lipo batteries

[pistol_pete_2011]

Hi ive got a losi 8ight 2.0 & ive just changed to lipos ie receiver pack & regulator..i charge & balance the receiver pack together but when i go to track my dx3s flicks to 4.8 R.X ect & warns me of this & as you will know stops on fail safe due to the battery level... This is only after 5-10 minutes tops..
Please help !!!!!Thanks Dave

[leeleefocus]

Sounds like high Ri cells or one of the cells is bad. You need to load test the cells so you can see what they are doing during use. Could be several other things although the fact it is working for 5-10 minutes points towards poor quality cells or they are going/gone bad.

What pack is it you have so i can get an idea of what the cells are supposedley capable of. Should be able to come up with a way you can load test the cells as long as you have a fairly accurate way of monitoring the voltage.

[pistol_pete_2011]

Hi many thanks...the battery is Turnigy 2200mah 4 cell lipo...as we speak i have put on the charger CORE UAC-40..and it is only picking up 3 cells and it says only to charger if both are identical..but this is 4cell ..?? thanks

[leeleefocus]

First you need to check if the balance lead is broken or one of the cells has gone to low for the charger to detect it.

If you have a multi meter it's just a case of checking the voltage of each cell through the balance lead.

The Turnigy batteries are very good if you have a healthy battery but they can be prone to a bad cell once in a while which normally highlights itself from new.

Does it charge without balancing.

[pistol_pete_2011]

Hi yes it does but only charges for about 20 mins each time at 2 amp and says its full then put in car and then as a result of using steering and throttle its draining battery into RX warning = failsafe.

[damselfly]

Leelee has it spot on.
A cheap and crude way to check cells under load would be to place a low ohm high power resistor in parallel with your voltmeter. Check the resting voltage before doing this (without the resistor) for reference though.
If the cell voltages drop when under load, the internal resistance will be high hence premature low voltages.
You don't need to use a resistor, but it's an ideal load and can be tailored for your use.
Personally, i'm not a big fan of Turnigy cells and have noticed a fair loss in performance from them within about 90 cycles of usage.