Answered - battery draw/drain with multiple Li-ion cells

[Old-Lumens]

I have a high amp need for a light. It takes four 18650 in PARALLEL.

The amp draw on high will be about 14 amps.

My question is this:

Will four cells in parallel all try to give the max amps at the same time, or will the inherent differences in four cells cause them to be uneven?

For instance, will one cell possibly give 5 amps and another give 3 amps, etc.?

Will four cells in parallel have any possibility of giving 14 amps? or will it just be a foolish attempt?

I'm thinking of the Sanyo red 2600mA batteries, since they look good on 5 amp tests and with four in parallel, I might just get the 14 amps?

[Old-Lumens]

I can't believe no one knows the answer to this?

[DBSAR]

@Old-Lumens

I have a high amp need for a light. It takes four 18650 in PARALLEL.

The amp draw on high will be about 14 amps.

My question is this:

Will four cells in parallel all try to give the max amps at the same time, or will the inherent differences in four cells cause them to be uneven?

For instance, will one cell possibly give 5 amps and another give 3 amps, etc.?

Will four cells in parallel have any possibility of giving 14 amps? or will it just be a foolish attempt?

I’m thinking of the Sanyo red 2600mA batteries, since they look good on 5 amp tests and with four in parallel, I might just get the 14 amps?

If all 4 of the cells are the same age, same type, simmilar internal resistance, from the same manufacturer group, and in the same condition (new?) they should “stabilize” each other when in parallel ( especially if they are the un-protected type which has no amp-limiting circuit) ( all postives across & all negatives across) much in the same manner as multi-cell electric fork trucks do.

One complex way of testing the amp load vs run time, is to connect four or five , 55 watt H3 incan Halogens in a circuit with a good analog Amp meter with a rating of 30 amps or higher to the 4 18650 cells in parallel in the circuit, and comnnect a volt meter to monitor the voltage drop with the increasing load over time, by starting with 1 bulb to the circuit, (in parallel also) and adding another one at a time untill you reach a 15 to 18 amp load, ( add a 15-amp auto fuse for saftey, and if it blows you know you were able to exceed 15 amps, ( each H3 is roughly 4 amps of static load if i remember correctly.

[Johm]

@Old-Lumens

My question is this:

Will four cells in parallel all try to give the max amps at the same time, or will the inherent differences in four cells cause them to be uneven?

For instance, will one cell possibly give 5 amps and another give 3 amps, etc.?

Will four cells in parallel have any possibility of giving 14 amps?

4 cells in parallel will try to give the same amps, if the cells are significantly different though they will not be able to do so.
If you are going for 14A total I don’t think you will have any issues with any good 18650 cell including these sanyos.
The current draw on each cell will be 14/4 or 3.5 A on each cell.
If you were going for 20+ Amps the high drain cells could be a better choice but for 14 i beleive these sanyos are a very good choice.

[HKJ]

@Old-Lumens

Will four cells in parallel all try to give the max amps at the same time, or will the inherent differences in four cells cause them to be uneven?

It will balance itself. The cell will the highest voltage and lowest Ri will supply most current, but only for a short time, then it will be down to the level of the other cells and they will help each other.

[Old-Lumens]

Thanks for the replies.