cruzomatic

My Feedback: (17)

I haven't flown my GP J3 Cub in a month or so, probably more. I charged up the plane about a week ago just to keep the batteries up. Last night I again charged it up for some early morning flying today. I had it on the wall charger all night, all was good. This morning after fueling it up and getting the engine started and doing all my preflight checks, I looked at the voltwatch. It was red, bright red..whoaaaa. I turned off the engine and checked the voltage with my loaded voltmeter. Sure enough, it was reading just belove 3.9 volts, a no go for sure. I figured I'd try to charge it up with my field peak charger and took up my trusty 4*60 in the meantime. After a 'peak' reading again, same bright red light on the voltwatch and same reading on the loaded voltmeter.

I'm assuming a bad cell, bad battery pack.

Saved my plane for sure.

flynte

I have voltwatches on most of my planes, and the ones that don't, I check with loaded voltmeter after a overnight charge just before flight. These are a quick,cheap and simple safe guard from disaster (not to relace checking with a loaded meter mind you). I plan to eventually have them on all my birds.

flynte

im_a_rcav8r

At 3.9 volts it sounds like your remaining 3 batteries were fully charged. Nice catch and good pre-flight saved the day… This is why I fly with 5 cell packs and a 4.8 volt regulator. If one of my 5 cells goes in flight, I will still have 4 cells to run the radio until I land. I have not had a cell fail yet, but I am ready if one does.

rctrax

I could wonder if with a five cell pack if one failed open you could lose all volrage and still end up with a dead battery situation?

cruzomatic

My Feedback: (17)

Honestly, I rarely use my loaded voltmeter and I just went with the voltwatch gizmos on all my planes. It could have been a bad, bad day for me.

Lesson learned for sure. Some my planes in the fleet are getting a bit old. This is the second battery I've had go bad. Thankfully, I've found the problem on my preflight checks just before taking off both times.

There's no doubt I would have lost the Cub.

Be safe out there.

Missileman

YES

im_a_rcav8r

If you loose a cell and it fails open, yes you will loose all voltage. However if you loose a cell because it will no longer take a good charge a 5 cell will save the day. The original poster lost a cell because it would not take a charge, had he not checked and took off with that pack he would have crashed for sure. With a 5 cell in the same circumstance, he would have had a successful flight.

The bottom line is a good preflight will find most of your problems before they become fatal to your plane.

chevisn7

I was thinking of buying the Volt Watch devices. From reading your posts it seems like a no brainer. Does't anyone use two battery packs with a Y connector. Wouldn't this be a good safeguard? The weight would be minimul I would think for the protection you would get. Is there a reason this is not done other than the weight and balance of the plane.
New to RC
ChevisN7

Gray Beard

My Feedback: (-1)

Depends on the plane but every now and then I will run two batteries and two switches with each battery going into an open RX slot. Other times I will run A big battery pack with two output wires going into two switches and two open RX slots. I never use Ys at all, seen too many of them fail, even brand new ones.
I use the volt watch or GEM 2000 on A few planes. They are OK but not as good as checking my batteries with A good volt meter under load before each flight.

Villa

Hi chevisn7
On my Canard I knew I would need a lot of ballast weight at the nose. Since my one battery was already in the nose I decided to use a second battery instead of more lead. I was going to do it with a Y-connector but after reading something about it on RCUniverse I decided that using two switch harnesses would give me the added security/redundancy I was looking for. I have seen too many switch harnesses fail.

Nathan King

Absolutely, the cells are wired in series. It's like Christmas lights. One bulb goes out and the string is toast.

Charlie P.

On my gasoline models I run two battery packs for the receiver on seperate switches through a battery combiner. This pulls voltage from the higher pack, so that if one fails it drops out of the circuit instead of just draining the good pack along with it.