Chassis Battery Condition

[LK23]

First let me say that I realize the glow plugs on the Cummins engine draw a lot of power and cause the "Low Battery" warning to illuminate when cranking the engine.

Today I turned my ignition key to check the mileage on the Freightliner display. The Low Battery warning illuminated almost immediately. We have been camped for almost a month on shore power.

Question: How best to check the condition of my chassis batteries? If I turn the battery disconnect off and check the voltage across the two batteries will that give me a good reading of battery condition?

And, is there a way to check if the BIRD system is charging my batteries while on shore power?

[ByeTheWay]

A Hydrometer is a good way to test the battery cells if the batteries are flooded.

To get an accurate test w/ voltage the battery should be at rest for several hours.

Here is a link that might help: RV Electrical

[palehorse89]

Originally Posted by LK23

First let me say that I realize the glow plugs on the Cummins engine draw a lot of power and cause the "Low Battery" warning to illuminate when cranking the engine.

Today I turned my ignition key to check the mileage on the Freightliner display. The Low Battery warning illuminated almost immediately. We have been camped for almost a month on shore power.

Question: How best to check the condition of my chassis batteries? If I turn the battery disconnect off and check the voltage across the two batteries will that give me a good reading of battery condition?

And, is there a way to check if the BIRD system is charging my batteries while on shore power?

While the voltage at rest seems OK ,when the starter load is put on them, they might have(1 or both) internal problems.
Does the engine start OK?
The best way to check their condition is to "Load Test" them. Either buy a load tester https://www.walmart.com/ip/Electroni...-Volt/44362282 be sure to disconnect them(Separate the 2) for testing if you buy one, or take them out, and haul them to a local automotive place that can do the load test.
As far as charging while on shore power, unplug, have a beer, take a reading, then plug back in and take another reading..........you should see a higher voltage.
http://www.precisioncircuitsinc.com/...nager-RevF.pdf

[Woodchopper]

Originally Posted by LK23

First let me say that I realize the glow plugs on the Cummins engine draw a lot of power and cause the "Low Battery" warning to illuminate when cranking the engine.

Today I turned my ignition key to check the mileage on the Freightliner display. The Low Battery warning illuminated almost immediately. We have been camped for almost a month on shore power.

Question: How best to check the condition of my chassis batteries? If I turn the battery disconnect off and check the voltage across the two batteries will that give me a good reading of battery condition?

LK23
That will only tell you the "state of charge" of your batteries.

You need a multi-meter with MIN and Max volt settings to determine the condition of a starting battery.
See:

https://www.youtube.com/watch?v=tsJUuLu1cw0

However IMO the most accurate way to determine the "condition" of a chassis battery is to have the battery "load tested":

https://www.youtube.com/watch?v=mxhz-yYrJys

[LK23]

Further clarification: Our 2017 Dutch Star 4369 is three months old. I need to determine the state of charge before we start the engine on Tuesday. And, I would like to determine if the BIM is working properly.

[palehorse89]

Originally Posted by LK23

Further clarification: Our 2017 Dutch Star 4369 is three months old. I need to determine the state of charge before we start the engine on Tuesday. And, I would like to determine if the BIM is working properly.

Answered towards the bottom of post#3......
I see it is new(Seen your posts) but even new batteries can fail internally.........and depending on how they were taken care of since installed in the chassis before you took possession of it.

[LK23]

We ordered our 2017 Dutch Star and picked it up when it arrived at the dealer. There should be no issues with battery abuse before we took possession.

[LK23]

OK, here’s my results. Using a multi-meter, I checked the voltage between the two batteries while connected to shore power and got 14.4 volts. I disconnected the shore power and it dropped to 13.8 volts. I waited a while and it remained constant. I reconnected the shore power expecting the voltage to rise and, instead, it remained at 13.8 volts. I had anticipated the voltage would rise after reconnecting the shore power, showing the BIM was charging. Maybe not…

On a whim, I turned the ignition to the first setting and immediately got a Low Battery warning. I quickly turned the ignition off with out starting. I rechecked the batteries and found 12.6 volts.

[palehorse89]

Originally Posted by LK23

OK, here’s my results. Using a multi-meter, I checked the voltage between the two batteries while connected to shore power and got 14.4 volts. I disconnected the shore power and it dropped to 13.8 volts. I waited a while and it remained constant. I reconnected the shore power expecting the voltage to rise and, instead, it remained at 13.8 volts. I had anticipated the voltage would rise after reconnecting the shore power, showing the BIM was charging. Maybe not…

On a whim, I turned the ignition to the first setting and immediately got a Low Battery warning. I quickly turned the ignition off with out starting. I rechecked the batteries and found 12.6 volts.

I was thinking it would also, My BIRD system does.......but it seems the BIM does not till the voltage drops some......
It sure seems like they are charging with your initial readings.......kinda high though? 14.4.......
Hopefully someone with a newer DS will jump in and be able to help out with better knowledge of your Coach..........

Operation:
The
Battery Isolation Manager
(BIM)
monitors the Battery Voltage of both
the Chassis and Coach Batteries over long
periods of time. If it senses a charging
voltage, it connects the two batteries
together. If the charging system is drastically
overburdened, the batteries will be isolated,
however, if the
BIM
sees a long term
charging of both batteries it will allow the
batteries to remain connected and allow the
charging system to do its job. Once the
battieries have reached a Float Charge state
for one hour, the
BIM
will isolate the batteries
to prevent overcharging, and will only
reconnect the batteries for charging if one of
the Battery drops to approximately 80%
charge, and the other is being charged. This
long term monitoring of the batteries prevents
the annoying relay clicking that exists in
simpler Isolation Modules today

[LK23]

Two hours later, with shore power connected, I checked the battery voltage again and found 12.7 volts. I'm certainly confused. I would have thought that the BIM would have charged the batteries back to high 13 or low 14 volts.

[dennis45]

Originally Posted by LK23

Two hours later, with shore power connected, I checked the battery voltage again and found 12.7 volts. I'm certainly confused. I would have thought that the BIM would have charged the batteries back to high 13 or low 14 volts.

The BIM has likely switched over to the house batteries and until the chassis voltage drops below its set point and switches back to the chassis, there will be little or no change unless you turn the ignition back on to draw the voltage down. At that time the BIM will switch to chassis and the voltage will rise again.
I can't say what that switching point is off the top of my head but it's likely in the 12.3 - 12.4 range?
Currently, your house battery voltage should be 13.5 +. Right?

[twinboat]

Following along here you had 14.4 on both batteries. Is it cold or did you have the charger off ?

You unplugged and it dropped as it should. What you read was a surface charge. It would have dropped to 12.7 over time.

When you plugged in, the house charger, it probably went to float 13.8. The BIM didn't connect the chassis battery because it was reading charged.

When you turned the key on, the BIM would sense that and remain open, so you didn't have 2 charging sources working together.

Until you wait out the delay and draw the chassis battery down, it may not reconnect.

Last but not least, I would think the low battery light would always come on, with the key, until the engine was running and the alternator was charging.

[palehorse89]

Originally Posted by LK23

Two hours later, with shore power connected, I checked the battery voltage again and found 12.7 volts. I'm certainly confused. I would have thought that the BIM would have charged the batteries back to high 13 or low 14 volts.

Agree with Dennis and the BIM operation posted.........Your chassis batteries are at full charge right now.

[dennis45]

Originally Posted by twinboat

Following along here you had 14.4 on both batteries. Is it cold or did you have the charger off ?

You unplugged and it dropped as it should. What you read was a surface charge. It would have dropped to 12.7 over time.

When you plugged in, the house charger, it probably went to float 13.8. The BIM didn't connect the chassis battery because it was reading charged.

When you turned the key on, the BIM would sense that and remain open, so you didn't have 2 charging sources working together.

Until you wait out the delay and draw the chassis battery down, it may not reconnect.

Last but not least, I would think the low battery light would always come on, with the key, until the engine was running and the alternator was charging.

Absolutely, and I agree with your last sentence. I don't see there being a problem other than perception here. Drive er like you own er... don't fix it if it ain't broke.