How to keep the battery charged?

[miroc]

To keep the battery in good shape in winter is not an easy task. Since October I fly barely once in three-four weeks mainly due to weather. In last two occasions I needed external power. I pulled the battery out and managed to charge it professionally.

It would be nice to plug a charger to the external power receptacle, cigarette lighter or wherever after a flight (the disassembly of the cowling would be not necessary) and the charger would take care of the battery. Charging it to full capacity and keeping it charged without risk of overcharging until the next flight maybe couple of weeks later.

I found some interesting gadgets in the Internet like BatteryMinder - Battery Minder for 24 volt Aircraft Batteries (http://www.batterystuff.com/battery-restoration/24-volt/BM24041AA-S2.html)
Do you have some experience with that kind of chargers?

What is needed to use it that way on my Cessna 172S? Where to plug the charger? The external power connector would be the best option but will it work? There are some cables sold as accessory to the charger like this one Charger Lug Harness: BatteryMart.com (http://www.batterymart.com/p-lug-harness.html) If I am correct, I could mount this cable to the battery and the other end can be connected to the BatteryMinder.

Thank you for your opinion.

miroc

[IO540]

External power connector wiring varies greatly from one plane to next. On some you can charge the battery through it; on others (like mine TB20) a power connection there operates a relay which disconnects the battery... but some early TB20s can be charged via the external power connector.

The US made Battery Minder aviation battery charger stands out above the rest in the tests. I got a quote for the Euro version a few months ago: E24041-AA-S2 $197.00 USD plus shipping.

[Rod1]

I have been using an Optimate 3 for many years. It is a very good bit of kit, but I have wired in a charging circuit with its own connector. I keep it on charge whenever she is parked up at home base.

Rod1

[DERG]

You gotta keep the sulphuric acid strong enough to prevent soilidifiying below minus 5C. Best way to do this in the uk is to employ the intelligent battery chargers on both 12V batteries. One charger per unit. God help you if you are in a hanger that will not allow mains voltage. Not rocket science.

[A and C]

The inteligent chargers are will and good but they hide things you could well want to know.

the only true test of a battery that you can do on an aircraft without removing the battery is to turn on the pitot heat and see how long it takes to get walm...........no heat is the best indication that the battery is scrap.

[Marchettiman]

I have used the Automatic Battery Conditioner made by Airflow on little used classic cars for years and can vouch that they work, I always have fully charged batteries even after months of not using the car. They also do a 24V intelligent charger which I use on the aircraft. Prices are good compared to most too.
The problem with using the external power plug is that it needs a constant live supply to energize the solenoid, that's why there are three holes in the plug!
Airflow is at Air-Flow specialise in car care products, car covers, air chambers and car accessories (http://www.airflow-uk.com).

[IO540]

the only true test of a battery that you can do on an aircraft without removing the battery is to turn on the pitot heat and see how long it takes to get walm

No, the only true test is wot happens when you try to start the engine :)

A pitot draws only about 10A.

BTW one needs to be careful with in-situ charging. One has to make sure the battery can vent freely, and this is why most people remove them for charging.

I think the "gel" batteries (Concorde etc) vent a lot less (and they are much better batteries anyway) but one still has to watch it.

[miroc]

BTW one needs to be careful with in-situ charging. One has to make sure the battery can vent freely, and this is why most people remove them for charging.The battery (Gill 241) has a kind of vent with a hose attached which other end is overboard. I hope this is enough for venting and it will not explode during charging. Finally, the charging current with engine running is ca. 6A. Charger gives only about 3A.

My C172 sleeps in hangar where I can use the mains. It will be not the only one, airport has an electrical tug always plugged in too.

I can see two problems here.

1. There has to be an accessible point/connector in the electrical wiring of the aircraft where to plug the charger/maintainer without dismantling of the cowling.

2. It is necessary to plug in the charger after the flight and forget it. It should be safe to let it on for weeks unsupervised.

Ad 1 - Can I use the supplied lead with rings permanently mounted on the battery? Is it legal? This wire with rings on one end should go directly to the battery and the other end has a protected connector for the charger. This looks to me like it could be mounted permanently. If this connector will be accessible through the opening where the external power connector is, the problem is solved. Or do I have a better option?

Ad 2 - If I need to go every other day to airport to see the thing :rolleyes: ... Of course, there are employees at the airport, it will not remain unsupervised for long time. What could happen? The charger is designed to be olways on. There is a legal question too, if it would be a charger for "aviation use" it would be "more legal" (insurance issue) or it is only my beginner's paranoia...

miroc

[IO540]

The battery (Gill 241) has a kind of ventYes, interesting. I used to have the 242 which didn't have a single vent. You've got to make sure it doesn't get blocked.

Finally, the charging current with engine running is ca. 6A. Charger gives only about 3A.The first should be a lot more than 6A. If my battery is a bit low, I see about 30A going into it, for some minutes. If you see only 6A, ever, there is something wrong with your alternator, IMHO. The charger will supply whatever it is designed to supply.

Can I use the supplied lead with rings permanently mounted on the battery? Is it legal?This one has been done to death on American forums. The standard answer is that it is at least a Minor mod (a logbook entry) and possibly worse. The practical answer is that you must have a fuse in that lead, in the non-airframe side (usually the positive one) and the fuse needs to be as close to the battery as possible, in case the lead shorts to the airframe further down.

Lots of planes have direct battery connections (e.g. mine has a wire for the yoke clock and the courtesy light; the stupid light is a great way to flatten the battery) and a lot of people have a mod done whereby one of their radios is connected directly to the battery, but these always use an inline fuse close to the battery.

There is a serious fire hazard in this because a short circuit, without a fuse, will instantly set the wire on fire.

would be a charger for "aviation use" it would be "more legal" (insurance issue)I doubt it... all this stuff is "portable". I know some hangar owners insist on an electrical tesf for all equipment used in the hangar.

[Jan Olieslagers]

There has to be an accessible point/connector in the electrical wiring of the aircraft where to plug the charger/maintainer without dismantling of the cowling.

This might find an elegant answer in the kind of trickle-chargers sold in car accessory shops, that plug into a lighter socket. There are commonly used in mobile homes, camping trailers and other vehicles with a 12V lead-acid battery, that are not used for several months, mostly during winter.

Make sure, though, to get one that fits YOUR battery - gel batteries might well have different requirements. And remember this is a trickle charger, its function is to defy trickle discharging, i.e. to keep a full battery full. It will and can not make a fully charged battery from a depleted one.

HTH,

[mikehallam]

FWIW.

No power anywhere near the strip. Plane Rans S6 with Rotax 912. Sunlight trickle charger has worked for two years now.

A solar cell on the shed roof with lead down to feed a/c battery via croc clips onto the Live +12 V behind the key switch and -ve to metal airframe. Find the live terminal with a light bulb or voltmeter.

It's too feeble to overcharge (smile).

In the Summer it is re-routed & charges the grass cutting tractor battery for easy starting.

mike

[IO540]

I looked into this.

In my plane, there is no way to get to the battery via the cigar lighter socket unless the Master is on, and then there is about 2A current draw due to the gyros etc. The CB on the cigar lighter socket is 5A, so the charger would have to be current limited to about 2A, and voltage limited to something which fairly accurately charges the battery at the same time. One could trickle charge in this way but anything faster you can forget, and the charger would have a hard time switching to a trickle charge mode due to the other avionics current draw. Also there is the pointless wear on the KG-102 gyro. One could pull the gyro CB but those CBs are not great for longevity :)

An "unofficial" connector via the clock or the courtesy light would work for trickle charging.

I have a solar panel (http://i101.photobucket.com/albums/m74/peterh337/solar.jpg) too, which delivers about 1-2A at full sunlight into a 24V battery. It rolls up into a tube and weighs about 3kg. I have carried it on long trips but it never got used.

Many years ago, in the days of my ex wife and her horses, I completely successfully used a 2ft x 2ft solar panel to charge a car battery used for an electric fence. That works very well.