globos

I've been reading these forums for about a week and decided to register today. I just put my avistar together and I'm almost ready to go. I just need to get a time worked out with my instructor. How often to you have to charge a field battery. Is there a good voltmeter for the 12 battery I should get? What should the voltage get down to before charging? I've heard that they can't handle a deep discharge like a nicd battery. Can I just use my car's battery charger to check the voltage?

RCBOZO

My Feedback: (1)

A normal 12V fiels battery will last for a month or so before you need to recharge it.

Montague

You get a month out of a 12V? Not much flying going on there, I guess .

Seriously, though, since these batteries don't like deep discharges, and they certainly don't mind being charged often, I just charge mine the night before I intend to go flying regardless of how much use I put on it last.

A typical car battery charger is fine, it shouldn't hurt your field battery.

tomass15

It really depends on what battery you use and the demand you put on it. Easy way to handle it is to get an automatic charger or battery tender for motorcycle size batteries. The tender you leave plugged in and your battery is always ready to go when you are. My self I use an automatic charger I got at Wal Mart for $25 and just charge when I charge radio gear.

If your battery is in good condition, you should get many days in the field. The problem being the one day it dies takes the fun out of it. The same as I do radio gear, I try to take to the field with all batteries charged.

As for the volt meter, a small one from Radio Shack will work. Test your battery after a full charge and then as you use it. Really depends on the battery as for voltage output. If the battery drops a couple volts, I would recharge. As you use the volt meter and get to know your battery, you will be able to tell it's peak charge and drained volts. To use a volt meter to peak charge a battery, with the charger on, as soon as the volts start to drop, it is fully charged.

DBCherry

My Feedback: (4)

Agree with Montague. You don't want to let a typical 12 volt discharge much. I re-charge before every trip to the field and at least once per month in the winter. My current 12 volt has been in use for 5 years now. (I didn't take care of my first one and barely got two years out of it.)
Dennis-

RCBOZO

My Feedback: (1)

I hit the field 4 to 5 days a week in the summer! I only use the 12V for my fuel pump, glow driver and the occasional starter. Maybe it might be a good practice to charge your battery once a week but the 12V battery is the last battery he should be concerned with! Every other battery that he takes to the field BETTER BE CHARGED! I have a Triton charger and I tend to let battery's get low and charge them up as required because it is so easy. Even with the Triton the 12V battery will take a good long time to charge. I usually just put it on an overnight wall wart.

Flypaper 2

I use a 7 ahr gell cell lasts about a month. A lead acid batt. is considered dead when it reads 12 volts.

AcousticTX

On my 12V I have easily gone a month without a recharge, and it powers my starter, electric fuel pump, glow driver, and a quick charger. However, I can only fly during the weekends so mine does not get used quite as much as alot of people. I also use the 12v version of the voltwatch on my flight box to keep an eye on it and charge accordingly. The voltwatch is pretty cheap and can be mounted on your flight box.

rik1024

My Feedback: (1)

Mine will be dead by the end of a good day of flying with my quick charger starter and fuel pump and glow starter. I only fly on week ends when the weather is nice here. That means as many flights as i can in one day some times i can get 2 days per weekend. I charge every night before flying and this battery is a 7 amp only 2 years old.

Dusty1

Here's a good inexpensive multimeter from Radio Shack that you can use to test your 12V gel battery, TX and Rx batteries.

http://www.radioshack.com/product.as...%5Fid=22%2D810

phread59

I just want to chime in here. I will tell you guys that I am an auto technician. You have to be careful with small batteries and chargers. If you use too much current when charging your batteries you can overcharge and destroy your battery or worse. I especially want to warn about a standard lead acid battery. The kind you use in a motorcycle or lawn tractor. If you overcharge the battery you will literally cook the acid out of the battery. You also will be producing fumes and hydrogen. So flames near a charging battery is a no-no. I would advise charging out of the house. Hydrogen is explosive and you can blow a battery being careless.

Now having scared you guys I want to say. An inexpensive charger will work fine. Look to see that it has a setting for 2 amps or less. A peak detecting charger is best. Mine is made by Solar. They make good chargers and are inexpensive. Just be sure that you have your charger on the 2 amp side. If you are not sure if yor charger is over charging here are 2 things to look for. The battery will be bubbling. Some small bubbles are fine and normal. But if it is sitting there boiling then you are overcharging. If you get into this situation and you still can't run for any length of time before the voltage drops then the battery is heading south. The other sign is heat. A battery will warm slightly when charging. If it gets hot then you are overcharging. A little heat is ok.

The last thing I want to say is how to hook up a charger. Be sure when hooking and unhooking the charger (whatever kind it is) that the charger is not plugged in. Hook up the + side first and unhook it first. Lastly let a battery sit for a little while after unhooking it before moving or handling it. 15 minuits should be fine. let the battery settle down and vent any built up hydrogen. Be careful and all will be well. Follow any and all instuctions included with your charger. Good luck and be safe.

Mark Shuman

PS: I am speaking from experience. I had one battery blow in my face when I was replacing it in a customer's car. If an accident does happen. Flush the area very,very,very well with water and seek immediate medical help.

rik1024

My Feedback: (1)

Good point phread59 i am a auto body tec i to had one blow on me it was shorted from a wreck and acid in the face is very very painful and if your lucky you will not be blinded or spend time in a burn ward in the hospital like a friend and x co worker of mine. Any battery can blow if over charged or over heated

randy41

Well: If you have a car then you dont need a 12v battery in your
field box. I never have to charge my battery my truck does that.
Yes the guys at the field has run down there battery and guess who
starts there planes the rest of the day(ME) LOL. I just took 2 banna plug
male and female and drilled 2 holes in my field box and installed 2 female
banna plugs and made a extenision cord and i plug it in my box and hook
it up to my truck battery(never have to worry about charging or forgetting
to charge and so on) It also makes the field box lighter. My field box is
heavy enough as it is LOL.

DBCherry

My Feedback: (4)

Except I'd need at least a 50 to 60 foot extension cord, or I'd have to carry a running plane from the parking area to the flight line.
Dennis-