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Model Forum / Radio Controlled / Air Models / July 2007Lithium Polymer batteries discharged to very low level with NO load.
Hi, I recently experienced a problem with a set of LiPos whereby the batteries became discharged to a very low level (one to 3.4V and one to 0.1V). I was in a rush when leaving for the weekend and simply removed the batteries from my vehicle by disconnecting the Discharge Protection Modules from the power distribution board. I did not remove the DPMs from the batteries however. Is it really possible that the DPMs draw enough current with no load attached to drain a set of 85% charged (22.2V) batteries to such a low level in the space of 48 hours? Has anybody else experienced this? The batteries in question are BalancePro Compatible 22.2V nominal with a 3200mAh rating. | I recently experienced a problem with a set of LiPos whereby the | batteries became discharged to a very low level (one to 3.4V and one | to 0.1V). I was in a rush when leaving for the weekend and simply | removed the batteries from my vehicle by disconnecting the Discharge | Protection Modules from the power distribution board. I did not remove | the DPMs from the batteries however. You mean this -- http://www.fmadirect.com/detail.htm?item=2046§ion=38 ? If so, docs are here -- http://www.fmadirect.com/support_docs/item_1191.pdf ... and they do say to remove power by disconnection the DPM from the battery, several times. | Is it really possible that the DPMs draw enough current with no load | attached to drain a set of 85% charged (22.2V) batteries to such a low | level in the space of 48 hours? Has anybody else experienced this? Well, let's do the math. 85% of 3200 mAh, divided by 48 hours = 57 mA. Could this device use 57 mA of current? I don't know -- that seems high, but not impossible. You might want to contact FMA and ask. You could also measure it yourself pretty easily. Actually, the instructions say that the current draw is 10 mA, last page. So if this is correct, and your battery really had 2700 mAh of capacity left, this should not have trained the battery completely in 48 hours. Was there anything else connected? Is it possible that the way things were set up that you also had your RX and servos connected and drawing power? Either way, don't ask us. Ask FMA. I'm guessing that few people have actually used this specific device, but you might find more people who have on rcgroups. | The batteries in question are BalancePro Compatible 22.2V nominal with | a 3200mAh rating. Ouch. Expensive mistake.  SignatureDoug McLaren, dougmc@frenzied.us "There are only 10 types of people in this world: those who understand binary and those who don't." > | I recently experienced a problem with a set of LiPos whereby the > | batteries became discharged to a very low level (one to 3.4V and one [quoted text clipped - 33 lines] > actually used this specific device, but you might find more people who > have on rcgroups. And most of those wouldn't touch anything to do with anything that FMA makes with respect to LIPOS. > | The batteries in question are BalancePro Compatible 22.2V nominal with > | a 3200mAh rating. > > Ouch. Expensive mistake. Yup. Reminds me of the UK situation to prevent death by electric shick. We have earh leakeg trips that plunge the whole house into darkness at te first hint of a surge. More people arer killed falling dpwnstairs to reset the trips in te drakk.. So it is with theese wonderful LIPO balancers! Protect Your Investment! Ruin Your Pack! And Fred bloody Marks gets to sell you the same crap TWICE!! Its GENIUS. > Hi, > [quoted text clipped - 11 lines] > The batteries in question are BalancePro Compatible 22.2V nominal with > a 3200mAh rating. Yup. Done similar. Left em plugged into my whattmeter over a weekend. The good news is they aren't dangerous., The bad news is you will have now got a very heavy expensive 1600mAh battery instead.. I have brought packs back from complete flattening, but the longer they are in that state, the less comes back. Frankly my friend, unless you are curious, bite the bullet and bin them They will never fly properly again,. Thanks for the input. They are indeed what I was using. I misplaced the docs early on though and hadn't managed to find them on the FMA site. Cheers Doug. I'm not worried about binning them, it's a shame that they're ruined, but I've got spares and there is plenty of budget left to buy more (I'm working on a research project). I just wanted to get to the bottom of it, but now that I have the docs, it's pretty clear that it's my fault. The best lessons are learnt the hard way. |
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