Battery Charging Issues

[Ricker]

Hi everyone! New member here and Delorean owner for just over a year. A Jan ’82 #11153 with 7,300 miles and original tires. I have been replacing things but now I have started having electrical problems. Specifically the battery charging. The original Motorola 90 amp alternator would run at +13 volts in the dash volt meter (and verified by a hand held volt meter) for a bit and then drops to 10.5 volts - just above the battery dash light coming on (sometimes it does briefly). Depending on how long I drive the car anyways depends on how long the battery tender takes to charge it back up - sometimes 3 days. The battery is one year old and I pulled it out and had it checked, it's supposedly fine. I replaced the alternator with a 140 amp unit from DMC. No change. Now it never gets above 10.5 volts. I used a battery out of my other car and connected it up to the + and - posts in the engine compartment, no change. Having the lights on, AC or revving the engine, no change. There is no change in the amount of light from the headlights either. I have not pulled the battery light in the dash but it does come on and flashes (due to the new alternator I understand). Also it worked for 9 months before. My thinking is that connecting the battery ground directly to the engine block eliminates the possibility of grounding issues between the battery and alternator. The v-belt is good and tight. I have nothing else I know of to check. The readings now are just under 12 volts across the battery itself. 11.5 volts on the engine compartment posts (engine not running). Once the engine is running the voltage goes to 10.5. to 11.0 volts at the engine compartment posts (I thought this should be +13). I would pull the alternator but no one around here knows the data to use for the testing machine.

Can anybody suggest anything else I can do, check, replace? I am presently in south central PA. Many Thanks in advance!

[Bitsyncmaster]

Since your battery light is working then that is one problem you don't have. So your alternator worked for 9 months and suddenly it does not work?

Most will suggest to check your grounds but with your car parked and nothing electrical on engine running your only drawing about 30 amps so your voltage should be about 14 to 14.5 volts.

My guess is your alternator has "bit the dust".

[Jonathan]

Can anybody suggest anything else I can do, check, replace? I am presently in south central PA. Many Thanks in advance!

Hello and welcome!

You touched on a lot of the main things that might get looked at, so good on you for doing your research and trying to figure it out.

One thing that came to mind was a wiring problem related to a replacement alternator that Rich_NYS had.

It is discussed here:

http://dmctalk.org/showthread.php?9682-Charging-issue&p=145298&viewfull=1#post145298

Not sure if that will end up being your problem as well but I wanted to bring it to your attention. Let us know.

[Ricker]

Since your battery light is working then that is one problem you don't have. So your alternator worked for 9 months and suddenly it does not work?

Most will suggest to check your grounds but with your car parked and nothing electrical on engine running your only drawing about 30 amps so your voltage should be about 14 to 14.5 volts.

My guess is your alternator has "bit the dust".

Thanks for the comment but this is a brand new DMC alternator which does the same thing the original Motorola unit did. Same with the battery - two batteries, same issue.

[Bitsyncmaster]

Thanks for the comment but this is a brand new DMC alternator which does the same thing the original Motorola unit did. Same with the battery - two batteries, same issue.

Ok, misunderstood. So the new DMC alternator never worked. Does the dash charge light come on with the new alternator?

[Ricker]

Hello and welcome!

You touched on a lot of the main things that might get looked at, so good on you for doing your research and trying to figure it out.

One thing that came to mind was a wiring problem related to a replacement alternator that Rich_NYS had.

It is discussed here:

http://dmctalk.org/showthread.php?9682-Charging-issue&p=145298&viewfull=1#post145298

Not sure if that will end up being your problem as well but I wanted to bring it to your attention. Let us know.

Thanks, I checked that out. There is one wire and to me it is in the correct (3rd) position of the plug (SFLP). Anyway, I thought this is what gets the dash light to light and mind does. Since it is low voltage (10-1/2) and not no voltage, is there a resistor (besides the light) in the circuit?

[Ricker]

Ok, misunderstood. So the new DMC alternator never worked. Does the dash charge light come on with the new alternator?

Yes. But with this alternator it flashes. I have read in other blogs this is proper with a DMC alternator as it is some kind of check.

[Bitsyncmaster]

Thanks, I checked that out. There is one wire and to me it is in the correct (3rd) position of the plug (SFLP). Anyway, I thought this is what gets the dash light to light and mind does. Since it is low voltage (10-1/2) and not no voltage, is there a resistor (besides the light) in the circuit?

OK, your dash charge light is on with the new alternator. There are only two other connections, ground and battery. There are no resistors in the charge light circuit.

[Ricker]

OK, your dash charge light is on with the new alternator. There are only two other connections, ground and battery. There are no resistors in the charge light circuit.

Ok. Thinking it might be the ground, I took cables directly from a second (exterior) battery to the ground on the engine block and positive to the post in the engine compartment (the main battery was disconnected). I started the car - same issue. I will add this that some times it will go up to the 13 volts for a while and then back to 10-1/2. I thought maybe something was over heating. Other electrical issue I have are (probable not related) is with the washer fluid pump (now disconnected). It grounded out when the bottled leaked and flooded it out. Also the turn flashers. They blink double time but with the emergency flashers it is regular. All lights are working. The Lambda light does not come on with the key turned nor does the seat belt light.

[Bitsyncmaster]

Sounds like a bad alternator. They should be able to test it at one of the auto parts stores.

[Ricker]

Sounds like a bad alternator. They should be able to test it at one of the auto parts stores.

I'll pull it out next weekend and have it checked. Is there anything that can cause a brand new alternator to go bad? Electrical surge? Bad something or other? Just a bad new alternator? It happened to the original one and now a new one. I'll let you know next weekend Thanks!

[Jonathan]

Other electrical issue I have are (probable not related)...

Hmmmm.... welcome to DeLorean ownership. You probably won't utter that phrase much longer :)

[Bitsyncmaster]

I'll pull it out next weekend and have it checked. Is there anything that can cause a brand new alternator to go bad? Electrical surge? Bad something or other? Just a bad new alternator? It happened to the original one and now a new one. I'll let you know next weekend Thanks!

Your original one just died (no output). So this one seems to have no output also. Not much you can do to an alternator with 12 volt battery voltage. Maybe bend or brake a connector stud.

[Rich]

....Is there anything that can cause a brand new alternator to go bad? Electrical surge? Bad something or other? Just a bad new alternator?!...

Any alternator, new or old, can die if the diodes or the regulator that are on/in the alternator get fried.

Something like this can happen if the battery and the alternator somehow get disconnected from each other on either the (+) or (-) circuits and the alternator tries to run open-circuit. Things like bad grounds, bad connections (as Dave M is suggesting) or opening a battery switch while the engine is running could do that. Not sure if it's true but I think I've heard that jump-starting a car with the jumper cables connected backward can blow such components, too.

An autopsy of the dead alternators may tell you which component failed in each one. At this point you might expect it to be the same component and then you get a clue as to what could have blown it.

[Ron]

Not sure if it's true but I think I've heard that jump-starting a car with the jumper cables connected backward can blow such components, too..Instant death to a internal voltage regulator!

[Ricker]

Any alternator, new or old, can die if the diodes or the regulator that are on/in the alternator get fried.

Something like this can happen if the battery and the alternator somehow get disconnected from each other on either the (+) or (-) circuits and the alternator tries to run open-circuit. Things like bad grounds, bad connections (as Dave M is suggesting) or opening a battery switch while the engine is running could do that. Not sure if it's true but I think I've heard that jump-starting a car with the jumper cables connected backward can blow such components, too.

An autopsy of the dead alternators may tell you which component failed in each one. At this point you might expect it to be the same component and then you get a clue as to what could have blown it.

If the diodes go bad will the alternator still put out 10.5 volts instead of 13.5? I plan to pull the alternator out and get it to an alternator shop. Also, it will go between 10.5 and 13.5 not just once, but a couple of times. Strange?

[Rich]

If the diodes go bad will the alternator still put out 10.5 volts instead of 13.5? I plan to pull the alternator out and get it to an alternator shop. Also, it will go between 10.5 and 13.5 not just once, but a couple of times. Strange?

First, when you say your alternator is putting out 10.5 volts it's likely not doing that. That's probably the latent voltage of the battery when the alternator is putting out nothing. And it's a pretty low voltage, so your battery may not be in great shape.

13.5V is a good reading for a system with a good battery and a good alternator, including all components. If your system voltage is changing such that it swings from 10.5-13.5V then you have probably got an intermittent connection problem somewhere, maybe even inside one of the alternator components. Could also be a bad voltage regulator - also inside the alternator.

So see if your shop can verify the alternator is OK. Seems like it CAN be OK which means it isn't broken all the time. Whether they can diagnose the voltage regulator separately I don't know.

If the diodes are bad then it won't work at all. I've never heard of diodes that work intermittently. But, again, maybe a bad diode connection somehow?

How old is your battery?

[Rich_NYS]

When I had a charging issue, it ended up being a few different things:

-Improperly wired plug....battery light didn't light.

-Bad alternator....intermittent 8-10 volts shown on the gauge.

-Weak battery......randomly drained overnight.

[Ron]

An alternator could put out 10.5 volts because of a bad diode. One open diode would be about right (shorted diodes result with less...). It will not last long.
Most any shop or auto parts store can test the regulator while installed in the alternator, many with it all installed on the vehicle.
The random 10.5-13.5V could easily be the brushes are on their last leg.

+1 on taking it to a shop for load testing.

[Rich]

An alternator could put out 10.5 volts because of a bad diode.

+1 on taking it to a shop for load testing.

Agree on getting it bench tested.

Could be right on 10.5V being an output voltage but it would mean a lot more if we knew what the battery voltage was after the car sits for 12-24hrs. If the battery is just managing to hold 10.5V before the engine starts then I'm not sure that a 10.5V reading with the engine on means much...

Wouldn't a good battery hold the system at something >11.5V with engine on for a while even if the alternator wasn't turning?

That's pretty much academic, though.

Get it tested. Am betting it will be fine, but you need to start ruling things out somehow.

[Ron]

Could be right on 10.5V being an output voltage but it would mean a lot more if we knew what the battery voltage was after the car sits for 12-24hrs. If the battery is just managing to hold 10.5V before the engine starts then I'm not sure that a 10.5V reading with the engine on means much...I'm with ya.
He would have to do something like, not trickle charge the battery back up when it was at 10.5V then boost it just long enough to start it and take a reading. (We know what happens if we swap batteries while it is running ;-)
(I'm assuming the battery is being charged to start the engine, not boosted or jumped when at 10.5V, since it wasn't mentioned. It would never start in the first place with 10.5V)


Wouldn't a good battery hold the system at something >11.5V with engine on for a while even if the alternator wasn't turning?Yeah, i.e. if the battery is strong enough to start the engine on its own, it should hold that, and run a long time, especially w/o lights, AC, etc. But note, once the battery gets close to ~12V, you can't trust voltage to guess power (not to mention the fuel system does not like low voltage at all).
Not sure that will be clear...bottom line is, I would agree it red flags the battery (both orig and loaner.....). Plenty of them flying here. lol


That's pretty much academic, though.Not really (could be your Spidey sense tingling...;-)
It goes with something that bugs me - Why would it take 3 days to trickle charge the battery back up enough to crank the engine? Especially starting at 10.5V. BUT, his known good battery acts the same, even when it will crank the engine using jumpers by itself (ie not actually installed). Takes damn good cables and battery to do that.
This alone, makes me suspect the alternator is internally shorted, but I would expect reports of the alternator getting very hot, whining/growling), maybe draining while shut down.
But then again, the ground from the battery->block->alternator and connections are not eliminated yet. (Same for path from the positive side.)
Too many unknowns yet...

+1 on start ruling things out!
At this point, I'd start with the known good battery from the other car, fully charged, and installed. Then connect cables from the battery directly to the alternator. If the voltage goes low, when slightly over idle, you know either the belt is loose, the pulley is too small, or the alternator is bad. (Verify voltage to the field/lamp terminal (light on then off)- If absent, apply 12V by momentarily jumping from main post (+), rev the engine once, or on those Delco style alternators, momentarily ground the little brush tab just inside the "D" shaped hole in the back casing, to kick the regulator in.) If the alternator shows bad, then take it to a bench tester. As for cause here, I would suspect the ground side components first, which can explain the old and new alternator/regulator blowing (~same for output side to battery). Verify resistance of both, shake test, load test if you have to to find it -- You don't want to buy a 3rd alternator or risk voiding any warranty.

RE: "Brushes on last leg"
I forgot he originally said it was a new alternator from DMC. So, please disregard.

[Ricker]

OK. I took some more readings. The battery fully charged has 11.5 volts, engine not running. Started the car. Now the voltage is 14.0 on the dashboard volt meter. At the battery terminals 14.0 volts. The engine is cold and is doing it's typical RPM hunting. As soon as the engine is warm it quits RPM hunting AND the voltage drops to 11.5. It has done this most of the time. Battery voltage with engine not running and headlights on 11.5 volts.

Can there be any association between the two? Does the micro switch tie in in any way? I plan on chasing the wires tomorrow with a continuity check.

[Bitsyncmaster]

A fully charged battery should read 12.5 volts. With the engine running, 14 to 15 volts is normal. It should not drop to 11.5 volts after it warms up with no loads.

[DMCMW Dave]

OK. I took some more readings. The battery fully charged has 11.5 volts, engine not running. Started the car. Now the voltage is 14.0 on the dashboard volt meter. At the battery terminals 14.0 volts. The engine is cold and is doing it's typical RPM hunting. As soon as the engine is warm it quits RPM hunting AND the voltage drops to 11.5. It has done this most of the time. Battery voltage with engine not running and headlights on 11.5 volts.

Can there be any association between the two? Does the micro switch tie in in any way? I plan on chasing the wires tomorrow with a continuity check.

Your battery is bad.

[Ricker]

Your battery is bad.

I'll pull it out tomorrow and get it tested.

[krs09]

My charging/constant dead battery issue was a bad main ground cable from the battery. The cable was totally shot (pulled the flag connector off with my hands) and the bolt was badly damaged. Got a new gm cable that matched beautifully, a new bolt and cleaned the mating surface really really good and no issue since.

[DMCMW Dave]

My charging/constant dead battery issue was a bad main ground cable from the battery. The cable was totally shot (pulled the flag connector off with my hands) and the bolt was badly damaged. Got a new gm cable that matched beautifully, a new bolt and cleaned the mating surface really really good and no issue since.

Good comment. The ground connection at the RH trailing arm is also a very common problem.

[Ricker]

Well, I went out into the garage and started the car - low voltage. Pulled out the battery and had it checked - no problem. Checked continuity from battery negative side cable to alternator housing - perfect. Pulled the new alternator from DMC and had it checked - FAILED. The guys at the auto part store immediately recognized it as a GM unit. So I am debating to get it repaired or go get another new one. I hope this solves this problem. I hope there is nothing else wrong that would cause the next alternator to fail. I know to install it with the battery disconnected. Anything else?

Thanks guys for all the input!

[DMCMW Dave]

Well, I went out into the garage and started the car - low voltage. Pulled out the battery and had it checked - no problem. Checked continuity from battery negative side cable to alternator housing - perfect. Pulled the new alternator from DMC and had it checked - FAILED. The guys at the auto part store immediately recognized it as a GM unit. So I am debating to get it repaired or go get another new one. I hope this solves this problem. I hope there is nothing else wrong that would cause the next alternator to fail.

Not arguing that an alternator can't fail (stuff happens) this diagnosis does not completely square with your post above:


OK. I took some more readings. The battery fully charged has 11.5 volts, engine not running. Started the car. Now the voltage is 14.0 on the dashboard volt meter. At the battery terminals 14.0 volts. The engine is cold and is doing it's typical RPM hunting. As soon as the engine is warm it quits RPM hunting AND the voltage drops to 11.5. ....

If the alternator is bad, starting the car will not cause the voltage to come up. In the first post the alternator is definitely working, at least for a while. It could be that the alternator works cold but not hot (it can happen) but since the store tested it cold I still don't get it.

I still think you have a connection problem since the battery does test good.

The most common causes of false alternator diagnostics are:
---disconnected/burned out battery light bulb (or installing an LED in place of the bulb)
---dirty mount where the alternator is attached to the engine. That is the ground for the alternator. You must clean the rust off that (cast iron) mount, and it's a good idea to clean or replace at least one of the bolts that screw into the side of the engine.
---loose belt

How old is the alternator?

[Ricker]

Not arguing that an alternator can't fail (stuff happens) this diagnosis does not completely square with your post above:



If the alternator is bad, starting the car will not cause the voltage to come up. In the first post the alternator is definitely working, at least for a while. It could be that the alternator works cold but not hot (it can happen) but since the store tested it cold I still don't get it.

I still think you have a connection problem since the battery does test good.

The most common causes of false alternator diagnostics are:
---disconnected/burned out battery light bulb (or installing an LED in place of the bulb)
---dirty mount where the alternator is attached to the engine. That is the ground for the alternator. You must clean the rust off that (cast iron) mount, and it's a good idea to clean or replace at least one of the bolts that screw into the side of the engine.
---loose belt

How old is the alternator?

Brand new. I put it in and it started at 13.5 volts for 2 minutes then down to 10.5. Every now and then it will go to 13.5 but not for long. None of this makes any sense. The grounds, I really believe, are good. Could it be the positive side wiring?

[DMCMW Dave]

Brand new.

It has a warranty. Contact the selling dealer (it may be me, but since I have no idea what your real name is I can't tell) and get another one.

[Ricker]

It has a warranty. Contact the selling dealer (it may be me, but since I have no idea what your real name is I can't tell) and get another one.

I got it 6/10/14 from DMC Humble, TX. I'll call on it on Monday. Thanks!

[Bitsyncmaster]

I could see a temperature sensitive regulator getting though factory testing but like Dave S said, how did it fail the test at the auto parts store. Unless they ran it till it got hot. Maybe a full load test heated it up quickly.

[Ricker]

I could see a temperature sensitive regulator getting though factory testing but like Dave S said, how did it fail the test at the auto parts store. Unless they ran it till it got hot. Maybe a full load test heated it up quickly.

The test took about 30 seconds. I was told it failed on one for low voltage. The other test it passed. Not sure what that was for. (mechanical engineer here, electrical has always caused me grief). Before I took it out it was low voltage - it did not start at 14 volts and then drop after a minute or two. This has been the case more and more.

[Ron]

After the latest, it looks more like a bad connection between the alternators and the system, and you are blowing the alternators (or regulators). Hook both sides of the alternator up with GOOD jumper cables and prove it or eliminate at least 50% of the guesswork and hair pulling....

Yes, either side (+) or (-) can and will cause the problem.

[Ricker]

After the latest, it looks more like a bad connection between the alternators and the system, and you are blowing the alternators (or regulators). Hook both sides of the alternator up with GOOD jumper cables and prove it or eliminate at least 50% of the guesswork and hair pulling....

Yes, either side (+) or (-) can and will cause the problem.

I am concerned that the new one will have the same thing happen. However, before I started the car the last time I checked the voltage at the alternator - same as the battery. Disconnected the battery and checked continuity from the + terminal wire end to the alternator + bolt - perfect. From the - terminal wire end to the alternator housing - perfect. I did it while moving wires and such, Not sure there is anything else. I guess I'll see in a week or two.

[DMCMW Dave]

Alternators are pretty simple. One big fat output wire connection, ground (the case mounting to the engine) and one idiot light wire. The thing that can mess you up is that the early Ducillier alternators had a second small wire for voltage reference. If you were to hook that wire where the idiot light wire goes, it should not hurt - but don't try.

The correct wire to connect to the small light wire on the alternator is the brown/yellow on the car harness. If there is a small solid brown wire, just tie that one back and don't connect it to anything.

Another thing that can ruin an alternator is trying to pull too much load, i.e. running it into an internally shorted / dead battery or two. This would be similar to shorting the output. It's pretty important that you not run the alternator into a completely dead battery. Ideally you will charge the battery with a battery charger before installing and connecting a new alternator.

For this reason, when you jump start a car it's a good idea to connect the cables and wait a few minutes before you start the car and remove the cables. Give the "donor" battery some time to bring the dead one up a bit.

[Bitsyncmaster]

I even charge a new battery before I install it. They typically are down about 25%.

[Ron]

^^ +1 Dave M


I am concerned that the new one will have the same thing happen. However, before I started the car the last time I checked the voltage at the alternator - same as the battery. Disconnected the battery and checked continuity from the + terminal wire end to the alternator + bolt - perfect. From the - terminal wire end to the alternator housing - perfect. I did it while moving wires and such, Not sure there is anything else. I guess I'll see in a week or two.I'd bet you are good to go...The ohm meter can not tell you how much amperage can go through the circuit. ie a 14 gauge wire to the alternator would read "perfect"(just like a flag that bad been hot might or a loose battery terminal bolt might), as would an 00 silver cable connected perfectly. The flag could have been heating up a loosing connection, zapping the alt/reg. Also, not only does the power have to reach the vehicle loads, it has to get to the battery (actually just another load, while it is being charged...)

I guess ya can now see how connecting the jumper cables would have pointed to the battery or the connections at it -- It would have always read well above 12 V...unless it lost connection totally, which can toast the alternator/regulator. And if it were the connection at he trailing arm it would have low, at least while the problem raised its ugly head ;-)

FWIW- if it does it again, that GM (Delco) should have the "D" shaped hole in the back as I mentioned above. Grounding the tab bypasses the regulator and wiring problems involving the 3rd wire (brown/yellow Dave mentioned) temporarily while testing.

BTW- Good Job :thumbup:

[Ricker]

It has a warranty. Contact the selling dealer (it may be me, but since I have no idea what your real name is I can't tell) and get another one.

I called - no nothing on electrical parts.

[krs09]

I called - no nothing on electrical parts.

Wow, Should really be covered if purchased within a year. Most have the warranty coverage time on the battery (in months) ie: 10/14/18 months

[Ricker]

Well it looks like I made this problem harder than what it was. Dave M. was right in the beginning. I got a new second alternator from Delorean Auto Parts, Inc. and installed it late yesterday. Voltage is now almost 14 volts. I just did not want to believe that the first new alternator from DMC was bad even after checking the battery light, battery and wires.

Well I'm glad that issue is over but there are a few more. Thanks for all the information and someday I hope I can be so helpful to the group.