alternator woes
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alternator woes
This morning I got into my aerostar and it started normally. But the voltage gauge in the dash read just above the red. I put a multimeter on the battery with the engine off and had 11.8V, started the engine and the voltage remained the same. Hit the throttle a few times and the voltage never moved.
Picked up an alternator and new belts at Knechts. The alternator was a remanufactured Titan. Swapped the fan guard and pulley and installed.
Checked my battery voltage before I started it up and had right around 12V. With the engine idling I was at 12.8, I could rev the engine and get it up to 13.4 or so but never 14 or 15 like I thought it should be at. The voltage moves with engine speed now but still isn't right.
Is there anything else I can test before I take the alternator back or maybe have it tested somewhere?
Kanute
'89 Aerostar 180k
Picked up an alternator and new belts at Knechts. The alternator was a remanufactured Titan. Swapped the fan guard and pulley and installed.
Checked my battery voltage before I started it up and had right around 12V. With the engine idling I was at 12.8, I could rev the engine and get it up to 13.4 or so but never 14 or 15 like I thought it should be at. The voltage moves with engine speed now but still isn't right.
Is there anything else I can test before I take the alternator back or maybe have it tested somewhere?
Kanute
'89 Aerostar 180k
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From: Mitchell, SD
Replace your battery. The old alternator toasted it by over/under charging it. If you don't shortly, you are looking at replacing your new alternator and go through the evil path of replacing alternators and batteries.
If that does not fix it, take in your new alternator and have it tested.
If that does not fix it, take in your new alternator and have it tested.
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From: Mitchell, SD
Originally Posted by Kanute
So I should be able to test this by putting my girlfriends mustangs battery in my aero and voltage should return to around 14 or 15?
Kanute
Kanute
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I agree with all previous posts, but go slowly, the reduced voltage could possibly be the result of the depleted battery taking a normal healthy charge. drive a few miles with low electrical load and test again. you may actually want to let it idle for an hour to gently (ON THE ALTERNATOR) recharge the battery. the plug in terminal on mine melted from just this loading the other guys are talking about so they are basically right. how come they dont use a stout bolt and terminal from a nuclear plant likemost other manufacturers?
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I always thought that if the battery was low, the voltage would be high as the alternator is "romping" on the low battery. I would expect a low battery to read at 10V or so but not 12. I'll let everyone know when I swap my battery for my girlfriends this afternoon.
Kanute
Kanute
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dead battery will have a high voltage when car is running because it is not taking a charge (loading) the alt. healthy but low battery will draw down voltage as it charges.
that connector/alternator is fragile though. with a fully charged battery, voltage definitely should be around 13.5 to 14 volts with engine running.
If the system normally runs at 14 volts, how come they call it a 12 volt system??
that connector/alternator is fragile though. with a fully charged battery, voltage definitely should be around 13.5 to 14 volts with engine running.
If the system normally runs at 14 volts, how come they call it a 12 volt system??
Post Fiend
Joined: Apr 2005
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From: Washington state
always charge up a new or old battery with a separate battery charger before starting up an engine with a new alternator.
puts far less load on new alternator until split rings and brushes have a chance to seat in.
these rebuild plants in Mexico and China do not make money from break in time, units output per hour pay the bills, slap in the bearings, rectifier packs, regulators and rebuilt rotor/slip rings with brushes and out the door, thousands per hour.
run with no accessories on for first hour.
would you take a new vehicle engine and run it at max rpm, horsepower or acceleration before breakin?
puts far less load on new alternator until split rings and brushes have a chance to seat in.
these rebuild plants in Mexico and China do not make money from break in time, units output per hour pay the bills, slap in the bearings, rectifier packs, regulators and rebuilt rotor/slip rings with brushes and out the door, thousands per hour.
run with no accessories on for first hour.
would you take a new vehicle engine and run it at max rpm, horsepower or acceleration before breakin?
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I believe that there is an easier way to deal with this 
. Go to one of those chain autoparts dealers that offer the free curbside analysis on the Starter, Battery, and Alternator. They hook you up in the parking lot 
and their test equipment tells you the load and supply of each component. Then they sell you the new or rebuilt part.Just better than swapping out parts till you run out of money.
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Ok...swapped with my girlfriends new battery which was at 12.8V. Started up the aerostar and voltage went to 14.4V at idle and everything was good. Took the old battery back to Bi-Mart where they tested it and confirmed it was bad and sent me away with a new one.
Thanks everyone for helping me avoid the battery/alternator vortex. I only ran it for like 5 minutes with the bad battery and new alternator so hopefully no damage was done.
Kanute
Thanks everyone for helping me avoid the battery/alternator vortex. I only ran it for like 5 minutes with the bad battery and new alternator so hopefully no damage was done.
Kanute
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From: Mitchell, SD
Originally Posted by Kanute
Ok...swapped with my girlfriends new battery which was at 12.8V. Started up the aerostar and voltage went to 14.4V at idle and everything was good. Took the old battery back to Bi-Mart where they tested it and confirmed it was bad and sent me away with a new one.
Thanks everyone for helping me avoid the battery/alternator vortex. I only ran it for like 5 minutes with the bad battery and new alternator so hopefully no damage was done.
Kanute
Thanks everyone for helping me avoid the battery/alternator vortex. I only ran it for like 5 minutes with the bad battery and new alternator so hopefully no damage was done.
Kanute
I doubt any damage was done in that five minutes, it is more of an accumulative problem that usually takes between a month and 6 months of daily running.