Generator/Alternator issues?

[agaisin]

If my battery and generator were in top shape, what would my voltage reading be at the battery when idling and up to 2k RPMs?

I just replaced my battery, have 110k mi on my '05, and I'm only getting 13.3-13.6 tops (mostly it was 13.3 when idling and 13.5 when gassing and getting to 2k rpm). I'm using Service Diagnostic mode (Display -> then in window, tap top left bottom left 3 times and go to Display Check and you'll see battery voltage).

If I understand correctly, according to the FSM 13.2-14.8 is within spec. Most generic alternator testing sites say 14.5 is typical. If others here confirm that >14 are typical readings then is my generator in need of replacement or rebuilding?

Also, I feel like I get a few more clicks b/f starting than I'm used to - Does that sound like the typical starter contact problem? I believe starter contacts would be a completely separate problem though - i.e. starter contacts effect starting, but generator is a charging system issue. So bad starter contacts shouldn't effect my voltage when running. Although bad genarator might mean my battery gets drained and can't start on a cold morning, right?

Background: The other day (cold night) my car wouldn't start and it seemed clear to me that it was the battery since lights were getting dimmer and the more I tried the dimmer the lights got. Also, I'm at 110k and the battery says 84 month warranty and I'm at month 84...

So I replace the battery. But a part of me asks the logical quesiton - should I check the generator to make sure it's working properly etc.

Any suggestions?

 

[trackmur]

A quality multimeter checking the voltage right at the battery would be a good way to determine if there is an issue with your alternator.

This brings us to a chicken vs. egg conversation. Do weak older batteries cause greater arcing at the solenoid and wear the starter contacts rapidly, or do worn starter contacts facilitate deterioration of an otherwise fine older battery.

 

[agaisin]

A quality multimeter checking the voltage right at the battery would be a good way to determine if there is an issue with your alternator.

If I find the numbers are the same low numbers 13.3-13.5 instead of >14 would you agree it's my alternator?

I have a multimeter and I'll check it, but just curious is there any reason I shouldn't trust the service diagnostic mode's value?

Also - pretty sure I know the answer but figured I'd ask: What do I risk to leave it until it dies? Will it kill my new battery faster, and can it leave me stranded?

Thanks,
Art

 

[Gottagetone]

How long ago was the other day? If your alternator was bad your battery would not last long.

 

[agaisin]

A quality multimeter checking the voltage right at the battery would be a good way to determine if there is an issue with your alternator.

Trackmur - thanks for the suggestion to use an old school multimeter

Here's the deal:
1) Multimeter reading at battery terminals is not the same as Service Diagnostic mode's. Multimeter shows me a whopping 14.49 while the Service Diagnostic Mode's showed me 13.8.
2) While driving, the Service Diagnostic mode showed me 13.3 at idle. While parked, the Service Diagnostic mode shoed me 13.8 at idle. I imagine there's a reason for that but the point is that while parked and idling the number was higher even in the diagnostic mode.
3) My battery's static voltage was 12.94 b/f I started her up (from a couple hours rest).

So - if I understand correctly, my Alternator is fine!

Now, gotta look into the darned starter contacts job...

How long ago was the other day? If your alternator was bad your battery would not last long.

Replaced the battery on Saturday evening.

 

[trackmur]

I imagine the diagnostic system is taking a reading after some length of wiring harness exposure, as well as being exposed to the shared loads of other systems.

I used to be a generator operator on movie sets. If a plant had an alternator go bad, or a battery, we would change both components and meticulously check everything in between.

I think the 100 series alternator is good for 200 000 miles, more if the vehicle does big highway mileage. Mine is at 250K. I always have some load on: Headlamps all the time, HVAC. I have gone through a few batteries though, but it has always been a simple option to change the battery the moment it appeared weak.

Having said that, do a very careful check of the battery and chassis grounds, battery clamps, and so on, and maybe look up under the dash to see if you have any windsheild seal leaks or sunroof drain leaks. And if you have 200 000 miles on the rig and are doing some major work, consider having the local alternator guy rebuild yours, or call cruiser Dan and go with a new one.

I suppose if you have to do the starter contacts you could have an auto electric day and get it over with.

 

[APKhaos]

Great news on the alternator voltage check. Those numbers look good, and now that you have a new battery it should be smooth sailing.

Low battery state definitely contributes to starter contact wear. My last battery [replaced a week ago] was not holding a charge very well, and there were many occasions when I had to start with obviously low cranking voltage. Low voltage = higher than normal cranking current, and the contacts were badly pitted and welded in spots. I replaced the starter at the point where the contacts actually welded themselves together. As long as the battery was connected the starter would crank! Took a minute to figure out why this was happening.

Many here have replaced the starter contacts [both the static contacts and the actuating piston contact]. Its not hard to do. PM if you want to try it and could use an experienced hand.

 

[agaisin]

Update - car won't start this morning. Just get the clicking - like 1 a second click click click. Battery Voltage at the terminals is 12.06. Temps out were ~33F.

I'm thinking I'll try to jump it and if it starts then it's my alternator but if it still doesn't start then it's the starter (contacts)?

Any other advice?

 

[Gottagetone]

Sounds right.

 

[spressomon]

If I had to guess I'd say its your starter contacts. You might try, using a long wooden dowel or similar, knocking on the starter...sometimes it works sometimes not to get it to function (an old GM starter trick).

Additional voltage via a jump start may get the starter excited too...

 

[APKhaos]

Update - car won't start this morning. Just get the clicking - like 1 a second click click click. Battery Voltage at the terminals is 12.06. Temps out were ~33F.

I'm thinking I'll try to jump it and if it starts then it's my alternator but if it still doesn't start then it's the starter (contacts)?

Any other advice?

You installed a new battery around 10 day ago, right? If so, then the battery terminal voltage is on the low side but should still be in cranking range unless it drops dramatically when you turn the key to crank.

The 'click....click....click' description sounds like a dead battery, which you can confirm by checking the terminal voltage with the key turned to crank. The typical starter contact symptom is one solid click then nothing when the key is turned to crank [because the contacts aren't energizing the starter motor].

You were reading around 13.5V at the battery when running, which is within reasonable range for the alternator. Something north of 14V would be better, but 13.5 is enough to fully charge the battery.

First step in diagnosis would be to fully change the battery, then check the voltage at the battery terminals in 'key off', 'cranking' and 'charging 2000RPM' states.

 

[agaisin]

You installed a new battery around 10 day ago, right?

Correct.

The 'click....click....click' description sounds like a dead battery, which you can confirm by checking the terminal voltage with the key turned to crank. The typical starter contact symptom is one solid click then nothing when the key is turned to crank [because the contacts aren't energizing the starter motor].

I misspoke. I just went outside to confirm that I just got the single click per key turn. I got multiple clicks b/c I kept turning the key again and each manual turn of the key gave me a click.
(In my head I was thinking about the cranking hold feature our trucks have that tries to continue cranking for up to 25 seconds automatically).

You were reading around 13.5V at the battery when running, which is within reasonable range for the alternator. Something north of 14V would be better, but 13.5 is enough to fully charge the battery.

Actually I got 14.49 at the battery terminals when idling (it was in Service Diagnostic Mode that it showed me only 13.8 while parked and 13.3-13.5 while driving). All that was within a day or two of having the new battery though.

First step in diagnosis would be to fully change the battery, then check the voltage at the battery terminals in 'key off', 'cranking' and 'charging 2000RPM' states.

Would you recommend using Battery Tender type product for fully charging? Will have to look at this later either way.
So what voltage numbers do I look for in the key off, cranking, and 2k RPM?
If I am able to start after recharging though, it would either be an alternator issue not recharging (enough) or a wiring issue causing my battery to discharge when parked right?

Didn't see any posts on the board about rebuilding our alternators but they look rebuildable (from what I can tell) - replace the brush and ideally the two bearings and good as new?

Thanks!
Art

 

[APKhaos]

I misspoke. I just went outside to confirm that I just got the single click per key turn. I got multiple clicks b/c I kept turning the key again and each manual turn of the key gave me a click.

That's classic starter contact behavior. I suspect your battery and alternator may be fine, but those starter contacts are on the downhill side of DONE!. You might get lucky just cycling the key. Mine would eventually crank after mayeb 20 or so tries. Until it failed completely.

Would you recommend using Battery Tender type product for fully charging? Will have to look at this later either way.

Cetek chargers are pretty hard to beat. Dead nuts reliable and very smart about preserving your battery's internals.

At this point, there's a good chance that both your battery and your alternator are in good shape. Those charging numbers are good.

 

[agaisin]

So after numerous start attempts earlier today my battery Voltage dropped low to ~9.6V iirc. To recap - it wouldn't start after multiple attempts, I checked the Voltage and it was 12.06, kept trying, slammed hood (suggestion from other starter problem threads), and checked again and it was ~9.6.

I bought a charger/starter/tester deal and decided to fully charge the battery. 6 hours later I was finally fully charged. Put it in and she started up (a little hesitation after turning over but she kept goin). Didn't have second hand so I couldn't read the voltage when cranking and when at 2k RPM so I'll have to do that later.


>>>-----------------------------QUESTIONS-----------------------------<<<
1) If it's just my starter contacts, is it normal for my battery to get so low on voltage after multiple failed attempts at starting?
2) Why wouldn't it start with ~12.06V (given that after a full charge ~14.7 it started fine - I'm assuming that even ~12V should be enough to start up our rigs)?
3) Given everything I've described does it still sound like starter rather than alternator?
4) Are the autozone/advanceauto alternator tests worthwhile?
5) What values am I looking for when cranking or at 2k RPM to determine if the alternator is doing it's job - am I looking for specific Voltage or Amperage?
6) Can I test the V and A off the batter terminals? The FSM Diagnostics have you checking the charging circuit off the alternator when running - wonder if that's the only right way to do it.
>>>------------------------------------------------------------------------<<<


Side note, I have a DH Plat Group 35 and bought the Diehard Plat 71227 Charger earlier today. I had read about Battery Tender like products and was under the impression that my AGM batter would need a slow charger (Battery Tender Plus is the BT product that's compatible with AGM and it is 1.25 Ah which is less/slower than Battery Tender). And reading confirmed that AGM should use slower charging. Well, I was surprised to read explicitly in the Diehard Plat Charger instructions that they have a special battery type setting for Diehard Platinum batteries and that the recommended amp charger setting for Diehard Platinum batteries is 40A (other settings were 2A and 15A). It was so explicit in the instructions that I decided to follow them despite being surprised since based on everything I had read 1.25 or 2A was the charge setting I expected. Anyhow, I used 40A setting and it got to green 6 hours later. Can anyone explain why 40A is right for Diehard Platinum when everything else I read says 2A or slower/lower for charging AGM?

Anyhow, at this point I still don't know whether it's the Alternator or the starter but I'm thankful that I have another car so I'm not stranded. I have starter contacts and alternator brush on order with beno so I guess I'll be getting busy as soon as it comes in.

 

[Sandroad]

I just measured 12.51 V at the battery of my ’04, even after it’s been sitting for a week in winter temps. Right now I have a 4 year old Toyota TrueStart battery. Here’s a chart of charge vs. volts when the battery is at rest (no load or charging). Repeatedly going down to full discharge will damage a lead-acid battery.


State of Charge 12 Volt battery (77F)

100%12.7
90% 12.5
80% 12.42
70% 12.32
60% 12.20
50% 12.06
40% 11.9
30% 11.75
20% 11.58
10% 11.31
0 10.5

AGM batteries do not require any special charging system or circuitry. The only consideration is to not overcharge them, since they are sealed and can’t vent. Simple, cheap chargers may say to not use a rate over a couple of amps so that over-charging doesn’t damage a battery. Quality chargers/intelligent chargers can use very high currents with AGM batteries, though most chargers top out at less than 40 amps.

 

[BamaHeel]

Don't know if his holds true on newer cars but having wrenched on pre 70's cars if you get a car cranked and disconnect the positive cable from the battery while running and the car continues to run the alternator is fine if it cuts out the alternator is shot. I know his doesn't help your current situation but maybe someone else.

 

[agaisin]

Don't know if his holds true on newer cars but having wrenched on pre 70's cars if you get a car cranked and disconnect the positive cable from the battery while running and the car continues to run the alternator is fine if it cuts out the alternator is shot. I know his doesn't help your current situation but maybe someone else.

i had seen that a few places but the section of fsm for charger starts off with a few warnings and one of them is not to disconnect the battery while the vehicle is running - i chuckled when i saw that and assumed it was bc of the old school approach to diagnose alternator issues. can't say why it's bad for the vehicle but i assume that's the reason for the warning.

 

[APKhaos]

Don't know if his holds true on newer cars but having wrenched on pre 70's cars if you get a car cranked and disconnect the positive cable from the battery while running and the car continues to run the alternator is fine if it cuts out the alternator is shot. I know his doesn't help your current situation but maybe someone else.

Even current models will run with the battery disconnected. Race cars need a kill switch to cut all power after an incident. Most kill switches disconnect the battery AND ground the alternator to actually stop the engine.

That said, its bad juju for ECU-equipped cars. Pulling the battery creates nasty arcs which can kill ECUs in a heartbeat.

 

[agaisin]

You installed a new battery around 10 day ago, right? If so, then the battery terminal voltage is on the low side but should still be in cranking range unless it drops dramatically when you turn the key to crank.

The 'click....click....click' description sounds like a dead battery, which you can confirm by checking the terminal voltage with the key turned to crank. The typical starter contact symptom is one solid click then nothing when the key is turned to crank [because the contacts aren't energizing the starter motor].

You were reading around 13.5V at the battery when running, which is within reasonable range for the alternator. Something north of 14V would be better, but 13.5 is enough to fully charge the battery.

First step in diagnosis would be to fully change the battery, then check the voltage at the battery terminals in 'key off', 'cranking' and 'charging 2000RPM' states.

OK - To recap, I fully charged my battery yesterday, car's been sitting since, temp tonight is 60 and didn't warm up the car.

Here are the numbers I got at battery terminals under the following conditions:
car off: 13.78V
cranking: 15.4V
2K RPMs: 15.44V
I also put a bit of load on with headlights, heat on high, radio and got 15.22V

Not sure how to interpret that... Would seem that my alternator is doing it's job, right?

So - why did I end up with a dead battery?
1) Starter contacts failing - would this drain the battery with each failed attempt (remember it went down to 9.6V after multiple failed attempts).
2) Do I have a slow drain on the battery? How would I diagnose this - any pointers?
3) Shot in the dark, don't know if this makes sense but isn't > 15V too high? If my alternator's regulator is bad (?) and it's overcharging my battery could that cause an issue (i.e. could overcharging while driving cause the battery to die after sitting for a week)?

I will point out - my LX driving habits have changed over the past 2 months. I had been daily driving my LX since ownership (~2 yrs ago). Due to major change in commute I got a commuter car 1.5 months ago and am now only driving LX on weekends...

Thanks in advance!
Art

 

[spressomon]

If you have an AGM type battery generally anything north of charging with 14.5V or more can be trouble.

Also: Due to parasitic draw I try to always connect my Battery Tender to both batteries (Odyssey) if its going to sit for more than about 3-days; works great. Repeatedly deep cycling/running the batteries down is detrimental to the life of the battery. Ditto for too much voltage.

After the vehicle has sat with with the key out of the ignition (headlights, off, etc.) disconnect the + battery cable at the battery and connect a multimeter, set to 10A DC, in between the + battery post and the disconnect + battery cable (take care not to short anything by touching any portion of the + wires to ground). What ever reading you get is your parasitic draw. I'm not sure what the normal amount is for your LC...but I would think anything more than .1A is not normal and would require the battery to be kept on a suitable charger when not being driven for a number of days.

Although I'm far from a battery expert your repeated 9.6V battery condition would be cause for alarm.