Alternator charging, need help

[Demonracer]

OK guys and gals, I need some help on the charging abilities of an alternator. If I mount my alternator backwards, as in the pulley facing the engine rather than facing the radiator, will it charge the battery? The reason I ask is, on the Demon, I cannot mount the alternator in the conventional manner without sacrificing the integrity of my motorplate.

Thanks,

Bill S.

 

[moparmarkk]

yes it will,it can turn ether way and charge,i'd like to see it when it is working,mark

 

[dodge freak]

Never tired it, you certain it has to be done ? I would had guess the polarity would be reverse

 

[dodge freak]

Why not mount it lower then the engine plate ?

I recall an old tip for cleaning up the engine bay, they mounted the alt under the car and had the drive shaft turn it. Only downside was it only charged while car was moving.

 

[Demonracer]

Reversing the polarity shouldn't be a problem, as it is a racecar "only". I can't mount the alternator lower than the motorplate without worrying about banging it on the ground when the front wheels come down.

 

[67Dart273]

It will run either way. Only issue I know of is the cooling fan. You CAN buy reversed fans for some alternators. The old Corvair generators/ alternators is one example. If this is on a race car, the fan is not an issue. We ran a standard Delco/ integral back in the 70's running backwards on our old Allis model M crawler, driven off a pulley on the mag drive.

 

[6pk2goDemon]

Raced for years without an alternator......Just charged the battery between rounds

 

[KitCarlson]

67Dart273 is correct the polarity will be OK. An alternator is a 3-phase AC generator, with a 6 diode full wave bridge output. The diodes control the polarity, so it will remain the same.

It might be possible to flip the fan, I think they are pressed on the rotor shaft. It might have clearance, or other issues to work around.

 

[BillGrissom]

67Dart273 and KitCarlson explained it perfectly. The diodes "rectify" the situation, so current can only flow out of the big stud. That is why reversing the field connections also doesn't matter. 67Dart273 was smart to think of the fan issue. Most of us wouldn't, since hidden away instead of outside like on GM alternators.

 

[skykeith]

Chrysler alternators have been used for years on airplanes with Lycoming engines. The engines turn opposite of car engines, so the fans are swapped end to end to change direction. It's an easy mod to do, but it requires removing the slip rings, which always break and it's very difficult to find replacement slip rings.