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

On 09/05/2020 21:27, Tricky Dicky wrote:
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


--
"It is an established fact to 97% confidence limits that left wing
conspirators see right wing conspiracies everywhere"

Tricky Dicky wrote:
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?

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

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"Tricky Dicky" wrote in message
...
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

On 10/05/2020 08:23, Theo wrote:
Tricky Dicky wrote:
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?

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

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.


--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.

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.

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 €œsmarts€�. 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

On 10/05/2020 10:04, Tricky Dicky wrote:
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.

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 €œsmarts€�. 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



--
€œI know that most men, including those at ease with problems of the
greatest complexity, can seldom accept even the simplest and most
obvious truth if it be such as would oblige them to admit the falsity of
conclusions which they have delighted in explaining to colleagues, which
they have proudly taught to others, and which they have woven, thread by
thread, into the fabric of their lives.€�

ۥ Leo Tolstoy

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

On 10/05/2020 11:06, Tricky Dicky wrote:
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

https://hobbyking.com/en_us/batterie...ries/lipo.html

get a battery that is the right physical and electrical size and then
mod the cars connector to take it. Also get a decent charger.

Does the car use Tamiya connectors?


--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

Tricky Dicky wrote:
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

There seems to be more to those than just pouch batteries
and glue.

"7.4v 2S Lipo Battery Repair" @ 3:52 minutes

https://www.youtube.com/watch?v=ziEcrK1b218

In the example here, the six pin chip looks like some
sort of protection device (measure cell voltage, disconnect
toy if pack is too low, disconnect pack if pack overheats).
I couldn't find an IC number, to locate a datasheet
with details of how it works.

http://www.bestechpower.com/upfilesn...1604283597.png

The (8 legged) dual MOSFET has the ability to disconnect the load,
when the controller wants it to. The notion of soldering
around the MOSFET -- that's like putting a penny in a
fuse socket :-/ Not a good idea particularly.

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 **** 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