Battery Charging Problem ***UPDATE***

Consider a solar system. Hardly ever breaks.

Before you start doing anything, you need to find out if you have a "smart" charging system ! With the house batteries disconnected and the engine NOT running, turn on the headlights and leave them on for 5 minutes. Now start the engine.

Check the voltage at the battery. It should be 14.0V-14.5V. Drive for at least 10 minutes. With the engine still idling, check the voltage at the battery. If the voltage is below 13.8V at the engine starting battery, you have a smart charging system.

A smart charging system WILL NEVER FULLY CHARGE A "HOUSE BATTERY BANK" !

If that is what you have, the best bet is to purchase a DC-DC battery charger. Not only does it does it provide isolation, but it boosts the supplied voltage to properly charge your house battery bank.

Likely your house battery bank is dead. Replace those dual Group 24 batteries (in parallel) with two 6V golf cart batteries (in series). They will provide a lot more power.

OK, as per the above post, i have a SMART charging system 2018. I was advised that I can bypass it. That's what my rv mechanic told me to do a few months ago when I had a problem with a faulty isolation battery charge manager. He told me to just bypass this garbage and do it the old way which worked just fine. Somebody convinced the rv mfg's to buy this gadget to charge our batteries.

I wasn't sure if this was the right thing to do or not because the system involves the converter charging things when we are plugged in to shore power. I was told bypassing it would not interfere with that converter portion of the system.
The part was a little over $100 to replace, not that expensive. I was torn what to do, in reality, it probably doesn't matter which way its done.



my follow up:
I ended up just replacing the OEM manager to see if it would work. It is working , alternating the charge voltage between my 2 bank coach batteries and my single chassis battery. However if my coach batteries show 12.5v at rest, they will NOT jump up to 13 or 14 volts when I start the rv. The chassis battery will charge off the alternator but not the coach set. Therefore , I'm not able to top off my batteries as I would by the old method. Those coach batteries will only click on via solenoid at a lower voltage of 12.3 or 12.4 volts. Once they reach 12.6v they cut off charging until they drop down again.
I guess this manager is suppose to be a brain like a type of charge wizard to charge our batteries as they drop in voltage and not in a constant float charge rate, that is actually a safe mode as far as I know, the way it was done in the past, as you stated. It appears if they are designed to kick on at a preprogrammed voltage.

I actually like the old way, it seems more simple without these sensitive digital electronic parts to breakdown. KISS is what I prefer and probably what I should have done, but I had to satisfy my curiosity.

This is a 2002 RV.

The existing system used to charge the house batteries. Until it failed, there was no problem. Driving down the highway keep us charged up.

Now, no charge with the engine running.

The solenoid is a kind of battery isolator. The system is quite simple conceptually: there's a relay (the solenoid) that connects a wire between the two batteries when the engine is running. Often this is done simply by powering the solenoid from a run circuit on the vehicle, similar to other accessories like the windshield wipers. If you can find the solenoid (which is occasionally a bit hidden), it shouldnt' be too hard of a task to sort out where the fault is: whether the solenoid itself is bad, or a connection to it, or a wire or fuse or something similar.

This is a 2002 RV.

If I had read that in the first place I could saved myself the typing . :S :B


Well then, if you ever buy a new rv, just remember what we said :)

Drew got it right .

I would get an automatic relay (BIRD)

Example here - shop around

Gosh. It sounds like it will be easy enough to fix.

It occurs to me I have no idea where my fuse panel is....

I guess I have been lucky up til now.

bobndot wrote:
I actually like the old way, it seems more simple without these sensitive digital electronic parts to breakdown. KISS is what I prefer and probably what I should have done, but I had to satisfy my curiosity.

The whole purpose for smart charging is to improve fuel economy AND IT DOES ! Not by much, but some.

Charging is controlled by algorithms (programs/strategies) inside the engine control computer. Some of these algorithms look at battery temperature or other special sensors. All of them are based on an assumption of the the size of the starting battery and the amount of energy used by the starter motor plus other information.

The voltage regulator inside of the alternator does the "heavy work" of controlling power to the field coil which is what controls the output voltage of the alternator.

Connecting your house batteries to a smart charging system will NOT TOP OFF YOUR HOUSE BATTERIES, but it will prevent them from going dead if you have DC loads turned on in back.

If you want to charge your house batteries while driving, you need a DC-DC battery charger.

whizbang wrote:
This is a 2002 RV.

The existing system used to charge the house batteries. Until it failed, there was no problem. Driving down the highway keep us charged up.

Now, no charge with the engine running.

What chassis ? Ford stated installing smart charging on some vehicles before 2002.

Humor me. Check the voltage at the starting battery in the manner I recommended.