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Top balancing why proper wire

GSXR1000

Solar Enthusiast
Joined
Nov 20, 2020
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I see up with the oem small wire vs 10 guague wire with ring ends.
with the 10g wire the power supply is putting out 5 more amps and running on current limit
with the small wire there was a .3 volt drop on the wire
20210119_145721.jpg20210119_150159.jpg
 
I see up with the oem small wire vs 10 guague wire with ring ends.
with the 10g wire the power supply is putting out 5 more amps and running on current limit
with the small wire there was a .3 volt drop on the wire
View attachment 33791View attachment 33792
Certainly, but I’m lazy and like to live dangerously.

I crank my similar charger up to it’s max 10.2A where voltage drop in the cable doesn’t really matter (4.1V delivering 3.36V to the terminals currently),

As cell voltages increase the charger reverts to Voltage-limited mode so it’s pretty easy to catch the beginning of the knee well before there is anything to worry about...

If you truly want to ‘set it and forget it’ got weeks, larger AWG wiring will speed things up but if a tiny bit of attention will make things even faster and leaving it for a few more days with the ‘easy/lazy’ alligator clips gets you to the exact same endpoint..
 
If you want to top balance quickly.
configure pack in serial with bms.
Charge with a high amperage system voltage charger until the bms trips on high cell.
Then configure as parallel and finish with a traditional top balance.
 
If you want to top balance quickly.
configure pack in serial with bms.
Charge with a high amperage system voltage charger until the bms trips on high cell.
Then configure as parallel and finish with a traditional top balance.
Yes, that’s faster (if you don’t mind rewiring your terminal connections more often.

My BMS just arrived so I may consider doing exactly that to speed things up...
 
But wouldn't there be a huge spark show from the different voltages when connecting in parallel after charging in series?
 
But wouldn't there be a huge spark show from the different voltages when connecting in parallel after charging in series?
Not necessarily because they would presumably be close to the same voltage and SOC unless they were way out of balance or one was a runner.
 
Not necessarily because they would presumably be close to the same voltage and SOC unless they were way out of balance or one was a runner.
I check my cells after series-charging and assure they are within 2mV of each other before connecting in parallel (using a power resistor or the charger if needed).

As long as you connect when all cells are near mid-charge (in the flat area well away from either knee), it shouldn’t be a problem...
 
If you want to top balance quickly.
configure pack in serial with bms.
Charge with a high amperage system voltage charger until the bms trips on high cell.
Then configure as parallel and finish with a traditional top balance.
16111080115163268404152655425938.jpg

my other pack charging at 12v 25 amp
 
LOL that is a good example of:
No BMS
Different Interconnects.
Alligator clips on nuts instead of lugs on terminal tops.
A human being is the BMS and stays up all night with a multimeter measuring cell voltage every 15 minutes.
I will stop at 13.8v then swirch.. only charge when in the room
 
LOL that is a good example of:
No BMS
Different Interconnects.
Alligator clips on nuts instead of lugs on terminal tops.
A human being is the BMS and stays up all night with a multimeter measuring cell voltage every 15 minutes.
Using a car battery charger is a good way to check for cell uniformity in the presence of higher charge current.

Unfortunately, my 25A car battery charger is 12V and my LiFePO4 battery is 8S...
 
I will stop at 13.8v then swirch.. only charge when in the room
I had confidence that you would do it the correct and safe way. After spending a few hours and some posts on another thread with a newby, your picture was the next thing I saw and I had to give it a laugh.
:LOL:
 
I had confidence that you would do it the correct and safe way. After spending a few hours and some posts on another thread with a newby, your picture was the next thing I saw and I had to give it a laugh.
:LOL:
Something that made me laugh is that I see my exact 12V car battery charger slightly out of focus in the background.

I’m only able to test charging my cells at 10 or 20A (0.036C or 0.7C) while if I test at 12V I could test at 35A (0.125C).

Is testing at that (modestly) higher charge rate worth the trouble? Have any Forum members recieved cells that failed under high-current charge?
 
Something that made me laugh is that I see my exact 12V car battery charger slightly out of focus in the background.

I’m only able to test charging my cells at 10 or 20A (0.036C or 0.7C) while if I test at 12V I could test at 35A (0.125C).

Is testing at that (modestly) higher charge rate worth the trouble? Have any Forum members recieved cells that failed under high-current charge?
I am trying to get my packs charged up so i can do a load test.... don't think these will ever see "high current" charge (.5c or 1c) one pack is charging at .1c and the other is .008c. today i will switch the packs around... i think my 4s pack is about 90% and finish with top balance
 

Ugh. The above picture pointed out to me that I fail to think out of the box sometimes. I had been looking around for the same type of connectors that came with the leads for my power supply. It never occured to me that I could simply put ring terminals on the output studs of the power supply.
redface3.gif
 
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