9 volts and dropping

[Yogi loves Rangers]

Hello all, did a brief search and couldn't find my exact answer but here's the problem: 1993 Ranger Splash,3.0 w/air,2wd,rebuilt motor at 97K now w/137K and it has been the best vehicle I've ever owned BUT, got in to start it last week and the fuel gauge pegged to full and after turning the key on and off a few times it went to the right amount then a few days ago at start up the alternator gauge showed 9 volts and kept dropping as I drove around the block. Tested the battery at an auoto shop,dead, bought a new one, connected it and same thing, 9 volts.Bad alternator? Fuse? Relay? Thanks for any help. I'm DITW without my "Little Mule-y".

 

[ericbphoto]

Two things, to start with.

1. Check your battery connections - make sure everything is clean and tight at the battery, the starter relay, the alternator, the starter, the negative connections at the battery, ground from battery to body, ground to engine block, etc.

2. What is the battery voltage with engine running? Immediately after starting engine, it should be 14.0 - 14.5 volts. After engine has been running for a couple minutes, it should drop to around 13.5volts, no more than about 13.8. If it's too high, it will overcharge or "cook" the battery. Too low and it will not charge.

Battery voltage at rest, with engine not running, should be around 12.5 volts. Technically, 12.6 volts would be a brand new battery in perfect condition. I've seen them read up to around 12.8, depending on the meter. Battery voltage can give an indication of the approximate age of the battery. When it starts getting close to 12volts, the battery is old and should be replaced. @RonD has a thumb rule for approximating battery age from voltage.

 

[franklin2]

Sounds like you are getting the 9v reading on the dash gauge. Always take a meter and test directly on the battery. Don't trust the gauges in the dash.

 

[Yogi loves Rangers]

Thanks ericbphoto and franklin2 for the advice.In my post I wrote that the gauge is reading 9 volts at start up with the new battery,same as the old battery. I know it's supposed to be 14volts + . It is not showing that. Turning any light's/electrical on and you can see the gauge drop a bit. Same while driving,just keeps going down.

 

[ericbphoto]

It really reads like a bad alternator. But it's best to do some troubleshooting first instead of possibly wasting money on parts that aren't needed.

 

[Yogi loves Rangers]

Thanks ericb, I'll continue to check and clean connections.

 

[SenorNoob]

If you're really at 9v, it wouldn't be starting.

 

[Yogi loves Rangers]

It WAS a bad alternator. Swapped it and the battery and it starts right up.Thanks for all the info!!

 

[ericbphoto]

Thanks for posting the results.