i have a 95 gt. when i turn the key to the on position the battery meter looks like it is at around 10 volts. when the car is on and idling the volt meter drops to the same position as when the key is in the on position. when i hit the gas the volt meter jumps right up to the middle. i have replaced the alternator with a 200 amp unit and i still have this problem also put a yellow top in. any ideas where to start to look for the problem?
charging problem?
- Thread starter jtb19nh
- Start date
mo_dingo
20+ Year Stangneter 
Simple test. Hook a DVM to each of the battery terminals. Record the voltage with the car off. Record it then again w/ the engine running.
If the voltage is higher, then the alternator/regulator is working likely.
Next pop the vent caps to the battery. Make sure the water is full in each cell, up to the bottom of the plastic case. You dont want it to be flush with the top of the holes, that's overfilled. So with the engine off, put neg. test lead to the neg at the battery. Then stick the pos. test lead in the water of the first cell closest to the neg terminal. You should read 2.2V. Then go to the next cell, and you should read 4.4V, etc etc.....
Each cell is ~2.2V, and the are wired in series, so each cell adds 2.2V to a total of 13.2V or so on a fully charged battery. Now if one cell doesn't add any voltage to the total count, you have a bad cell.
Another thing to mention, with the car running , measure the voltage at the battery. Should be initially 14.4 or so, then drop down slowly. Once it reaches around 13.6 or less, turn the car off. Then measure the voltage again. It should be slightly less, but maintain above 13V for a while. If it drops down drastically, it's not taking a charge. maybe the acid is gone, or something. Bad battery, time to swap.
note: this should be done with all loads off. That includes the dome light and the hood light. No amp draws should be present, that includes your stereo and such.
Scott
If the voltage is higher, then the alternator/regulator is working likely.
Next pop the vent caps to the battery. Make sure the water is full in each cell, up to the bottom of the plastic case. You dont want it to be flush with the top of the holes, that's overfilled. So with the engine off, put neg. test lead to the neg at the battery. Then stick the pos. test lead in the water of the first cell closest to the neg terminal. You should read 2.2V. Then go to the next cell, and you should read 4.4V, etc etc.....
Each cell is ~2.2V, and the are wired in series, so each cell adds 2.2V to a total of 13.2V or so on a fully charged battery. Now if one cell doesn't add any voltage to the total count, you have a bad cell.
Another thing to mention, with the car running , measure the voltage at the battery. Should be initially 14.4 or so, then drop down slowly. Once it reaches around 13.6 or less, turn the car off. Then measure the voltage again. It should be slightly less, but maintain above 13V for a while. If it drops down drastically, it's not taking a charge. maybe the acid is gone, or something. Bad battery, time to swap.
note: this should be done with all loads off. That includes the dome light and the hood light. No amp draws should be present, that includes your stereo and such.
Scott
HGFireHazard
Member
Do you have any kind of system in your vehicle? When you upgraded your alternator did you run larger wire as well? Other than that the post ^^^ should have covered everything else.
Methodical
15 Year Member
Yeah did you upgrade the wire between the battery and alternator. I have the 200 amp alternator and I upgraded to the 4 gauge wire - if my memory is correct - which also came with a larger fuse - again if memory is correct. Either way get rid of the stock cable if you have not done so.
Peace
Al
Peace
Al
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