Using a Battery Charger

[MK1_Oz]

The lads Celica sunroof has stuck open and I think I have diagnosed it as a control box fault. Having poured over some wiring diagrams I think I understand how it works (several relays, position switches and operating switches). New ones are $300 so I want to test this one before I buy new/wreckers (not that I can find one).

Rather than pull a 12v battery out of a car to use as a power supply for testing is it possible to use a car battery charger as a 12v source? Although mine is rated at 8A the component will only draw what it needs so shouldn't cause any damage? I guess a car battery is rated at a whole heap higher than that anyway.

Thoughts?

[Miniliteman]

Depends on the charger.
Some pro-chargers (Bosch) need to "see" a voltage first to start the charging-cycle.
Cheap chargers can give upto 18-20 Volts when there is no load (battery); this high voltage could possible destroy the electrics of the control box.
I normally use a start-booster for testing electrics of a car, see photo.

[jsa]

In rush on startup will be multiples of the running current. Depends on the charger and the motor size as to how that plays out.

Fuse size for that circuit will give you a clue on what it draws.

[ozstang65]

I've seen chargers with have a blade type fuse in them, from memory 5A in one of mine. If your motor draws more than that it will blow, 8A in your case. (a bit less than 100W)

Better off just using a battery.

BTW, I have a complete Soarer sunroof here, and probably the controller somewhere too. If you had a part number i could have a look for it and see if its the same.

[MK1_Oz]

Hey Oz. The part number is either 85921-20060 or 166000-2071. Both are printed on the front of the control box.

Appreciate the help!

[ozstang65]

I'll have a look when i'm in the shed tomorrow.

[ozstang65]

I have 85921-24020. 166000-2162

[MK1_Oz]

oh well thanks for looking. No idea of teh difference but bound to be something...limit switches or the like