Dang it!

[scavanger]

If you do a lot of real short trips the 100 amp alt. could be a problem. I agree if everything else checks out bigger alt.

Scav.


trade the truck for a new one.

[hotrodpc]

Originally Posted by scavanger

If you do a lot of real short trips the 100 amp alt. could be a problem. I agree if everything else checks out bigger alt.

Scav.


trade the truck for a new one.

I'd think it would sure take alot of short trips for 100amp not to be able to charge both batteries. I sure wouldn't trade that truck. Maybe buy a newer one and transfer the box to the new one. Then put a flatbed on the 99 and keep it or sell it private party. That 99 has been fairly beefy modified springs under it, so you'd probably have to go with a 3500HD for certain to get close to the capacity of this 99.

[BernieB]

Originally Posted by scavanger

If you do a lot of real short trips the 100 amp alt. could be a problem. I agree if everything else checks out bigger alt.

Scav.


trade the truck for a new one.

Sell Harvey?

No way!

Seriously, I'd have to be nuts to sell this truck. The engine, at 76k, is just barely broken in, and as PC says, that suspension has been really beefed up, making it perfect for my work.

As for the batteries, I believe they're simply hooked in parallel, without an isolator. I'll try to confirm that one of these days, but I'm pretty sure the hot lead from the right battery comes across the frame and up to the positive post on the left battery.

And yes, I do make a lot of fairly short trips, which would not allow time for the batteries to fully charge from starting. But, with all the lights, radios, etc in the truck, a 100a alternator simply can't keep up. Just idling with the lights on at the side of the road you can watch the battery voltage steadily drop. I've never had it actually die doing this but there was one time I was at an accident scene and left the truck idling on the shoulder with all the lights on, and the wipers and a/c, for about 45 minutes. When I climbed back in the voltage gauge was just above 9 and all the lights were dimming. Even revving to 1,500 isn't enough to kep the system charging under those conditions, so that's the main reason I'm planning to go with a bigger alternator.

[hotrodpc]

Originally Posted by BernieB

Sell Harvey?

No way!

Seriously, I'd have to be nuts to sell this truck. The engine, at 76k, is just barely broken in, and as PC says, that suspension has been really beefed up, making it perfect for my work.

As for the batteries, I believe they're simply hooked in parallel, without an isolator. I'll try to confirm that one of these days, but I'm pretty sure the hot lead from the right battery comes across the frame and up to the positive post on the left battery.

And yes, I do make a lot of fairly short trips, which would not allow time for the batteries to fully charge from starting. But, with all the lights, radios, etc in the truck, a 100a alternator simply can't keep up. Just idling with the lights on at the side of the road you can watch the battery voltage steadily drop. I've never had it actually die doing this but there was one time I was at an accident scene and left the truck idling on the shoulder with all the lights on, and the wipers and a/c, for about 45 minutes. When I climbed back in the voltage gauge was just above 9 and all the lights were dimming. Even revving to 1,500 isn't enough to kep the system charging under those conditions, so that's the main reason I'm planning to go with a bigger alternator.

Yep, and if you do lots of idling, then you have the right idea. And also right again, about some higher CCA batteries too. My box van has 1000 CCA Duralast Gold in it. Its 4 years old now. Because I am so used my Yota Rolla and my other GM trucks that have auto headlights, I have left those lights on before in the box truck for over 24hours. Headlights, marker lights and all. Thought, Oh crud, need to get out the charger and cord to recharge it. Nope, started right up.

[scavanger]

BernieB Do you have a tow truck ? If so I can't believe you have gotten by this long on a 100 amp alt. most cars have 125 on them. I think my 89 Riv had a 125 amp on it.

Scav.

[BernieB]

Originally Posted by scavanger

BernieB Do you have a tow truck ? If so I can't believe you have gotten by this long on a 100 amp alt. most cars have 125 on them. I think my 89 Riv had a 125 amp on it.

Scav.

Service truck, not a tow truck. (photo below)

The 100 amp alternator was standard for '99 C3500's with the 6.5L diesel, I just can't understand why they kept it after putting on the lightbar and strobes. Still, I can take a 140 amp from the same year extended cab version and it's a direct bolt-in replacement, and that's probably what I'll do. I could also get a 200 single wire unit from Jegs and a few others for a reasonable price.

[BernieB]

Oh, almost forgot... Had both batteries load tested at AutoZone today (tested single and paired) and they checked good. I also took a look at the wiring and confirmed the batteries are in parallel and not isolated.

And then, after I was all done with the testing and hooked the batteries back up... the truck refused to start. Cranked just fine, wouldn't catch. Let it sit for a minute and tried again and it still wouldn't catch. I noticed though that the glow plugs were only coming on for a split second (the truck was still fairly warm from being driven there) so I cycled them a couple of times and then cranked it and it fired right up.

I'm definitely planning on changing the glow plugs now, and I may also hook 'em up to a manual switch.

[hotrodpc]

Originally Posted by BernieB

Oh, almost forgot... Had both batteries load tested at AutoZone today (tested single and paired) and they checked good. I also took a look at the wiring and confirmed the batteries are in parallel and not isolated.

And then, after I was all done with the testing and hooked the batteries back up... the truck refused to start. Cranked just fine, wouldn't catch. Let it sit for a minute and tried again and it still wouldn't catch. I noticed though that the glow plugs were only coming on for a split second (the truck was still fairly warm from being driven there) so I cycled them a couple of times and then cranked it and it fired right up.

I'm definitely planning on changing the glow plugs now, and I may also hook 'em up to a manual switch.

Good news then. May just be the glow plugs. That manual switch may be a great idea too. Of course you are talking a push button switch right? Not a toggle switch? You can hold a push button for 5-10 seconds if need be, but you sure don't want to forget to shut off a toggle switch or hit accidently and leave it on unknowingly. I'd have to agree with you now too, with all the idle time you do which I was unaware of, the 140 would be a great upgrade.

[BernieB]

Originally Posted by hotrodpc

Good news then. May just be the glow plugs. That manual switch may be a great idea too. Of course you are talking a push button switch right? Not a toggle switch? You can hold a push button for 5-10 seconds if need be, but you sure don't want to forget to shut off a toggle switch or hit accidently and leave it on unknowingly. I'd have to agree with you now too, with all the idle time you do which I was unaware of, the 140 would be a great upgrade.

Yep, a push button setup is exactly what I'm thinking of.

I may still replace both batteries though, even though they both load tested as good. I've never had a problem with the batteries and cranking when they're freshly charged, but let it sit overnight and they aren't holding enough of a charge for me. For example, when I checked voltage on them yesterday after the truck had sat overnite I was showing a voltage of 12.6. Put 8 glow plugs on that for 10 seconds and the voltage drops to about 11. With the batteries freshly charged though, such as if I just came back from a trip and let it set for a couple of hours I get a proper 13.8.

I know there's no heavy drain on the truck when it's sitting. Just the computer, radio/clock and my GPS (keeping it charged in standby mode - about 50ma) so I figure the batteries aren't as good as they could be.

The good news is that while I was at Costco today I found they had Group 78's with 800cca (and a 100 month warranty, with 36 month replacement) for only $65. Much better price than the $90 each for the Duralast Gold at Autozone, and with the same specs and warranty. We put one of the Costco batteries in my g/f's Dakota three years ago and have had no problems with it at all, so I trust 'em.