Chassis Battery Voltage

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Chassis Battery Voltage

February 10, 2018, 12:50:23 pm

Last week when I took my coach out for a short spin to see if I had fixed my power issues I did a no no when I parked it, I left the head lights on.

I did not notice it until yesterday when I drove up there to do a weekly check of running everything up and first off there was no dinging of the air system and the gauges didn't move. When I turned the key to start nothing happened. Then I checked the batteries and they showed 2.4 V so I started looking for why they were drained and found the head light switch still on.

Well hoping for the best I turned the switch off and checked the voltage at the converter and it was showing 14 V. So after about a hour of measuring the holes for the CO and LP detector, unplugging the shore power and running the generator the voltage was up to 3 volts.

I went back up there this morning to see if they can on up or not and they did not. I checked the battery on closest to the outside and it was back to 2.4 volts. I checked the instide battery where the converter wires were and I can tell if the voltage is jumping from 2.4xx and 3.2xx or if it is 24xx – 32xx. The needle is moving so fast I cant tell if there is a decimal point or not.

So long story short with the converter showing a steady 14 volts out is it OK?

And of course I did not have a tape measure with me so what type of red top batteries and what size?

Signed DA

Re: Chassis Battery Voltage

Reply #1 – February 10, 2018, 01:01:33 pm

It doesn't seem that the inverter charge is getting to the batteries. Can you unhook the battery ground and check voltage at the input of the batteries? My inverter charger would keep up with headlights on.

Re: Chassis Battery Voltage

Reply #2 – February 10, 2018, 01:13:14 pm

Quote from: craneman – February 10, 2018, 01:01:33 pm

It doesn't seem that the inverter charge is getting to the batteries. Can you unhook the battery ground and check voltage at the input of the batteries? My inverter charger would keep up with headlights on.

Thanks craneman, I can do that but it may be Monday, as the temp where the coach is was 28° at 11 am and falling with a mist and chance of rain

Are there any devices between that converter and the batteries?

Re: Chassis Battery Voltage

Reply #3 – February 10, 2018, 01:39:42 pm

The invertor goes to the house batteries not the chassis batteries. You have to have the boost switch on to hook them together. Most have a dedicated chassis charger, Echo, Trickle start etc.

Re: Chassis Battery Voltage

Reply #4 – February 10, 2018, 01:43:54 pm

You could buy a inexpensive digital voltage reader (about $5) that plugs into you dash cigarette lighter. It should read the engine start batteries voltage.
I leave one plugged into all my cars.

Re: Chassis Battery Voltage

Reply #5 – February 10, 2018, 01:55:36 pm

Quote from: craneman – February 10, 2018, 01:39:42 pm

The invertor goes to the house batteries not the chassis batteries. You have to have the boost switch on to hook them together. Most have a dedicated chassis charger, Echo, Trickle start etc.

maybe that is why when I picked it up the boos switch was on?

I know the light on the boost switch does not work and I did turn it on to see if I could start the coach with it on but no power.

I do have a regular battery charger I can take out there and hook up if that might help?

Re: Chassis Battery Voltage

Reply #6 – February 10, 2018, 01:57:47 pm

Quote from: Lon and Cheryl – February 10, 2018, 01:43:54 pm

You could buy a inexpensive digital voltage reader (about $5) that plugs into you dash cigarette lighter. It should read the engine start batteries voltage.
I leave one plugged into all my cars.

Thanks Lon I will see if I can find one

Re: Chassis Battery Voltage

Reply #7 – February 10, 2018, 05:42:02 pm

After you get your start battery bank charged up, how about preventing the same problem in the future: Have a buzzer that alerts when lights are left on:
Vehicle Headlight Reminder Build or buy one...
It has saved us.

Re: Chassis Battery Voltage

Reply #8 – February 10, 2018, 06:27:50 pm

Quote from: Barry & Cindy – February 10, 2018, 05:42:02 pm

After you get your start battery bank charged up, how about preventing the same problem in the future: Have a buzzer that alerts when lights are left on:
Vehicle Headlight Reminder Build or buy one...
It has saved us.

My thoughts exactly "LOL"

Thanks, I was not sure what to search for

Re: Chassis Battery Voltage

Reply #9 – February 10, 2018, 06:34:24 pm

Quote from: Super8mm – February 10, 2018, 06:27:50 pm

My thoughts exactly "LOL"

You are not alone, I left ours on just after we had bought the coach. When I heard banging on the door in the middle of the night, I was not pleased, but it was a kind soul who noticed and saved me from discharge!

Re: Chassis Battery Voltage

Reply #10 – February 10, 2018, 06:36:16 pm

Well I went out looking for the Isolator under the bed and I dont think I found it.

I found that the voltage in this box was a bit over 13 V to the large Red wire and the ground block.

In the engine compartment I found this and it only had 3 V on both sides of this.

Re: Chassis Battery Voltage

Reply #11 – February 10, 2018, 07:29:50 pm

The battery isolater is behind the driver side dual wheels mounted on the frame you can see it by opening the small door behind the rear wheels left side of coach or drivers side.

Re: Chassis Battery Voltage

Reply #12 – February 10, 2018, 07:37:41 pm

I did the same thing. Replace the batteries never was right afterwards.

Re: Chassis Battery Voltage

Reply #13 – February 10, 2018, 07:40:36 pm

Quote from: red tractor – February 10, 2018, 07:29:50 pm

The battery isolater is behind the driver side dual wheels mounted on the frame you can see it by opening the small door behind the rear wheels left side of coach or drivers side.

Thanks red tractor, I will go back out there Monday and see if I can find it.

I did put a battery charger on it, I let it run about 30 minutes on 10 amps then turned it down to 2 amps before I left.

Re: Chassis Battery Voltage

Reply #14 – February 10, 2018, 11:23:37 pm

The engine compartment back wall with 3volts is a Cummins relay that controls intake manifold electric grid heater & fuel injector that comes into play when engine is cold. It also manages the dash "wait to start" light, which stays on longer when engine is colder.
Don't mess with it.

Re: Chassis Battery Voltage

Reply #15 – February 10, 2018, 11:36:30 pm

Thanks Barry, all I did was check the voltage on it.

That is why I take pictures and ask before I mess something up, I am good at that

Re: Chassis Battery Voltage

Reply #16 – February 11, 2018, 04:02:23 am

Steve,

I do not know how good your batteries were before your headlight incident, but based on everything I have heard (on this forum), they are now TOAST. They need to be replaced, period.

Just the messenger,

Trent

Re: Chassis Battery Voltage

Reply #17 – February 11, 2018, 07:38:49 am

Quote from: TulsaTrent – February 11, 2018, 04:02:23 am

Steve,
I do not know how good your batteries were before your headlight incident, but based on everything I have heard (on this forum), they are now TOAST. They need to be replaced, period.
Trent

Thanks Trent, that is probably true but there is still the issue as to why or how to charge the chassis batteries from shore power. The coach batteries are charging just fine but evidently not the chassis ones.

If having the Boost turned on should charge them all then that is not happening as when I turn on the Boost it make no difference to the voltage going towards starting the coach

Re: Chassis Battery Voltage

Reply #18 – February 11, 2018, 07:45:34 am

Quote from: Super8mm – February 11, 2018, 07:38:49 am

If having the Boost turned on should charge them all then that is not happening as when I turn on the Boost it make no difference to the voltage going towards starting the coach

Steve,

With this symptom you need to check the boost solenoid. It is what is closed when you activate the "Boost switch" on the inst. panel. This should be located next to the isolator on the same mounting plate. Reply #11 from Red Tractor will give you this location I am talking about.

Mike

Re: Chassis Battery Voltage

Reply #19 – February 11, 2018, 08:33:07 am

Thanks Mike, I have a running word document that I paste all the info into so I will print it out before I go back out there. By printing things out lessons the problems with CRS

I also have the trouble shooting info I have found in the document and list of thing I need to take with me, I hate it when I drive 45 miles to get that and realize oh I forgot something

Re: Chassis Battery Voltage

Reply #20 – February 11, 2018, 10:30:35 am

Simple steps to check the functionality of the boost solenoid:

1. First, locate the BOOST solenoid. (This may be the hardest step for a new owner. Search the Forum for tips on how to find & identify)

2. With BOOST switch off, check the voltage on each of the large contact studs. (In your present situation, voltage readings will be different). Then check the small coil stud (or studs, if there are 2) for voltage - small stud (or studs) should not show any voltage present.

3. With BOOST switch on, check the voltage on each of the large contact studs. If solenoid is working, voltage should now be the same on both large studs. If it is not, try tapping the solenoid body lightly with a suitable tool, then check large studs again. If voltage readings are still different, check the small stud (or studs) for voltage - it ( or one of them if 2 studs) should show 12 volts. If small stud is "hot" but solenoid is not working (closing), replace the solenoid.

If you need a replacement solenoid, the model linked below is commonly recommended by our members. Whatever you buy, be sure it is rated for continuous duty and sufficiently high amperage. Replacement solenoids can have one or two small studs. If there are 2 studs, connect the control wire (from dash switch) to one and a ground wire to the other - they are interchangeable.

While waiting on a new solenoid, you could temporarily bypass the defective unit by removing the heavy cables from both of the large posts, and connecting them together with a nut and bolt. Be very careful to keep these connected cables insulated and away from any chassis ground points to avoid suffering a HIGH AMPERAGE short circuit. Also remember that IF the two battery banks are (temporarily) connected together, ALL of your batteries be drained if any loads (like the headlights) are left turned on.

Cole Hersee 24213 12V 200A Continuous Solenoid | eBay

Re: Chassis Battery Voltage

Reply #21 – February 11, 2018, 10:37:00 am

Thanks Chuck, I will go check it tomorrow. We still have freezing rain and sleet for today, right now it is on the west side of Fort Worth so I plan on staying inside and warm.

Re: Chassis Battery Voltage

Reply #22 – February 11, 2018, 10:56:24 am

Here's a few photos for your reference. The first shows the isolator's general location. I took this photo with the air cleaner removed but you'll see the isolator in back of and above the air cleaner. The second photo shows what you might see when you locate the isolator board. Hopefully, yours in in better shape than this one. You might not see the boost solenoid as it may be hidden behind a jumble of wires and cables. It's there on the lower right. The third photo shows it better. Mine is a 97 270 so I'm guessing yours will be similar.
jor

Re: Chassis Battery Voltage

Reply #23 – February 11, 2018, 11:02:27 am

Thanks jor, that give me so good reference points

Re: Chassis Battery Voltage

Reply #24 – February 11, 2018, 12:24:16 pm

When you shut down for any lengthy period, you should have a check list to make sure nothing is left on. The boost solenoid while continuous duty is not meant for continuous duty day after day. It's only should be used for emergency starting or allowing the generator to charge the engine batteries in case of an alternator failure. The Cole-Hersee solenoid is not a latching solenoid so it uses juice and creates heat any time it's on. Many have needed to be replaced as the "continuous" duty rating is abused.

I just run a cord from the dash lighter plug to the HWH side panel lighter plug receptacle to tie the two battery banks together while the coach is not being used or even when dry camping with the solar in operation. Below is a photo of the house and engine battery voltage while the coach is plugged in at home. This the the reading since we purchased the coach back in 2008 using the stock OEM charger. I just replaced our engine batteries but the AGM deep cycles are still in good shape many years later.

In the photo with the twin voltmeters, you can see the lighter plug at the bottom as used to tie the banks together.

Pierce

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