Rotax 503 charging problem

[navajo]

Have a Challenger w/ a 503. Been sitting still for a yr and just bought it. New batt, fully charged but after 2 hrs of flying not enough in batt to turn over engine & start. Strange thing though was the batt came up again fully charged on a 900 mw charger within 2 hrs which seemed real quick. Put the batt back in but about 2 hrs flying again and 3 strtups it was dead again -or at least not enough to crank engine. Ammeter shows 0 all the time so I am speculating that in addition to not charging, there is drain on the batt somewhere. Only thing I had on was handheld GPS and an Icom both of which would run for a day even on their own internal batt.
Any clues re what it might be causing the batt to discarge and hoe to test charging system to find problem (s)?
Not too up on electrical systems so talk slow pls. Tks

[Trev Page]

Sounds like you have a short in your system that's draining the battery. Have you checked the voltage regulator? They're notorious for failing and not uncommon for them to be the source of the drain when it happens.

If this is the culprit may I recommend you replace with it with a "Key West" regulator. Best one on the market.

[navajo]

Tks Trev. Not familiar w/ sources of parts yet - where would I get a Key West reg. ?

[macandrews]

Tks Trev. Not familiar w/ sources of parts yet - where would I get a Key West reg. ?

I had a problem with elect back a couple years ago. I cked the output from the lighting coil and found intermittent to no power. Wire inside had come loose after buying rect/reg that wasn't problem. If you go on internet type in" Rotax 503 charging system" you will find article there by Jim Hayward and Doc Green or CPS California Power Systems Mike Stratman. It's all there and very easy to understand as even I could fix it eheh!!!!! safe flying!
Mac

[bill white]

Drifter A 503 fitted with Elect start (E gearbox) ignition system OK but lighting system has no power output to regulator. checked wiring connections at first connector from motor (yellow and yellow/black cables), no leaks anywhere and accessories all function correctly from battery but battery will not charge. aircraft fitted with voltmeter and ammeter. Voltmeter indicates true voltage ok but under running condition the ammeter does not move to indicate either charge or discharge. Any hints?

[Jord83]

Rotax-Owner.com

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