Chassis electrical not charging house batteries when driving.

[Ljgaud]

Hi, I noticed my chassis electrical isn't charging my house batteries when driving. Solar, gen, and shore power do charge the house batteries. Alternator and chassis electrical system seem fine. I assume there is a fuse/relay/solenoid somewhere that has failed.
On a side note, last trip to a shop (pre current trip) they must have left some chassis electrical on over the weekend because the chassis batteries needed a battery boost when I picked it up on a monday. The boost button seemed to deliver the boost but then upon cranking the engine it seemed to lose the extra boost power and would not crank. I had to jumpstart the chassis with my pick up truck.
Any ideas? thanks.

2005 34' Beaver Monterey IV Cat C9 DP, updated electrical to Li house and AGM chassis batteries, new inverter, solar, solar controller,

[d23haynes57]

Originally Posted by Ljgaud

Hi, I noticed my chassis electrical isn't charging my house batteries when driving. Solar, gen, and shore power do charge the house batteries. Alternator and chassis electrical system seem fine. I assume there is a fuse/relay/solenoid somewhere that has failed.
On a side note, last trip to a shop (pre current trip) they must have left some chassis electrical on over the weekend because the chassis batteries needed a battery boost when I picked it up on a monday. The boost button seemed to deliver the boost but then upon cranking the engine it seemed to lose the extra boost power and would not crank. I had to jumpstart the chassis with my pick up truck.
Any ideas? thanks.

2005 34' Beaver Monterey IV Cat C9 DP, updated electrical to Li house and AGM chassis batteries, new inverter, solar, solar controller,

How long have you had the RV and how well do you know it? Does it have provisions for charging the chassis battery from the house battery/charging system? Many do not have this feature. If you have the diode set up for charging the batteries off the alternator or a simple ignition switch activated relay it is likely that you do not have automatic house to chassis battery charging. My 2008 Nimbus has the diode system so it works this way. The boost switch is a maintained switch so when I want to charge the chassis batteries off the house system, I need to turn it on. The caveat here is that when using the batteries if I do not turn this switch off, I can kill all the batteries stranding myself. So, it takes some discipline.

There are a number of options from adding another battery charger to adding an automatic voltage-controlled battery combiner. The later works well as it will also function with solar or other house battery charging system. My favorite is this one,
https://www.bluesea.com/products/762..._-_12V_DC_500A
The electrical and mechanical lock-out/override can be handy features.

[travelin2]

Sounds like your battery isolator may have a problem. Easily replaced and not too expensive. If it has failed to keep your house batteries isolated from your chassis battery, causing house loads to drain the chassis battery, you can verify that condition, good or bad, with your multimeter.

[twinboat]

You should have a big boy solenoid in the battery control center. It will have battery size cables on each large post. The solenoid get burnt internal contacts. Make sure there is chassis and house battery voltage on each side, cabkrs could have been left off at the battery.
Push and hold boost switch and voltage on both large posts should be equal.

[Ljgaud]

I've had the coach for a year. Yes it did charge the house batteries from the chassis before this trip. There is also a battery charger to charge the chassis from the house when plugged in. I'll check the suggested items in the following posts. I brought a spare solenoid.

[426smartin]

Originally Posted by twinboat

You should have a big boy solenoid in the battery control center. It will have battery size cables on each large post. The solenoid get burnt internal contacts. Make sure there is chassis and house battery voltage on each side, cabkrs could have been left off at the battery.
Push and hold boost switch and voltage on both large posts should be equal.

I agree----Just replaced my big boy solenoid because the contacts inside were burnt and not making good contact. Voltage was off about half a volt when energized.

[Persistent]

Lots of good advice posted above.

It is possible that both the chassis and house batteries were depleted during servicing.

Engine charging may not last long enough to charge both sets of batteries. Engine charging of house batteries may not begin until chassis battery is fully charged. It depends on the bridge circuit design.

Inverter charger may not start charging until house battery is above a cutoff voltage.

Use an external charger to get house batteries above the restart voltage so inverter / charger will take over.

Fully charge both sets of batteries for at least 18 hours. They may benefit from 24 hours of charging since they have been deeply discharge for a long period.

The chassis batteries may have permanently lost some cold cranking capacity since they are not designed for deep draw.

If engine charging does not return to normal, then the bridge circuit may need repair.

[THenne1713]

TIP: Anytime boosting/ jumping, better= allow 3-5-minutes charge to dead battery from boost b4 cranking; sometimes, if battery terminal (hidden or visible corrosion) stops it from charging, boost cannot put anything into dead battery or dead battery not actually dead, just corroded terminals. I did find one time that slight cell water overfill can output acid fumes on overnight charging and find freshly cleaned terminals all corroded again next day.... Good Luck

[twinboat]

The OP said his HOUSE batteries stopped charging while driving.

How did so many of you turn this upside down to house battery charging the chassis battery ?

[rdchildr]

On my motorhome the manual states that when driving, the House batteries will start charging when they fall below 80% state of charge. This is based on battery voltage. When I switched to Lithium they would not charge while driving because the voltage never dropped low enough to start the charging. They still charge while hooked to shore power, when running the generator and from my solar panels


When driving my solar is turned on so they show they are being charged. I didn't realize my alternator wasn't providing a charge until one day I was driving and had my solar controller turned off.

[Ljgaud]

I upgraded my batteries and had to replace the failed zantex inverter power system when I bought the coach. I installed a Renology dc to dc 60 amp charger to charge the coach batteries while driving from the chassis. The renology dc to dc charger failed and needed to be replaced. This was the cause of my problem. The battery boost had nothing to do with it and was just a coincidence that both batteries were run down after servicing. The coach sat for a few days and the chassis and coach batteries ran down on their own. I usually keep it plugged in while storing so this isn't usually a issue. If I store it without power I'll be sure to switch off the batteries. The battery boost is working fine.

[YC1]

Take some pictures of your battery compartment and any related electrical areas with heavy cables.

A few pictures will really make it much easier to diagnose.

[tderonne]

Problem Solved

[THenne1713]

Since you have LITHIUMCOACH BATTERIES, YOU HAVE A LITHIUM CHARGER to protect alternator; many operate with timed On/ timed off periods to allow alternator cooling from the extreme loads of the lithium, so maybe 20 oñ/ 20-30 off. Brand/ model of your controller required to try and dig put specifics.