Some more alternator/electrical ?'s - Diesel Forum

ajohansson · 10-04-2008, 03:39 PM

I got my new DB 200 amp alternator on and have slow charged my 2 month old duralast gold batteries. I have a few questions. How does the alternator work? When I start my car it shows like 11 volts. I assume the energy from the glow plugs and starter really draw these things down. It will remain at 11 volts for like 20 seconds and then the volts start to climb sometimes up to 14 volts at idle but mostly to 13 and maybe a little over. Why does it take the 20 seconds to start to climb? Then I go drive sometimes the volts start to drop again. I tested it at idle after driving it for about a half hour on the freeway. I turned on headlights, factory stereo, both AC's (excursion) and have my electric heaters for my veg system on and I was getting 12 volts on the nose. When I accelerate it rises to 12.5. This morning car started fine but battery light was on, I waited for the 20 seconds for the volts to rise and they did but only to 12.5 and the light stayed on until I gave it some rpm's. I was expecting better voltage readings. Do I have too high expectations? Could one of my batteries going south. I have not been impressed with Auto Zone (where I bought the batteries) on helping diagnose any electricl isssue. They have the equipment but at least at my store not the expertise on how to use it. I put a new charge wire on and fuse. I know the alternator is working because I am at least getting above 12 volts but not the 14 as often as I was expecting. Without spending even more money on cables what else should I be checking. Am I over reacting? Any help would be appreciated.

AJ

jdholder · 10-04-2008, 04:07 PM

I have the same questions as you do!! I just put in a 200 amp alternator, and driving out to the Offroad Expo today I checked the status of my charging (by pressing the "Charge Protect" button on my Idle Controller) and was surprised to see 11.9 volts. Usually I see 13.1 to 14 volts while driving along.

I was worried!! When I got back out of the show and started the Excursion, the Idle Controller read 13.4 volts - then watching it going down the road it all of a sudden read 11.8 volts - 15 minutes later it was back up to 13 volts.

Is there a "module" or a wire that "controls" the alternator and tells it when to make power? Looks like a two wire plug on top of it, and the thick charge wire. Where do the two wires go? HELP!! If you want me to remove this post, let me know and I will start another one, but it sounded like you and I are having a similar problem!!

sweet dually · 10-04-2008, 04:31 PM

i cant tell you exactly where the wire leads to but it does tell the alt to turn on... sounds maybe like a short in the wire or its not connecting into the alt that well............. check your connections and don't forget to upgrade your charge wire. factory wire only good for 130 amps. add a second 4g wire to the batteries off the back of the alt. i made a dual system for my truck and all the wiring for each alt had to be upgraded to a mim of 4g

AJ, let the truck idle for a 5-7 min with the hood open. if it alt is really hot then you have a bad battery. changing it out will fix all your problems! PM me again if there is anything else i can help you with........

ajohansson · 10-04-2008, 10:12 PM

I will check that tonight. What is really hot? Too hot to hold my hand on for more than a few seconds? Thanks.

AJ

sweet dually · 10-04-2008, 10:37 PM

Quote:

Originally Posted by ajohansson

I will check that tonight. What is really hot? Too hot to hold my hand on for more than a few seconds? Thanks.

AJ

if you hand burns off then its no good. lol. it should be "Warm" at just idle for 5 min. if you touch it and its really hot or hurts then your battery is hooped. let it run for a bit though and then check.

fulltimer50 · 10-05-2008, 08:28 AM

I can add that the PCM keeps the alternator off when first started. Perhaps to avoid burning out the glowplugs.

ajohansson · 10-05-2008, 10:58 AM

I did not get to it till this morning and here is the play by play. Popped the hood and turned off all accessories in veg system and no ac nothing running. Started truck, just like before it showed 11 volts for about 20 seconds and went up to 14 volts, now I understand from a previous post that the alt does not produce current while the glow plugs are running so that makes sense. I let it sit for 7 minutes and checked the temp on the alt. It was luke warm not hot. I went in the cab and checked the voltmeter and it was still showing a tad over 14 volts. I was happy. I started to tun on accessories in my veg system first. I turned on my two electrci heater wraps that go on my filters. It dropped to 13 volts immediately, turned on AC dropped to like 12.5 turned on headlights dropped to say 12.2 I raised rpm to 1500 and it rose to 12.5. I guess my biggest question is, Is this normal or OK? SHould I be concerned with everything running at 1500 rpms I only get 12.5 volts. Any suggestions to get more voltage. I am hardly an automotive electrical know it all so any suggestions would be great.

AJ

sweet dually · 10-05-2008, 12:08 PM

All i can think of is larger wire to you veggie stuff and maybe better or heavier ground wires. check over all the grounds that you currently have and make sure that they are all good. bad grounds make more draw. ??!! hope that solves some issues. As for pushing 12.5 volts, what size wires off the back of the alt? do you have or can you borrow a multimeter that will show you draw? if you can hook it to the atl output wires and see if you alt is actually producing 200 amps. i know allot of companies claim large numbers but the size of the case required for it is not realistic. thats why i went to a custom shop to make sure mine were producing what they claimed. Most "High output" models have been tested no higher than 150 amps!!!! they can get away with it because its so hard to prove due to all the factors involved. beyond checking the alt output and all your wiring and grounds there is nothing else i can think of?!?!?!?!

ajohansson · 10-05-2008, 01:48 PM

I will check all of my grounds and upgrade my wiring for my heater wraps. The original installer put in 12 gauge wire, I think I may upgrade to 10 gauge. I went for a 30 mile drive this morning down the freeway at 2000 rpm and kept at just about 14 volts probably more like 13.8 with just my veggie heaters on and that was it. I turned on my lights and both ac's full blast and droped to 12.8 roughly, got off the freeway and at idle at the light I was 12 and then fluctuating to 11.8 for a second and then bak to 12. If I gave it 1100 rpms I would jump to 12.5. So I guess I am better than I was with my old alternator but would think that the new HO one would be better. I will trace all my grounds. I put in a 4 gauge wire from the back of my alt to the drivers side battery which is fused with a 250 amp ANL fuse. Perhaps I should go with a bigger wire. I got them for free so i am not out any money except for the fuse block which wil take up to a 1/0 gauge wire. I'll keep you posted.

AJ

jdholder · 10-08-2008, 01:31 AM

Ok,

I have figured out my problem and I thought I would share.

It's fuse 29 inside the cab. My symptom was that I would be driving along and my volt meter would read 11.8 volts and be dropping - in other words, the alternator was not charging. Then all of a sudden the volt meter would read 14.1 volts. Then 11.8, then 13.7. Charge, no charge, charge, no charge.

So - I started troubleshooting. No corrosion. All connections good. Fuse 9 under hood good. But when I checked fuse 29 under the dash, it literally almost fell out of the fuse holder. Fuse 29 was not making a connection across the circuit. This lead to my intermittent charge/no charge situation. It looks like some yahoo before me had used a "fuse tap" to gain access to that power. You know those "fuse taps that get shoved down into the fuse socket, and then the fuse is also placed into the socket. So the socket was stretched out. So, a little bend to the fuse and PRESTO - no intermittant charging.

The batteries are on the charger tonight - they got down to 10.4 volts driving home this evening before my trouble shooting - and I will report back more info tomorrow.

Thanks for the information on this board!!!!

ajohansson · 10-09-2008, 01:39 AM

I know the fuse panel in the cab for your 2001 and my 2003 are different. I will double check all my fuses. What does the #29 supposed to do?

sweet dually · 10-09-2008, 11:45 AM

Quote:

Originally Posted by ajohansson

I know the fuse panel in the cab for your 2001 and my 2003 are different. I will double check all my fuses. What does the #29 supposed to do?

should be charge signal but that does not seem to be your problem. yours sounds like undersized wire or poor ground because without the heaters on it works just fine according to your last posts...

jdholder · 10-09-2008, 06:17 PM

Quote:

Originally Posted by ajohansson

I know the fuse panel in the cab for your 2001 and my 2003 are different. I will double check all my fuses. What does the #29 supposed to do?

It controlls the voltage regulator, but I would agree that it doesn't sound like your problem. When I wiggled the fuse the alternator would either chrage or not. Nothing in between. On or off!!

ajohansson · 10-10-2008, 01:37 AM

Copy that.

AJ

WAMPAKU · 10-23-2008, 12:16 AM

did you find anything out? i am having the same problem with my 02 excursion. called db and he basically said its a problem with the ex. wants me to change belt, etc. then he said to send it back for a check up. that would be over a week down time.