Originally Posted by Skiddins

Why not get the usable voltage test to stop at 7.5V etc for the pack?
No-one will be running a pack below as low as 6.6V unless they've forgotten to change it from the last run

Originally Posted by jedi

John, are you using a 24 volt power supply to charge 2s batts at 25amps or will a 12 volt power supply do? If not, what is the maximum charge rate using a 12 or 14 volt power supply? Thanks.

Originally Posted by John Wallace2

12V Car Battery so I can discharge at over 20 amps (cannot do that with a power supply on the ICHARGER). Don't know what the max charge rate is for a 2C pack with a 12V input power, but I've done 25 amp and no problem from the charger point of view (just make sure your battery has enough C rating to take that charge rate), but I usually charge at 20.

Originally Posted by Miholc

Capacity winner of 2S HC pack: LRP 7500, 7200mAh usable from 4.2-> 3.3V/cell @ 200W constant discharge.

Originally Posted by EAMotorsports

Sure you can discharge at 40 amps on the icharger using the power supply if you use a resistive load such as bulbs or resistor bank. I do it all the time.

With my 12v power supply I can charge 2 2S packs at 40 amps each with no issues either. 24V is not required.

EA

Originally Posted by dave-man

This may be a silly question but how can you measure capacity?

Originally Posted by EAMotorsports

Sure you can discharge at 40 amps on the icharger using the power supply if you use a resistive load such as bulbs or resistor bank. I do it all the time.

With my 12v power supply I can charge 2 2S packs at 40 amps each with no issues either. 24V is not required.

EA

Originally Posted by Miholc

You are obviously not understanding how 4010 charger measures the IR.

IR can only be measured on the 4-wire Kelvin method, you can see more here: https://www.youtube.com/watch?v=N8QhXewcAXY

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

If you read instructions carefully you will note the charger gives you few different IR readings :-)


Now the answer what causes the IR to change. It is the temperature! Generally - more temperature gives lowe IR, but not all LiPo chemistries have the same behaviour. If you can controll the temperature you can heat up the cells from room temperature up to 110 F you will definately see IR decreasing.

Charging at higher amps heats up the cells, thus IR goes down. You can also cycle the lipos fast in sync mode on 4010... 1S goes nice with 40Amp discharge

Edit: Yes, you need to have also balancing conector setup for 1S to have IR measured correctly. Sorry...

I measured a lot of LiPos lately. No time for report yet :/

So far:
IR winners: LRP 7500 big mama at 40°C only 0.7/0.9 mOhm/cell on the test sample.
Capacity winner of 2S HC pack: LRP 7500, 7200mAh usable from 4.2-> 3.3V/cell @ 200W constant discharge.

Originally Posted by Outlaw 44

All that high charge/discharge rate hoopla is bull**** if you ask me.

Been racing oval for 22 years now. I think I have a decent feel for what actually makes my car go faster, that stuff isn't one of them.

I race in St-Hyacinthe Quebec, TOUR Spec class with the Salvas Brothers every two weeks, 146 foot runline on new CRC carpet. Two Sundays ago I was part of a 5-car field which all finished on the same lap (an average lap is about 3.6 seconds) after a 100-lap race. The race lasted about 6 minutes.

This past Sunday at the New Year's Dash in Oneida NY, Steve Salvas finished 2nd in the TOUR Spec A-main against some of the best drivers in the business, Eric had a 2nd or 3rd place car before getting involved in a wreck. this is just to give you an idea of who these guys I race against are.

I charge between 6 and 8 amps between qualifying and feature rounds, and never discharge between runs. I'll charge at 12 amps during practice just so I can hit the track again faster. There's no point in charging at a higher rate, my battery will just be done charging before my motor gets a chance to cool down from it's last practice run or before I can finish making changes to my chassis.

I've been running the same SMC 7000mah battery for all my practice/heat/main runs since I bought it new in June. I don't see the need for high charge or discharge rates period, I truly believe that the life span you lose in the battery isn't worth the infinately small extra ''punch'' I can't even feel on the track anyways. The battery still feels like it did back when I bought it, I think a less aggressive approach to charging has helped me keep it in good shape.

Before June 2014 I was running a used battery I bought from a fellow racer. When I went to the new battery, I couldn't feel any difference in speed. What helped me is working on the chassis, and managing my tires. Some hints from the Salvas brothers helped me on the chassis setup end of things.

Don't give into the hype