battery care...
 

Am flying a trainer on average a couple of times a week with a superb instructor - ah the joys of retirement!. I charge both rx and tx batteries overnight each time. Is this overkill? Is it damaging or at least failing to fully develop the nicad capacity? should I not discharge the nicad flight pack peridoically?(700mAH 4-cell nicad) As the tx is NiMH I suppose this is less critical? Do I need a load voltmeter - and if so which one to get? Do I need a battery cycling device? If so any recommendations would be gratefully received.
All less than one year old -Spektrum DX7/AR 7000. It is in a slow flying ARF Nexstar, which is about as agile as the Goodyear blimp...nice motor though, OS .46AX
As I hope this gear will survive whatever insults I visit upon it in for some time I don't want to mess it up needlessly. I get conflicting advice and even what I read is not always consistent.
Thanks. It's great to be back at this stuff again - especially building something more ambitious which will be waiting in the wings...

RE: battery care...
 

Hi,

It's a good idea to cycle the nicads to stop surface charging/stroke memory but no problem with your Tx batteries. If you don't have a cycle charger just leave the Tx and Rx on for an hour or so before the overnight charge. However a charger that will deal with cycling and a variety of battery types is something your bound to need sooner rather than later as you progress in the hobby/addiction;). Isn't retirement wonderful. I have no idea how I ever found the time to go to work.

Cheers,

Colin

RE: battery care...
 

overnight it with a wall charger....then use a peak charger on the way to fly if you have one ....tbh i usually peak charge at about 1/5 c the night before go fly on my nhmh batteries...they will usually last me all day sat and sun ...about 6-7 flights or so

RE: battery care...
 

Ahhh, yes, Retirement,

" I start the day with nothing to do, and by the end of the day I can't find time to finish everything" !!! I LOVE IT !!!!!!!

RE: battery care...
 

The Joys of retirement.



To wake up with nothing to do
and having to get half of it done.

:D


Bob

RE: battery care...
 

Thanks v much Colin: I'm not sure the same gear available "down under" is available here: but I think I'll invest in a decent cycler. What d'you think of a load voltmeter - useful or not?
Best,

Robert M

RE: battery care...
 

Hi Robert,

IMHO I would purchase the cycler/charger first. The load voltmeter is certainly useful but not as critical. If you think you may also dabble with electrics a device to measure current draw as well as volts is very useful, it's also useful if you move to larger models with ganged digital servos. Check out Hobby King/City on the web they have some chargers and in-line current measuring devices at prices that won't break the bank. They are in Hong Kong and delivery is usually one week to OZ but like all online shops check that what you want is in stock otherwise it can be a long wait.

Cheers,

Colin

RE: battery care...
 

talk about overkill, most of the time 4-5 flights will only use 200ish mah, most wall warts charge at around 100 mah, so 4 hours should be more than enough. i would throw it on the charger and once it starts getting warm its done
or just buy one of these http://hobbycity.com/hobbyking/store...idProduct=7028 when they come back in stock

RE: battery care...
 

ABSOLUTELY NOT!!! Once it begins to get warm enough to feel the heat, it's already done to much damage. That's why the charge rate should remain below 1C, and best to be done at the slowest possible rate to get the job done.

Never let them get hot enough to feel the heat. All that heat is contained internally and is doing damage. Charge them slowly, and never exceed 1C.

CGr.

RE: battery care...
 

Thanks again Colin: I think this is sound advice and I'll follow it.

RE: battery care...
 

Your habit of charging your 4.8v 700Mah NiCd receiver pack "overnight each time" may very well have saved your plane. Your AR7000 receiver has a minimum voltage input rating of 3.5v. Flying a 4.8v receiver battery with less than a full charge on it could lead to "brown out" or "lock out" conditions as your receiver resets while flying it if your receiver pack dips below the 3.5v minimum input threshold, even for a split second. This can happen easily enough if multiple servos are drawing maximum power from the battery (say while using your rudder to straighten a out an inside loop while you're managing the throttle) after you've already had a flight or two that day.

You should seriously consider upgrading your receiver battery to a 6v NiCd or NiMH pack. You don't need one with a huge capacity, a 1000Mah or 1200Mah 6v receiver battery will give you even more flying time than your 700Mah 4.8v battery does now. The extra voltage should keep you well above the AR7000's minimum input level, even if you're doing some spirited basic aerobatics on your 3rd or 4th flight of the day. It will also provide insurance in case one of the cells goes bad in your receiver battery; a 4.8v pack drops to 3.6v if just one cell fails, while a 6v pack will still have 4.8v if it loses a cell.

I'm glad you haven't experienced any problems with your current setup so far. I hope you won't wait until you do experience a lockout before you beef up your receiver battery just a bit.

Good luck and good flying!

RE: battery care...
 

CG. I just picked up a JR 2300 Mah MiMh. put it on my oynx 230 charger set as factory charge defaults for a 2300 MiMh. within about 20 minutes it was complete and it was very warm to the touch. Are you saying I could've potentially killed it?

RE: battery care...
 

If you let your battery get very warm from charging, you won't necessarily "kill it" right away unless you used really outrageous settings (charging a 2300 NiMH at 10 or 15 amps, for instance). Even that wouldn't necessarily ruin a battery completely.

Quick charging and getting the battery very warm breaks down the compounds that make up the battery's chemical components more quickly. It will "age" the battery prematurely and the battery will need to be replaced a year or two earlier than it might have been if slow charging and only occassional quick charging had been done to it.

RE: battery care...
 

Hi!
Yes!
You should always slow charge you NiMH cells! Remember the charge rate is 0,1 C ...that means you charge with one tens of the capacity of the battery pack, lets say you have a 1500 mAh 4,8V battery, you then charge with the wall charger you got with the radio (probably a 50-150mAh charger) for 20-24 hours.

RE: battery care...
 

Yeah, with most NiMH/NiCd batts, even 1C is a bit much. I try to keep my charge rates for NiMH packs at 1/4C or lower (a 4+ hour charge time). I find even at 1/4C, my packs start to get warm before they peak out.

That's the nice thing about LiPo batts, they can take a 1C charge with no heat at all. I converted all my TX packs to 3S LiPo, now I just have NiMH RX packs in my nitro aircraft.

RE: battery care...
 

I can't get into any battery debate, what I do to mine would make people shudder!!!! Meters I will debate, I have a couple of them and yes, a loaded meter is one of the most used items in my field box.. Doesn't mater if it's one of the cheap analog meters from tower or one of the good digitals from a number of sources. I really like the tach/meter combo from Horizon. Most all of the cheap tachs are crap but I have tested a number of the Horizon tach/meter combos against my TNC tach and so far all of them have been on the money. NO, you don't need a tach but if you are buying a good volt meter why not take a look at it, a good combo unit. While you are in the Horizon web site take a look at there chargers/dischargers too. I have four chargers, all different brands but I like the ones I got from Horizon best. It pays to shop around though, a good charger is a true joy!!!;)

RE: battery care...
 

Thanks BigEdM...
sounds like good advice.