medicap

My Feedback: (11)

Good morning. I am fairly new into the hobby and am convertingfrom the old tried and true NiCads and going with NiMh both TX and RX. I was just informed that the normal charger I have been using forever only charges at 50Mh/hr so would take about 4 days to charge a 2200 MH NiMh.

Suggestion for charging. Pitfalls in charging. What kind of thing can I do to damage the batteries. How to field test them at theRC strip. What kindof performance should I expect from them...etc etc etc

Thanks for all the input.

Steve

Steve Percifield

My Feedback: (14)

Man are you openning yourself up to a barrage. There will be 100 posts telling you to throw them away and go to Lithium of some type. But, in reality, there is nothing wrong with with Nimd, or Nicd's for that matter.

Here's what i have learned, from actually using Nimh batteries

1. They have the highest self discharge of any of the batteries we use. That means , while not in use, they loose capacity. Up to 10% per month. So they need to be recharged frequently when you are not flying.

2. They don't like to be fast charged. Charge them at C/10 rate. In your example of 2200 mah, that would be 220 ma or something close. This is considered an overnight charge rate, and will not damage the batteries if left for an extended period. BTW, with your wall wart charger at 50 ma, the charge time is 2200/50 = 44 hours, not 4 days. Just get a variable charger that will put out 200-300 ma

3. You can test them just like you do Nicds with an expanded scale volt meter with a load.

4. Actually, there aren't many advantages of Nimh over Nicds. The biggest is energy density, whcih means that a 2200mah Nimd will be smaller and lighter than a 2200mah Nicd.

5. If you do want to try peak charging, make sure you get a charger with a Nimh setting, and I have found to use no more than 1C rate. In your 2200ma example that would be 2200ma or 2.2 amps. I have found they false peak at higher rattings. People might tell you to go higher, but I find it doesn't work.

6. just so you know, I use 5 cell Nimh in all my planes, (right now)., and am very familiar with handling them.

steve
www.hoosierdawnpatrol.com

k3 valley flyer

My Feedback: (18)

Good luck. I tried them and got rid of them. NiMh discharge rapidly, will lose most of their charge in a 30 day period. The new NiMh batteries are Eneloop and they retain 90 % charge for a year, I use them for tramsmitters now. Went back to Nicads for receivers. Sure you will get different opinions, a friend of mine worked in the battery industry for his whole life, I consider him very smart about batteries and he agrees that NiMh are not the way to go.

Lnewqban

http://www.radicalrc.com/nimhfaq.html

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

Tall Paul

Don't overheat/overcharge!
That'll destroy them.
Otherwise, they're better than NiCads, but not as handy being heavier (a lot heavier) than the equivalent Lipo.
Which needs a special ESC.

Rodney

I think I've found the best of the NiMh's, the Sanyo Eneloops. They are NiMh but they hold a charge very well, will still be at 85% after a year of storage. I now have them in my transmitters as they are chargeable with the wall warts that come with most transmitters and, if I forget to turn off a transmitter, no harm is done as they seem to take an deep discharge without damage. I steer away from LiPo in the transmitter especially due to the charging hassle and certain ruin if you forget and leave a transmitter on to long.

TimBle

I'll say it, forget NiMH and go straight to LiFePO4 or lithiun iron phosphate.They retain charge, can deliver higher current and can be super fast charged at up to 5C for A123 brand.They're much less hassle .

daveopam

My Feedback: (9)

I use a lot of these and really like them. http://www3.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML
I use a plain jane charger and plug them in the day before I go flying. The price is right, I don't need a special charger, and they are not going to burn my shop down.

David

-pkh-

My Feedback: (2)

I'll second that, go for LiFe/A123 packs.

If you go for NiMH, get yourself a good peak charger and charge them at 1/4 C charge rate or slower (4+ hour charge rate). Anything faster will get them too hot before they peak out.

Gray Beard

My Feedback: (-1)

I have been using NIM sense they came out and like them a lot. I have made up several packs using the Eneloops, I bought a bunch of them when a camera shop was moving and had a big sale. I fast field charge all the time these days and haven't seen a shortened life span but when they first came out I was only getting about a year out of a pack if I fast charged. I have noticed in the last year or so the new packs need to be cycled about four times before they come up to full power. Other then loosing there charge over time I see no reason to be changing to the 123s.

huck1199

I went to LiPo for TX and A123 for RX and never looked back.

Gray Beard

My Feedback: (-1)

I am in need of a new TX battery and was wondering about the new battery types. Can you state some of the goods and or bads with the LIPO pack you have for your TX. Do they hold charge a lot longer or just when shut off? Anything special you needed to do??

scooterinvegas

My Feedback: (1)

You just set your TX low voltage alarm to 10v, and put a post it note on the inside of your windshield that says "Tx off?" LOL

NiMh are fine, charge them slow and cycle them once in a while. Scoot

42etus

My Feedback: (2)

I quit using Hydrimax batteries and switched to this place http://www.cheapbatterypacks.com/ . My receiver packs are 6.0 volt Nimh, made with five 2000 mah 4/5A cells. $16.25, how cool is that? Plus, shipping is free on orders over $50 and they advertise right here on RCU. Check 'em out.

Murphey

My Feedback: (11)

If you want a resource to learn a lot about many battery technologies, go to http://www.hangtimes.com

Murphey (As in Murphey's Law)

GarySS

My Feedback: (13)

If you decide to go with regular NIMH's do as Steve Percifield and others do and RECHARGE them on a set schedule or you will loose them to reversed cell(s). I painfully found this out with an expensive HangTime NOOBs battery that I neglected for about 4-5 months this year. Set up a paper schedule reminder or an electronic calendar to stay on top of this..............

DavidAgar

My Feedback: (108)

You also need to make sure they have enough horsepower for your servo's. Futaba has warnings about the use of these types of batteries with most of their servo's. Good Luck, Dave

-pkh-

My Feedback: (2)

For NiMH, I usually used A cell packs, not AA cell packs, since they have more capacity and higher current rating than AA's.

Lnewqban

Just a tip about it:

http://www.hangtimes.com/id32.html