dmaz

First, I would like to say bear with me please. I need some basic info about batteries,chargers,volts,and milliamps.

I have an 8.4v 600mah Ni-Mh battery. My charger will charger at rates from .5 amps to 4.5 amps. I should set my charge rate at .5...correct? If I have a 1500mah battery then I should set it at 1.5..correct? And so on. Can I change the rate to make it charger faster or are the higher rates for larger batteries? Do you always want to stay under a certain rate for your battery? After my battery is charged, should it read 8.4 volts or will it be higher after it is charged?

I`m also trying to figure out what kind of flight times I can expect out of this battery. I have a graupner 300 plus motor (model#6365). How can I find out how many amps this motor will draw. I think the formula is 600x60 divided by amps. I think it draws 5 amps, but I`m not sure. If it is 5 amps the flight time would be around 7 minutes.


Thanks for your help
Dave[sm=confused.gif]

PaulVi

Your in the right ball park for flight times

On NiMh do not charge above 1c or the rating of the cells. NiCad and NiMh will read higher right after a charge (Peak Voltage) or about 1.25vdc per cell in your pack a dead pack would be an ideal 1.0v per cell

but what happens in reality is one cell will drop much lower than the rest. becarfull to not dischage your pack so that one cell goes to 0v if that happen the you start reverse charging that cell (can happen while flying) and it will creat exsessive heat and most likly vent.

Venting is a term when a cell generates to much internal heat and ags and must relise it (safty valce on the cell) like any battery when you loose electolite you loos capacity to staore charge and your pack will degrade.

I have had big POPS when charging nicads at a 5c to 7c rate (RC Cars) usally folowed by a small fire...

Bob At BP

DMAZ; You have a 600MaH NiMH pack. Consumer NiMH's are usually limited to 5C discharge. Unless you have a KAN
pack that could be 10C. The Graupner 300 motor will draw 5 to 6 amps depending on the prop size. Your 600 NiMH will supply about 3 amps continuse causing the LVC to cut out prematurely with a Graupner 300 motor.. Bob

dmaz

Thanks for the info guys. What kind of battery would be the best? My charger only charges Ni-Cd and Ni-Mh batteries.

Bob-what do you mean by 5C dicharge? Is this battery to small to work well with this motor?

Thanks,
Dave