

What kind of lap time differences are you seeing in back to back to back testing?

You guys do know that C ratings cannot be trusted. Can you imagine trying to discharge something at 400+ amps.

My local track just opened about 1.5 months ago, and I haven't ran the pack at anything other than a 10c charge and 40amp discharge at the new track, but at my old track it was .5+ seconds a lap. That old track never really had jumps that mod can do and stock can't.

The current layout at the new track has two tripples. My battery has finally started to lose capacity and punch. The IR is still about 2.5+ mOhms when I pull them off the charger. Both cells have stayed pretty close, but one cell definitely started to fail a bit before the other. The ir has about trippled, and my pack has lost about 1/3 capacity.

I digress, I will have a new battery soon, and I'll test the difference between a low C cycle and a high C cycle. With my failing pack I could only do the one tripple if I go wide, and it is the first couple laps. With the new battery hopefully I can do the tripple enough to put together a perfect lap while hitting the tripple. Probably worth .2-.3 I'll let you know Kraig.

I don't put any value in C ratings. Capacity and IR don't lie. I would love to see what the battery would do under a real 100C load. Spectacular failure is my guess.

Lap times vary from track to track. At my home track where typical is 16.x seconds, I can get 16.5 vs 17.0 using the Ultimate. The biggest difference is "punch" - being able to power out of a corner and being able to make or not make certain jumps.

Totally agree that C times or mah ratings cannot be trusted. This is why I always take baseline readings going back to the good old days when I used a Competition Electronics Turbo Matcher (anyone remember these?) to validate mah and avg voltage claims.

Yes, I know of the light bulb trick. Glad you're going to school for ME. I have a bachelors in ME, MS in EE (photovoltaics and battery technology) and MBA from Tier 1 schools (not to mention AA in Writing). Discharging the batteries at 40 Amps (or whatever higher) will not reveal a different qualitative result compared to what I have already done. It's still going to say that the SMC and Revtech will provide less punch than the Ultimate. They will not automagically get better just by discharging them at a higher amperage.

You don't know until you test it. I have tried the Orion 3200mah, and also a Trinity low profile pack.

They each display different characteristics when you push them, trust me, I have done the testing. Not on the same packs you are testing, but the same testing.

I'm just reporting what I have personally witnessed.

Additionally, being that you are not cycling the battery hard enough to make heat, your packs could likely have been at different temperatures, unless you specifically made sure they were the same temps. Do you track temps?

My protek hv packs have over 30 cycles and have way way lower IR. When I cycle them the IR drops a good bit too.

Yes, I'm monitoring temp and other variables.

The IR is going to vary depending on which equipment you use. There doesn't seem to be consistent standard among manufacturers yet (or at least I haven't come across it). For instance, if I use my Orion to discharge the batteries, I get an IR of around 5 to 10 mO for each battery. It doesn't seem to read a large enough difference from battery to battery. I also found it to be inconsistent for the same battery. It could read 5 one day and 10 another day for the same exact battery, temperature, charge rate, etc. Whereas when I use my old Duratrax ICE, it gives me consistent IR readings. So I'm using that so that the readings can be all relative to that particular discharger.