Engine Battery not charging on shorepower?

[Jim & Alice]

We parked our 2007 National RV Dolphin (Ford F53 Gas unit) on our lot back in November… set it up for storage, disconnected shore-power, did a ‘battery disconnect’ (button/light off),  and left… returning two months later.   At that time the Engine Battery was dead, and the motor would not turn.   Our weatherpro awning would not deploy either.   All else worked.   A week later, we had an appropriate new Interstate Battery installed, 13+Volts, engine started, weatherpro worked just fine.   Things looked good.

24hrs after the new install, I noticed the new battery was not recharging – House batteries at 13.2V, Engine battery at 12.5V.   No question, our Dolphin is set up for shorepower recharging… and has not had a problem (7 years) with this prior to now.

Has anyone encountered this kind of situation before?   I guess at this point, I am looking for suggestions on where to get started…

Thanks for any help!

Jim

[Darryl&Rita]

Somebody missed a wire when switching batteries. Start in the battery bay.

[Kirk W]

9 hours ago, Jim & Alice said:

No question, our Dolphin is set up for shorepower recharging… and has not had a problem (7 years) with this prior to now.

Has anyone encountered this kind of situation before?   I guess at this point, I am looking for suggestions on where to get started…

Since many motorhomes are not connected to supply a maintenance charge to the chassis battery you should probably start by looking for data for your coach. That connection should be fused so start by checking all of the fuses for one that is open. If you have the original manuals there should be a listing of the fuse blocks, where they are located and what each supplies. The lead to the battery should also have a blocking diode in it so that could help to identify the lead that you are looking for. 

[oldjohnt]

Jim & Alice, you state your Dolphin is set up for shorepower recharging, can I assume that means its set up so the RV's Converter/Charger (for house batteries) also has a connection to your engine battery to charge it when plugged to shore power ??? (often NOT the case)

 If that's actually the case ?? I suspect a blown fuse,,,,,,,,,,,,,,,,, or tripped circuit  breaker,,,,,,,,,,,,,,,,,or a faulty diode,,,,,,,,,,,,,,,,or a bad/open/missed  wiring connection between house and engine batteries. If that's the system you have when plugged to shore power Id expect your engine battery to go to 13 to 14 or so volts similar to your house batteries. Stick a voltmeter on your engine battery and see if voltage begins to rise when plugged to shore power??? If it never changes your onboard Converter/Charger must not be connected... 

 I have also seen solid state dual battery isolators used for connecting the house and engine batteries and they can go bad or a wiring connection open.

Often an RV has no permanent connection between house and engine batteries UNLESS an emergency switch/solenoid is pushed/activated or there's a simple switch or some sort of a relay to connect the two if and when needed, but many RV's don't use the onboard Converter/Charger designed to charge house batteries to ALSO charge the engine battery. I have seen SEVERAL of those systems that use a 100% duty rated high current solenoid (connects house and engine when activated) fail.

 There could be a diode wired between engine and house batteries to allow the Converter/Charger to charge the engine battery but NOT allow the engine battery to discharge into your coach loads. If that's the case and its bad or got disconnected and your system is as you state ?? if it is bad or got disconnected the onboard Converter/Charger cant charge your engine battery.

REGARDLESS you need to find the cause why your engine battery is discharging and cure that.

SUMMARY look for a blown fuse or tripped breaker or a missed wiring connection or a bad diode and make sure the system is as you stated can help other troubleshooting if required. Put your best glasses on and look for wires that aren't  connected or fuse holders (round glass or blade type) with blown fuses.  I have seen a rats nest of a bunch of wires connected to the battery terminal, maybe its simply that one didn't get reconnected like Darryl was talking about above ??

John T  

         

Edited February 10, 2020 by oldjohnt

[Ray,IN]

Since this happens only when on shore power, an effective and lowest cost method is to simply use a set of jumper cables between battery banks..

[rickeieio]

44 minutes ago, Ray,IN said:

Since this happens only when on shore power, an effective and lowest cost method is to simply use a set of jumper cables between battery banks..

Yup, you beat me to it.  They wouldn't need to be large gauge.  10 ga. and some alligator clips......  Heck, you could wire them up permanently and put a switch in the + line.

[dogyard]

In the event you find there really isn't a connection between the house and engine (starting) battery I can heartily recommend this add-on - 

http://www.lslproducts.net/UTLS_FAQs.html

Took me about 10 minutes to install and gives me confidence that as long as I'm getting house batteries charged while on shore power my starting battery is also being maintained.

[Tee Jay]

Encountered this twice, one was a broken wire going to the engine battery charger,  one was a disconnect of the feed circuit.  Check the fuse and wire integrity and connections.

[Jim & Alice]

Thanks for the Suggestions, folks.   Much appreciated.   I think we're going to start in the battery bay... and double check all connections.   I know from the IRV2 site, and personal observation that my Dolphin does charge the Chassis battery (in addition to the House Batteries) concurrently while on shorepower... I am currently at 13.2V (House) and 12.4V (Engine - holding steady).  Johnt, thanks for your write-up -- I am going to have to read it a few times to more fully understand... but we're retired!   After I get this problem fixed, I will post the 'fix' here.

Thanks again, Folks.

Jim 

[oldjohnt]

Jim, you're welcome, thanks for the update. Based on it here are a few more thoughts:

 On units that indeed connect the house to engine battery WHEN ON SHORE POWER there may be a mechanical isolation relay that's engaged under those conditions (or by using an emergency switch). They use a 100% duty rated high current solenoid (resemble old Ford starter solenoids) AND IN 49 YEARS OF RV OWNERSHIP I SAW MANY OF THOSE FAIL. They can develop burned resistive contacts or a missing or broke wire or blown fuse  prevents their proper operation. Just last week I helped a buddy remove and repair his isolation solenoid/relay which like yours failed to adequately connect his engine battery to house battery.

 Still the KISS principle may hopefully lead to easy simple fixes like a broken wire or missing connection or a blown fuse etc...Still find and cure the cause of why the engine battery is discharging ???

 John T  

[Kirk W]

11 hours ago, Ray,IN said:

Since this happens only when on shore power, an effective and lowest cost method is to simply use a set of jumper cables between battery banks..

The down side of that would be that you would have to rig the every time you want to use them. In some configurations it would be a real pain. Our class A had the coach batteries under the step, with access inside of the step and it wa a mid entry door. 

[Jim & Alice]

Here is a followup to my original posting in this topic.

Since the original post, I followed the suggestions made... did some more research on IRV2 and Yahoo... and wrote up a 'Stmt of Work' to facilitate calling in a Mobile RV Technician.    Most advice that had been offered suggested a solenoid malfunction between the shorepower and Chassis battery, and that is what I wrote into the 'Stmt of Work' for the Mobile Tech.   Unfortunately, the (very capable) Technician scheduled in shortly after I had a hip joint replacement surgery... and the work got done, but I was 'just a sitting' around the lot.

So anyway, for my 2007 National RV Dolphin, replacing the solenoid restored shorepower charging to the chassis battery.

Thanks again, folks. 

[Kirk W]

8 hours ago, Jim & Alice said:

after I had a hip joint replacement surgery...

Hope that you are recovering well! Pam had that done 5 years ago and did quite well. 

[oldjohnt]

Jim & Alice, Congratulations and thanks for the feedback, I appreciate hearing what the problem was. That's one more (among a ton in the past) solenoid failure I can add to my list of causes to your problem.  

Best wishes, take care

John T  Live from The SKP Resort in Wauchula Florida

 

[Jim & Alice]

Thanks, Kirk & Johnt!

Yea, Kirk, Alice and I met you folks up in South Dakota several years ago - give our best to Pam!   I had the surgery done in Yuma, AZ, and it all went very well.   I am in week #3 of recovery, and walking unaided.   Yay!

And Johnt, thanks for your experience shared!.    The mobile Tech that came out read your write up and went right to the problem.   He was from a good company in the Foothills of Yuma.

Thanks again, guys - I'd better get back to my recovering/loafing. 😎

  

[Kirk W]

6 hours ago, Jim & Alice said:

Alice and I met you folks up in South Dakota several years ago - give our best to Pam! 

I'd not thought of it until you mention the location we met but that was also the summer immediately before her hip experience. Her surgery was about Dec. 1 or so after we were up there.