The LiPo Spec that should REPLACE the C Rating!!!

[@richduperbash2966]

Another great video 🤗. Very clear explanation my friend. It's unfortunate that Lipo manufacturers can fudge discharge ratings it seems to turn more sales.

[@RCexplained]

Well said Rich!

[@bbyautographics7106]

SMC uses a power factor number to rate their packs, which is basically voltage per cell under a constant load. So 3.92 would equal 392PF on the label. But since they are the only company that uses this not helpful between brands.

[@ericklein5097]

This is the one I expected to see….I just assumed that if we weren’t using C-Rating we wouldn’t use IR since they’re directly related….except in the RC world where lying out your ass is the norm

[@michaelcondrey8681]

Another great video what charger is that and can you make a video on that charger

[@RCexplained]

Hi Michael, thanks for the comment! I haven't done much in terms of product videos. What features may you be interested in?

[@ericdisisto3926]

Love this idea! Some of the battery sellers would go out of business almost overnight lol…I’m looking at you powerhobby 👎🏻

[@omarolman]

you explain things very well thank you

[@RCexplained]

Thanks, this is never what I am thinking when editing the video!

[@markdawson8583]

Judging by those values the C rating is possibly based on power dissipation within the battery, ie the 4 cell would generate the same internal heat as the 6 cell if they had the same current draw. eg if you pull 10A the 4 cell battery will generate ~1.26W and the 6 cell ~1.12W, pretty close allowing for the age of the packs.

[@RCexplained]

Hi Mark, I'd hope that they do consider power dissipation but this becomes complex as well. The example cells, 4s and 6s packs, both started their life at nearly the exact same IR. The 6 cell pack has more surface area to remove waste heat. I am unable to use the 4 cell packs in an 8s setup due to excessive heat build up.

[@brettdavies2744]

Thanks for the vid, can you elaborate for me how the IR changes with state of charge and state of health? Trying to understand how some battery testers can give you an AH state of health reading from a quick IR test??

[@RCexplained]

IR increases with health of the battery. IR stays roughly the same through the better part of the batteries charge. IR increases when state of charge is low.

[@shadow7037932]

So your example seems to be with batteries with cells in series? Say you have something like a 3S2P pack with say IR of 3 mOh vs a 3S1P pack of 2 mOh. Which of these would provide more power?

[@RCexplained]

Yes cells in series. Any parallel cell groupings charge, discharge and balance as a single cell within the pack. If I understand your example specifications as described, a LiPo manufacture would much rather use 1.5mohm per parallel grouping vs 3mohm per cell anyway. It's better for marketing, it's accurate and less confusing. Similarly, No manufacture specifies the capacity of a single cell within a parallel grouping. The manufacture states the capacity of the whole pack which add the capacities of each individual cell placed in a parallel group.

[@shadow7037932]

@@RCexplained right, but my question was more about which battery would have the higher real world discharge/power draw capability? Like would having a 2nd cell in parallel counteract the higher IR?

[@RCexplained]

Yes, I did put the resistance of your example in my reply. 2x 3mohm cells placed in parallel will perform at 1.5mohm and would be better than a 2mohm single cell.

[@keepitreal1984]

Hi ive just got a 11.1v lipo 3.7v 8c. It has 4 conectors coming of it. I think i no one of them is lipo charger. But it has a servo end and 2 others that i dont see on google or anywere i just dont want to plug out in and bang. Any help will be greatfull thankyou

[@RCexplained]

You may send an email to the dealer you purchased from requesting more information.

[@CharlesGarnierRC]

Should I measure iR at 3.85V?

[@RCexplained]

Sounds good. Which ever you choose be consistent.

[@NabiL_Lam]

The spec might be max discharge current?

[@soundmindtv2911]

IR is a good measure of the life remaining in the cell - the health of the cell. But not for the application of the cell. Individual cells are manufactured with discharge rate as a factor. I don’t mean the assemblies - I mean the cells themselves. Some are manufactured specifically as high discharge cells, able to deliver more current, while some are manufactured as low discharge, for applications where long cycle times and low current are needed, such as modems. Batteries for modems, for example, can still have a low IR, but a low C rating. IR will increase over time as the cells develop crystals on the cathode. The problem is that manufacturers flat out lie about all the ratings. Many Chinese manufacturers especially will sell cells labeled with ridiculous numbers, even 18650 cells labeled as 9,000 mAH - which is physically impossible. When you test these, you find them to be more like 700 mAH. Likewise, there is no such physical thing as a 2S2P assembly that fits in a RC car that’s capable of delivering 150C. The highest physically currently available in that configuration would be 60 Amps. There is simply no cells that are capable of those numbers - yet these manufacturers are permitted to slap whatever label they want on the pack and sell it as 7,000 mAH 150C or whatever. But when you measure its performance, you find it’s actually 5000 mAH and 30C - which is actually a really good pack, just nowhere near what the label claims.

[@LawrenceTimme]

I don't want a c rating I want an a rating. 😎

[@KasprGoodman]

The IR statement is incorrect. You'll need to add the IR values together. You don't just ignore a heat source because it is not as strong as the other. The heat each cell produces aggregates so you need to take total IR. Your method only gives the C rating for one cell. Unless I missed a step you did. Did I miss you dividing the capacity by the number of cells? If you didn't then your calculated C rating is wildly incorrect even for a single cell.