The International Cessna^® 170 Association

I have a Gill G25 battery. It has been on a tender and the light was green, but it would not start the engine today, barely turning it over.
I hooked an automatic battery charger to it; the charge rate dropped to about 3 amps, and then fewer, in matter of seconds, and in a matter of a very few minutes the charger switched over to float.
Yet the engine barely turned over, and no start. Any idea what's going on here?
Prior to this morning the plane had sat in the hangar for three weeks since its last flight. It started fine then. It has not been especially cold (it was much colder last winter and I had no problems starting). I have run the tender on and off and during periods of cold weather or when I planned to use the airplane in a day or two.
The battery is 18 months old. I'm inclined to think it's toast, the last Gill I had was 18 months old when it died.

Are you sure the connections are good, especially the ground?

Agree that all connections should be checked. Also, if you can, the voltage drop across the starting switch/relay. Batteries sulfate when they sit too much. I've had that problem with my tractor, airplane, etc. You might try a couple of cycles of discharge and recharge Just leave the master on for four or so hours, then recharge. After a couple of cycles then try it.
Another thing is battery rejuvenator. I don't know if it's legal, and I haven't used it in aircraft batteries. It sure rejuvenated my old Farmall 6 volt battery recently, and a couple of car batteries some years ago. This is what I could find, but there are others - check your local auto supply. http://www.amazon.com/Charge--Concentra ... ejuvenator
Surprised you are having such short life from Gill batteries. I've had quite long life from them - like 6-8 years. Is your charging system working correctly? Just ask, because if it is over charging, that will shorten battery life.
Good luck!

Jerry, are you using an automatic charge designe specifically or aircraft batteries? Aircraft batteries use a heavier electrolyte than cars. And so chargers calibrated for an auto will not work correctly on an aircraft battery in the auto mode. This includes trickle chargers that monitor battery condition.

How old is this battery? Seems like you wouldn't expect it to be bad at this point.

You should read and charge the battery per Gills service manual found here: http://www.gillbattery.com/pdfs/Flooded ... Manual.pdf

And if it then does not have the required capacity, replace it.

It's been noted by many that dry charge flooded lead acid batteries such as the Gill 25 do not have the life they once had. I've heard because of changes to chemistry required by EPA. Most folks are replacing these batteries with initially more expensive with the Concorde recumbent gas AGM style RG-25 I bought. http://www.concordebattery.com/flyer.php?id=36. This is what I did last time I needed a battery.

A stock 170 grounds the starter through the firewall and engine mount. This path can develop poor connections. Your voltmeter hooked to the battery negative terminal and the engine case during a start attempt would give you a clue, as would a starter activation cable that gets hot during a start attempt.

Thanks all.
We will definitely look beyond the battery this time, but I'm probably going to go in a direction other than Gill, based on much of what I have read here and elsewhere in the Hangar forum.
I have a "recondtioning" charge going into it tonight... there's nothing else left in my bag of tricks. We'll see what tomorrow brings. We're getting a rare spell of good weekend weather, it would be nice to fly it.

Again I hear of another pink battery dying prematurely. Concord batteries give the best service . We refuse to fit those pink batteries in our shop. The pink batteries seem not to recover after a real big load and the volts drop down . Check the voltage out put on load and watch the amps also .

The last pink battery I had vented acid through the caps while the airplane sat in the hangar (without any kind of battery tender on it). That was a mess to clean up, but I replaced it with a Concorde sealed lead acid battery. I'd have to look in the logbooks to see when that was, but it was about 5 years ago. In those 5 years, the airplane has averaged maybe 10 hours a year. Not a single problem with the battery, and it has not had a tender on it any of that time! I did charge it up before the last series of flights I did, but I didn't try starting it before, so I really cannot say for sure if it really needed it. Concorde for me going forward.

Bruce,
You lose me when you refer to different electrolite required for the various lead-acid batteies, automotive and aviation.

Could you please list the specific gravity of the electrolite reqiured for the various types ? I have always used the same hydrometer for both types.

I have used the same battery charger for many years on both my automotive and aviation lead-acod batteries and have nsver had a problem. I don't think I understand why the type of electrolite would apply to the charger.

I've had several "pink" batteries in my 170 over the years, and at least once in the life of several of them, I've let it go flat from disuse. As long as the battery was less than 3 or so years old I've not had any trouble bringing them back with my 70s vintage automotive charger.

Installed a Concorde RG‑25XC 4 years ago along with a new regulator. Have done nothing to it except use it and still cranks the motor great.

blueldr wrote:Bruce,
You lose me when you refer to different electrolite required for the various lead-acid batteies, automotive and aviation.

Could you please list the specific gravity of the electrolite reqiured for the various types ? I have always used the same hydrometer for both types.

I have used the same battery charger for many years on both my automotive and aviation lead-acod batteries and have nsver had a problem. I don't think I understand why the type of electrolite would apply to the charger.

From the Gill Battery site:

• Can I use automotive electrolyte in my battery?
  
  • No……not recommended! Automotive electrolyte is only 1.260 Specific Gravity. By using automotive electrolyte the battery will not function to it’s intended capacity because the cell electrolyte balance would not be up to the required levels. Gill electrolyte is 1.285 Specific Gravity. Warranty will be void if the proper specific gravity electrolyte is not used.

• I have a new 12 volt battery and a 12 volt automotive charger. Can I use this type charger to charge my battery?
  
  • First determine the type charger…Constant Current or Constant Voltage. Follow charging instructions as outlined with battery or in Gill Service Manual available on the Gill website.

What this last answer means is that you can use many chargers so long as you follow Gill's charging protocol. It is unlikely your automotive automatic charge will follow it.

If you use a hydrometer marked for auto electrolite, the charge % markings will be incorrect for an aviation battery.

I have no idea whether my hydrometer is made for automotive or aviation batteries, but it would sure as hell be extremely difficult o determine between 1.260 and 1.285 specific gravity. I have used a number of Gill batteries over the years, and I don't EVER remember reading any instructions in caring for them in a manner different than any other lead-acid battery.
I did not have much life success with Gill 25 batteries in my '52 C-170B, and found that the use if an inexpensive 12v garden tractor battery with an annual replacement was my answer.