Grandson has a RC car with two 7.4V Li-Po batteries one is showing 0V the other 1.5V, I have had both on charge for several hours with no effect. Is there any way to revive them or is it a case of mend it with a new one?
Richard
they wont ever run properly.
Buy new. Not expensive
What are you charging them with? Often smart chargers won't go near them, but you can get the voltage up by trickling them with a few mA until they get to about 2.5-3V per cell. Then the smart charger will take them, although I'd try and set the charge current low if you can.
That might revive them, but I'd be thinking of budgeting for new ones anyway.
Theo
New Battery, though it would be interesting to find out what was done to them, ie left discharged for a long time in varying heat and cold conditions does for them quite quickly. Brian
It will not revive tjem. below about 3.3v per cell LIPO are irreparably damaged
i've tried, and what you get is a fraction of the power and capacity back.
I think you hit the nail on the head there Brian as to the problem. The charger if that is what you can call it is basically a lead that plugs into a USB supply, the USB plug is somewhat extended and contains a circuit which I presume provides all the ?smarts?. As I said before one battery showed 0V and after several hours and still showed the same whilst the second started at 1.5V and showed no further change after several hours. So it looks like it is mend it with new ones just sourcing them seems a problem the original spare was bought from Amazon with the car they are currently shown as unavailable and may or may not be restocked. Bangood do have them on their Chinese website but not on the UK but will not ship from the Chinese site to the UK. Aliexpress have some but from comments from purchasers it seems they are clones and some people have had trouble getting them into the battery compartment which is quite small and a tight fit.
Richard
Buy generic cells and a generic proper charger and mod the car to take em
LIPOS are best left half discharged - 3.7V per cell. Always take them out of the model after use. Leaving them in a switched on model is really the only way to wreck them like this. They don't self discharge at all.
I recovered nearly all mine after 4 years out of the house while my Ex wrecked it
Thanks TNP I will spend a bit of time wading through all the options on Aliexpress, seems to be quite a variety of costs and delivery charges.
Richard
Try this place - its much better
Does the car use Tamiya connectors?
There seems to be more to those than just pouch batteries and glue.
"7.4v 2S Lipo Battery Repair" @ 3:52 minutes
When you measure zero volts, it could be the MOSFET is set to the disconnect state. The pack that measures 1.5V, the protection has likely not triggered and it's still open for business (even though too low to charge by an intelligent charger).
Paul
In the end after trying various UK suppliers, mainly RC model shops I managed to track down the exact battery required and it looked like I would have to import them from China myself. The only problem is nobody was prepared to import them in to the UK. Anyway by pure luck after modifying my search criteria I managed to secure some on Amazon, only snag they would not be delivered till the end of June. Yesterday the camels must have made it along the Silk Road and they arrived and were delivered to by my favourite courier (not) - Hermes.
Now the irony of this situation is that the year before I bought one of those emergency battery power packs, the type used to charge up phones and tablets, for a friend and could not get anyone to legally deliver it, including Hermes. The restricted items list that RM and couriers have just seems to be an arse covering policy throwing the onus on the customer because they are obviously not enforcing it and they must know that these items are still being shipped, mobile phones just for a starters. So for 99.9% of the time people are shipping restricted items until eventually some depot or a van goes up in flames and for some unfortunate sap the shit will hit the fan.
Back on the batteries, I know LiPo batteries can set on fire and there are flameproof containers available. My question is why cannot delivery services have these fitted to vans where clearly marked items can be placed. I for one would be happy to pay a bit extra for the facility and to cover additional insurance costs and lets be upfront about these things rather than making criminals of us all because we have to surreptitiously pass of dangerous items as something else?
Richard
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