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Greetings, the alternator on my '97 GLT does not appear to maintain proper charging voltage while driving with accessory on (lights, blower, rear defroster, etc.) top voltage appears to be approx. 13.5 volts but drops to 12.2 volts with a load applied. as most of my trips are short, I'd like to see something closer to 14.1-14.5 volts. alternator was replaced (PO) with a Bosch AL0053X, which is not what's speced for my ride, but appears to cross reference. my experience with alt/volt regulators is that they work til they stop working. not sure what would cause "low" volts rather than "no volts". battery was replaced (less than a year ago, test good). ideas ? check for bad grounds ??
Thanks
Peter
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Have done a load test on all the wires positive and negative side???
If you replace the alternator w/ aftermarket part, the current statues of these parts is not very good. Lots of crap parts even on good boxes.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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I'm not sure what you mean by "load testing" wires.
I can and have done some "resistance" tests on wires.
I'm also familiar with "voltage drop" tests on wires.
the car already has a replacement alternator, a Bosch AL0053X, which is allegedly speced for a Volvo 960 (go figure)
currently have moved on to replacing the radiator and somehow repairing the intercooler, both of which are leaking.
gettin'grimy
Peter
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Peter,
Go here for info on load testing.
The Sun package includes a carbon pile to load system volts to 12.0
and then you measure alternator current with a series ammeter in the B+
They discuss theory in the user manual.
Post back with any findings
SUN VAT 40
Quick Reference guide
https://archive.org/details/VAT40QRG
User Manual
https://archive.org/details/SUNVAT40Ops1979
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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that "load tester" that you are referring is to is for testing battery's and alternators DIRECTLY, it has nothing to do with "load testing wires".
a simple "voltage drop" and/or "ohm" test is all that is required to verify the condition of a wire.
cheers
Peter
I have more pressing issues to deal with now on this car right now.
If and when I solve this low charging issue, I'll get back to ya.
thanks
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Yes, you need to load test the positive and negative side.
You can also measure the alternator output directly with a Voltmeter from output side to battery ground.
Do not assume the alternator is good even if you just bought it. I had one that was low charging out of the box.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi,
I Agree with what B.B is telling you all the way around.
There are No flat out rules here but a willingness to flex. (:-)
You have to remember that the coldness effects rest voltages of batteries.
Amperage and capacity will vary as so will the charging voltage rate.
Governing it is built into the regulator’s circuitry to protect the alternator or the whole electrical system as one piece as far as that goes.. It is a stand alone, take care of itself system.
A few tenths of a volt means a lot to the regulator.
That’s why “good connections and conductions are required.”
12.65 is a full battery and 12.0 is nearly dead and may not crank but blows a horn.
Alkaline cell batteries are measured from good to dead in a few tenths of a volt.
Basically, you need the minimum of one volt over resting voltage to maintain a battery or more to apply a charge to make current move into the cells plates.
Temperatures and charge status varies with loads but like B.B. says low is better than over 14 volts.
The best range, in my experiences, have me look for the car to be 13.2 to 14.2. Very very seldom I see the high end. In the thirteens is good.
A High charged condition to a low charge condition has to be put into this “equation” as entries are allowed to vary like the weather or demands.
If you are having problems it goes back to “good cells and connections are required.“
Phil
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Phil, thanks for your response.
as someone who is very well versed in battery & charging technologies, I under stand what your saying.
my purpose posting here on the BB was to find out what the charging experience is with other 850 owners.
if other owners claim that their alt./reg. is able to maintain above 13 volts charging under load, but mine does not, then it appears that I have a problem somewhere in my charging system that bears further troubleshooting.
battery & belt are relativity new, so I'll have to revisit electrical connection which for now appear to be good.
when better weather arrives, I'll have a better look at some chassis grounds.
Peter
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Peter,
Did some shop do your T-belt, and then say all is OK? Or did you do it?
Is there a new S-belt? perhaps the tensioner is weak and the belt glazed or stretched. Possibly slipping under load.
The other thing I wonder is how many amps load you are putting on the alternator?
The stock alternator is 100 amps, NOT 100 watts.
That would be about 1400 watts max.
You're not running a high power amp for a stereo by any chance?
You can't run more than 1400 watts with a 100 amp alternator.
The cable between the starter and alternator has to carry all the current to keep the battery charged. Cable ends are first to get dirty and /or have the crimps
die from old age and corrosion.
See 14.0 VDC at the battery with everything on and engine running to relax.
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Peter,
Have you had any odd noises and perhaps stiff steering along with the
poor charging?
You could also have an issue with the serpentine belt or failed belt tensioner.
The belt can get old, glazed, covered with oil, stretched, misaligned, etc.
Here's one of many write-ups:
https://www.samarins.com/glossary/serpentine_belt.html
Poor charging under heavy load is common with loose/glazed/misaligned vee-belts
Others might comment about problem S-belt symptoms.
I'd still look for a ratty cable crimp or alternator connector first.
Post back with your findings, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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BILL, Thanks for your tip on the serpentine belt issue.
However, I am ruling out this possible cause as I have recently performed a timing belt service, so new serp. belt and all pulleys/tensioner checked out good.
main concern is charging voltage dropping below 13V under load. (lights, blower, wipers, defroster, etc.)
will go back to checking electrical connections, which for now appear to be good.
Peter
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi,
Yes checking the chassis grounds is always a good idea.
The negative side of all the cars circuits IS one half the whole system in one fell swoop. But there are two grounds. One for the engine block and the other for the cars chassis or body components.
The positive side splits at the starter and another circuit goes onward to feed the fuse panel.
Failure in these are noticed with each item when it doesn’t work.
You are looking towards a system failure itself for under charging.
It could be a worn alternator after knowing it has good connections.
A battery that old can fool the regulator to some extent by itself. One cell could cause a false feed back but you are saying the battery is rather fresh.
So we are looking for bad cables.
The alternator works directly back and forth on those main cables and the housing of the alternators. The regulator itself senses tenths of a volt changes to ground.
This after the excitation from instrument clusters D+ wire and the idiot light goes out. The alternator is an independent system working on the cables.
Corrosion on the cable ends need to be inspected.
I have read the following and there maybe You Tube on this procedure someplace.
This is an old school test procedure.
I have used it much because I keep my cables in good working order.
It is a way to check the circuit side with a voltage meter to see if you can get all zeros on both sides.
It involves put both leads of the meter on terminal post to either a ground point or the other end of the positive side. Both leads on the same side should give nothing to read. Zeros.
A voltmeter needs to be across the battery’s potential to read 12.65.
If you get any reading at all there is a resistance somewhere along the cables or ground points.
It want be much but more than a digital on internal hunting or if the leads are closed.
It’s worth a shot.
I was able to troubleshoot a persons diesel truck once.
It was more interesting because he had two batteries so twice as many possible bad connections but only one alternator system.
It was a starter connector and possibly the engine ground, so it was the positive side and a ground.
You inspect and clean them all in this case.
In fact we decided a new cable was in order as there’s nothing extra is left in length on them from the manufacturers. Save a few pennies here cost dollars later but not on them!
What I don’t remember is whether a circuit has to be on some where but most of the time there is something on in todays cars.
So play around with it and see if the voltmeter can indicate an issue.
Anyways good luck and thanks for all the feedback it keeps interests up on the BRICKBOARD.
Phil
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Peter,
You want around 14.0 charging volts.
14.5 Volts is too high, you'll blow out lights too fast.
Service the battery and alternator connections.
Look for suspicious corrosion at wire crimps.
Check the heavy red wire between the starter and the alternator first.
Pay extra attention to the alternator D+ Red-white lead that works with the Voltage regulator.
Service the alternator connector and use a little dielectric silicone
on reassembly (Maybe there's corrosion?)
Good luck, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Bill, believe I've checked the major wire connections, but I make another go-around including the engine ground straps when the weather gets above freezing.
with 100 watts on tap, I feel that even with all the acc. on, the alt. should be able to maintain approx. 13.5 volts during a steady cruse .....
thanks
Peter
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi Peter,
I'm assuming the the starter motor spins normally, so look carefully at the starter motor where the big wire to the alternator goes into the crimp. Bad crimps often have green copper oxide visible. Wiggle/Tug on the wire see if it is loose in the crimp. Take those two lugs off and wire brush or sand the lugs and the other copper hardware and reassemble with a little dielectric silicone or copper anti-seez.
The D+ wire has to be right, that gives feed back to the VR.
Just because it's a new alternator doesn't rule it out, with maybe some issue with the VR, brushes or a bad connector.
You don't want 13.5V either, 14.0V is normal charge volts for happy motoring.
Post bad with your results, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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LOW CHARGING ISSUE SOLVED !
The culprit turned out to be the positive battery terminal clamp/connector.
internal corrosion (not visible) was causing to much resistance to allow all the proper charging current to get through.
a voltage drop test will revel the issue or simply place your hand on the terminal after the engine has been running awhile and feel how hot it is compared to the negative side.
solution is to replace the battery terminal clamp & clean all the wires.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks for the update/resolution. Always like a happy ending. Now, "I don't touch what while touching the other" :)
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