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Deep discharge if not on tender

Ed Cesnalis

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You can put a resistor in between the positive wire and the battery. Leave all the switches off like you would have it while it is stored.

Put a voltmeter across the resistor. It should read 0 volts (or whatever your meter reads when you touch the leads together). It will confirm that it's the battery being the battery... Lead acid batteries just don't hold charges.

Anything else and there's a vampire and you need to find it.

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I purchased a new Odyssey battery about a year ago as the old one had plenty of years on it and appeared to be loosing strength.  I run the Odyssey charger and believe I'm following the maintenance correctly.  I didn't have to keep the old battery on the charger much at all, flying once or so per week, was more so for winter or longer times between flights.  The new battery I've noticed I need to keep on charger.  I'm not fighting electrical issues, just appears the new battery needs to be maintained more.  Never went full dead like your issue, but thought I'd share I'm not finding the latest Odyssey battery as good for sitting off the charger. 

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  • 4 weeks later...

I have not found the drain.

I just put a third new battery in and now that it is installed my smart 5amp Genius tender never gets to maintenance mode (still flashing green 100%).  Prior to installing the same charger did get all the way to maintenance mode (solid green 100%)

With the batt master on and D100 I see a -1 or -2 amp discharge going on and I assume this is at least partly the D100.  IF I turn off all the breakers 1 at a time nothing happens except when I get to the D100 breaker.

Can someone please tell me how to locate the drain?  I do have a new ADSb out radio installed that I never interface with.

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Voltage drop testing.

Your ammeter is a shunt, and works on the same principle. It's a very tiny resistance, but that's all it has to be. Power flowing across the shunt will drop a voltage and it can be picked up with a voltmeter. If you have a known supply voltage, you can calculate the amperage.

So, you do the same thing, putting a shunt on the battery negative, pop all the breakers, and see if you have voltage across the shunt. The amount of voltage that you read doesn't matter, because the breakers are popped, anything above a few milivolts (with a digital meter) is an issue because that translates into a lot of amperage fast. D'arsonval movement solenoid meters should read -0- period.

Cycle breakers one at a time, and check for voltage each time.

Then turn on all breakers but leave all seitches off and check (this checks for daisy chained wiring and I have seen it!).

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10 hours ago, Mike Koerner said:

1 to 2 amps is huge. 1 amp is the normal current to a Dynon D100 when it's all lit up and operating. It's maximum current (when it's recharging its internal battery) is only a little more than 1 amp. It can't get to 2 amps.

If the cooling fans are running when the master is on the amp draw will be a little higher.

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