I have a 1994 Mazda Protege and the battery will not stay charged. About 2 weeks ago I replaced the battery thinking that might be the problem, I also changed the terminals as they were looking quite bad. When that didn't fix the problem I got a new alternator. These are both testing good. Any ideas on why the alternator won't charge the battery? I can drive it about 60 miles before it dies.
2007-03-28 01:42:31 · 6 answers · asked by Mrs A 1 in Cars & Transportation ➔ Maintenance & Repairs
You have what is called a 'parasitic load', or a dud alternator. You say that you can drive it 60 miles before it dies. If this is the case, and the engine is not switched off during this time, then the alternator is at fault. This is easily checked. If you have a voltmeter, when the engine is running, the voltage across the battery should be around 14Volts. If it is not, then the regulator or your alternator is at fault.
If the battery goes flat by itself, with the engine switched off, you have a 'parasitic load'. The source of the 'parasitic load' can be traced by putting an ammeter in series in the circuit, and pulling fuses until the source of the load is located. It could be something as simple as the light in the trunk not turning off. An auto electrician could fix this pretty quickly.
2007-03-28 01:53:21 · answer #1 · answered by Michael T 5 · 0⤊ 0⤋
With the battery charged (you will have to charge it with a battery charger), place a volt meter across the battery - it should measure 12 volts. Start the car and again measure across the terminals of the battery - it should read 14-15 volts. If not, your battery is not charging and the alternator is suspect. You say the alternator is checking good so I will assume that you have had it tested. If your alternator is not charging the battery in the vehicle, the supply wire may be compromised, so find the big (usually red) wire to the alternator. With the car shut off, place the positive lead of the volt meter on the alternator wire and the negative lead of the volt meter on the case of the alternator or negative post of the battery - you should read 12 volts with the car shut off. If you get no voltage, the supply wire to the alternator is bad and needs to be replaced - you can just run an 8 gauge copper wire from the alternator to the positive battery post to repair this problem and abandon the bad wire. If the original wire shows the 12 volts, then check the voltage on the connection with the car running - it should be 14-15 volts - if not, replace the alternator (even new ones sometimes have problems).
There is a remote possibility that there is a short causing a problem. To test for this, remove the positive cable of the battery and test for current draw with the car shut off using an ammeter. All of the above assumes that you have tested the battery to assure that it is good - remember, just because it is new is no sign it is good - have it load tested at Wal-Mart if all the other info proves no help. Good luck.
2007-03-28 10:34:30 · answer #2 · answered by Doug R 5 · 0⤊ 0⤋
Turn on the ignition without starting the engine. Does the alternator warning light come on?
2007-03-28 09:00:40 · answer #3 · answered by Seopard 3 · 0⤊ 0⤋
It could be faulty starter connection either ground or hot wire to the starter check that
2007-03-28 08:49:10 · answer #4 · answered by Anonymous · 0⤊ 0⤋
it probably is charging the battery...sounds like you have a major short in the electrical system
2007-03-28 08:48:38 · answer #5 · answered by Robert P 6 · 0⤊ 0⤋
Maybe its the solenoid for the starter.
2007-03-28 08:55:39 · answer #6 · answered by ? 7 · 0⤊ 0⤋