Battery cutoff settings

@Namasaki E switch is on and left it for 45 min after it was 42V and charger LED went green.

can you post a specific wiring diagram of your bms and setup?

Same as here but 10s. I used this diagram to set mine up.

Shall I leave it for longer? It quicker to do it with hobby charger :wink:

Iā€™ll try it today again, one of my bms ( have two) is acting up lately.

I just pulled the lid off my battery and checked individual cells and found that the bms did not pull high cells down while trickle charging with power supply. And the bms did not balance cells down while it was turned off. Iā€™ve got my board on now to see if it trims them down.

Has no one noticed heā€™s got 3.5v as cut off!?

I did :muscle:t2: And advised better numbers

1 Like

Ohhh letā€™s see how long it will take.

@Namasaki what BMS do you have ? Most of Iā€™ve seen only balance when charging and hit above 4.1-4.15

I wish in description of my charger there was trickle charge amperage

36V 37V 42V 45V 5A Battery Charger For 10s 10x 3.6V/3.7V Lithium Li-ion Battery

Lithium isnt supposed to be trickle charged , itā€™s CCCV. Iā€™ve never seen a datasheet for a lithium cell that supports trickle/float charging

my power supply doesnā€™t drop all the way to zero current. it only goes down to 50-40ma. That could be because the Vescs and receiver are on while charging.

Bestech HCX-D223V1

Itā€™s supposed to stop after a certain time, I donā€™t remember the exact formula but Iā€™m sure itā€™s in the datasheet for your cells

Results

After leaving the E-switch on for apx 30 min voltages are as follows

Pack1 4.185 4.195 Pack2 4.198 4.192 Pack3 4.195 4.195 Pack4 4.195 4.195 Pack5 4.195 4.190 Rounded numbers Pack1 4.19 4.20 Pack2 4.20 4.19 Pack3 4.20 4.20 Pack4 4.20 4.20 Pack5 4.20 4.19 I canā€™t find the list now but some of the voltages where 4.204-4.206 before balancing. I think these numbers are acceptable but I will let it balance for a while longer and check them again. I have seen where even a hobby charger could not balance some packs perfectly.

This looks promising. Hmm I guess I need proper power supply as this one cuts out at 42V sharp. I guess you couldnā€™t achieve balancing with your brick charger, right?

How do boards like Boosted or Raptor work around this? Their BMSā€™s must be set for lets say 41V balancing start and chargers to 42V cut off?

Iā€™ll have to test with my brick charger to see

I would be grateful if you can some time. I was hoping for plug and play set up and its fine apart of balancing part :confused:

after an additional 30 min with bms on the total pack voltage dropped from 41.90 to 41.85 After rechecking the cell voltages it seemed that there was no improvement to balance however after rounding the numbers there does appear to be a slight improvement. Still, I would conclude that the original 30min balancing is adequate. Note that differences in cell internal resistance will affect their ability to charge and discharge evenly 4.179 4.184 4.192 4.188 4.190 4.190 4.190 4.190 4.186 4.185 numbers rounded looks good. pack 1 4.18 4.18 pack2 4.19 4.19 pack3 4.19 4.19 pack4 4.19 4.19 pack5 4.19 4.19

Edit After rounding the numbers and seeing a slight improvement to overall balancing after the additional 30 min of balancing. This could imply that the bms is constantly balancing while on and not charging. How great would that be?

Hallo @Namasaki Nice info about the bestech 10s 80A BMS :slight_smile: Thanks

Im building my 10s Trampa at the moment, with the same BMS. I know the E-switch have to be on when charging. But i dont like that my focboxs is powered on in several hours while charging. I notiched when no load on the BMS output, the voltage is nearly "vbat" level on the load pads. But do you think its okay, to ad a loopkey to the chain ? Between the bms and vescs. So while charging i could pull the loopkey, so the vescs is not powered while charging ?

And do i need to leave my charger connectet in 45min after end charged to ballance my cells, or is it okay to remove the charger after the LED turns green, and then let the E-switch being on for 45min ?