guver

My Feedback: (325)

If a number of nimh batts are hooked in series and discharged together will the higher voltage cells discharge at a faster rate or at the same rate for all?

I am told that the slightly highest voltage cells will discharge faster, but don't know whether to believe it.

AS-EE

The batteries in series all have different internal resistance and it is not possible to equal discharge distribution across each battery. You would have to discharge each one individually.

guver

My Feedback: (325)

Ok, would you say that on a pack of 3000 x 8 cells (that was charged full and each cell held 3000 mah) when discharged in series all the cells would not deliver around 3000 mah at exactly the same time?

guver

My Feedback: (325)

If I am understanding you properly then on a typical batch of random (8) cells if all were discharged in series then what may be the high and low spread for mah? like from 2800-3200? or might it be a lot closer than that like 2990-3010?

AS-EE

When you connect batteries in series or for that matter electrical loads in series then you will have the same current flow through ALL of them. Now the voltage drops of the individual elements will be different, but as stated the current WILL be the same throughout all.

Flying Geezer

My Feedback: (14)

Guver, it's not healthy to think about batteries too much.

JNorton

My Feedback: (2)

The cell with the highest internal resistance will limit the output of the entire pack. Internal resistance is dynamic depending upon load and temperature. If one cell in the pack has a measured capacity of 2600 mAh and the others are a measured capacity of 3300 mAh. You basically have a 2600 mAh pack. Hope that answers you question.

John

guver

My Feedback: (325)

I t sounds like you'all in agreement that every cell in the pack will deliver the same rate. (If they therorecitically had the same capacity) Here's the link by the way.

http://www.pro-trak.co.uk/

JNorton

My Feedback: (2)

Guver, even if they don't have the same capacity. In a series circuit all currents are equal so in this case the weakest battery will limit the entire string to that capacity. So if you build a pack with three 3300 mAh batteries and one 1100 mAh battery (and they were charged individually before the 1100 could be reversed) your packs total capacity would act exactly as if it was composed of 1100 mAh cells.

guver

My Feedback: (325)

I was theoretically building a pack with all the same capacity (3300) yet the question was with the average voltage or even the IR of the cell. It is said that the higher voltage cells will actually discharge at a greater rate even thought they are alll hooked in series.

I willdo some reading on the pr0trak site and see if I am mistaken or see what they claim.

Flying Geezer

My Feedback: (14)

The current I is the same at all points of a series circuit. Kirchoff's law, I think.