Lipo takes a while to balance

DIY Builds Battery Builds
#1

For the E-TOXX psychoframe, I bought 5x TATTU Lipo 4S 22000mAh 30C.

One of them takes a while to balance.

I first balanced/stored with Turnigy QuadKore to 3.85V. I was quite long.

Then, after some tests of the psychoframe, I noticed cell voltages were a bit different (but above 3.80V).

So I balanced/stored with SkyRC D100 to 3.80V, thinking it might be a better balance charger. Quite long again.

Yesterday I balanced/stored again with Turnigy QuadKore to 3.85V and it took 174 min to charge from 3.80V to 3.85V, most of the time at 0.3A (charging current was set to 20A).

Resistances on all the cells are very good, from 2 to 3 mOhms, as reported with these two chargers.

I never experienced this kind of issue in the past with lipos that have normal cell resistances.

1 Like
#2

if it balances with 100mA f.e I’m not very surprised it takes that long. What accuracy are you balancing with? 1mV? 0.1mV?

2 Likes
#3

At the beginning of charging, it starts at 20A, but in the end it takes a lot of time to balance accurately. That’s why it ends at 0.3A.

One of the cell comes fast from 3.80 to 3.85V and it takes so long for the three others ones to reach 3.85V.

I don’t think I can change balancing accuracy. Process is normal with the four other lipos.

#4

20A is for sure not the balancing current but the charging current. Normally balancing
bleeding is around 100-500ma.

Hard to tell, but it looks like you have 4 channels on that charger, have you tried charging the same pack in one of the other channels?

1 Like
#5

Yes I even tried with another charger (SkyRC D100) and got the same behaviour.

#6

Discharging the lipos to a set voltage does take long, I’d go for a ride till I get them close to a voltage I want and then discharge to balance

1 Like
#7

Why some are slower then others could be one or more cells are higher in voltage then the others, pain to balance

1 Like
#8

Yeah, but what surprised me is that balancing the whole pack from 3.80V (store voltage of SkyRC charger) to 3.85V (store voltage of Turnigy charger) took 174 min, in spite of the fact this pack was balanced to 3.80V two days before.

I would not have been suprised if I was balancing this lipo for the first time.

#9

That is weird, my ultrapower charger charges up at max amps till it’s 0.2-03v away from balancing then rapidly drops to 0.2a, that’s at full charge but on discharge alone I know it takes forever, a balanced pack suggests your chargers not charging each cell in sync or the pack is not charging up the way it should.

Was there any voltage drop from the pack in those 2 days?

1 Like
#10

Not sure at what voltage the charger starts to balance but I think 3.8 is a pretty common default. looks like the 3d cell is the one beeing bled since its highest, you could try discharge it manually with a bidirectional voltage supplyor an e-load. Even a resistor would work(you need a power resistor with bit bgger wattage) 20 Ohm would yield roughly 200ma (around 1W)

Such a fancy charger should be configurable tho? Try change when to start balancing and it should attempt charging to w/e level you set

1 Like
#11

Fking epic you bought the psychoframe !
Hope u solve your problems neighbor.

1 Like
#12

No the pack was not connected to anything.

Yeah of course, what concerns me is the weird behaviour in balancing of this lonely pack compared to the four other ones. I’m afraid it’s faulty. I wonder if resistance measurement is good for such big capacity lipos (22000 mAh).

I sent a mail to GenAce. I have not even charged to 4.2V yet, but I bought these packs in July. Maybe a bit late for RMA.

For what you are saying, I mean charging or discharching a cell the fast way, I found this nice video :

Thanks! This is a very huge build, I question myself about police reaction if I see them going out… :sweat_smile:

#13

Don’t know where you live in France but I think I’ll be ok if you go off road.

Don’t drive this thing through Paris… :rofl:

1 Like
#14

I did a store/balance test again.

It took 59 min for the weird lipo which was store/balanced yesterday!!!

But only 3 min for one of normal lipo which was store/balanced already the same way but maybe a week ago.

Yet, resistances look normal on the weird lipo… :face_with_raised_eyebrow:

IMG_20211220_142315
IMG_20211220_1423151920×2560 193 KB

IMG_20211220_152350
IMG_20211220_1523501920×2560 106 KB

IMG_20211220_160108
IMG_20211220_1601081920×2560 181 KB

#15

I wanted to write here that GENSACE.DE after sale service is simply awful.

I didn’t have any answer from them in spite of many mails. I didn’t even ask for a replacement…

I’ll never order from them anymore.

Hobbyking is way more helpful when you have an issue. The same with any Aliexpress vendor.

1 Like