NiMh
 

Okay, after reading much about Batteries, I've decided to replace my 600 MaH NiCads with 1650 NiMH batteries. Any thoughts or comments?

RE: NiMh
 

Hey Bill,


Good choice, I'm using 2000 mAh's NiMh myself in
my 40 size Stick.


Bob

RE: NiMh
 

That's good. The more mAh the better (longer flight time on the battery).

Do you have a charger to charge it? The regular charger you have (radio's supplied one) will take a long time to charge a 1650 mAh.

RE: NiMh
 

I've switched to 4.8v, 2000 mA NiMH for virtually all of my planes. The 55 mA charger is slow, but will get there. You will love this change. My voltwatch rarely comes off the top LED.

I also upgraded my 9.6v TX battery from 650 to 2000. While I have not done it yet, because we don't get two nice days in a row on the weekend in the PNW during the winter, I'm pretty certain I could fly both weekend days without recharging. Having changed both, I will be buying a Hitec NiMH charger which charges a 110mA (130?) for both RX and TX, instead of the stock 55mA.

Jack

RE: NiMh
 

I use 3 of these and it will charge anything you have for this hobby... and more.

It can be had at Tower Hobbies.

RE: NiMh
 

Hi Bill. The only thing not mentioned yet is that you will have a heavier battery pack and you need to re-adjust, or at least check, your center of gravity with the new higher capacity battery pack.

Hey, as said, the larger the better. I have 1200 mah 5 cell (6 volt) NiMH packs in my planes, but there is some controversy about how to charge the 5 cell packs in another thread... don't want to get into it here.

Also, remember, of course, that it will take considerably longer to charge that battery than the 600 mah pack will. A 50 ma wall wart charger (the one that came with your radio) will charge it just fine, but at 50 ma, it will take about 32 hours plus about 10% (3.2 hours) to fully charge it from completely drained. A field charger, or accu-cycle charger (or similar.. I have an ICE and Triton as well as Accucycle) will give you an indication of when it is fully charged, and will give you a choice of charge rates, that will speed up the charge rate... but never exceed .1C ( .1 times ( 1/10 ) the capacity or no more than 1.65 amps for your pack of choice) charge rate.

You are doing just fine.

CGr.

RE: NiMh
 

Thanks all,
Read the thread on the battery charging. Will invest in the correct charger I think. Not simply because it does a better job, but will do the job and more. I plan on bering in this hobby for the rest of my breathing days, so might as well do it right, or at least try too. My plan is to replace both the Rx and Tx batteries.

RE: NiMh
 

One more question. I'm heading for LHS this afternoon to buy the battteries. I assume I want a 6 volt for the Rx and a 9.5 volt Tx??

RE: NiMh
 

Make sure you get the right pack for your TX. Connectors and cell configurations are different for different models and brands of TXs.

I use 2200mAh A-cell NiMH packs in all of my planes. The A cells are a little larger than AA cells, and have a higher max discharge rate.

RE: NiMh
 

Thanks all,
I plan on taking the Rx and Tx with me to the LHS to be sure I have all the right connections. I also realize that I will have to check the balance of the plane. And if I keep this up, the balance of the bank account as well!! HA!

RE: NiMh
 

Pay attention to the charger voltage and KNOW how much your house sockets are capable of supplying. I have an AC/DC Charger that I can't use anywhere but plugged up to my vehicle battery. My house plugs don't supply over 12V constant...so as soon as the volts drop to 11V an alarm go's off, stops charging, and gives me an input voltage error....it's annoying as hell.

RE: NiMh
 

The sockets in my house put out 120V AC, which is plenty to run my chargers! :);)

But seriously, if your can't charge your batteries while plugged into a wall outlet, then your charger's power supply is bad, or your exceeding the chargers intended current or voltage specs.

Most of the better peak chargers require a separate DC power supply, and you'll have to be sure it can put out the current & voltage required by the charger you choose.

RE: NiMh
 

I recently purchased a set of four 2500mah receiver batteries. I am more than happy with them. One bit of fine print on the pack was to not charge over 1 amp rate. Heading this has keep me happy and back to trusting the NIMH packs again. My charger documentation states that you can charge them at 3 amps and I tried it with a previous couple backs and I killed both of them. Same for a TX battery I bought. I overcharged the first and it almost cost me a plane. Turned the TX on and it showed 11.2V and three minutes into the flight the low voltage alarm went off and when we landed (I was still on the buddy box then), the TX was showing 8.3V.

As for taking to long to charge, an over night charge on the wall wart that came with my radio is all I do for charging most of the time. That and top off the RX at 1.0amp with my field charger after three or four flights. It usually is back up to full after 10 to15 minutes on the field charger.

The RX batteries cost me $10 each on Ebay and the TX batteries were also very low priced. I forget the seller now, but if I need more, that is where I'll buy them.

Don

RE: NiMh
 

Curiosity got the best of me on the weights

Digging through my batteries, here is what I found.

Futaba 4.8V Batteries
500 MAH square pack = 92.7 gms (White Cover)
500 MAH Flat Pack = 95.7 gms (Grey Cover)
600 MAH Flat Pack = 88.5 gms (Red Cover)
1000 MAH Flat Pack = 118.3 gms (Yellow Cover)

Ebay 2500 MAH NIMH Flat Pack = 122.5 gms

Note: I had replaced the lead on the 1000mah pack, so the weight may be a little different than a stock battery

Don

RE: NiMh
 

Yes I'm aware it's a 120V socket. I certainly hope the power supply isn't bad...the charger is brand new out of the box. As for overloading it, the cycle was set up per written instruction from the manufacturer to letter. Start the charge....3 to 5 seconds...loud alarm...Voltage Input error. Plug it up to my 12v truck battery, no problems what-so-ever.

RE: NiMh
 

CG, actually 1.65 amps into a 1650 mah pack is 1C, not 1/10 C. I typically charge my Nimh batteries at 1/4C, which would be about 400 ma for the pack the OP had in mind. On another note, I have found that new Nimh packs take several charge/discharge cycles before they reach their full capacity.
Paul

RE: NiMh
 

I switched over to all NiMH a couple years ago. 1650mAh 9.6v Tx and 1450mHh receiver - but kept the 4.8v. If I need more - as in my 27% Ultimate, I add a second set and a combiner but keep to 4.8v. That gives longer flight time and I don't need the added torque as I used big enough servos to begin with. If I was starting from scratch I 'd probably go with more mAh, but I can charge the 1450 and 1650 with my existing chargers and fast with my Triton.

RE: NiMh
 

Hmmmm....one thing about bigger battery packs is that they weigh more. Yes, larger packs are better if you have high current needs, but a 600 mAH pack in almost all sport planes is plenty for about 6 10-minute flights. If you want to do more, then just take a field charger with you. You can add quite a bit of charge to a model in 5-10 minutes between flights. That will allow you to fly all day, and you'll not have the weight penalty of the large battery pack.

Just another option.