How long should a Concord RG35a last?

[philiplane]

South Florida heat is a battery killer. I never expect more than 3 years from any battery. The manufacturer's instructions say to store batteries below 95 degrees. But planes here experience 95 degree for half of the year. Sometimes more, in these un-insulated hangars, where it gets to 110 degrees from June to September.

You'd have to take the battery out between flights and store it in an air-conditioned space to get more than 3 years from one. When I lived in Connecticut, I could get 7 to 9 years from a battery. 

[N201MKTurbo]

When I was commuting with the Mooney, I flew it at least 6 times a week. My batteries would last 5-7 years. Even here in AZ where the hangar temps can top 135 F. 
 

Now that I don’t fly as much they seem to crap out in 3 years or so. 
 

I think disuse is more a killer than heat.

[Stephan Kablitz]

Don Maxwell’s value of 28.8V for the buss voltage seems consistent with Concorde‘s RG Series Owner/Operator Manual:

So when the battery sits in the uninsulated tailcone, it will be receiving the charge most of the time below 15°C/59°F and it is also my experience that even when I return from a longer flight and attach the battery to a charger in the hangar, it still will slowly charge for another hour before the charger indicates the battery to be fully charged. So adjusting the battery voltage to a lower value will result in a lower capacity available in case of an alternator failure.

Of course the gold-standard would be a voltage regulator that takes the battery temperature into account.

[Fly Boomer]

3 hours ago, Stephan Kablitz said:

Of course the gold-standard would be a voltage regulator that takes the battery temperature into account.

BatteryMINDer

https://www.batteryminders.com/batteryminder-model-244cec2-aa-s5-24v-4-amp-concorde-aviation-battery-charger-maintainer-desulfator/

[A64Pilot]

I want to clarify “trickle charger” they are still out there, what they are is low amperage chargers that ideally charge at 14ish volts but as they are most often cheap devices many or most over time will go much higher and leaving a battery on a trickle charger will eventually dry out the mat that holds the electrolyte.

I’m certain what most are calling trickle chargers are actually tenders / maintainers etc that will charge until a very low battery acceptance rate, then drop to float voltage usually 13ish volts, they extend any lead acid batteries life by keeping it fully charged which slows sulphation, but does not overcharged and cook off the electrolyte.

Just make sure you don’t actually have a trickle charger leaving one of those connected will kill a battery.

For those that go to a LifePo4 battery, do NOT float them, ideally for storage a Lithium battery should be stored between 30 and 50% charged, but as was brought out earlier in the thread doing that cooks alternators, and nothing will cook an alternator faster than a Lithium battery of any chemistry, LifePo4 included.