Chevy C10 Battery Not Charging Diagnosis And Fix

In this video I diagnosis and fix the battery not charging in my 1975 Chevy C10. I go through the charging system on this truck and this GM 3 wire internally regulated alternator. In the end we eventually find the issue and it surprised me.

[@richardprince5758]

Thank you for showing where the junction box is ,Many Technicians can fix ,only a few can teach !

[@jimcabezola3051]

Yes…that would blow MY mind, too! That a bad battery affects what the alternator does is weird to me. I recall things called “voltage regulators” and “ballast resistors” (especially in Mopars) seem to give people fits as well. Thanks to your video here, I will have to watch some more videos that may shed light (har-dee-har…) on those electrical subjects. Well…in any case…you’ve got a lovely new battery and alternator. So…road trip, LOL! Having seen your drive to work, I dare say that your traffic situation is far better than what I used to encounter when I drove a car here. Enjoy your drives.

[@bluesxt]

Thanks for watching :) I’ll definitely be driving this truck with all the new shiny parts

[@patdesrosiers6423]

Great little video here, very informative. My C30 isn’t charging well. Similar to this with a battery as old as the hills and an alternator I replaced last year. Looks like new battery time!

[@santaclause2875]

Hey bluesxt, truck is looking better all the time. By now I'm sure you found the issue with your alternator. I spotted it immediately at the beginning of the video...the belt is way too loose and must be tensioned much tighter. When revving the engine, you can hear the belt slipping and screeching as the alternator tries to produce power. So, once the belt is snugged up quite a bit, it should generate power with no problems. Also, it looks like to me that the adjustment slot of the alt. bracket is all the way to the end of it's travel, keeping you from properly tensioning the belt. Usually what causes that is a belt that is way too long (wrong size) or a stretched belt. Usually, when the proper belt is installed, the alternator adjustment bolt will be about midway in the adjustment slot, give or take a little. Generally, a properly tensioned V-belt will have about 1/8 inch to 1/4 inch play (when pressed with one finger) between two pulleys. Good luck!

[@bluesxt]

Thanks for the comment! You’re correct my belt is a tab bit too long :)

[@franciscoalmaguer3507]

In Mexico they have m16 . When I visited my grandparents I kept seeing cops with those and they told me it was normal issue for cops

[@nemoyuno1627]

A battery that consistently spins the starter over at a high rate is doing it's job, and is not defective. I have read the instructions for a later, alternator and it says to idle the engine till warm, then hold throttle at 2000 rpm for a few seconds, when it will be charging. This has in some cases replaced earlier methods of activation, and like ordinary driving.

[@bluesxt]

My 1979 corvette is like that where the alternator does not start charging until you rev above 3000rpm

[@Caleb_S26]

A little late but if your running any kind of accessories like Electric fans, subs, lights etc you’ll have charging issues because the alternator doesn’t put out enough amps to keep up so you’ll need a bigger alternator Just for anyone who can’t figure out what’s wrong with there truck

[@switchbackmusic2938]

I have Themis same issue right now, new alternator, and now have gone through 2 batteries. I did have the alternator charging with electrical load during the initial install, but it’s bad again. Any tips?

[@bluesxt]

Are you using a volt meter to determine your alternator is not charging anymore? If so, what voltage are you seeing at the battery and at the alternator?

[@israeldiaz2217]

I just got the truck but same thing

[@israeldiaz2217]

I have to turn it on every day , I just change alternator battery but I don’t know the voltage since I don’t have one but truck once it turn on she is a beast

[@israeldiaz2217]

I think there is something running but cable I don’t think since there old cars , but I think it may be some ground falling help help thanks

[@israeldiaz2217]

I get like 12 around voltage

[@poptartgofast]

Better and cooler

[@chevybigblock3311]

That belt is too loose.

[@baddbradd89]

belt is loose dude