sx3-swe

Interesting thread. how would a 7,4V charge impact on capacity?
Lets say we have 6100 mAh 7,6 HV lipo. Guess the capacity would decrease if charged as 7,4V LiPo?
Is there any way to recalculate the mAh so it's corresponding with 7,4V?

Example [email protected],6V or [email protected],4V

TurnNBurn

First off, don’t assume that higher voltage means more speed - if your cells don’t have a low Internal Resistance, all bets are off. It’s all about Ohm’s Law… The owner of the hobby shop I used to buy from back in the day used to say, “At your level of competition, batteries win the race - don’t spend your money anywhere else if you don’t have the juice to drive it.” Believe me, back in the days of matched and graded sub-C cell packs, better batteries quickly got me up from the C mains to the top of the B’s statewide, and winning series’ at my local track. Anyway, IMHO, it’s just a matter of time before the sanctioning bodies just allow charging to 4.35. I think the biggest driver is that as cells deteriorate and people end up buying new cells (LiHV), there will be less worry and pushback about people having to buy new packs.

I wouldn’t go around saying that LiHV’s are just glorified LiPo’s though. By classifying them as LiHV’s, the companies are basically assuring you that you can charge it to 4.35/cell SAFELY (as safe as LiPo’s cells can be, anyway). I know that I wouldn’t feel comfortable charging a standard LiPo cell to 4.35V. Care wise, I would just charge them to 4.20 (if competing under current sanctioning rules, special allowances excepted, of course), and store them at 3.8V, or whatever voltage works for you (I know people have differing opinions on that)… but I predict that one day soon, ROAR and the other sanctioning bodies will raise the ceiling to 4.35V when they think it will have minimum impact on the user base.

gigaplex

iTrader: (2)

I don't think there's much point to allowing charging to 4.35. The voltage curve drops rapidly at that level, it won't make racing better, and it just wears out the batteries faster.

Plus not all new packs are sold as LiHV. There's still a lot of high end batteries that advertise standard LiPo voltages.

Logante

iTrader: (3)

For me it has not been about that extra voltage , but it seems to have less degradation over time and easy to maintain!

Team Steve

Testing my own batteries, it's roughly 10%

gigaplex

iTrader: (2)

I've not seen any improvements with longevity between my LiPo and LiHV packs.

Pocket_Fred

Good read interesting to know.

mac853

As I saw many rules in Europe, US or even in Japan are tighly restricted of batteries just charge until 8.4, if goes into 8.44 would be considered overcharge then would be hardly penalized.

But i saw in somewhere of Southeast Asia still allow charge until 8.44.

Then I verified Lipo would swelling in case charge it 8.44.

Could someone tell in case the rules is allowed 8.44 would have advantage for LIHV than LIPO?

Could someone tell me LIHV could be charge with 2C?

Anyone would fully charge LIHV until 8.7 then discharge it until 8.4 before race for better perform?

gigaplex

iTrader: (2)

Charging a regular LiPo to 8.44 won't cause swelling by itself, that's within normal voltage tolerances.

LiHV won't benefit from 8.44V any more than a LiPo would.

LiHV and LiPo can both be charged with 2C (assuming the rules allow).

Charging a LiHV to 8.7V then discharging to 8.4V won't perform any better than just charging to 8.4V directly, other than marginal internal heating which could lower the IR. But you can do that without overcharging, people already cycle the packs.

mac853

Thanks for clarifying about LIHV which I never used before therefore I still don't understand why there's many manufacturers only release LIHV then many people like to use them.

gigaplex

iTrader: (2)

Marketing/perception. Usable capacity, weight, IR are all that really matters.

malkiy

iTrader: (10)

For indoor black carpet the trend is ULCG batteries. After checking 8 band new batteries, most of them LIHV, from different manufacturers the big majority of them have ok to terrible IR. You have to blast them with high current for them to have average IR.

gigaplex

iTrader: (2)

ULCG batteries tend to have higher IR in general - smaller cells with less surface area.

Xrayray

What's a good IR? Brand New protek 7400 lihv with 1.8 IR both cells.

gigaplex

iTrader: (2)

Your charger and charge leads will play a big part in the measured numbers, but under 2 per cell is pretty good.