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Disclaimer: These IAC pages are developed by individual IAC members and do not represent official IAC policy or opinion.

Collected by: Chuck Graves


The little 17.9 Amp Hour battery in my I0-360 powered Pitts is just not up to the task. While this battery only weighs 13 lbs. , it's just not enough to turn the prop more than one blade at a time. (it's also brand new) Can someone drop me a line and let me know what they are using.... Thanks in advance.

Chuck Graves
Pitts S1S


I have experienced some of the same battery problems and concerns in our Skybolt with an IO540. We have a Gill jell Cell and it will only do one blade at a time. After our first couple of run ups (fresh overhaul) we fried the starter solenoid. I called Skytech about the problem I they were very helpful in sending me a wiring diagram on using the solenoid already mounted on the starter. So we replace the starter solenoid behind the rear seat with a continuous duty and installed a switch so we can omit having that #2 wire hot all the time. So far it has worked fine and will turn more than one blade now.

check the 'ground' wire to the engine. That is a common source of problem. If you don't have a good ground return that can limit the cranking amperage. Of course, the positive wire must be in good condition and gauge also.

Check B&C for a 25 or 35 amp-hr batty. The one in my S1C will crank the engine for about 3 minutes before getting tired.

Before you give up and buy a new battery, check the terminal voltage of the battery, directly on the battery, when you are cranking (which should be around 10 volts or so under heavy load). Then check the voltage directly on the starter when cranking. If there is any real difference, the problem may be in the cables to the starter or poor grounds, such as the connection between the engine and the acft frame which should be as heavy as the main battery cables, i.e. #2 AWG or heavier. Sometimes there is a light weight strap intended to carry the alternator current, the builder forgetting that the starter requires much heavier current (100 to 300 amps for the short duration the starter is engaged).

It could be beneficial to run the same gage copper wire from the battery negative terminal all the way to the engine case to reduce voltage loss in the steel airframe. Making a voltage measurement between the battery negative terminal and the engine case while cranking will show whether there is any appreciable loss in the ground portion of the circuit (i.e. the combination of the steel airframe, the engine mount and the bonding strap between the mount and the airframe ).

Lastly, GelCells don't seem to have very good battery life the way we use them. About a year is all you can expect. Sealed lead acid batteries seem to do a bit better. The one in my Luscombe is on it's second season.


Chuck, I've used this battery since completion of my S1S in Sept of 94. A good no hassle battery. I don't have an alternator so I keep my battery on the charger as necessary. I also bought the battery charger that Concord makes, a little pricey but totally automatic. They say you can leave it on all the time because it can sense the amount of charge necessary and ten stops putting out when the battery is full up. It's so smart it won't let you hook up the terminals backwards. Trade-A-Plane sells everything!

If it's a b&c battery, something else has to be wrong. I have one in my T with 10:1 pistons and it turns it over with no problems. First,check out the battery & make sure it's putting out 17 amps, then check out the connections to the battery , then check the cable to the starter. It's probably too small a gauge to work with the battery, especially if you have a light weight, permanent magnet starter. 4ga is OK 2ga, is better.

The 17.5 works ok for me. i know some with very high compression new motors it works for too. maybe check your starter. New B&C seems pretty good. Starter coil resistance may be dropping amps. or you're using higher resistance aluminum cables.

If all else fails, some have doubled up two 17AH batteries to run a 24V starter. typically for high compression io-540 installations. radios can still run off just one 12V battery.

Many short flights add up to lots of dead batteries for us akronauts. If a battery lasts longer than one year, you have been flying lots of cross country flights or have something in excess of 30 amp hours.

We put an APU plug receptacle on everything !!! PIPER STYLE APU plug receptacle, installed where the pilot can toss away while sitting in the plane.

If you make a policy of always using the APU and starter cart ( Red Wagon holding my old car batteries ) at your home airport, your plane will actually start virtually all the time when you travel cross country.

I am using the Concord RG25, not the high output one just the stock RG25. This is a sealed Recombinant Gas battery. Appears to be working OK. I is in a S1T for the last yr (IO360 200HP). Also have same battery in my RV4 and in a C170A.

Industrial Battery in Columbus, Ohio, has supplied me with batteries for years. They are quick and competent and have every battery you can imagine. Their e-mail is:

I used to have to buy a new Globe gel-cell every winter. Then I switched to a sealed lead acid battery ( B&C). It lasted almost five years in my Pitts S 1T with a pumped up engine and a heavy starter. I had failed to turn off the master switch three times in that period of time. Pretty good little battery.

I had a glasair I that had problems. the previous owner had installed a sky tech starter and that also did not help. When cold it had to be popped to start. after it was how it started with no problem. My mechanic said that the cable was big enough. The battery was in the baggage compartment. I tried a 35 amp battery and that did not help.

I suggest a 25 amp RB battery and they make one that has extra amps for starting.

If you have aerobatics related information that you would like to make available, please contact me at the email address below.

Last Update: Sat Aug 29 16:11:25 2009

© Dr. Günther Eichhorn
Retired Email Guenther Eichhorn