karolh

I just purchased a new glow driver unit which came with a NI-MH 1800 mAh battery but no charger. Can I use a regular Nicad charger to charge the NI-MH battery.

Karol

JNorton

My Feedback: (2)

Look at the specs on your charger. It should say the number of cells it will charge. My problem with the question is what is a normal NiCd charger? Is it a constant current charger like a wall wart that comes with you transmitter, a timed charge unit, a delta peak unit like the Triton or Multiplex LN 5014. In the case of the Triton or Multiplex unit they will charge it with no problem. With a 60 mAh wall wart it is very close to not having enough current and will take 2 days to charge. A 180 mAh wall wart would charge it perfectly in 14 to 16 hours. I wouldn't use any timed unit period.

Hope it helps.
John

karolh

Hi John,

Sorry if my question was a bit confusing, as the term 'normal' was referring to the constant current wall wart type of charger that is supplied with most Nicad powered glow drivers.

In retrospect, maybe I should simply have asked if a Nicad charger can be used to charge NI-MH batteries.

Karol

gerwen

A peak charger for nicads only won't work with nimh's. Your trickle charger will if it supplies enough current. You want it in the 150-200 mah range. Less and it will take a long time to charge if it ever gets to a full charge. More and you'll have to pay attention to charging times to avoid overcharging.

JNorton

My Feedback: (2)

Karolh
A constant current wall wart charger can indeed charge NiMh cells at a C/10 rate. Just be sure not to leave it connected to the pack after it is charged, as NiMh cells do not like constant C/10 charging which doesn't seem to hurt their NiCd brethren as much. Neither type should be left on continuously anyway.

If you don't have a high current wall wart NoBd has them. Check the middle of the page. CH96 High Output System Slow Charger 120/180ma $18.00.
http://www.hangtimes.com/chargers.html
John

karolh

I have a Mc Daniel's glow driver wall wart charger that is rated at 125mA which I plan on using, and which should provide a full charge after approx. 18 hrs.

Karol

JNorton

My Feedback: (2)

Sounds good.

PIRANA

Hi: i have a 5 cell Ni-Mh battery pack (6v-2500mah) can anyone tell me if it would be ok to slow charge this pack with a 6v 200Mah power supply, and if so how long would it take from flat to full, also is there some way that i can fit some kind of indicator in line, eg: a diode or meter, any tips would be much appreicated.


Damien.

JNorton

My Feedback: (2)

Damien,
Check the actual voltage from the 6v 200 mah supply. You need more than 6 volts to charge a 6 volt pack. You need about 1.5 volts to charge a cell so the minimum voltage needs to be around 9 volts. 2500 mAh pack / 200 mA = 12.5 hours to charge.

NiCd and NiMh cells do not have a linear voltage discharge characteristic like LiPo or lead acid cells do so it is difficult to use a volt meter to check the cell's capacity. After setting a while a surface charge builds up and fools the voltmeter into thinking you have more capacity than there actually is. Tower Hobbies sells a voltwatch that works if you use it directly after landing the airplane or running the car.
http://www2.towerhobbies.com/cgi-bin...&I=LXHDJ2&P=ML

John

PIRANA

Thanks for this info John, this psu that i had hoped to use is only 6v 200mah, but as you have said that it would take apx: 9v to charge my battery pack, i am wondering now if i could use my futaba mains charger, as the TX output is reading 9.3volts @ 70mah, i want a slow charge as the battery pack is in my nitro boat, and would probably only be used at max once a week, so there is no need to charge them fast. if this charger would suit, how long do you think it would take to charge this 6v 2500mah Ni-Mh pack..?

Thanks again John:

Damien

JNorton

My Feedback: (2)

You divide the current available from the charger into the pack capacity to get hours. Unfortunately 70 mA is below the threshold that can effectively charge a 2500 mAh pack. 2500 / 70 = 35 hours. To slow charge C/10 you want something in the 200 to 250 mA range.
John