alternator not charging battery? So beaterZ ran the battery low, borrowed new battery from Zinister TT and got beater up and running. Next while the car is running, I got my voltmeter and checked the voltage. It read at 14 volts! So to me the battery should be charging. However the battery is still slowly draining and not charging fast enough? Eg, I drove from work , turned off the Z , checked battery volts @ 12.34. I would have expected a more charged battery after hwy driving
From the voltages measured your alternator appears to be working correctly. You would do better to charge the battery overnight & if possible load test it. It wouldn't hurt to check for parasitic current draw.
14V means alternator is fine. Battery voltage 12.34 means likely that the battery is getting on the old side - do a Crank Amp Test to confirm. Parasitic Drain will only effect the battery after some time - not directly after it has been stopped - unless you have heaps of amps pouring out, in which case your likely to know it
Forgot - If your short a crank tester - go to supercheap auto - they have one and will do it for free for you.
Every discharge of a lead acid battery will reduce the amount of charge it can take on the next charge. The deeper the discharge, the greater the effect. If the battery is sufficiently old, or has had numerous deep/deepish discharges, then the latest flattening might have been all it could take.
I have got a same problem, but my battery is only few months old. And while driving ecutalk says 13.8 or 14volts. One day I open up the terminals and filed them inside, worked for a week. But next week again same problem. As soon as I put keys in ecutalks says 11.8 or 12 volts but once I try to start it. There is no current(dead)
just because its reads 12 volts it does not mean its in good condition, as stated go get it properly tested, if it does not have the amps to run properly or it has a bad cell it wont work as needed when needed most.
Check your connections! Correct. Terminal Voltage is in no way a guide. The only way to be sure is to either crank test the battery or do a Specific Gravity test. If your battery is only a few months old, Just be aware that a good battery with a loose/ broken or poor terminal connection will appear to be a bad battery as well, even though it is in fact good. Reason being that battery is discharged from the current draw on it but when started the alternator cannot push the charge into the battery from the loose/ broken or poor connection, so the alternator shows a high reading and so does the gauges/ecu however the battery isnt recieving a proper charge and will show up low as soon as the alternator/ motor is stopped. So both of you should check your connections just to be sure it is tight and not broken or loose as it can appear similiar in problem. In addition most batteries have a 12/ 24 or 36 month warranty depending on quality, so it pays to keep the reciept for return if it fails.
also check inside the connections, its fine to clean the terminals on the battery but if the inside surface of the terminals is also got corrosion on it you wont fix your problems without sorting that out.
I had problems that were similar for a while including the car stalling after I hit a bump. It turned out that I needed to replace the positive battery connector. The old one just didn't clean up right. The ecu codes showed it was the crank angle sensor, but it was the battery connector. So I agree, check the inside of the battery connectors. If they do not look brand new, clean them or replace them. Autobarn tested my battery and I had to buy a new one. Then it was still playing up. I admit that the battery looked a bit melted, and like it had been sitting next to a hot engine for a few years, but maybe they should have tested the battery terminals, not the connectors.
