20s10p battery charger power?

Hello.
A short question. If i have a 20s10p battery 72v 30Ah. What would be the optimal charging current for it? Is it 10% of its rated capacity so 3A or more? And voltage also? 84v or more?

The most important thing what chemistry what is the exact cell that you're going to use yes the name of the cell the model number.

It would be li-ion battery model : LG 18650 HG2 3000mAh.
But i will see if a better deal comes up by the time i will be buying cells.
Im asking in general terms for 20s10p pack with 3000mAh batteries.
What would be reasonable amperage to charge them so batteries don't get abused?
Charging time is not criticall.
Thanks

Cerko said:

What would be reasonable amperage to charge them so batteries don't get abused?
Charging time is not criticall.

Click to expand...

The slower the charge the better.

If you need them fully charged in 3 days...

Say you start with 10AH charge still left:

20A / ( 3 * 24 ) = 0.28A charge rate

It also depends on the BMS you using at 10 amp you should be able to handle 10amps if your BMS will let it.

The data sheet for the HG2 states 1.5A standard charge and 4A fast charge.
I charge my 8P pack of Samsung 35E at 5A. Its data sheet states 1.7A standard, 2A max, and 1A "for cycle life", so I guess 5A is pretty slow/conservative, since 8A would be "for cycle life"

Seems like you could do 15A, or 8A-10A for cycle life. All contingent on how your BMS works.

I understand now. So I should check the data sheet for the cell. Take the cycle current and multiply it with amount of parallel sections in my pack.
That makes perfect sense.
Thank you for the help.

Slow charging is definitely better for battery lifespan. Yet, it is cell temp during charge that is the indicator of abuse. As long as charging does not increase battery temp, it is not abusive by any means. This is directly related to cell spec in terms of internal resistance, or charging C rate.

When we need fast charging, we select the cells for this purpose: low IR/high charging C rate. We accept some heat during charge, a compromise between the expected life and the advantage of fast charging. High C rate cells are better surviving abuse, and they have the longest life expectation when treated conservatively.

The best charging method is adjustable, volts and Amps. Only then, you can set charging for your requirements, for specific cell spec or monitored temp. For a longer battery life, you set lower voltage and lower Amp, for slower charging and stopping below full charge spec. It is as simple as that.

Then, for extended battery life, you must apply the same principle to discharge: LVC must be set higher than cell min voltage spec, and Amps setting lower than cell discharge C rate.

0.4C is plenty gentle for good longevity assuming warm temperatures, full recharge in about 2 hours.

For 30Ah that is ~12A, around 1000W

Any slower only needed if getting colder than sweater weather.

In hot weather 0.7 up to even 1C will not shorten life cycles much, so twice as fast when needed.

If your gear is safe enough to leave unattended say overnight

then 0.1C of course means 8-9 hours recharge time.

The fact is a 10amp 72v charger is easier and more available to get than anything above that plus you have to be able to plug it into your wall and not pop the circuit. How much is a plug and play 72v 12 amp charger or above ? Availability.
I recently bought a 72 volt 10 amp charger and I plugged it in and it blew fet . They wanted me to take it apart and soldered back together but I decided to just have them return my money. So then I bought a boost charger I've used it a couple times it seems to work. But still looking for a plug and play 72v 10 amp battery charger. Kingpan had one for 85.00 plus shipping 86.00 What ? I guess this is where Trump's tariff comes into it. So still looking.

I am used to paying many hundreds of dollars per charger, and having an electrician install dedicated high-amp circuits

but yes of course cheap ones will be lower power.