NIMH Problems!

[andybl]

Hello everyone!

I have got back into rc helis lately, but have been experiencing VERY short flying times. They last around 30 seconds (with the throttle close to full).

I have 2 X 9.6V 600MAH NIMH battery packs, and use both the charger that came with it and my multiplex charger.

Neither of them give a good enough flying time, never lasting more than 1 minute.

I'm sure that the gears are ligned up properly, and know of nothing that could be causing it. I do however, wonder if my multiplex charger is finishing the charging too early?

Any help would be greatly appreciated, also out of interest what charge should I charge those batteries? Should it be 1A?

Thanks

[acwman]

More info on what heli it is would be helpful..
...But it could be the batterys are on their way out, or could possibly be the motor/motors.

Andy

[murph]

Hi
I would try cycling the charge a few times with your multicharger, see if that improves them, and only charge at the battery rating ie 0.6A not 1A.
What heli is it?

[Tom Burgess]

How old are the packs and have they been left for a while?

[Helimadlarry]

It could be a number of things but here are a few that spring to mind.
First how old are the batteries and how many charges have they had? Although NiMh batteries are not prone to the "memory effect" that NiCds are they will significatly reduce in capacitiy after 1000 charges or so.

Are you charging each battery pack individually or in series? If you are charging them in series one of the cells in either of the packs may be giving off a false delta peak signal to the charger hence cutting the charge cycle short. Also make sure that your charger is not detecting the delta peak too early. Some chargers have an option to set the leeway for detecting delta peak in mv/cell. Thats millivolts per cell. A good starting point is between 5 and 7 mv/cell.

Finally what helicopter are you using these packs for? It may be that the motor is just sucking all the power out of these batteries in the 30 seconds you get out of them.

Hope this helps.

Larry

[Janek]

I'm guessing these are old batteries, and I agree with the above, you need to cycle them to get rid of "memory effects".

As for charging, I've always charged NiMh's at 2C, which in this case is 1.2A, in otherwords, if charging from fully discharged, they will be fully cooked in about 30 minutes

[unleashed666]

if the heli is worth keeping, you could convert to use 3s or 4s lipo packs.

if the batteries you have have been left for a while theres a good chance that they've had it and need replacing, cycling them could revive them tho. i remember i had these problems back in my rc car days.

[Tom Burgess]

NiMh's do not cycle well, they suffer from memory badly, time to replace them me thinks

[andybl]

thanks very much for the replies, I'll try cycle the battery later on.

By the way, my heli is the century hummingbird V4:

click here to see my helicopters web page

[andybl]

Still to no prevail, I think it may be the helicopter itself now.

I have fully charged (according both my chargers) 4 batteries, 2 NIHM's and 2 Li-Po's.

All of these have offered so little power.

Is there anything that could be causing this on my heli? I have checked the gears and they seem to be working fine.

Any replies would be appreciated..

[acwman]

Quite a few of these post have come up with these smaller helis.. especially the contra rotating helis having no power, little power, or just short flights and just dying.. all turned out to be the Motor.

ANdy