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Battery or charger problem?

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Old 07-05-2013, 06:38 PM
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bowtah
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Default Battery or charger problem?

I'm just starting getting into RC boats and 3 weeks ago I bought Minimono with a Venom Balance charger and a 13C 3-cell Venom LiPo battery. I broke the drive shaft on my first run and the coupler on the second run, but I was able to replace/repair both.

Yesterday my boat was going very slow and then stopped completely, even after I had just charged the battery for a couple hours. The rudder would still move and the prop would move for a second or two when the transmitter was paired, but it wouldn't move after that. I called Hobbico and they asked if I had a voltmeter which I didn't so they said they would send me a new ESC.

Today I went to a local hobby shop where I got a new 13C LiPO and picked up a voltmeter. I checked my old battery and it was way unbalanced, something like 2/3.8/3.8.

I put the boat in the water and it ran fine for a while. It started to slow down a bit and then died before I could get it back to shore. I checked the batteries when I took it out and the 1st cell read about 2 and others were at about 3.74. I charged it for serveral hours and cell one came up to about 2, but quickly dropped down to < 1 as I watched the voltmeter.

So now I have two batteries that have a bad cell 1 and I'm wondering if it's my charger that's damaging them. So, my questions are:

Is the problem with my charger, the ESC or do I just havebad luck in batteries?

Are my batteries recoverable?

Is it safe to leave these batteries charging for hours with how unbalanced they are? I've read up on how LiPo batteries can become unstable, so I've been charging them in the fireplace behind a screen just in case.

Thanks for the help!

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Old 07-06-2013, 08:42 AM
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Default RE: Battery or charger problem?

Sounds like you are unlucky in the battery department. But there is something you can try.

Your balance plug has 1 red wire and 3 black wires. Your statement of "2/3.8/3.8. says to me that cell #1 is the culprit.

If you have alligator clips for your charger, connect the red clip to the LARGE red battery wire.

push a small pin into the balance connector black wire next to the small red wire and attach your black alligator clip to that.

Set your charger to 1 cell. It should read the voltage of that one cell. Charge that one cell. If it's not too low, it'll charge.

Take the above charging advise at your own risk. In theory it should work. I haven't tried it myself with one cell, but I have brought back a non puffed 3 cell battery that was only putting out 1.8v total. (A friend left his esc switch on for 2 weeks.) [X(]
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Old 07-06-2013, 10:48 AM
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bowtah
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Default RE: Battery or charger problem?

Thanks crispyspa. I have just the basic venom balancing charger. It has no switches, just 3 indicator lights. Right now my battery is showing 1.9/3.74/3.75 After charging for several hours but cell 1 drops quickly as I watch the voltmeter. The charger's lights are all green. So I'm wondering if my next purchase should just be another battery or a better charger or both.
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Old 07-06-2013, 01:56 PM
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Default RE: Battery or charger problem?

a better charger is worth every penny as it MAY prevent loss of more cells.  It sounds to me as though cell #1 is already lost due to the large voltage fluctuations.  This may be as a result of the charger.

If you get a new battery, check all the cell voltages before doing anything, write them down.  Then allow the charger to "fully" charge your battery.  Fresh off the charge, get you cell voltages (don't be alarmed if they are different - top balancing is stupid)

Let the charged cell rest (just leave it alone) for 24 hours or longer and check the cell voltages, they should be the same or at least close.
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