Battery or Charger Issue?

[swampgator352]

I woke up this morning after a night of boondocking to very low batteries (9.4 Volts). I’ve spent several hours on the road this morning and expected the batteries to be at least a bit charged up but they are still reading at 9.4 Volts. What is the best way to determine if the issue is with the batteries, the charger or something else? Since I’m on the road I have minimal tools with me. Thanks for your help!

[dkoldman]

Originally Posted by swampgator352

I woke up this morning after a night of boondocking to very low batteries (9.4 Volts). I’ve spent several hours on the road this morning and expected the batteries to be at least a bit charged up but they are still reading at 9.4 Volts. What is the best way to determine if the issue is with the batteries, the charger or something else? Since I’m on the road I have minimal tools with me. Thanks for your help!

Sounds like you have a way of reading voltage of batteries in question. I am assuming it is the House batteries that is the concern. When you connect to Shorepower and in Use mode or start up engine; the voltage should jump to above 13.2 vdc

If it does and you have gone about 3- 4 hours and still do not have fully charged batteries, it would say you have issues with the batteries with minimal diagnostic.

It would help to say what type and how old are the batteries in question?

[lwmcguir]

As always grab your VOM and you have the answer in a few minutes

Then you proceed with the correct plan to remedy your situation

[DavidEM]

What is the model and year of your coach. It sounds like you either do not have a BIM (a device that connects or isolates the chassis and the house batteries) or it has failed.

I would expect the voltage to rise after several hours on the road, even if the batteries were bad.

David

[Judge]

As David alluded to...... a lot of Class C's don't have a BIM or a BIRD that allows the alternator to charge the house batteries.

I took a quick look at a Siesta brochure not knowing your specific year and I don't see it listed on the brochure. Doesn't mean you don't have one but you will want to talk to someone who knows your model well to verify.

You can also look around your house battery compartment. If you have and BIRD or BIM it is usually near the house batteries and looks line one of these devices.

If your coach doesn't have one, then shore, generator or solar is the only way to charge the house batteries.

[swampgator352]

Many thanks for the helpful replies! After a few more hours on the road I was able to get the house batteries up to about 11 volts. I then fired up the generator and was reading around 13 volts (while it was running) so decided to replace the batteries. So far, so good! I appreciate the advice!

[Hooligan2]

Year and model of your Siesta would help.
My 2016 Siesta uses a trombetta solenoid to connect the Chassis alternator to the house batteries when engine is running. The solenoid is located under the drivers seat. It has a 5 amp fuse, also under the seat.Check voltage at the house batteries with engine running. Compare to chassis battery, about 14 volts.. . Easy way to check that is the red chassis battery terminal alongside the air cleaner, drivers side.

[swampgator352]

My Siesta Sprinter is a 2014. I was able to dig up an electrical schematic Thor sent me a while back that shows an isolator solenoid between the chassis and house batteries, I will see if I can locate it under the driver seat as you suggest.

I definitely do not get 14 volts on the house batteries when the engine is running, however.