Chassis batteries not charging

[Hanabc]

I have a 2002 HR Navigator 40 PBT. My chassis batteries are not charging from any source, sources include shore power, generator, solar panels or alternator when driving. ( the house batteries are being charged by the inverter charging system with the generator running and also on shore power) Any help would be appreciated I have searched and not really having any luck. The boost relay does work as that's how i got the MH home last night, by using that intermittently as I drove home yesterday approximately 600 miles.

[vito.a]

Wow, very nice coach.  You should have an Intellitec Big Boy relay in the rear electrical run bay (next to the engine).   Under the proper conditions it ties the two battery banks together (or it should when working correctly).  These relays are notorious for going bad.  They get a large amount of carbon buildup on the copper contacts. 

You can remove it and rebuild it (instructions below).  Or, you can replace it.   

Expect it to stop working again in a few years.  

Big Boy Relay rebuild instructions.pdf

[Hanabc]

I did this today but it didn't make any difference. Thanks for the reply. Thanks for the PDF it is very informative.

 

Edited November 10, 2020 by Hanabc
duplicity

[Frank Bergamo]

I think there is a BIRD relay that works with the BIG BOY. Sounds like the BIRD relay has failed and is not closing the BIG BOY solenoid to complete the circuit or the BIG BOY itself has failed. Do a search on BIG BOY/BIRD relay to understand how they work. Hope this helps.

[Hanabc]

Thank you. I’ll have a look tomorrow. 

[Frank Bergamo]

Just reread your original post, if your boost relay works to tie batteries together, then BIG BOY is functioning properly. I suspect your BIRD has failed. Hope this helps.

[Bobbyboy]

Seems to me if your batteries are not charging from the engine alternator, the big boy/bird relay has nothing to do with it.  The engine alternator charges your chassis batteries directly; I would check the alternator first.  Just my humble opinion.

 

Bob L, 08 dynasty

[Hanabc]

5 minutes ago, Bobbyboy said:

Seems to me if your batteries are not charging from the engine alternator, the big boy/bird relay has nothing to do with it.  The engine alternator charges your chassis batteries directly; I would check the alternator first.  Just my humble opinion.

 

Bob L, 08 dynasty

Thanks for the reply and I am working toward that, but the difference is that the chassis batteries are not being charged by any source and should be able to be charged by  shore power, generator or the alternator as well, so i think something else is in play. I am working outside and the weather is not cooperating at all. 

[Bobbyboy]

Ouch;  I  see what you mean.  too cold for me.  If your inverter/charger is working (i.e. charging your house batteries and not the chassis batteries then, yes, the big boy/bird would be the logical problem.  However, if your alternator is not charging then that would be a different problem.  A separate check of the alternator would answer that question.   I  may be oversimplifying but at least you have some options to check;  BUT not in that weather.

 

Bob L, 08 dynasty

[Guest Ray Davis]

When you are driving does the alternator keep the air cond , heater and headlights operating properly ?

[Hanabc]

2 minutes ago, Ray Davis said:

When you are driving does the alternator keep the air cond , heater and headlights operating properly ?

No I had to keep using the boost relay to get home. 

[Guest Ray Davis]

Sure looks like the alternator but of course you want to be sure .

If you can twist wrenches a little you could pull the alt and have it checked .

You have a side radiator so it shouldn't be terribly difficult to remove .

Or the name A J Electric has been mentioned on here as having exact replacements .  If you want to gamble you can just order a new one .

[Hanabc]

1 minute ago, Ray Davis said:

Sure looks like the alternator but of course you want to be sure .

If you can twist wrenches a little you could pull the alt and have it checked .

You have a side radiator so it shouldn't be terribly difficult to remove .

Or the name A J Electric has been mentioned on here as having exact replacements .  If you want to gamble you can just order a new one .

I am working at it slowly and looking at all things including battery maintainer and battery isolater, but weather has hindered me. I have a Lambert LE 415 maintainer. I have been reading how to test these and will do so once the weather cooperates. It maybe the alternator but want to check everything and was looking for hints. Thanks very much for your reply. 

[rcl285]

I don’t see anywhere that you have checked or suspect the chassis battery condition or their connections.  If they aren’t charging from any of the sources (generator, engine, or the convertor) the common thread is the batteries or the connections. If you have another charger, disconnect them from the rest of the coach using the battery main switch or float the ground connection and see if they will charge.  
 

dick L. 04 Imperial

Edited November 11, 2020 by rcl285
of changed to or

[Hanabc]

I have checked all connections and all are good. I think I have a ground issue. The battery maintainer and the battery isolator all check good. The alternator is the next culprit. I have checked all other problems except the headlight switch is giving me some some problems. I will check it out with the system. 

[Tom schafer]

It can’t be your alternator or your house batteries would not charge also. I had the same problem it was the battery isolator  The blue box $102 very easy to change you said you  checked it I would take it off and have it checked at a alternator shop

[Guest Ray Davis]

Did he state that the house batteries were being charged by the alternator ?  They should be but I didn't see that .  Wouldn't be the first thing I have missed though .

Monaco used a convoluted system to charge but keep seperate the 2 battery banks .   When the OP determines the alternator is functioning properly I would forget the present system and install a Blue Seas ML-ACR Automatic Charging Relay with Manual Control - 12V DC 500A            that's what I plan to do .  Several others are using it and claim it eleminates the problem prone stuff Monaco installed .  It simply mounts in place of the BigBoy .

Blue Sea Systems 7622 ML-ACR 12V DC 500A Automatic Charging Relay with Manual Control, Gray

[Hanabc]

Update. I have been away for a few days and haven’t done any more checking. So far all checks out good except haven’t had the alternator tested. It doesn’t seem to be putting out any power so looks like it will be the culprit. I cleaned all connections to all batteries and tested the battery isolator and the lambert maintainer. All checks out good. The chassis batteries are now being charged by shore power. The chassis batteries were new in August. 

[Hanabc]

Update

I removed the alternator and had it tested. It is no good and I am replacing the stock 200 amp with the same alternator but in a 280 amp version. I have not installed this yet due to cold temperatures. I also had an issue with dash gauges and other items not working properly and it was the ignition actuated relay in the front run box. All seems good now. Thanks for the help and suggestions from everybody that responded.

New alternator with taxes was $925 Cdn. / $708 US

[Frank Bergamo]

Good news!!

Glad to hear you found a solution to your problems.