Chassis battery issue after power outages

[mahdi]

I have my coach at home with 50 amp power connected. Living in the PNW we have had two wind (and rain) storms where the power is cut for 14 to 16 hours respectively. The coach is not connected to the house generator due to limited capacity (KW).

When the power is back I go to check on the coach. Lines 1 would be drawing 20 amps, line 2 nothing. I check the batteries on the coach. Both times the house batteries were OK (above 12.5 v) the chassis batteries however are down at 10.5 and 10.1 v respectively. The Magnum shows bulk charging. After 12 hours batteries are charged and Magnum in trickle mode. Line 1 shows 6-8 amps.
Has anyone had a high draw like that from fully charged in such a short time. Freightliner support said take to FL dealer. That is 90 miles away. I would like to find an easier way than spending a whole day going there and possibly 2 days if they decide to keep it. There is a FL approved shop 15 miles away but they do not do warranty work. I just had my 30K miles service there.
I have a voltmeter.
Any suggestions would be appreciated.

[Skip426]

Pull the chassis batteries out of the coach and have them load tested , I'll bet the battery that shows 10.1 volts has a dead cell and is dragging the second chassis battery down.

[mahdi]

Thanks for the advice. The coach has been connected to 50 amp for a few days. The chassis battery read 9.5 v. I took the coach down, disconnected chassis batteries and isolated each one. Load test was negative. The batteries are good. Any ideas where to go next?

[cbennis]

Originally Posted by mahdi

I have my coach at home with 50 amp power connected. Living in the PNW we have had two wind (and rain) storms where the power is cut for 14 to 16 hours respectively. The coach is not connected to the house generator due to limited capacity (KW).

When the power is back I go to check on the coach. Lines 1 would be drawing 20 amps, line 2 nothing. I check the batteries on the coach. Both times the house batteries were OK (above 12.5 v) the chassis batteries however are down at 10.5 and 10.1 v respectively. The Magnum shows bulk charging. After 12 hours batteries are charged and Magnum in trickle mode. Line 1 shows 6-8 amps.
Has anyone had a high draw like that from fully charged in such a short time. Freightliner support said take to FL dealer. That is 90 miles away. I would like to find an easier way than spending a whole day going there and possibly 2 days if they decide to keep it. There is a FL approved shop 15 miles away but they do not do warranty work. I just had my 30K miles service there.
I have a voltmeter.
Any suggestions would be appreciated.

The charger will kick into bulk charge on mine even after a few hours of not having it plugged in. It doesn't stay there long, but it starts there with a high draw. Don't remember how much. The Magnum manual explains the charging process. The only thing that connects the chassis batteries to the house batteries is the BIM (or BIRD, whichever you have). If you can, disconnect the chassis batteries and put them on a manual charger. See if they will hold the charge.

Are you in WA.? Which direction from Seattle - N, S, E or W? FL will check the chassis charging system, find it good, and say it is a Newmar issue, as Newmar installs the BIM and all cabling.

[Dutch Star Don]

One of the things I did a few months ago, was to pull both chassis batteries, cut the labels on top and removed the battery caps. Both batteries were each at least a pint+ low on water. These are sealed maintenance free batteries and supposedly don't need servicing. I've never believed in such a thing.

On the DS, the batteries are just a few inches away from the DEF exhaust system, which heats that box/bay that contains the batteries and the PDM (Power Distribution Module). The PDM's are under a recall.

I believe that checking and filling those batteries will increase their life. I also added a layer of insulation to the back side of the battery/PDM box, trying to reduce heat in that area.

Lastly, even if the coach is parked at home, you can set the generator to Auto Start so it runs during power outages. It can be set to run at specific hours. We have a similar issue in the third world country of California, where we have power outages and no water.

[mahdi]

Thank you Cbennis for your information. This confirms what I have been seeing on my coach.

When I was getting ready to take the coach for the load test on the batteries, I noticed the chassis battery was at 9.5 volts. Once I got it started the alternator charged the batteries up the 13.5v. I then after my return disconnected the chassis batteries overnight. The charge remained at 12.6v the next morning.
I did call Newmar yesterday and went through the process of checking power on the two limbs of the transfer celluloid. At the time both limbs had good voltage. He suspected that the power transfer to charge the chassis battery would get stuck and not charge the chassis battery. I ordered a new celluloid which should be coming soon.

I am concerned about my ability to install that and would appreciate any suggestions.
I am 8 miles west of Seattle by ferry in Kitsap county. Are you in western WA?

[mahdi]

Originally Posted by Dutch Star Don

One of the things I did a few months ago, was to pull both chassis batteries, cut the labels on top and removed the battery caps. Both batteries were each at least a pint+ low on water. These are sealed maintenance free batteries and supposedly don't need servicing. I've never believed in such a thing.

On the DS, the batteries are just a few inches away from the DEF exhaust system, which heats that box/bay that contains the batteries and the PDM (Power Distribution Module). The PDM's are under a recall.

I believe that checking and filling those batteries will increase their life. I also added a layer of insulation to the back side of the battery/PDM box, trying to reduce heat in that area.

Lastly, even if the coach is parked at home, you can set the generator to Auto Start so it runs during power outages. It can be set to run at specific hours. We have a similar issue in the third world country of California, where we have power outages and no water.

Thank you DS Don. I agree the batteries are close to the heat source below. I have insulated the DEF compartment and partially the battery/PDM compartment. I have had my PDM recall done already. I noticed the battery issues after the recall but do not know if they are related. I have the generator set at 11.5v but according to FL it will work when the HOUSE batteries go down and not the chassis batteries. I am not sue about that statement.
I am wondering if I can disconnect the chassis batteries and put a charger on them without hurting anything else. Do you know?

[Persistent]

When the power is back I go to check on the coach. Lines 1 would be drawing 20 amps, line 2 nothing. I check the batteries on the coach. Both times the house batteries were OK (above 12.5 v) the chassis batteries however are down at 10.5 and 10.1 v respectively. The Magnum shows bulk charging. After 12 hours batteries are charged and Magnum in trickle mode. Line 1 shows 6-8 amps.
Has anyone had a high draw like that from fully charged in such a short time.

There may be nothing wrong with the system. The 20 amp for 120 volt L1 may be to power the battery charger plus other things. An electric water heater or other electric appliance may be consuming a considerable amount if it is just been turned "on".

The key is the battery bank voltages after 12 hours of charging. Voltages may be 13.2, 13.6, or 14.4. These voltages indicate batteries are fully charged or nearly fully charged and chargers are working.

Test batteries:

There could be nothing wrong with the chassis batteries. If the batteries start the engine easily when not connected to shore power for a while, that is a good sign.

However, chassis batteries may be weak. They should not discharge to 10.5 volts in 16 hours.

Measure terminal voltage while charger is "on" and connected to chassis batteries. Starting volts should be 13.2, 13.6, or 14.4 volts while on shore power.
Turn charger "off".
Allow chassis batteries to rest for 3 or more hours.
Voltage should settle on 12.7 volts and decrease slowly for weeks. Discharging in 16 hours is way too fast.

If discharging fast, do this:

Measure battery terminal voltage while charging.
Disconnect the positive terminal. (Positive first is necessary for Magnum inverter chargers.) Wrap the cable end to prevent accidental short circuits.
Let the batteries rest for 3 or 4 hours.
Measure battery terminal voltage again.
Ending voltage should be 12.7 volts or higher after resting.
If voltage stabilizes at 12.7, they may be still acceptable.
If voltage continues to drop over the next few hours, they are self-discharging. Replace them.

The alternative is there is a heavy draw on the chassis batteries or the battery capacity is defective. It could be mirror heaters, engine heaters, or other device that is not shut off when ignition is "off".

I wish you good luck and happy trails ahead.

[cbennis]

Originally Posted by mahdi

Thank you Cbennis for your information. This confirms what I have been seeing on my coach.

When I was getting ready to take the coach for the load test on the batteries, I noticed the chassis battery was at 9.5 volts. Once I got it started the alternator charged the batteries up the 13.5v. I then after my return disconnected the chassis batteries overnight. The charge remained at 12.6v the next morning.
I did call Newmar yesterday and went through the process of checking power on the two limbs of the transfer celluloid. At the time both limbs had good voltage. He suspected that the power transfer to charge the chassis battery would get stuck and not charge the chassis battery. I ordered a new celluloid which should be coming soon.

I am concerned about my ability to install that and would appreciate any suggestions.
I am 8 miles west of Seattle by ferry in Kitsap county. Are you in western WA?

We're practically neighbors, from looking at your profile.

celluloid - gotta love spell check.

[cbennis]

Originally Posted by Persistent

...
Test batteries:

There could be nothing wrong with the chassis batteries. If the batteries start the engine easily when not connected to shore power for a while, that is a good sign.

However, chassis batteries may be weak. They should not discharge to 10.5 volts in 16 hours.

Measure terminal voltage while charger is "on" and connected to chassis batteries. Starting volts should be 13.2, 13.6, or 14.4 volts while on shore power.
Turn charger "off".
Allow chassis batteries to rest for 3 or more hours.
Voltage should settle on 12.7 volts and decrease slowly for weeks. Discharging in 16 hours is way too fast.

If discharging fast, do this:

Measure battery terminal voltage while charging.
Disconnect the positive terminal. (Positive first is necessary for Magnum inverter chargers.) Wrap the cable end to prevent accidental short circuits.
Let the batteries rest for 3 or 4 hours.
Measure battery terminal voltage again.
Ending voltage should be 12.7 volts or higher after resting.
If voltage stabilizes at 12.7, they may be still acceptable.
If voltage continues to drop over the next few hours, they are self-discharging. Replace them.

Another quick test is after charging the batteries, turn the key on - no need to crank the engine - while monitoring the battery voltage. You should see a drop in voltage to something like 12.5 - 12.3 (guessing, depends where it started). If it goes below 12, the battery(s) is bad. 12.1 - 12.2 probably is not good either, depending on the voltage before turning the key. If bad, when you try to crank the engine, the voltage will really drop to the 9 - 10 range.


Caveat - at least this is what I have seen in autos, but I don't see why it wouldn't be true in this case also.



Caveat#2 - this won't tell you if the batteries are good, it will only tell you if they are bad, or 'at least not real bad'. If the latter, more testing is needed as Persistent posted.

[mahdi]

This morning the chassis voltage had come down to 10.25. I went over to the charging bridge and gave it a couple of hit with my finger. I heard it click. I came back 2 hours later and the voltage on the chassis batteries was up to 13.5v. To me this made the diagnosis of a malfunctioning bridge.
I have one question about how long the charging will go on and whether the bridge BIM will flip back to not charging the chassis again. If so, I would connect a battery charger until the Newmar part arrives.
Any body know

[cbennis]

Originally Posted by mahdi

This morning the chassis voltage had come down to 10.25. I went over to the charging bridge and gave it a couple of hit with my finger. I heard it click. I came back 2 hours later and the voltage on the chassis batteries was up to 13.5v. To me this made the diagnosis of a malfunctioning bridge.
I have one question about how long the charging will go on and whether the bridge BIM will flip back to not charging the chassis again. If so, I would connect a battery charger until the Newmar part arrives.
Any body know

Not 100% sure about this, but the BIM will disconnect after about an hour. This is to prevent overcharging the batteries. It will then reconnect when a certain voltage threshold is reached. This is what I remember from the manufacture's literature for the one in my coach. Check out the Precision Circuits Web site. You can also call technical support for help.

[mahdi]

Originally Posted by cbennis

Not 100% sure about this, but the BIM will disconnect after about an hour. This is to prevent overcharging the batteries. It will then reconnect when a certain voltage threshold is reached. This is what I remember from the manufacture's literature for the one in my coach. Check out the Precision Circuits Web site. You can also call technical support for help.

Thanks cbennis for you response. 2 hours after the BIM clicked (connected?) the batteries were both 13.5v. Next morning (today) chassis was back down to 10.25v while house battery was still above 12.5v. So I connected the battery charges to the chassis and is hold well over many hours at 12.5v. This is with the chassis battery left in in on position.



my plan is to leave it there until I receive the new BIM from Newmar and install it. I looked at Precision Circuits information this morning and they say their bridge will block overcharging both ways. i.e. when alternator (or battery charger) is running for many hours the house batteries will not over charge and if the coach is plugged in for a long time the chassis batteries will not over charge. Currently the battery charger on the chassis is in "maintenance' mode.
Any thoughts?
Thank you

[twinboat]

You say your house batteries are above 12.5 volts.

For the BIM and other voltage controlled relays to work properly, the voltage needs to be above 13.2 volts. If not, they don't bridge.

Many times the house battery float voltage doesn't get to 13.2 volts because of an out of range battery temperature sender, ( BTS) connected to the inverter/charger.