12 volts charging?

[jaguar6165]

I installed a 12 volt system on my A about a month ago and love it however it seems like the alternator is only keeping the battery about 75% charged. It keeps enough charge to start with no problems but the lights will dim at idle and the horn doesnt have that pick me up it first did when i installed the system. I put a charger on it and it obviously worked better but do I have to keep charging it every once in a while or is it my alternator slacking on recharging the battery. I drive it daily so its not sitting for any long period of time for the battery to die.

 

[BRENT in 10-uh-C]

What is the condition of the battery? Is it shorted or possibly low on acid?

Also, is the wiring deteriorated (maybe the reason for the conversion?) where there is corrosion giving a false signal to the regulator? A 3rd thing that could affect this is the the pulley (too small) on the alternator. Start by using a VOMeter and see what the voltage output is at idle, --and at 1200 rpms. Compare the two. Then do the same thing with all the lights on and let us know what you find.

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[Purdy Swoft]

I installed a 12 volt system on my A about a month ago and love it however it seems like the alternator is only keeping the battery about 75% charged. It keeps enough charge to start with no problems but the lights will dim at idle and the horn doesnt have that pick me up it first did when i installed the system. I put a charger on it and it obviously worked better but do I have to keep charging it every once in a while or is it my alternator slacking on recharging the battery. I drive it daily so its not sitting for any long period of time for the battery to die.

It could be a problem with the alternator. Is the fan belt tight ? the fan belt needs to be tighter when using an alternator. Just for the record the smaller alternator pulley that is offered by the vendors will speed up the alternator and increase the low speed charge rate. This should help the dim lights at idle.

 

[Chris in CT]

Hi Jag, Is it a one wire, 2 wire, or three wire system? If its a one wire, the alternator needs about 1400 rpm in order to kick in. What alternator are you using? If you are using the one wire, one of two other things must happen. The sensor lug must be wired to the output terminal of the alternator, either internally or externally. Without this connection, the alternator does not know what the battery voltage is and the internal regulator will not function properly. In a two wire system, the other lug is the exciter which must be wired in series with the ignition switch. The exciter charges the field of the alternator and causes it to begin operating as soon as the engine is turning over. In a three wire system, the sensor is wired to the main fuse buss, sensing 12 battery volts there at all times (alternator output is 13.5/14 volts), the exciter starts the charging as soon as the engine turns over, and of course the #10 output terminal suppies power to the entire electrical system. I think your difficulty is somewhere in this wiring description. The main thing to check is if the sensor is connected to the output terminal of the alternator, either internally or externally. Good Luck!

 

[Purdy Swoft]

I should have added, If you use an alternator you will need to rev the engine up to excite the alternator for the charge to begin. Once the alternator begins to charge you won't have to rev it again until the next time that you crank it up. I always let the engine idle for a minute or two to get the oil circulating before reving. A guy posted a method on Ahooga a week or so ago to rig up a wire and button hooked to the alternator to start the charge. I think it was Bill Steiner, maybe he will see this and tell us how to make this modification.

 

[jaguar6165]

It is a single wire, unfortunately im at work right now so i cant check everything but i will later. thanks of all the info ill keep you update if i have more questions.