Aircraft battery question

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bahama flier

Pre-takeoff checklist
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bahama flier
My truck battery died from listing to the radio all day at my hangar. I needed a jump, only battery was my gel 12V aircraft battery. Got out jumper cables.... truck would not start with a jump from the aircraft battery....

Any body know what the difference in the aircraft battery and truck battery, just regular 1500 truck V8 motor...?
 
Difference between aircraft battery and truck battery? Price (assuming your aircraft has a 14 volt system and not a 28 volt system).
 
Usually a bit smaller.

But most likely your problem was the jumper cables and/or one or more of the connections.
 
The airplane battery doesn't have the same amp capacity as the truck. I don't know what truck you have, but the V8 in my Toyota Tundra has one massive battery. Nearly twice the size as the G25 in my plane.
 
Yeah, connection or not enough amps, or did you somehow connect downstream of the master switch relay?

I've jumped a few 12v planes from cars before, no biggie.
 
If it was terminal to terminal, I guess I'm surprised it didn't at least try to turn over.
 
The Gill G-25 in my plane is rated 225 cranking amps. That should start a light duty vehicle engine. Especially in warm weather and when the vehicle has run lately. I would wonder about your jumper connection - maybe allowing a lot of voltage drop.
 
bsdunek said:
The Gill G-25 in my plane is rated 225 cranking amps. That should start a light duty vehicle engine. Especially in warm weather and when the vehicle has run lately. I would wonder about your jumper connection - maybe causing xxxxxxxx a lot of voltage drop.
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FTFY.
 
bsdunek said:
The Gill G-25 in my plane is rated 225 cranking amps. That should start a light duty vehicle engine. Especially in warm weather and when the vehicle has run lately. I would wonder about your jumper connection - maybe allowing a lot of voltage drop.
Click to expand...

The last battery i put in mh old Honda was pushing 500 CCA . . . Can't imagine a full-size trucks would use a smaller one. My new neighbor was not impresed that my Concorde sealed battery cost over $300, as the one in his giant Dodge V10 truck. Then he saw how tiny it was, and his chin hit the floor!
 
Hank S said:
The last battery i put in mh old Honda was pushing 500 CCA . . . Can't imagine a full-size trucks would use a smaller one. My new neighbor was not impresed that my Concorde sealed battery cost over $300, as the one in his giant Dodge V10 truck. Then he saw how tiny it was, and his chin hit the floor!
Click to expand...

I see you didn't have the heart to tell him how much a new Mooney, even excluding the battery, costs compared to a new giant Dodge truck. :D
 
Size is a reasonable measure when comparing the same technology (lead-acid batteries in this case). Yeah, if you want to throw something in with a different energy density or internal resistance, yea, things will be different.
 
I will say this. In general if one battery is 14V and the other is 13V, when you connect them together in parallel you will read 13V (pretty sure of this) and current will flow from the 14V battery to the 13V battery until the 14V battery is discharged to 13V, discharging the 14V battery some (and its hard on the battery). Now a jump start is fairly short amount of time, and the starter doesnt care how many volts it has so long as it has enough to crank.

Batteries of different cell type have slightly different voltages even if they are "12V" batteries.

Having said all that, a 12V airplane battery should be able to start a 12V car (12V is nominal). Not that its recommended.
 
A lead-acid cell is a lead-acid cell. The charging current is upwards of 2.35V a cell making a 14V six-cell system. The battery itself varies from 1.8 to 2.1 V depending on the charge state and load. A 12V car battery and a 14V aviation battery are the same as far as voltage is concerned.
 
coloradobluesky said:
But aren't some batteries something else besides lead acid cells?
Click to expand...
Some batteries aren't lead-acid on jets, helos, and experimental aircraft. Most (all?) certified spam cans are lead-acid.
 
Connect the cables and let the battery absorb some charge for five minutes or so THEN try to start the jumped vehicle.

That said, the difference in capacity is significant. Personally I would not subject my expensive, delicate aircraft battery to such a strain, but that is just me.
 
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