2007 Chev charging intermittents

[roadbiker1]

Dash voltmeter, idiot light, audio alarm, and aftermarket DVM all indicate intermittent no charge and then decaying system voltage at times, then recovery to normal for no obvious reason. Stock system save a master battery
disconnect. Anything to try? Would the OBD show anything useful?

If I flat the truck battery, can I jumper the house batteries up to the truck's at the charge separator safely?
Thanks for any tips ;- )

j

 

[booster]

Dash voltmeter, idiot light, audio alarm, and aftermarket DVM all indicate intermittent no charge and then decaying system voltage at times, then recovery to normal for no obvious reason. Stock system save a master battery
disconnect. Anything to try? Would the OBD show anything useful?

If I flat the truck battery, can I jumper the house batteries up to the truck's at the charge separator safely?
Thanks for any tips ;- )

j

If you are talking about the engine and chassis power running the engine, it sounds like you might have bad connection at the positive or negative cables. They can get hot and shut open up and then cool off and work for a while sometimes. Other thinks like an overheating alternator also happen that way. Also look to make sure nobody has an auto reset circuit breaker in the system for the starting battery as a failing breaker would do the that. Loose or corroded connection in either the positive or negative wiring is most likely, or a loose plug or failing alternator next, I think.

 

[roadbiker1]

If you are talking about the engine and chassis power running the engine, it sounds like you might have bad connection at the positive or negative cables. They can get hot and shut open up and then cool off and work for a while sometimes. Other thinks like an overheating alternator also happen that way. Also look to make sure nobody has an auto reset circuit breaker in the system for the starting battery as a failing breaker would do the that. Loose or corroded connection in either the positive or negative wiring is most likely, or a loose plug or failing alternator next, I think.

Yes talking about the van side of things here. Did replace the battery, had no problems on 3 starts / stops, was hopeful but cautious about declaring victory. Then the NO CHARGE syndrome came back. Have wiggled the big wiring I can get to, and checked seating of the
plug into the alternator, but I'm sure much remains hidden.
Still wondering about the charge iso / sepo... the little red box with destroyed labels;- )
Is it solid state inside? A big fat relay? And if / when the van batt goes flat, can I safely jumper some current back thru the iso / sepo POS - oh ? This in the 2008 RT / 2007 chaissis. Cheers, and Thanks!

 

[booster]

Yes talking about the van side of things here. Did replace the battery, had no problems on 3 starts / stops, was hopeful but cautious about declaring victory. Then the NO CHARGE syndrome came back. Have wiggled the big wiring I can get to, and checked seating of the
plug into the alternator, but I'm sure much remains hidden.
Still wondering about the charge iso / sepo... the little red box with destroyed labels;- )
Is it solid state inside? A big fat relay? And if / when the van batt goes flat, can I safely jumper some current back thru the iso / sepo POS - oh ? This in the 2008 RT / 2007 chaissis. Cheers, and Thanks!

If it is an isolator that box certainly could do that type of thing. A separator shouldn't be able to.

If it has just two big cables on it, one from the alternator and one to the coach batteries it is a separator and some electronics plus a relay coil.

If it has multiple cables to it you have an isolator and that is made up of big diodes to steer charge to starting and coach batteries. It may also have a small trigger wire to it.

Do you have a picture?

 

[Paga]

Checking for Alternator Output Voltage

I happen to be in Portland currently, I see you are in Oregon.

Is the alternator voltage output, measured with a voltmeter at the battery between the post clamps (not the posts themselves) between say 13.4 to 14.5 Volts DC or so, when the engine is running?

If so, then turn on loads like head lights, dash AC & fan and read it again. It should be regulating and maintaining between the same voltages. Measure this with a Voltmeter (Multimeter). You can then also put a clamp DC Ammeter on the lead from the alternator to read the current it is delivering, if you have that instrument. But a simple voltage reading of your power source is always the most important first step. The Voltmeter is your best friend in this.

Then repeat this test between the actual battery posts to verify the battery is seeing the alternator voltage as well, that the clamps are working.

Any troubleshooting has to start with taking that first reading above. If it is below 13 Volts DC while running, like 12.5, then something is wrong with the alternator or the wiring between it and the battery terminal clamps. No point looking beyond the alternator and it's wiring to the battery clamps if it isn't actually working reliably and making power (which is DC Volts and the associated current measured in Amperes, depending on the actual load it sees).

As a caveat to the above statement, some battery isolator systems may be wired in to adjust the output voltage of the alternator to compensate for the 0.7 Volt drop across an isolation diode. I don't think this is too commonly installed but if so could affect reliability if there was a wiring issue.

But back to a suspected alternator with intermittent output:
A next check then is be sure the belt driving the alternator is tight enough, that the belt isn't slipping, which can also be heard as squealing sometimes. This problem is much less likely now that serpentine belts are commonly used, so this may be unlikely.

A classic failure issue with alternators with some miles on them is the two small spring loaded carbon brushes which are mounted inside it. They run on the normally smooth spinning rotor copper slip rings. This combination delivers the field current to the spinning rotor coil to excite the alternator stator (fixed) coil output windings. These are true 3 phase AC alternator windings with diode rectifiers to produce the DC voltage the truck requires to run and also recharge any connected batteries.

As these spring loaded carbon brushes wear over time they can begin to become intermittent, or even hang up in their holders and stop self adjusting to maintain contact with the slip rings, which means the ability to produce voltage and thus current output to run the truck and charge batteries fails.

The intermittent output will eventually become no output (ZERO) at all, once the brushes wear to the point of zero contact. But while they are intermittent they can begin to arc and thus pit and burn one or both slip rings. The ring(s) can often be restored, but the key here is to replace your brushes as a maintenance item before one finds the truck has no power source to charge the battery or even run, in the middle of nowhere, with the family onboard.....

One can replace these brushes fairly easily, they are inexpensive. Many alternators with mileage are replaced just for want of a $12 or so brush set. While this may not be your specific problem, it is something all RV owners need to know and be ready to address or check when an alternator is acting up or is removed for some reason. Check the brushes. There are ways to inspect them.

Your Voltmeter / Multimeter is your best friend, one should always carry one and know how to use it.

 

[Paga]

Jay, I also just noticed you have a 2008 Roadtrek 210 Popular, which matches what have at home in Texas.
Pete

 

[Paga]

Jay, In thinking about my 2008 210 Popular, the original isolator which is still in use on ours has the Alternator positive output going to one of the 5/16 studs on it directly. You can read from that post to the battery negative clamp wile running to see the alternator output voltage directly, altho there may be a circuit breaker in that lead as Booster suggested. Those can be an issue. I don't have my schematic here to refer to about the specific wiring of that isolator. But the point is you can measure the alternator voltage there as well to determine that it actually is working.

Now I understand you may have a dead or low starting battery, can you get a 120 VAC battery charger on it to keep it charged to get it started for these tests? On these 210's the TrippLite charger for the house batteries doesn't charge the stating battery as you know.

I have jumped the house battery stud and engine battery stud together on the original isolator on mine in the past temporarily. when desperate to get the engine battery charged, but DO NOT try to start the engine with this jumpering, the wiring will not carry the starter current. Only use it to recharge the engine battery. Take the jumper off before starting........

I now keep a smaller maintainer on the engine battery all the time when parked. putting separate charger on that battery now is the safest way to charge it.

If you are near Portland and want some help let me know, I'm in town for awhile, this being May 30th.

Pete

 

[roadbiker1]

If it is an isolator that box certainly could do that type of thing. A separator shouldn't be able to.

If it has just two big cables on it, one from the alternator and one to the coach batteries it is a separator and some electronics plus a relay coil.

If it has multiple cables to it you have an isolator and that is made up of big diodes to steer charge to starting and coach batteries. It may also have a small trigger wire to it.

Do you have a picture?

I had a short trip imminent, went for the spend, had a local shop put in a new alt for $776.
Did about 300 miles, no non charge events BUT system NOW throwing OBD codes where
it had not been before the new alt. Codes mostly related to the MAF, and the downstream
O2 sensors. Have another trip starting Monday, threw more bux for a new MAF installed
today, drove home with fewer $ but NO codes ( so far ).

the iso / separator pix should / may be below:

thanks for any thots on this thing ;- )

j

 

[booster]

I had a short trip imminent, went for the spend, had a local shop put in a new alt for $776.
Did about 300 miles, no non charge events BUT system NOW throwing OBD codes where
it had not been before the new alt. Codes mostly related to the MAF, and the downstream
O2 sensors. Have another trip starting Monday, threw more bux for a new MAF installed
today, drove home with fewer $ but NO codes ( so far ).

the iso / separator pix should / may be below:

thanks for any thots on this thing ;- )

j

The MAF sensor is on the air cleaner and might have been unplugged and air cleaner removed to get to the alternator. They have an odd plug on them with a locking cover that can be hard to unplug and get plugged back in right. It may have just been loose or not quite plugged in, but too late to tell now.
The good is that it is all working like it should now.
That is an isolator and the two things screwed to the top are circuit breakers, so good place to start to look at issues if there are any.
Personally, I would replace it with one of the automatic charge relays as they get rid of the voltage drop issues.

 

[roadbiker1]

The MAF sensor is on the air cleaner and might have been unplugged and air cleaner removed to get to the alternator. They have an odd plug on them with a locking cover that can be hard to unplug and get plugged back in right. It may have just been loose or not quite plugged in, but too late to tell now.
The good is that it is all working like it should now.
That is an isolator and the two things screwed to the top are circuit breakers, so good place to start to look at issues if there are any.
Personally, I would replace it with one of the automatic charge relays as they get rid of the voltage drop issues.

Sorry about the format of my red mystery box... it was in Apple's HEIC, next one should be in
gud ol jpg ;- )

just moved the rig to plug in the refridge to shore power, noted right off that I was in the no charge
situation again. Shut off rig. Restarted, and was now charging. I remain confused... I assume the van's alt feeds directly ( but as you suggested, maybe thru a breaker? ) to the van's system, regardless of what the iso / sepo. thing is up to, and when I see the no charge, it is on both the van's panel and my little cig plug DVM.
this is with a new alt, so my previous alt's internal regulator field drive fail theory is probs out the window.

anyway, on the road tomorrow for another trip ( bikes in the Klamath wildlife refuge! ), will carry a spare battery ;- )

Again, thanks for your help ;- )

 

[roadbiker1]

Jay, In thinking about my 2008 210 Popular, the original isolator which is still in use on ours has the Alternator positive output going to one of the 5/16 studs on it directly. You can read from that post to the battery negative clamp wile running to see the alternator output voltage directly, altho there may be a circuit breaker in that lead as Booster suggested. Those can be an issue. I don't have my schematic here to refer to about the specific wiring of that isolator. But the point is you can measure the alternator voltage there as well to determine that it actually is working.

Now I understand you may have a dead or low starting battery, can you get a 120 VAC battery charger on it to keep it charged to get it started for these tests? On these 210's the TrippLite charger for the house batteries doesn't charge the stating battery as you know.

I have jumped the house battery stud and engine battery stud together on the original isolator on mine in the past temporarily. when desperate to get the engine battery charged, but DO NOT try to start the engine with this jumpering, the wiring will not carry the starter current. Only use it to recharge the engine battery. Take the jumper off before starting........

I now keep a smaller maintainer on the engine battery all the time when parked. putting separate charger on that battery now is the safest way to charge it.

If you are near Portland and want some help let me know, I'm in town for awhile, this being May 30th.

Pete

 

[roadbiker1]

thanks Pete... I'm in S Oregon, headed out tomorrow for the Tule Lake Refuge for bikes, birds, and beer party ;- ). I threw money at my probs... new alt, new MAF, new credit card alerts, thot I was ok, but just this am, had the no charge syndrome.. shut off engine, restarted and voltage was fine.
I'll try your measuring right on the isolator next time, so may not be very long ;- )

Cheers from Ashland! j

 

[roadbiker1]

now wondering about the diodes in the red box... do you think they are SCR ( as in silicon controller rectifiers ) ? And the whole thing is solid state with no moving parts / relays inside?
Something like a truck system voltage has to exceed a threshold before the box will feed system
current to the house batts? And then prevent back feed from the house to the truck when
the truck's system's voltage is below the house batteries?
YayHoo! How fun is this, unless you're on the road in the dark, and the rain, and the
mosquitoes ?

 

[roadbiker1]

I had a short trip imminent, went for the spend, had a local shop put in a new alt for $776.
Did about 300 miles, no non charge events BUT system NOW throwing OBD codes where
it had not been before the new alt. Codes mostly related to the MAF, and the downstream
O2 sensors. Have another trip starting Monday, threw more bux for a new MAF installed
today, drove home with fewer $ but NO codes ( so far ).

the iso / separator pix should / may be below:

thanks for any thots on this thing ;- )

j

Hiya, pt many... are you saying the iso box steers alt current to both the truck AND the house batteries, depending on reasons? I would have thot the truck would get its very own dedicated
feed, skipping the red box entirely ...

 

[Paga]

Hello Jay,

Here is the schematic for the 2008 210P if that is indeed what you have. Hopefully you can read this and know schematics, see the Isolator in the drawing. In the isolator are two silicon power diodes the anode of each are connected to the large center stud (terminal A on the drawing) which comes directly from the alternator positive output, with no circuit breaker or fuse.

See pdf drawing file attached......

In your photo, as on this drawing, the left large stud (terminal 1 on the dwg, and "Rig" on yours, goes to the engine battery directly. No circuit breaker or fuse. The power diodes aren't SCR's, and will only connect via the anode --->I--- to the engine battery, but not allow any reverse current if the alternator is not running.

By the same token, the other diode is allowing the alternator to also charge the house batteries as it is connected to the large right stud (terminal 2 on dwg) but in that case there are two 50 Amp auto reset circuit breakers in the line to the house batteries. The voltage drop across these diodes may be 0 .7 Volts

So if you read the alternator voltage when the engine is running you should get around 14.5 Volts or more, on the center stud A, with your negative lead on the negative battery post. If you then move your red lead to the left terminal 1 Rig stud it should also read above 14 Volts with the engine running.

And you should see that voltage at the engine battery positive post as well. If you lose the charging voltage at any of these points then the battery will not be charging.

Here is an interactive demonstrator that will show you the charging paths for alternator, generator or shore power charging on your RV:

http://www.metrotrekkers.org/utility/electrical.htm

Click on the appropriate ON /OFF buttons to see the charging paths for engine alternator, Onan generator or Shore power sources.

If you are losing the charging voltage we'll have to go to the next step. Let's see what you get for readings. Do you have a 120 VAC battery charger with you on this trip, a portable one? If you have ground power or running the genset have it charging your engine battery until this is resolved.

Note that the Tripplite battery charger for the house batteries does not charge the engine battery, which is a serious design flaw in the system, and why Booster suggested a two way relay type isolator. It seems you need to take some voltage readings while you are on this trip. I have to address that on mine, but I'm preparing to change to LIFePo4 house batteries and so charging them with the alternator isn't so simple....

I sent you a message.
Pete

 

[Paga]

Jay,

I was able to locate the notes I have on your isolator, and the smaller terminal between the center and left studs (terminal E on dwg) should have 12 Volts on it when the ignition is turned on. If not there is a chance the alternator will not receive the 12 Volts it requires just to begin charging, the initial excitation voltage. Check for 12 Volts on that smaller stud when the ignition switch is ON during your tests.

I have attached the write up about the issue where engine battery charging was lost due to this lack of the 12 Volt excitation to terminal E.
Pete

 

[booster]

Personally, I would not disconnect any cables to check voltages from the alternator with engine running until it is confirmed where the alternator is getting it's voltage reference. It probably is running on the internal regulator in the alternator for a 2007 and AFAIK that was the the last year that used the internal regulator to control voltage. After that it moved to the PCM computer so the alternator would have a sense and activation wire from the PCM. Again IIRC the 2007 can be a bit deceptive in what you are looking at because it has an activation wire to the alternator from the PCM and a "field percent" feedback loop to the PCM that appears to be used to adjust idle speed and other engine running parameters. If you accidentally lose the reference voltage or battery connection to alternator bad things can happen if the engine is run.

A number of years ago there were a lot of stories about particularly truck camper folks moving the sense wire to the coach side of the isolator on vehicles that have the separate sense wire and many of them overvoltaged their engine controls in cold starts in cold weather when the voltage gets turned up initially the most.

The .7v drop of the diodes really messes up the charging of the batteries because the voltage is too low. Slow and incomplete charging is common. A relay temp separator/charge controller has essentially no voltage drop and does a better job of charging batteries, with the exception of lithium which need to be run on a battery to battery charger or at least with current limiting of some way. We run our lithium on a 2nd alternator with current limiting remote alternator running the alternator for better control of voltage and current.

If I were the OP, I would ditch the isolator and put in a charge relay, but at that point the 6ga wire to coach should be upsized to at least 4ga with 80 amp breakers to take advantage of the higher voltage without tripping the 50 amp breakers all the time if there is enough battery bank to absorb it all.

When Roadtrek went from using wet cells to AGM batteries, we heard lots of stories about irritating clicking and lack of charging continuously because the AGM accept more current and were tripping the breakers, even 80 ones if they had two batteries in the van.

 

[Johnnyfry]

I had a short trip imminent, went for the spend, had a local shop put in a new alt for $776.
Did about 300 miles, no non charge events BUT system NOW throwing OBD codes where
it had not been before the new alt. Codes mostly related to the MAF, and the downstream
O2 sensors. Have another trip starting Monday, threw more bux for a new MAF installed
today, drove home with fewer $ but NO codes ( so far ).

the iso / separator pix should / may be below:

thanks for any thots on this thing ;- )

j

Looking at the photo, the center terminal on the isolator is the Alternator, the left terminal goes to the chassis battery (Incorrectly labeled "rig") and the right terminal which goes through tthe self resetting circuit breaker goes to the coach battery. The other creaker goes to the small 4th terminal and is alternator excitation. If the isolator is bad you can do a temporary fix (or test) by moving all 3 fat wires to the center terminal, effectively bypassing the isolator. If it operates correctly and both batteries start charging, you have diagnosed the problem. You can leave it in this configuration until you get a replacement, with one caveat, When you are using the coach battery both batteries will discharge in tandem, so you don't want to have a no start condition in the morning!

 

[booster]

Looking at the photo, the center terminal on the isolator is the Alternator, the left terminal goes to the chassis battery (Incorrectly labeled "rig") and the right terminal which goes through tthe self resetting circuit breaker goes to the coach battery. The other creaker goes to the small 4th terminal and is alternator excitation. If the isolator is bad you can do a temporary fix (or test) by moving all 3 fat wires to the center terminal, effectively bypassing the isolator. If it operates correctly and both batteries start charging, you have diagnosed the problem. You can leave it in this configuration until you get a replacement, with one caveat, When you are using the coach battery both batteries will discharge in tandem, so you don't want to have a no start condition in the morning!

That is the standard test for an isolator, but with the excitation wire, with breaker here, you have to get that also moved to the right place, which is probably to the alternator or it may not work. I have heard several times of people that switched to a charge relay and then the alternator quit working because of the excitation going to isolator they used to have didn't get moved.

 

[roadbiker1]

Jay,

I was able to locate the notes I have on your isolator, and the smaller terminal between the center and left studs (terminal E on dwg) should have 12 Volts on it when the ignition is turned on. If not there is a chance the alternator will not receive the 12 Volts it requires just to begin charging, the initial excitation voltage. Check for 12 Volts on that smaller stud when the ignition switch is ON during your tests.

I have attached the write up about the issue where engine battery charging was lost due to this lack of the 12 Volt excitation to terminal E.
Pete

got back from second little trip, van did ok, maybe one start w/ no charge but immediate restart brought back charging.
I like yr idea of the field current getting whacked on occasion, probs by a relay. Have been trying today at home base to get it to NOT CHARGE, but it stubbornly will not. When it next does not charge, I'll jump on the E terminal as you suggested, and if it is 0 volts, I'll jumper it over to one of the batts... as you may note, I not only have them in my belfry, there is at least one in the isolator.

Cheers, and thanks! If this works, name yr beer ;- )

j