Battery charging question

[2robinhood]

My Futaba radio wall charger has 4.8V 100mah for the RX battery.
What I want to know is, is a 100mah, 100mah?
Can I charge my 6V RX packs with it? Does it matter that it says 4.8V ?
I have a 6V charger that is 50mah, would the 4.8V 100mah charger, charge the battery faster and would it be a full charge?
Or 4.8V to 4.8V and 6V to 6V only.

[DR10044]

I would think that 100mah is 100mah. My Ace chargers allows me to set the Mah. It does not ask whether I am charging a 6 volt pack or a 4.8 volt pack.

[2robinhood]

	Quote: Originally Posted by DR10044
	I would think that 100mah is 100mah. My Ace chargers allows me to set the Mah. It does not ask whether I am charging a 6 volt pack or a 4.8 volt pack.

I have a Hobbico charger with four ports. It says it will charge up to 12V batteries. There is no voltage switch to change voltage, only mah switches.
10 - 500mah.
I was wondering though, the Futaba stock RX battery is 4.8V 60mah Nicad and they are charging it at 100mah, as a overnight charger?

[Spaz]

yes you can use it but with a wall wart the voltage is inversly propotioanl to the current .. so the higher the voltage output the lower the current will be.. also its mA not mAh, mAh is a messure of capacity not charge current..
with a 4 cell pack you will get a 100mA charge current, with a 5 cell pack you will get less probably about 70-80mA.. so it will charge slightly faster than the 50mA 5cell charger you have.
check it out here

http://www.rcbatteryclinic.com/

[2robinhood]

OK, so the the voltage doesn't mean anything, go by the Ma, right?

[JoeAirPort]

Go ahead and use the Futaba charger. I have for years on my 6 volt batteries. It takes a little longer but charges the batteries 100% from my experience (I always check them under load). The only thing is that if you get into bigger batteries, 2000mah and up, it will take 24 hours or more to charge, that's kind of long IMO. Works good for form charging a new battery. So it all depends how big your battery is and how long you want to wait for it to charge.

[dick hanson]

FWIW:
the voltage being used to charge your cells MUST be higher than the charge level you want to see.
this basic 101 charging -
you can have more total current -depending on cells and how long you want to charge them
BUT- 4.8 volts will not charge up a 6 volt cell-
you are completely misreading the charger
get someone with a v meter to show you. ( the charger is delivering more than 4.8 v)

[2robinhood]

	Quote: Originally Posted by dick hanson
	BUT- 4.8 volts will not charge up a 6 volt cell- you are completely misreading the charger get someone with a v meter to show you. ( the charger is delivering more than 4.8 v)

I connected a meter into the chargeing system with a Y-harness.
The charger is a Futaba stock wall charger.
Charger is ( RX ) 4.8V 100ma.
Charger with nothing connected but the meter reads 5.66V.
A stock Futaba 4.8V 500mah nicad pack reads 5.15V ( took off my self for test ).
Connected it to the charger and reads 5.28V and climbing.

I took the same charger as above ( 5.66V with nothing connected ).
A JR 6V 2300mah NIMH battery which reads 6.68V.
Connect it to the charger and it reads 6.78V and climbing.

If you are saying a 4.8V charger won't charge a 6V pack then why is the voltage going up when the charger is plugged in. By what you are saying, the battery has more voltage the what the charger can put out, so there is no way that the voltage should go up.
But it is.
Can you give me more info why this is?

[dick hanson]

I said 4.8 volts won't charge a 6 volt battery-
I will have to see why THAT charger applies more voltage

[2robinhood]

	Quote: Originally Posted by dick hanson
	I said 4.8 volts won't charge a 6 volt battery- I will have to see why THAT charger applies more voltage

I am only using the RX side, but does it matter that the TX side is 9.6V ?

To me it seems like it is charging a 6V pack just fine.
Just want to be sure.

[USN_POPS]

The Charger "No Load" shows a voltage higher than 4.8, therefore it has enough push to charge the pack. If the "No Load" voltage were below 4.8, it most likely would not do the job.
Same with Li-Po for Electric. you need a charger that will put out a voltage greater than the pack voltage, or it wont charge. Which is why the Li-Po chargers are rated by cell count. If you use 6 Cell Packs, you have to have a charger rated for 6 cell packs, etc.

[Spaz]

	Quote: Originally Posted by 2robinhood
	I am only using the RX side, but does it matter that the TX side is 9.6V ? To me it seems like it is charging a 6V pack just fine. Just want to be sure.

yes you can do that, check it often to make sure it doesnt overheat, it should thremal shutoff if it does but keep an eye on it.

also it might be a good idea to check the mAh that the charger is putting out with a meter in series while charging to see how long you need to charge..

really the best option is to buy a good digital peak charger.. one that does nimh, nicad, li-ion, li-poly, Pb, LiFePo...
something like this one
http://aircraft-world.com/shopexd.asp?id=4899

[dick hanson]

followup---------
the wall charger is a very inexpensive charger and does NOT show you the actual voltage it is applying to the battery-- basically it will never show that voltage on a vom- bottom line --don't worry about it .
when you hook it to a battery it does show more like the voltage applied -but that voltage is also being reduced by the load of batt being charged (again normal)
these devices charge at a low rate to do the job very safely and the 4.8 charger will in most cases actually charge at a sloooow rate, a 6 v pack - I checked my JR stuff -it all works the same way. your 6 v pack is charged when it reads 7.2 v or higher.

Ideally to charge NiMh cells --get a inexpensive charger that will charge at 1/10 of the pack rating and then cycle it a few times then charge at up to 1 times the pack rating.
If you must know the reason the charger works like this - ask a battery charger guy- in a nutshell -he will tell you is has to do with the meter only seeing peaks of voltage -(you are seeing AC)