I am needing help on finding a electrical problem with my truck. When I drove it last I noticed that the gauge did not come back up to the A/L in NORMAL. I let it sit overnight and it was dead this morning. It could have been dead last night so not sure if it is parasitic or not yet. So I replaced the alternator as it looks very original and smelled hot. It won't get above the O/R at idle, even with the GPR unhooked and even with the new alternator.

Here is what I have done so far:
Clean and inspected battery connections, Starter relay connections, GPR connections, starter connections.
Disconnected my main power lead to my after market radio/sub.
Disconnected the power to my gauges.
Disconnected the power lead to my headlight harness (LMC)
Replaced altenator
Took GPR out of the system-problem presists.

After charging the batteries individually for an hour apiece or so one is at 12.03 volts and the other is at 12.22 (truck off)

My starter is two years old but has less than 5K miles on it. Looks brand new. My batteries are Motorcraft and right about two years old. Water level in them is good. They take a charger off my charger. I have them charging individually right now while I decide what to do next.

That's where I need your help. What do I need to do next? I am not very knowledgeble with a multi meter but have one.

I believe my next step is to charge the batteries awhile longer then fully hook them back up and see if they go dead overnight with all the disconnects done? I appreciate your help!

 

My first instinct is voltage regulator - but that should be part of the alternator which you replaced...

 

I think that should be ok considering both old and new give same result. Also, my glove box light is not on lol... I have been reading!

 

Your batteries are clearly not charging or else are shot. One is low and for all intents and purposes one is dead. Charged batteries should be at 12.6-12.7 VDC.

Steve

 

^^^^ This; a LOAD test of the batteries (separately) would confirm the diagnosis.

And yes, a good charging system trying to charge old batteries will read low on the dashboard voltmeter.

 

Can also just put the multimeter on the batteries to start with and see if the alternator is putting out. That would save pulling them out, if it is the alternator, but given it was just changed out, probably not.

Steve

 

You don't need to pull the batteries to load test them. Disconnect ONE of the negatives, and they are isolated from one another. Then just put the load tester on each battery and hit the button.

Voltmeter on the batteries will also read lower than usual, when hooked up to tired-out batteries. But it will at least read higher than when the engine's not running, so that will indicate the alt is doing something.

 

I was guessing the OP did not have his own load tester, but may be wrong. I was thinking he would haul them to Advance or some such. I agree the volts will be low, but as you say, should come up some with engine running.

Steve

 

I appreciate your help. I do not have a load tester and the batteries are already unhooked so I will just pull them and have them tested. You have me questioning whether they are good so I will find out for sure. If they test good, then I will be back for more help!

 

Sounds like a plan!!

Steve

 

Batteries load tested good but showed 0% charged. Can a battery load test good and be bad or is my charger not doing its job? I did charge them for a couple of hours apiece yesterday but maybe that was not enough time on my 1970s Sears charger. Learning as I go...

 

Does the charger have a meter on it? Can you borrow another charger?

 

It does have a meter that ranges from 0-8. Currently showing 5 on the battery that I have it on now. Measures in ampheres. Is 8 charged or 0 charged? If my charger becomes suspect then I will go get a wheeled Schumaker charger, they are on sale.

My plan is to leave the one battery on the charger I have for the next 4 hours before I have to leave and take it with me to test it again as I think it should show charge by then. I charged them each for for aproximately and couple of hours last night before I shut it down. May not have been enough time.

 

That's a pretty slow charger, which is actually good. Puts a more healthy charge into the battery. If it's an automatic charger, the meter should start out high, then slowly gradually go down. IOW, it should slow down the charging rate as the battery charges up. When it gets down less than 1A, the battery is close to completely charged. If it's still putting 5A into one of the batteries, that battery still needs some charge time.

If there's an auto/manual switch on the charger, switch it to auto, but DON'T switch it while it's plugged in. I did that once with an old '80s era Schumacher, and I think I goofed up the auto operation; it only seems to charge at a constant rate now.

 

I was rushing this abit to get the truck up for the bad weather we were getting in but it looks like they are backing off the forecast.

I am going to leave the battery on the charger the rest of the day and see if I can get a second charger for the other battery to see if they will come up. If they don't then I will assume the batteries are bad.

Thanks for the help. I will let you know.