battery resistance

[urbs00007]

I have (2) 2-year old thunderpower 65c 6-s 5,000 batteries. one no longer shows resistance numbers on my cellpro charger. the other one does. they both show individual cell voltages. what gives?

[Make-a-Wake]

Found this on a Lipo tutorial:

In simple terms, Internal Resistance is a measure of the difficulty a battery has delivering its energy to your motor and speed control (or whatever else you have a battery hooked up to). The higher the number, the harder it is for the energy to reach its preferred destination. The energy that doesn't "go all the way" is lost as heat. So the internal resistance is kind of a measure of the efficiency of the battery.

The first reason internal resistance is important has to do with your battery's health. As a LiPo battery is used, a build of up Li2O forms on the inside terminals of the battery (we'll go more indepth on this later in the Discharging section). As that build up occurs, the IR goes up, making the battery less efficient. After many, many uses, the battery will simply wear out and be unable to hold on to any energy you put in during charging - most of it will be lost as heat. If you've ever seen a supposed fully charged battery discharge almost instantly, a high IR is probably to blame.

http://www.rogershobbycenter.com/lipoguide/

Your bad lipo probably needs to be retired or hit the salt water bath

[kevinpratt823]

How does the pack perform?

[urbs00007]

reads resistance sporatically. just put into storage mode and it read all the cells well within decent readings then charged the pack and saw no readings. going to check other packs to see if its the charger??!! very strange. have been running those tp packs in one-way saw boat, just down to 3.9 volts per cell. will run in my oval rigger to test .

[kevinpratt823]

I meant is it still giving adequate power and runtime? I've had a couple that wouldn't read, but still performed for some time. The chargers depend on several readings to calculate IR, and it's really only accurate towards the end of the charge I believe. The charger may just not be able to get the info it needs to calculate, I wouldn't consider the pack spent, as long as it performs and charges/balances OK, and the charger isn't giving you any kind of warnings, but that's just me.

[urbs00007]

I meant is it still giving adequate power and runtime? I've had a couple that wouldn't read, but still performed for some time. The chargers depend on several readings to calculate IR, and it's really only accurate towards the end of the charge I believe. The charger may just not be able to get the info it needs to calculate, I wouldn't consider the pack spent, as long as it performs and charges/balances OK, and the charger isn't giving you any kind of warnings, but that's just me.

just found out the charger doesnt give readings when fully charged , only when charging. sorry for wasting your time.

[785boats]

reads resistance sporatically. just put into storage mode and it read all the cells well within decent readings then charged the pack and saw no readings. going to check other packs to see if its the charger??!! very strange. have been running those tp packs in one-way saw boat, just down to 3.9 volts per cell. will run in my oval rigger to test .

I'm not sure about the ICharger (I don't have one), but my Hyperion won't display an IR value on the cells if a charge is started with the cell voltage at 3.9 or above. Just not enough load or time, or both, to form the calculations as Kevin suggested above
If I discharge down to 3.8 or below & then start a charge, the IR numbers come up after a few minutes.
Maybe the ICharger does the same thing. Take the pack down further & see if it does.
But Kevin is also correct in saying that the most accurate reading is at the end of the charge, when the pack is full. The numbers can change during the charge.

[Mike Caruso]

i106B any time I select and press the button I get IR. pretty cool