Urgent Need Of Help - Charging System

[scottm0821]

did you try changing the batteries out yet or testing them? the only wiring that would make that happen is if the positive it getting grounded out so checking the cable between the alternator and batteries wouldn't really help, if anything start the truck and disconnect the batteries and see what happens, if its your alternator the truck will die if your alternator is good and its the wiring or the batteries the truck will stay running.

[mrnecsteve]

Originally Posted by scottm0821

did you try changing the batteries out yet or testing them? the only wiring that would make that happen is if the positive it getting grounded out so checking the cable between the alternator and batteries wouldn't really help, if anything start the truck and disconnect the batteries and see what happens, if its your alternator the truck will die if your alternator is good and its the wiring or the batteries the truck will stay running.

not a good idea..the risk of frying electronic components throuout the truck is pretty steep, if the alternators voltage regulator malfunctions.

[mrnecsteve]

Anyone that opens their hood for anything beyond checking and adding oil should have these three basic tools.
1 Simple but reliable digital volt meter.
2 battery terminal cleaning tool
3 battery hydrometer
ALL THREE can be purchased for about twenty bucks total.

Steps to take with your problem:
Charge the batteries fully with an external charger.
While the posts are disconnected clean all four posts and terminals,even if they look ok.
IF possible take the battery cell cover(s) off and check the specific gravity
of all 12 cells ,before and after charge. If any cells are low,refill with new battery acid or distilled water.
After chargeing (its always a good idea to externally charge extremely low batteries.....if your alternator is dying OR remanufactured with chinese electronic components...rechargeing two low batteries simutaneously will be the biggest demand ever on your alternator)A marginal alternator will die for sure.
Next step(with freshly charged batteries : start the truck....let it idle for 5-10 minutes. Turn the headlights on. Measure the voltage at the posts. It should measure 13.6 volts thru 14.3 volts.

If the truck started ,your batteries,basic wiring,your starter,and starter solenoid are probably ok.
IF not,and your certain the batteries were freshly charged...check the wiring,INCLUDING CHASSIS grounds

IF the alternator is NOT providing 13.6 to 14.3 (measure at the output of the alternator as well as the batts)...check the condition of the belt first(motor off) Is the belt tension ok? Is it glazed?Is the tensioner working? If your confidant that the alternator is not slipping....focus on a malfunction of the alternator.

Other than mechanical issues ,the common failure of an alternator is usually one of two things....faulty regulator circuit or one or more internal diodes bad.
You just checked the regulator function. To check for diodes bad,you need a way to monitor if the output is pure direct current..( the batteries do mask the malfunction somewhat).
An oscilloscope would be best. Next choice would be to set your DVM to AC
and measure AT the alternator post. The AC component should be next to nothing at idle (compare the output to a working vehicle if you need to) Third choice ...turn your sound system on to a dead channel . If you hear a strong noticeable whine that increases with the rpm...you have a blown diode in your alternator. Replace the diode,diode pack, or the alternator.

If after all this youre sure that the alternator is chargeing,the batteries can charge,....leave the truck sit overnite. IF its dead in the morning....you have a drain problem. Immediately recharge the batteries. A drain problem needs to be approached methodically ,with a current measuring device in place (unless you like throwing parts at the situation)



Still not convinced about having a DVM??? Think what it would be like if someone said : My tire is shaped kinda funny...it's not round on the bottom! You suggest checking the
air pressure...but the person doesnt have a tire pressure guage.
Thats when someone else comes along and says: I had that problem once ...I replaced all four tires and the problem went away...that must be the best FIX!!!!

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Last edited by mrnecsteve : 10-31-2009 at 04:36 AM.

[FlagMissed]

Originally Posted by 2003PSD

Which connections & with what? on the alternator? I just bought a 200 amp high output alternator, but batteries still aren't taking a charge. At this point, I just want my truck to run and charge

Just the battery connections with terminal cleaner and after I cloated it with a red type of sealant that my neighbor had. He owns a company that specializes in rebuilding odd alternator and starters for heavy equipment. He was also the one I that helped me troubleshoot.

[scottm0821]

out of that longggg post you come out with pretty much nothing except confused if you dont know anything about electrical,if i used your, and any other drop-out educated auto zone employees, method of troubleshooting i would have gone through quite a few alt.'s. it is highly unlikly to hurt anything by disconnecting the batteries with the truck running, i dont care what "auto repairs for dummy's" says.the whole point of the forum is to give ideas from other people that have had the same problems. If you want professional advice go to a dealership. but there is no since in doggin other people just trying to help. So if you want to take the advice then do so, but at your own risk, just like i warrantied my batteries out and they were defective and were pulling a load off the alt. causing it to look like there was a low output from the alt., and the only way i found to check for that without taking off the alt. and taking it to the auto store or going to the dealership is to disconnect the batteries, thats what worked for me, might not be your fix but if your batteries are under warranty, why not go swap them out? No one on here is forcing you to go throw parts at somthing, but somtimes thats what you have to do if you dont want to play to get it checked.

and just like an engineer with your smarta** comment at the end, i have one for engineers, "well it said it would work in CAD!!". if i had a dollar for every time i heard that come out of an engineers mouth i wouldnt have to work.

[mrnecsteve]

I'll say it again.( for the benefit of the other readers.)
If youre working on a running vehicle with an alternator issue...and the issue with the alternator is a shorted field regulator transistor...the field of the alternator will go into full "excitation" . In a matter of a few hours running it will damage one or both batteries by overchargeing. (The batteries being connected will prevent the voltage from getting much higher than 15-16 volts.) If you disconnect the batteries during this type of alternator malfunction (with the engine running), MANY electronic components throught the truck, could easily be destroyed in a matter of seconds.

[2003PSD]

Thanks everyone for all the input. Alternator and batteries are both good. I have had them all out and tested seperate. Cleaned all connections and put everything back in and still the batteries are not charging. Even my old alternator is good, which is what gets me know. Everything was good and something happened where batteries wont charge.

[2003PSD]

Anyone know where the grounds are. I found 1 next to passanger side battery, one on passanger side fram rail from cab mount to frame. Is there another one? I want to make sure all grounds are good. I will probably charge batteries and get truck washed first (a LOT of mud down there)

[thorx4md]

I had the same problem. First thought it was the batteries but no. Then thought it was the alternator, but no. Had it at a couple different garages and nobody could figure it out. I kinda figured it was a bad ground so I ended up running a ground wire from the passenger side negative battery terminal to the engine for a good ground. That fixed everything. A ground cable can be bought at any parts store for about $10.00 Hope that helps.

[2003PSD]

Originally Posted by thorx4md

I had the same problem. First thought it was the batteries but no. Then thought it was the alternator, but no. Had it at a couple different garages and nobody could figure it out. I kinda figured it was a bad ground so I ended up running a ground wire from the passenger side negative battery terminal to the engine for a good ground. That fixed everything. A ground cable can be bought at any parts store for about $10.00 Hope that helps.

Thanks! I only get daylight on weekends now, so I will be cleaning all grounds and checking all wires. I will probably run a ground to be same. Looking through the Chiltons last night and I have already done all possible checks.