The Samsung spec sheet states the charging rate of single cells as 1.5 amps for longevity.

 

Am I correct in thinking that a 13S4P battery pack can safely be charged using a 6 amp charger?

Many 48 V batteries come with 5 or 6 amp chargers.

 

For that cell it would be .5C wouldn't it?

Many 48 V batteries come with 5 or 6 amp chargers.

 

For that cell it would be .5C wouldn't it?

The dolphin pack I've been looking at only comes with 2A charger. I've not seen any vendors supply these packs with anything higher.

 

Just wanted to confirm if it would be ok to use a 6 amp charger instead, or is there a reason they don't come with higher as standard?

Edited July 21, 20169 yr by Fordulike

Best to stick to the charger supplied the BMS may not support higher charge current. It should be in the specs for the battery, sometimes you see "fast charge current..."

Best to stick to the charger supplied the BMS may not support higher charge current. It should be in the specs for the battery, sometimes you see "fast charge current..."

Aha, the BMS, yes of course. Thanks for the info anotherkiwi

I've been trying to get my head around the principals of voltage and amps again. I know I know, by now I should have a clue lol.

 

My understanding is, that a device will only draw enough amps for what it needs. I.e. a charger just supplies amps and doesn't push them into a device.

 

So, if I were to use a higher rated charger, the BMS will only draw enough amps for what it is rated at, or needs. Would this assumption be correct?

Edited July 22, 20169 yr by Fordulike

I've been trying to get my head around the principals of voltage and amps again. I know I know, by now I should have a clue lol.

 

My understanding is, that a device will only draw enough amps for what it needs. I.e. a charger just supplies amps and doesn't push them into a device.

 

So, if I were to use a higher rated charger, the BMS will only draw enough amps for what it is rated at, or needs. Would this assumption be correct?

Maybe not.

 

Charging a battery is an unusual case.

 

In order for current to flow into the battery, the charging voltage has to be higher than the battery voltage. The battery itself has a small resistance. This and the voltage difference (V/r) determine the current. In many cases this would result in too greater charge rate, so the charger will restrict the max current (say 2A) to prevent damage/fire/divorce.

 

As an example, a battery at 32v, connected to a 42v source has a volt difference of 10v. If the batteries internal resistance is 1 ohm, 10amps would be drawn when connected, so that's why the charger must limit current.

 

 

The batteries internal resistance is an important factor, and will also govern the point at which current begins to drop below the 2A limit. In the above example, with 1ohm, when the battery reaches 40V the current will begin to drop below 2A, tailing off to 0A as it approaches 42v

Edited July 22, 20169 yr by Alan Quay

The current that flows is dependant on the battery and charger resistance and voltage difference between battery and charger.

Is the higher rated charger higher voltage or higher current.

 

What is the bms settings is it a cut out protection or current control?

All these and more questions spring to mind.

Ok havin read Alan's post above I do have a factor to add.

The supply resistance if it was 1 ohm and the battery 1 ohm then the current would be 5 amps.

Normaly the supply resistance is so much lower than the load engineers don't usually factor it in but lithium batteries are very low load resistance.

Edited July 22, 20169 yr by D8ve

Thanks Alan and Dave for your replies. As it's not so clear cut, and for the reasons of safety, I'll probably stick with the supplied 2A charger.

 

Very interesting info though!