PanzerAce Posted August 14, 2010 Share Posted August 14, 2010 So, I'm fairly certain the problem is with the battery, but I figured I'd run it past you guys first. Problem started when I went out to my car, got in, tried to start it....and nothing happened. ampmeter didn't twitch, electric fan didn't come on, nothing. I figured I'd left the lights on or something, so I jumped it, took it for a drive, and noticed that the ampmeter wasn't indicating that it was charging the battery. It was holding steady just above the 0 mark, where it would be if I was cruising with a good battery. When I got back to my house, I started the car again, did fine. The next day, same problem, no power at all. I'm figuring at this point that since it ran fine once started, that the battery is the problem. The only issue is that it's only a few months old. So is there any other way that the symptoms I describe (no power at all, runs fine after a jump, alternator not charging the battery) could happen? Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted August 15, 2010 Share Posted August 15, 2010 take it to a battery shop they will load test the battery and test the charging sytem for FREE if you go to the right place. better than the minimum wage clerk at Oreillys generally. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 17, 2010 Share Posted August 17, 2010 Voltage test on the battery after starting, without revving, should be 'low' maybe 11.XX volts to 12.9 volts. Check alternator, likely will be the same as battery. Give the car a quick blip of the throttle (excitation of alternator) and then check again. Voltage should be 13.8 at the battery, and at the alternator output terminal (negative meter cable on negative battery post). Run RPMS up to 2500 or so and check again. Alternator voltage should be 13.8-14.2 or thereabouts. Battery should be the same. If battery is not getting voltage from alternator, find broken wire/fusible link/etc. If alternator is not exciting and getting to 13.8 and staying there, alternator/regulator is your issue. With a severely discharged battery you can toast the new alternators and regulators if you aren't careful. I just did this at the Skunkworks, left the lights on all day came back dead as a doornail. Ammeter went halfway up when revved (and idling voltage was around 12.9 against an original battery voltage of...uh...single digits...) stayed there all through my three hour drive to the club meeting, and then after a two hour rest started kinda slow but about 30 minutes down the freeway with the lights on, the meter went back to 'just right of center' like always and it's been fine since. If the battery was 'dead' and wouldn't start the car at all, I would expect the ammeter to be halfway up for a little while until the battery was back up and running. A bad diode will drain the battery overnight...see if you have AC in the system---it can kill your lights, and if you had EFI the ECU as well! I found a 240 recently which had great alternator voltage, but nothing to the battery. Damned frustrating, but realized the guy that modified the car for all the nice gauges (and did the internal regulated alternator harness conversion) likely neglected to tie the two ammeter wires together when he removed the ammeter! D'OH! I put an 8 gauge wire from the alternator to the battery and the car drove back across the country from the Left Coast with nice bright lights... Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted August 17, 2010 Author Share Posted August 17, 2010 unfortunately, most of my tools are in storage a good 150 miles away right now, so I can't test voltages, I have to just go by the ammeter in the car :/ From what you're saying though, since the ammeter never indicates that it's doing more than running the coil/plugs, guages/etc, that it's likely to be the alternator rather than the battery? Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted August 18, 2010 Author Share Posted August 18, 2010 And TonyD wins a cookie! Turns out the regulator was completely blown. Atleast a replacement alternator was less than 30 bucks Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 18, 2010 Share Posted August 18, 2010 Learn this trick: Harbor Freight Tools Digital Automotive Multimeter goes on sale for $9.99 occasionally. Buy one and keep it in the car! I have a small one I got in Australia which is VERY nice, and fits in the glovebox---a bit fatter than the normal compact calculator. When this kind of stuff comes up, having even a $9 cheapie meter is a lifesaver. I actually have one in most of the cars, like half a dozen! Keeps me from fretting my $450 Fluke will draw attention and result in a broken window one day as well! Good to see you found the issue. Didn't sound battery, sounded production related. One thing to realize is that the regulator (external) will FRY ALMOST IMMEDIATELY if it looses ground while powered-on. I ALWAYS put a coiled-wire pigtail on the foot of the thing with a sheetmetal screw and star washer---and I connect this to the chassis ground someplace nearby. That way, if I forget to power off the car when removing the regulator, or the bracket it mounts on (in the 260/280Z) I don't fry the reg again! It also lets me put the regulator up on the fender and do probing if need be, without being upside down or with my fingers near a whirring alternator fan. Quote Link to comment Share on other sites More sharing options...
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