Battery Maintainer

russell911 · May 2022

I have a Concorde battery installed in my Arrow. I want to start using a battery maintainer because the plane sometime sits for up to two weeks between flights.

Any recommendations for good maintainer and how should I hook it up? On my cars, the CTEK battery tender is connected directly to the + and - terminals of the battery; not sure if that technique applies to aircraft batteries also.

TIA.

empannin · May 2022

I use an AGM battery charger but not an aviation specific one. I do not leave it on all the time. there is a short connector that links the charger to battery.

russell911 · May 2022

Eric,

Do you connect the leads from the maintainer directly to the terminals on the battery?

empannin · May 2022

Yes, they have a fused wire harness with ring terminals. My maint shop is ok with it and fairly typical. There is a quick disconnect on the end

griff390 · May 2022

Russell911;

Make sure you match the charger to your battery type. Your Concord battery is most likely AGM.

Most of the newer microprocessor controlled chargers will auto-detect the battery type and adjust themselves accordingly. Trickle charging is the safest bet no matter which battery type.

russell911 · May 2022

https://piperowner.org/talk/discussion/comment/1438172#Comment_1438172

Thanks Eric. 👍️

Seneca38173 · May 2022

Russell,

I use a Concorde-specific BatteryMinder, connected directly to a 35-AXC. This combination has run continuously for the past seven years, with the exception of a week when the charger went back for a display repair.

Honestly, that week impressed me the most of all. Unlike your typical IT help call (is your computer plugged in?), I got a knowledgeable tech on the phone, who diagnosed the problem and issued an RMA within a few minutes. A week later it was back in my plane, at no charge to me, and has run like a train ever since.

Which brings up a question for you guys: the 35-AXC starts my engines first time, every time, and passes regular reserve capacity checks. But it’s also seven years old. Should I replace it on calendar alone; or should I wait for it to start complaining?

Bob

Unit74 · May 2022

I’d wait for issues to start speaking to me. A properly maintained battery will last a very long time.

empannin · May 2022

I think after 4 years you are on borrowed time but at least you are doing capacity checks. If you replace a battery that has not failed yet you can also use it as a GPU for updating panel avionics, etc.

The capacity check should be done at your typical IFR minimum power draw. Sometimes what happens over time is the internal resistance increases and you see issues with current delivery at high draws.

russell911 · May 2022

https://piperowner.org/talk/discussion/comment/1438178#Comment_1438178

Thanks Bob. I will look for a Concorde specific BatteryMinder.

BTW - you are doing very well with your 7 year old Concorde. I agree with Unit74, wait for issues and then replace.

Scott Sherer · May 2022

You can wait till it fails and hope you're not stuck in an airport on a Sunday morning or get a new one now and not have to worry about the inevitable. For me, reliability is key. I just replaced my battery at six years even though it was performing well. Just my thoughts.

Unit74 · May 2022

I don’t take chemotherapy before I’ve been diagnosed. YMMV

empannin · May 2022

https://piperowner.org/talk/discussion/comment/1438182#Comment_1438182

AGM batteries can last up to 10 years but on average are ~ 3-5 years. Things that damage AGM batteries:

1) Voltages over 14.6 volts can vent water (that cannot be replaced).

2) Discharging beyond 50% capacity dramatically reduces life (maybe capacity testing is not a good idea...).

If you left a light on and the battery drained completely the lifetime would be about 1/5th. I had a Gill battery that drained over the winter to the point it would not start the engines and I replaced it with a Concorde.

Weak batteries are hard on the entire electrical system. They are hard on the starter and act as a poor buffer for voltage fluctuations from the alternator.

garserio · May 2022

Concorde specific Battery-Minder. Also buy the airframe interface kit to make hookup after each flight easy. The kit does need an A&P sign-off in your maintenance log, but totally worth it.

griff390 · May 2022

Eric et al;

Thank you.

We've both emphasized the importance of matching the charger to the battery, and for those who think a battery is a battery, please read this carefully. The wrong charger can/will destroy a battery. A lead acid battery has no problem with 14.6V-14.7V, but as Eric posted, it's a death sentence to an AGM.

Lead acid, AGM, and Li-ion all have different charging profiles AND different float voltages. Lead acid batteries can accept high amperage charge rates, while AGM batteries respond best to a low and slow charge cycles. Charging an AGM at high rates will shorten the life of the battery. Why? When the electrolyte fluid in a wet cell battery (lead-acid) boils and off-gasses (as hydrogen), it can be replenished by adding water. When the electrolyte in an AGM battery off gasses (also as hydrogen), it cannot be replaced and the battery life is shortened.

Considering the price of airplane batteries, using the correct charger is cheap insurance.

empannin · May 2022

Agree Jim. Another detail here is the Piper voltage regulator is typically set to 14V but it is possible it could be a little higher at the battery or mis-adjusted. The over voltage relay does not come on until ~16.5V and typically there is not a voltage monitor in the plane (only current). So, it is possible to have 14.6+ volts to the AGM battery and not even know it.

Many electronic displays can show bus voltage as an option and I typically use a 12V cigarette plug with a USB port and a voltage display.

Eric

Unit74 · May 2022

My JPI EDM 830 has given me one OV alarm in 6 years. I turned off the alternator, then back on a few seconds later and it was back to 14 volts. No clue what the issue was, but it has not repeated in 200 hours. Good to have an audible notification in any case.

empannin · May 2022

Unit74, the EDM 830 is a nice monitor. Most pilots do not have the ammeter in their primary scan. For alternator failures (that don't turn on a light) often the first clue is when the radios start shutting down. Voltage alarms are nice as they alarm immediately as soon as the bus voltage falls.

Battery Maintainer

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