Charging Voltage, '97 Suburban

[Renken2000Classic]

I'm getting 13.75V at the battery and about 14 at the alternator at idle. That sounds like the alternator's failing to me.

It's dragging a bit when I start it sometimes. I mentioned that as part of a (not so great day at the lake) recently, but I attributed it to batt cables not tight enough at the time. It's doing it again though.

 

[Alumarine]

Doesn't sound too bad. What are the numbers at 1200-1500 rpm?
What does dragging mean?
Have you had the battery tested?

 

[Renken2000Classic]

Didn't try it at other than idle, right after we drove it today. Gauge on the dash indicates a bit under 14V while driving; didn't fully trust that though. The one in the boat reads about a volt and a half low compared to when I put a meter on it.

By dragging I mean the first crank-over sounds slow sometimes (like the batt is weak), then it goes ahead and cranks and starts quickly.

Haven't tested the batt. It's a 1 1/2 year old "NeverStart" as someone on here besmirched it as in another thread, lol.

 

[flashback]

Load test the battery, if it checks good then clean and tighten all terminals, if you still experience slow cranking it's possible the starter motor is dragging. They do fail and age is an issue..

 

[Renken2000Classic]

Yeah, it's been so long since I changed a starter (decades), that really didn't occur to me. But yes, this has 197k on it now, and I've had it for coming up on 11 years.

 

[Scott Danforth]

Bad cable connections would also explain both the slow cranking and the difference in voltage you are seeing

 

[Renken2000Classic]

Yes; I will pull those and check them. The positive has given me a little trouble in the past, getting it/keeping it on securely, since it's two stacked together and a little awkward.

 

[topgun3690]

Yes; I will pull those and check them. The positive has given me a little trouble in the past, getting it/keeping it on securely, since it's two stacked together and a little awkward.

Do you have side post terminals on your battery?

 

[Renken2000Classic]

Yes, side posts; you know, the sort of recessed ones.

I pulled off the cables and they had some corrosion. Positive had signs of getting too hot. Both were tight.

I trimmed back some of the red plastic that wraps around the terminal edges so those ones would mate up better, and cleaned them all off real good. After they dry I'll WD-40 them and put them back together.

Basic, basic stuff, but that hadn't dawned on me since you can't see the corrosion with that style of terminal ends. Pretty sure that was it...

Thanks for the ideas...

 

[topgun3690]

I have dual batteries on my truck....passenger side has 2 positive cables and had the same problem keeping them tight. I got rid of the crappy GM battery bolts and used 3/8 course thread bolts/nuts to secure the cables. Works really well and no problems since.....thought I would pass this along.....

 

[Renken2000Classic]

Thank you. Looks really good. They overdid the rubber protector part (not there on yours) so that it's hard to get good contact with them. Trimming that back should help too.

 

[Scott Danforth]

Yes, side posts; you know, the sort of recessed ones.

I pulled off the cables and they had some corrosion. Positive had signs of getting too hot. Both were tight.

I trimmed back some of the red plastic that wraps around the terminal edges so those ones would mate up better, and cleaned them all off real good. After they dry I'll WD-40 them and put them back together.

Basic, basic stuff, but that hadn't dawned on me since you can't see the corrosion with that style of terminal ends. Pretty sure that was it...

Thanks for the ideas...

the clamp-on cable terminals are junk. only way to clean a cable that is corroded between the strands is to replace it.

get a set of properly made cables with properly terminated ends. I usually make my own using marine battery cables (tinned copper)

 

[Bob_VT]

the clamp-on cable terminals are junk. only way to clean a cable that is corroded between the strands is to replace it.

get a set of properly made cables with properly terminated ends. I usually make my own using marine battery cables (tinned copper)

AGREE! Our local Interstate Battery will make cables on the spot and use "tinned" wire (AKA Marine wire) which work great. Yeah corrosion is one of the worst enemies because it is normally hidden.