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Bobby F · 01-05-2021, 12:58 PM

Here I am stuck in the back lots of Quartzsite, La Posa South.

1993 Ford chassis, 460ci.

House batteries are just fine. Was running the generator and it started to stumble. Thought "fuel", but then realized it was electrical - no dc power to run the spark. Turned the key in the RV cab and the generator died immediately, so I knew the issue was with the chassis battery.

Chassis battery at 11.7v. Won't turn motor over. Generator starter just clicks.

So, obviously, I'm not getting a charge to the chassis battery. So, my question is, why? (The rest of this post will make it clear I'm not an electronics expert.)

There are two relay-type items right next to the chassis battery - I've pictured them below. One runs through the Pos cables, one runs through the Neg. side. What are these, exactly, and which one do I need to replace? (Or am I off-base in even suspecting these parts?)

Thanks for any help you can give me. I'm currently charging the chassis battery off of house batts with a 1.5 amp charger through the inverter, so I don't think I'm actually stranded, and I have enough in the 400aH house batt group to survive two nights of furnace use, so I'm not in dire need, but it's worrisome.

Ranger Smith · 01-05-2021, 01:19 PM

Take a house battery out. Hook it up to where the chassis battery is. Start the RV and go get a new battery.

Bobby F · 01-05-2021, 01:40 PM

Thanks. But, that's one of the downfalls of using the Renogy huge 24"-long 140lb 200aH AGM house batteries. Sort of built in.

Plus it's a near-new chassis battery. I really don't think that's it. It appears to be taking a charge now.

twinboat · 01-05-2021, 01:49 PM

The second picture looks like the Ford starter relay. Not the problem.

The first relay may be it.

Check voltage on each large terminal and see If it matches each battery.

If it does, that relay should close with the key on.

If you see charging now, disconnect the small wire and see if it stops.
Failing solenoids can work sporadically.

subford · 01-05-2021, 02:33 PM

Do you have a better photo of the bottom item it the top photo?

twinboat · 01-05-2021, 03:26 PM

I think what the first picture is showing is an early model of this.

https://redarcelectronics.com/collec...tery-isolators

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Bobby F · 01-05-2021, 04:37 PM

Quote:

Originally Posted by twinboat

I think what the first picture is showing is an early model of this.

That's what I suspect, but here's where my non-electronics mind starts to lose track.

If that's an isolator, then it allows for the engine alternator to charge the house side when the engine is running and then opens when the engine is turned off so the house doesn't drain the chassis battery.

But through what pathway does the generator charge the chassis battery when it's running and the engine isn't running? Or does the solonoid also close in that situation?

The generator acted just like my cars did years ago when I unknowingly broke an alternator belt, and the battery just slowly died to the point the engine wouldn't spark, and then the engine died.

(Oh, and, thanks, all.)

twinboat · 01-05-2021, 05:01 PM

Quote:

Originally Posted by Bobby F

That's what I suspect, but here's where my non-electronics mind starts to lose track.

If that's an isolator, then it allows for the engine alternator to charge the house side when the engine is running and then opens when the engine is turned off so the house doesn't drain the chassis battery.

But through what pathway does the generator charge the chassis battery when it's running and the engine isn't running? Or does the solonoid also close in that situation?

The generator acted just like my cars did years ago when I unknowingly broke an alternator belt, and the battery just slowly died to the point the engine wouldn't spark, and then the engine died.

(Oh, and, thanks, all.)

Yes, the one I posted is by-directional.

It will sense charging from either side and close the solenoid. If no charging, solenoid opens.

You can replace it with a Cyrix 120

https://www.amazon.com/Victron-Intel.../dp/B07VHF8M75

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Bobby F · 01-05-2021, 05:33 PM

Perfect. Thank you!

John Wayne · 01-05-2021, 06:01 PM

I think you will need to install a "TriK L Start" or "Amp Start" Most not all MH the converter just charges the house battery, not the starting battery. The two above mentioned items put a trickle charge from the house battery to the starting battery when the converter is charging the house battery. You could do it with just a jumper wire but if you forgot to take it off the starting battery would drain with the house batteries.

twinboat · 01-05-2021, 06:40 PM

Quote:

Originally Posted by John Wayne

I think you will need to install a "TriK L Start" or "Amp Start" Most not all MH the converter just charges the house battery, not the starting battery. The two above mentioned items put a trickle charge from the house battery to the starting battery when the converter is charging the house battery. You could do it with just a jumper wire but if you forgot to take it off the starting battery would drain with the house batteries.

His solenoid looks to be bi-directional. Chassis to house OR house to chassis charging.

A Trik L Start / Amp L Start only charges one way, house to chassis.

It would keep the chassis battery up, while the generator is running, but it wouldn't charge the house battery while the engine is running.

Since about 2007, most MHs have bi-directional charging.
Trik L Starts are not needed.

Bobby F · 01-05-2021, 07:31 PM

In any case, now that I understand what's going on, I'm back in business. House batts were almost full, so I plugged in my motorcycle trickle-charger to the house outlet and charged up the chassis batt enough to start the engine and finish charging the chassis batt off the alternator, and then started the generator and finished charging the house batts. (Non-tilting solar panels in the winter combined with running the furnace every night made the generator a requirement every third day. Need more panels . . .) So long as I either run the truck engine or run the trickle-charger when I run the genny, I'm good to go!

So, thanks for the help!

sbleiweiss · 01-06-2021, 06:48 AM

Don't know if you need/want this now, but there is a place in Cottonwood AZ that specializes in automotive electric issues. They work on motorhomes. They have been great the two times I have used them. If you want the info PM me or ask here.