Battery IR Readings
 

I have been having a fit with performance in my 10th scale vehicles and could not figure it out, it was killing me. I would run them on the bench and everything was fine, but put them on the ground and they took off fine, then run very slowly. At first I thought it was the ESC, so I ordered one, not that. I ordered some new batteries as I know mine are getting old, then checked the car out, and it was fast again. I also ordered a 4s for the e buggy, and it was stupid fast again. So I remembered hearing about IR readings and went on line to see what that meant. My I 206 charger can read IR. The article said basically that over 20 MA OHMS is worn out for a 2s battery and should be replaced. One of mine read 112! What a shocker, no wonder it was dead. I also checked the others and all my shorty packs were trash. So I got a bucket of water and disposed of 8 batteries. I am still going to use my 4s basher batteries at 45 ma ohms, but when they hit 50, good bye. I noticed that the longer 2s batteries held up the best. This has been a very frustrating experience, but now I know how to check my batteries and not waste time and money trouble shooting other areas. I am sharing this with you so you will avoid the mistake I made. Please check your batteries before the race season begins, so you don't have to wonder why you finished back in the back and went slower in the race.

For racing, all my batteries are under 2 milliohms per cell (more like 1.2 or less depending on age). When you see really high IR numbers, it's often the connector isn't making good contact. I would check that first before tossing out batteries. Just split the bullet with an xacto knife and it should read properly again. Not saying this is the case for your batteries, but it happens to me every so often with loose charge cable bullets.

If your charger is also multi- channel, it helps to see how the measurement compares between them. For example, my Protek 2 channel charger always reads almost double the IR on channel 2 vs. Channel 1 using the same battery and cable. Makes me think that the internal circuitry between channels is contributing to the difference, but have not been able to compare to another unit.

The readings were so bad that there was no way I was keeping them. 112 is a horrible battery no matter how you look at it, and 85 is not much better. So glad I got on board with reading IR on my batteries. Now I can concentrate on other areas, and quit wasting money because of batteries burning out.

What kind of batteries are you using that you are getting 1/2 for IR? ... and how are you charging/cycling them? thanks

I think you must have misread I put 1.2 milliohms per cell, so 2.4ish total on a 2 cell (I've never seen 0.5 milliohms per cell). I'm currently on the Team Powers 6600 in my 17.5 TC.

A cold battery will have higher IR (maybe around 3.6 ish per cell if you haven't used it in a while). So cycle at 40amps in the morning, run during practice charging at 40, and while waiting for your heat, cycle 40 amps at least once, more if you have time.

I got 1.2 + 1.4 on one on one of the TP 6600s that I've had since last summer. On a newish battery, I can get 0.9 per cell maybe lower but it's not really worth the trouble, probably deteriorates the cells a lot quicker, and usually involves technically being ROAR illegal (your battery cannot be more than 5 degrees over ambient).

If you use the battery through the race day, the IR should be the lowest right as you finishing your mains charge.

There are definitely safety concerns, probably wouldn't do any of this if you're just starting out. Use silicone 10awg charge leads bullets only. All connectors should have a tight fit. Don't use the cheap plastic wire or connectors since these will heat up and melt.

IChargers I'm told are calibrated from the factory so provide much more accurate readings of voltage, IR, etc... They are pretty much the gold standard of high-end rc charging. Especially the 406 duo which has been around since at least 2012 you will find when you go to basically any stock race. You can also adjust the end voltage calibration to get as close to the legal limit as possible.

My batteries are usually in the 1 to 2 IR per cell, and they're a mix of brands (Orca, Team Powers, Sunpadow). I charge at 10A, no cycling ('cause those are the rules where I race). The quality of the charge cable and connectors can make a big difference to the IR readings so comparing between different chargers/cables can be iffy.