bit of a lipo problem!

[Team Orr]

hi guys,

I have been having trouble charging the lipo or dead meat, I have charged for at least 48hours and when I plug it in to the speedo?nothing

But when I plug the speedo into a huge 120g a-a battery pack it is buzzing along fine.

The lipo isn?t blown (I have checked)

This is the lipo

http://robotbirds.com/catalog/product_i ... cts_id=651.

This is the speedo
(Sabertooth dual 5)


http://www.technobots.co.uk/acatalog/On ... rs_34.html

this is the power source

http://www.allelectricrc.co.uk/power-su ... -996-p.asp

this is the charger

http://www.sussex-model-centre.co.uk/sh ... sp?id=5530


any help appreciated

cheers

jack

[Link fixed by Admin]

[BeligerAnt]

The lipo isn?t blown (I have checked)

How have you tested the LiPo? Just measuring its voltage is not enough, you need to see what it does under load. Flat or otherwise dead batteries (of all types) have a nasty habit of looking perfectly OK if you just put a voltmeter across the terminals.Try connecting a suitable load (e.g. motor, torch bulb etc) to it and measure the voltage under load.

The charger you have looks (from the description) to be totally wrong for the LiPo pack you have shown. The pack is rated 250mAh, the charger has output current settings of 1000mA, 1500mA and 2000mA.

A LiPo pack should be charged at no more than 1C, i.e. the charge current (in mA) should be no more than the capacity (in mAh). So a 250mAh pack should be charged at no more than 250mA.

It should take no more than 4 hours to fully charge a LiPo pack, assuming a 1C charge rate. Like most rechargable batteries, they may take several charge/discharge cycles to reach full capacity. They will work on the first charge, but the charge will not last quite as long as it should.

The maximum continuous discharge current for that LiPo pack is 1.8A. Depending on the motors you are trying to run, you could easily exceed that trying to start 2 motors at once.

[peterwaller]

A coupler of things spring to mind what is the output voltage of the battery as many chargers either inhibit chargeing or limit it to a few ma if the battery is below a certain level. Are you sure the charger is set to the correct number of cells.

[leo-rcc]

I have the exact same Lipo in Katjuscha (or at least I used to) from the same supplier and so far they have been hit and miss. Some are great, and the second one I had in there held out for a long time (well over a year) but I've also had 2 of them die pretty much on the spot. I've got one in "DBA Evil but not quite so evil as the previous evil but still right up there" that I've used for demo's and that works very well so far.

The ones that died on me don't look swollen and still supply a voltage but when it is time to draw a current they just fail.

Right now I am looking at the atomic workshop Lipo's and the Kokam cells to save some weight.

[Cavecrusher]

I have the exact same Lipo in Katjuscha (or at least I used to) from the same supplier and so far they have been hit and miss. Some are great, and the second one I had in there held out for a long time (well over a year) but I've also had 2 of them die pretty much on the spot. I've got one in "DBA Evil but not quite so evil as the previous evil but still right up there" that I've used for demo's and that works very well so far.

The ones that died on me don't look swollen and still supply a voltage but when it is time to draw a current they just fail.

Right now I am looking at the atomic workshop Lipo's and the Kokam cells to save some weight.

I've used the atomic workshop ones in DBA Evo for several competitions, no problems so far.