Pulse 860 mah battery high internal resisitance

[tworst]

I just got 4 new Pulse 860 mah batteries for my 250 and put them on the charger. I noticed that on all of the batteries, on all of the cells, the internal resistance was about 25 mohm. These are brand new, never used yet, and this seems way high for the internal resistance. I have a lot of other batteries and even my oldest ones don't show anything this high. Am I missing something?

[Slyster]

Well two things. The smaller the capacity the higher the IR. So already they are normal.. plus you need to use them 5-10 times before the IRs will drop to their new normal.

[tworst]

Thanks for the info Sly. I will see what my old 850 Align batteries are currently at on IR for comparison and also check my new 860's after a few cycles too.

[Xrayted]

Originally Posted by tworst

Thanks for the info Sly. I will see what my old 850 Align batteries are currently at on IR for comparison and also check my new 860's after a few cycles too.

IR is inversely proportional to capacity within the same battery.

For example if you have 5000 mAh packs of any particular brand and C rating (very important) and your cell IR is 2 per cell, then that same battery at 2500 mAh would have cell IR of 4, and then double again as the capacity gets cut in half and so on.

Higher true C rated cells will have lower IR overall, but the capacity rules still apply, so first you would need to know if the other same size batts you are talking about have the same C rating as the current one.

The problem with that is what's on the label is rarely ever the truth, and even the actual capacities can be off from what they are labeled, so all the IR can really do for you is to establish a baseline for that particular battery so you can see changes over time or detect a bad pack if one cells IR value is drastically different than the others.

[tworst]

Thanks for the education. I had no idea batteries were different like this.

[Number]

That's about what mine were.

[Smoggie]

Also IR varies strongly with temperature. A battery that is warm either because it's been in a worm place or has been active (charged or discharged recently) will have a significantly lower IR than a battery that's rested in a cool place. You can see this is you charge (or discharge) the battery then check it's IR again immediately after, it should be lower.

Furthermore IR varies quite dramatically depending on what you use to measure it with. Powerlab chargers for instance will often give IR values half of what other devices measure.