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Need help on figuring out the problem with my batteries.

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Old 12-27-2018, 11:32 PM
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Jacob Horsfall
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Question Need help on figuring out the problem with my batteries.


Ok sorry if this is a long post I just want to include all of the information. I have had about 5 batteries since I got my rc truck and they all suffered similar fates. It all started about 4-5 years ago when I got an exceed rc infinitive brushless truck for my birthday. It worked fine at first, but battery life was short. It came with a 8.4V 3000mAh NiMh battery. (Note: all batteries I had were 7 cell NiMh batteries) I went out and got a second battery, this one being an 8.4 volt 5000mAh NiMh Onyx battery. About this time I was also given a Traxxas ez peak charger and swapped from the original connectors to Traxxas connectors. They onyx battery lasted a few charges/discharges and then didnít work at its normal power. I felt the battery afterwards and some of the cells were hot while others were cold/room temp instead the entire battery being warm. Needless to say, I took it back and exchanged it for an 8.4V 5000mAh Venom battery, which then suffered the exact same fate. I took that one back and exchanged it again for the same battery except this one worked. After a couple times of me using it, I took it outside in the middle of winter to mess around in the snow, and the battery suffered the same fate, where some of the cells stayed cold and other got hot, except this time the ones that got hot got so damn hot the plastic around some of the cells melted, while some of the other cells stayed normal temp. I take that battery out, and put in the one that came with the car from the factory, because that battery has lasted forever, AND IT DOES THE EXACT SAME THING AS THE VENOM BATTERY BEFORE IT. So now I donít have a single battery and Iím trying to figure out what the hell is going on. I am pretty good at the mechanical stuff, but when it comes to the electrical stuff I am just a dumpster fire. I know itís probably user error so donít bash me for it just please tell me what Iím doing right/wrong and/or how to fix it. Thanks it advance.
PS. I would include picture but apparently I need 10 posts so if there is a work around for that lmk. Thanks
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Old 12-28-2018, 06:35 AM
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A. J. Clark
 
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Have you checked any of the other parts that the battery supplies power to. Sounds like your battery is being over loaded. Before you blame the battery for all your trouble you should ckeck other items to. Drive train for binding and drag. Motor and esc. Anything that would cause a lot of unnecessary friction. Good luck.

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Old 12-28-2018, 08:01 AM
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Jacob Horsfall
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Originally Posted by A. J. Clark View Post
Have you checked any of the other parts that the battery supplies power to. Sounds like your battery is being over loaded. Before you blame the battery for all your trouble you should ckeck other items to. Drive train for binding and drag. Motor and esc. Anything that would cause a lot of unnecessary friction. Good luck.
The mechanical stuff seems to be fine, but how would I check the electrical stuff like the esc?
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Old 12-28-2018, 10:51 AM
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If your charger is capable of cycling batteries you can check battery capacity. If you have or can get a watt's up watt meter it can be put on your vehicle while it in use for testing. You get voltage, amp, and watt hour readings with watt meter.
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Old 12-28-2018, 12:17 PM
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Jacob Horsfall
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So I went into a local hobby store and the guy there said that my speed controller was draining my battery too fast/too much, and that I would probably need a new speed controller. Does this sound right to you, and is there a way to test this too? I’m sorry for asking a bunch, but when it comes to electronics I know next to nothing.
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Old 12-29-2018, 03:12 PM
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Originally Posted by Jacob Horsfall View Post
So I went into a local hobby store and the guy there said that my speed controller was draining my battery too fast/too much, and that I would probably need a new speed controller. Does this sound right to you, and is there a way to test this too? Iím sorry for asking a bunch, but when it comes to electronics I know next to nothing.
That's a new one to me. I never heard of such nonsense. Your motor, and drivetrain are what's gonna suck the life outta your batteries.
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Old 01-26-2019, 11:31 AM
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It sounds like there is something wrong with your charger or you are not making the correct settings on the charger. Before you kill another battery pack, read the instructions for the charger very carefully to find any mistakes in settings you may have made. If you don't find anything, send charger to manufacturer with a clear note about the problem you are having and have your charger checked/repaired by the manufacturer. If this is not practical, buy a new name brand charger, read the instructions carefully and follow them to the letter charging a new good battery pack.
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Old 01-29-2019, 10:04 AM
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Jacob Horsfall
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Default Think Iíve figured it out.

So I tested my speed controller with a multimeter and it was only running about 8-10 amps full throttle, so I went back and to him the speed controller wasnít the problem, what else could I be. He looked at my rc car and without hesitation said that the whole system was originally meant to run more power than what the battery could provide. It originally came with that NiMh battery but it also came from an off brand website and was really cheap, so Iím guessing the battery it had was dirt cheap just like he truck. Anyway, I decided to try out a venom 2S lipo. All I had to do was change the settings on my esc so it had a cut-off and away I went. After the first run, it was all good. The battery wasnít at all hot and the truck now has a lot of power. You wouldnít think that the difference between an 8.4v NiMh and a 7.4v lipo would be that much but this heavy 4x4 truck now does wheelies like itís nothing. Itís almost as if the truck was meant to run a lipo the whole time. (I did have to heavily modify the battery holder though). Thereís no heat issues while charging or discharging, and power is continuous. Iíve probably drove it 4-5 times already and thereís no problems whatsoever. This lipo battery (so far) has lasted longer than the NiMh batteries.
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Old 01-29-2019, 10:55 AM
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You didn't mention what you are using for a lipo battery charger. You need to use a charger/power supply designed for lipo batteries and it should have a balanced charging option where you connect main leads and balancing connector to the battery. You select number of cells and charging rate in amps. For example if you are using a two-cell (2S lipo) and it is rated at 5000mah set charger for 2S and 5 amps. Usually lipo balancing chargers display number of milliamps put into the battery and the voltage of each cell when fully charged, it should be around 4.2 volts per cell when fully charged. It is not good to charge lipos fully and not use/discharge them for more than one week, they deteriorate faster when stored fully charged. Your charger may have a "discharge" or "storage charge" feature which you use to discharge a battery pack to 3.8 volts per cell which is the safe storage voltage. It is not good to discharge lipos too far. Speed control low voltage cutoffs should be set for around 3.7 volts per cell. Voltage will usually recover to 3.8 or more volts per cell after disconnecting from the load( your truck) . You can make a battery discharger from 3 automotive tail light bulbs connected in parallel with a connector to mate with your battery packs. You can connect a simple cell checker to the battery balance connector that will sound a loud beeping alarm when total voltage drops to the preset 3.8 volts per cell.
If you already knew all this, sorry !
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