max charge for 72V battary

Joined
Aug 1, 2022
Messages
11
Hello

I own electric quad atv 72V 100AH battery

I bought this charger from AliExpress.the 84v version

https://www.aliexpress.com/item/1005004174738245.html?spm=a2g0o.order_list.0.0.9acb1802ZLqkc6


After first use (via slow charge 4ah in this case) the result was 84.7V

That’s mean - 84.7V after the charging is done.

p.s,
1.my stock charger usually show 83.9 or 84 after charging…
2. the reading of 84.7v is saw both on the atv display and also via votol software in the "display" page
3.i know that 90% charge will be safer, but I am looking to understand what is the correct number for "100% of charging"


My question is:

What is the max voltage that battery can carry in long run without damage it ? its 84.7 is o.k?
May Other have the same experience with that charger ?

Thanks

Uri
 
What is the max voltage that battery can carry in long run without damage it ? its 84.7 is o.k?
You'd need to provide more info about the battery itself. How many series cells, and of what chemistry? Without knowing that, you can't know much about it's voltage, charging, etc, other than whatever is marked on it's labelling. If you don't have that information, you may be able to get it from the manufacturer of the ATV. (possibly the seller, too, but they often have no information about the things they sell).

What were the original charger (that came with the ATV) specifications?

Most likely you would not want to use any charger with a higher voltage or current (amps) than what came with it, for safety, unless you know for sure the battery is designed specifically to handle as much as a different charger can output.

uri@re-avenue.co.il said:
Hello

I own electric quad atv 72V 100AH battery

I bought this charger from AliExpress.the 84v version

https://www.aliexpress.com/item/1005004174738245.html?spm=a2g0o.order_list.0.0.9acb1802ZLqkc6


After first use (via slow charge 4ah in this case) the result was 84.7V

That’s mean - 84.7V after the charging is done.

p.s,
1.my stock charger usually show 83.9 or 84 after charging…
2. the reading of 84.7v is saw both on the atv display and also via votol software in the "display" page
3.i know that 90% charge will be safer, but I am looking to understand what is the correct number for "100% of charging"


My question is:

What is the max voltage that battery can carry in long run without damage it ? its 84.7 is o.k?
May Other have the same experience with that charger ?

Thanks

Uri
 
Hello

i dont have any more information but the info that i have on the battary case - see photo
 

Attachments

  • נתוני הסוללה שלי.jpg
    נתוני הסוללה שלי.jpg
    4.5 MB · Views: 1,220
p.s, what dose it mean in the "discharge current <200" ?

i have a votol em150s that can support 250AH on s mode,

its that mean that my max current on S mode sould be no more than 200AH?
 
The battery says ‘use a lithium ion charger’ so you have the right one. Charge to 100% is usually fine.

It does seem to be finishing a bit high up tho. I would expect it to finish at 20x4.2Volt which is 84V exactly. You might want to contact the seller and ask if that’s normal

You need to set the current limit on your controller at max 200A draw, otherwise it will attempt to pull more from the battery and it might damage it or go into protection mode shut down.
 
thanks for the information : )

the seller from aliexprees answer me this:

Dear friend,
We understand your concerns,
Usually sold batteries are marked with a voltage of 4.2V
But the battery cells are protected, generally 4.25V
The pictures I posted above are companies that specialize in wholesale batteries, they describe battery parameters,
As can be seen from the battery parameters they gave, the charging voltage is normal at 4.25V,
Some companies directly indicate that the maximum charging voltage is 4.25V
Please do not worry,


what you can say about it? sould i belive it ? going to 84.7V
 

Attachments

  • Screenshot_20220803-105423_AliExpress.jpg
    Screenshot_20220803-105423_AliExpress.jpg
    139.3 KB · Views: 1,191
Do you include "shortening lifespan" in your definition of "damage"? Or only major immediately obvious problems like swelling or bursting into flames?

4.2Vpc is the MAXIMUM voltage allowed to avoid the latter. IOW stressful, more likely to create problems, wearing the bank faster.

4.15, and just stopping when touching that, not holding a long CV / Absorption cycle, is much better for longevity.

There is no reason to go higher, no significant range difference. Unless badly designed balancing gear requires holding V that high, better to get an adjustable unit.
 
damage for me is all the scale of damaging lol... shorts the life of the battary is enogh for me and yes - this is somthing i dont want at all.

the problem is not just the question if going so high, but if to use this charger at all.

if i will use it, i cannot be sure that i will have the right timing to disconnect it befor going so high, and in anoter words, that mean i will trwo this charger away and a i just spent more than 100$ for nothing.

p.s the seller also said that the +0.7v will not kill or short the life of the battary in general, but the currnt of the charging is,

for the current - i am using 5ah or max 10ah so with this parmeter i am o.k

so what will be the bottom line? not using this chager?
 
Even a dumb PSU can be used if you put in an HVC circuit to terminate its source.

Or a cheap additional BMS repurposed.

The point is, do not allow the pack to be mistreated, up to you how you do that.

Should not be charging unattended anyway, relying on automation too much is dangerous.
 
Ask the seller if there is a trim pot for voltage adjustment ?
And can you adjust it and keep warranty ? ? Depends on your bms mine is adjustable BT.. so different bms are all set different as far as balancing.
For long life charge to 4.0v x 20s = 80v and don't come close to full discharge. For long like. But bms might not balance at 80v or 81v ?
Yes confusing as China is..
 
uri@re-avenue.co.il said:
so what will be the bottom line? not using this chager?
Yes, the charger will be fine.

One thing to note is that if the old charger onky charged the battery to 84.0v and the new charger charges it to 84.7v, its means the BMS is allowing it.

After charging to 84.7v and letting it sit for a day, is it still 84.7v or did the bms bleed it down to 84.0v?

With a basic BMS kike you have you cant see whats going on without taking the battery apart. But if the charger charges it to 84.7v and it holds, it means the balancing is done at 4.23v.

If you don’t fully charge it until the balance function does it job, you can actually have a battery with 19 bricks at 4.23 and one brick at 3.53v (about 40% charge). This brick will be the one that shuts down the battery even when the pack voltage is high,

10a or even 12a is within the 15a limit and should be very gentle on a 100ah battery. Its still a slow charger with that huge battery.

If you want to extend the life it depends how you will use this. If its for weekends then let it sit below full charge all week and charge it the night before you use it.

With my dimb lithium ion pack and charger i let it balance charger for a day and then drain it to 80% because it sits idle most of the time.


With my smart LiFePO4 pack i set it to stop charging at 3.5v and bleed to 3.44v (3.65v is max charge). I can monitor it and when it’s balanced I unplugged the charger.

If i had a battery as big at that one you have, it would have a Bluetooth BMS so i can see whats going on without taking it apart.
 
So,

i will charge again to 84.7 and leave it for a day and see what will hapand

if its stay at 84.7 - thats mean all the celles is balnced at 4.23v its indicate that this charge levle is o.k and safe to my battary ?

thanks you :)
 
Back
Top