Hello all i have a multiplex mentor and i hooked up a separate battery for the receiver .. Now it looks like the battery dosnt hold a charge for very long.
what i did was battery to sw and sw to receiver geer sw ..
The speed controller has signal wire and ground to the throttle
receiver is spektrum 6200
new battery hydromax 750 i have charged and discharged a few times and it dose take a 1/2 hr to discharge but it hangs around 4.5 volts
i am discharging with a futaba br 2000 at 1 amp
i re charge the battery for about 8 hrs with the spektrum radio wall charger
just dosnt seem normal to me
thanks all..

Could you explain this in more detail?:

"what i did was battery to sw and sw to receiver geer sw .."

battery plugs into switch then on the other end of the switch is the receiver normal hook up
the speed controller is hoked to the throttle terminal with out the red power
i am only using signal and ground from speed controller so i don't get any lipo battery power to receiver


my real concern is the hydromax 750 ma battery
it is new from tower and when i take it off the charger it shows 5.5 volts but will not hold it very long
my first thought was i wired it wrong and it was draining
but i have done some research and found that the battery and speed controller is wired ok.

so just wondering about the health of the battery

First you have to write things that are understandable. Re read your posts. However I think your problem is you don't tell us the voltage of battery you're using and you'r,e not leaving it on charger long enough to get full charge.

There are 6 volt batteries and 4.8 volt batteries. If its a 4.8 volt then at a full charge it would be about 5.5 volts. There are several things to remember. Nimh batteries will drop up to 30% of their charge soon after beingf charged. a 750MAH is not a big battery. The voltages given for batteries are the nominal voltages and MAHshould vahuely tell you how long they will last NIMH are notorious for needing topping off. I think this should explain what you think you are seeing as battery problem are really just drawbacks to the type/size you have chosen. To get better performance try topping the battery off at the feild also lookat when you are replacing it look for more MAH and possibly 6 volts/ 5 cell vice 4 cell. I use glow engines which would well equate to your setup. I was getting 3 flights from 4.8v 600MAH I upgraded them to 6.0v 2200 MAHand now Iget as many flights as I want for a weekend on one charge.

Hope this reading helps reducing the confusion:

http://www.hangtimes.com/rcbattery_faq.html

http://www.hangtimes.com/nickel_metal_hydride.html

Do a pre-flight test under load each time and check also for binding servos that may eat a lot of juice in a short period of time.

How long is not long? If it won't hold full charge for a week, then that's normal. If it's dropping half its capacity in an hour, there's a problem. You're also talking about measuring voltages to determine your charge. That's not an accurate way to do it. You need to cycle the battery to really know if it is giving you the capacity that it's supposed to.

Did anyone else notice that he said that he's discharging at 1 amp? A 750mAh battery should only take 45 minutes to totally discharge at that rate. He says he's getting a half hour. If he's only "ballparking" the discharge time, he might not be far off. He also said something about the voltage hanging at 4.5V. Assuming discharging a 4 cell pack to 1.1V per cell, he's not fully disharging the pack. Also, that high discharge rate will load the battery more and will not be as accurate a measure as a more typical discharge rate of 300-400 mA. Try charging a NiCd at 1 amp on a peak detect type charger. after it finishes, try again at a lower charge rate and you'll see that it will take more charge. I think his pack is probably pretty close to normal, but without more info, it's hard to tell for sure.