POLISHH22

Hopefully someone here can make heads or tails of this battery charging issue i'm having. A couple of months ago i noticed my battery was getting low on charge. I checked all the grounds, got the alternator tested and rebuilt, checked the battery fuse, all to no avail. The battery posts and connectors looked pretty clean but i decided to clean them anyway. After the cleaning, i started the car up and the battery voltage shot up to 14 volts. However, even though it looked like it was charging, the battery drained over time again and again, to the point where i have to clean the connectors and posts every couple of days, otherwise when i start the car, the voltmeter shows the same voltage when the car is off and when idling. At this point, do i condemn the battery or is there something else that might be going on? Car is a 98 Prelude Base 5spd. Any help would be greatly appreciated. Thanks

v4lu3s

did you test the battery yet?

POLISHH22

yes, the battery checks good and holds a charge. Also an update, the connector cleaning did nothing, as i found out the voltage from the alternator drops from 14 to about 12.3 after the car heats up. So pretty much every time i take the connectors off the battery and reconnect them, it resets everything and the alternator goes back to charging at 14 volts, but only for a very short time. So i'm now thinking the issue might be ECM and/or ELD related?

holmesnmanny

Hondas charge in two modes, low output and full output. It will only charge in low output after the car is fully warmed up, 12.6ish, either at idle or low steady crusing under 45 mph or so.

How exactly did you determine that your battery isnt charging ?

POLISHH22

I made a 830 mile trip to Florida from Virginia, before i left i checked my voltage, it was around 12.6 volts, when i got to FL it had dropped down to about 11.2 volts. I ran accessories like the radio and sometimes the A/C during the trip and it sucked the battery life down enough to not be able to start the car. Did 65-75 mph at around the 3500 rpm range the whole way, all interstate driving. Everytime i stopped i could tell the starting was becoming weaker and weaker until eventually it just wouldn't start.

holmesnmanny

Let the car completely and totally cool down. Get your multimeter ready. Start the car, it should be idling about 1500. Test for voltage. It should be putting out atleast 14 volts. Turn on the headlights, it should still be putting out 14 volts. Then put everything electrical on in the car except for the air conditioner. It should atleast be putting out 13 volts.

Report back your findings.


Keep in mind that the alternator starts putting out it's maximum power at 1500 rpms and above so it's going to be putting out slightly less than it would otherwise be putting out while cruising, at idle.

POLISHH22

Ok, i hooked up the voltmeter to the battery in the morning with the car cooled off, it read around 12.06 volts since i just finished an 830 mile trip. Started the car, and the initial voltage reading i got was around 13.8 which was a good sign, but immediately it started to plummet all the way down to 12.3 after about a couple of minutes or so. Turning on different accessories did absolutely nothing to change the voltage. So in conclusion, the alternator is only putting out 12.3 volts, no matter the rpm or temperature. It did this with 3 different alternators that were put in, so i'm pretty confident in saying the alternator is not the issue here.

holmesnmanny

start the car and then disconnect the green connector going to the alternator .. see what voltage you get

AndyD

iTrader: (1)

Have you made sure your ground cable is nice and clean where it connects to the chassis?

POLISHH22

Ok found the problem, had a short to ground in one of the alternator cables in the engine harness, got some help in checking the resistance, found quite a bit in the cable, opened it up to inspect it and found plenty of corrosion under the insulation. Replaced the cable and everything works as advertised. Thanks for the advice everyone.