Chassis battery

[Lakescepter]

2004 HR Scepter ISC350 Onan 7.5. Chassis batts are not charging from altenator, generator or solar. House batts are staying charged, with gen running have 14.68-74 at house batts but only 11.68 at chassis batts. any ideas where to look would be appreciated have no wiring diagram for system.

[BFlinn181]

Your chassis batteries should be charging from the alternator at least. Check all connections between alternator and the batteries. What voltage do you read from the running engine at the alternator? Check that the battery isolation switches are on and allowing electricity across terminals of the solenoids.

[Lakescepter]

Thanks Bob for reply. Can't get to alternator with eng. running but does not appear to be correct at chassis batts (no change of voltage). that does indicate alternator prob. except I do not show any voltage increase with gen running or from solar. put external charger on batts and I see that voltage at alternator indicating complete circuit. am I incorrectly assuming I should see charging at chassis batts from gen or solar?

[poordave]

Have you checked the buss fuses? They are flat type, about one & half inches long with a piece of plastic in the middle. They are mounted within 18 inches of the battery. Dave

[Lakescepter]

Poordave no buss fuses on chassis side that I can find.

[BFlinn181]

Originally Posted by Lakescepter

Thanks Bob for reply. Can't get to alternator with eng. running but does not appear to be correct at chassis batts (no change of voltage). that does indicate alternator prob. except I do not show any voltage increase with gen running or from solar. put external charger on batts and I see that voltage at alternator indicating complete circuit. am I incorrectly assuming I should see charging at chassis batts from gen or solar?

I thought most Monaco RVs did charge both house and chassis batteries on the converter/charger, whether powered by generator or shore power. Do you have a boost switch on the dash to 'jump' start either bank of batteries? If it doesn't work, it might point to the problem. Many systems need one set of batteries charged before switching to charge the others, are all your batteries in good shape?

[Lakescepter]

Batteries are next on list. Will remove and load test tomorrow. Chassis batts are now charged to 12.3vdc with external charger. I believe I saw somewhere that leece-neville alternators need at least 12 or so volts to fire up. could be a batt problem after all is said and done. so many interlocked systems to sort through. ah the joy of rving.

[JFC]

Originally Posted by BFlinn181

I thought most Monaco RVs did charge both house and chassis batteries on the converter/charger, whether powered by generator or shore power. Do you have a boost switch on the dash to 'jump' start either bank of batteries? If it doesn't work, it might point to the problem. Many systems need one set of batteries charged before switching to charge the others, are all your batteries in good shape?

Many Monaco products only charged chassis batteries from alternator when engine is running. I had dead chassis batteries several times after storage in my 2007 Scepter. I checked with Monaco as did the shop and was told this was the case on my coach. Monaco would sell a modification or I could have (as I decided to do) an echo charger installed since the coach is stored plugged in.

[captw3]

My Neptune does not have aBIRD and does not charge the chassis batteries when on shore or genny power. I added a trik L start for 29.00 and the chassis batteries now take charging current from the house batteries. When ever the house batteries are charging so are the chassis batteries. Takes 10 minutes to install.

[YC1]

Disconnect from shoreline and turn generator off. Start engine and measure the voltage on the HOUSE batteries. IF you see 13.5 or so then your alternator is functioning and you have an isolator problem that is preventing your engine batteries from getting the charge. This isolator could be a big relay or more likely a Diode type as show by the link. Single Battery Isolator

[dpinvidic]

Originally Posted by Lakescepter

2004 HR Scepter ISC350 Onan 7.5. Chassis batts are not charging from altenator, generator or solar. House batts are staying charged, with gen running have 14.68-74 at house batts but only 11.68 at chassis batts. any ideas where to look would be appreciated have no wiring diagram for system.

Lakescepter (Whats your first name?).
There are two charging circuits in an RV. The engine/Alternator charges the Chassis batteries, and the Inverter/Charger charges the House batteries.

The only connection between these two systems is the "Isolation Relay".
This relay puts both sets of batteries in parallel. Your AUX-Start switch activates this relay also.

Most coaches activate this relay when driving so that the alt will charge the house batteries. But when on shore power, each coach is different. My sons Fleetwood will activate the solenoid to keep the chassis batteries charged, but my Phaeton has a separate battery minder for the chassis batteries when on shore power (does not use the relay).

What sounds strange is that your chassis batteries are not seeing a charge voltage from either the alternator (normally a direct connection) or the generator/AC (connect thru the isolation relay). This may be expected for your coach...it is on mine.

I suggest you check that your isolation relay works. Make sure you measure both sides "BEFORE" you activate it. one side is house and one side is chassis. You should see two different voltages. The activate the AUX-Start and make sure the relay closes. Do this WITHOUT shore power. Just because this relay works, it does not mean the coach uses it while charging the chassis batt. from the house charging circuit.

When on generator, this is the same as shore power, the inverter/charger charges the house batteries. Solar also charges the house batteries. So these two sources rely on what ever circuit the RV uses to tie the batteries together(if any).

On the other hand, the alternator should be a direct connection to your chassis batteries. I would focus on that problem.
Alternators have a internal voltage regulator. So the "BATT" connection on the alternator should be directly wired to the chassis battery (maybe fused). See if you can measure the same chassis voltage on that terminal.
This will show the wiring connection is good.
Also check your chassis battery ground connection.

Let us know what you find..

Regards,

Dan

[doublechevy]

I had a similar problem on my 2008 Knight. chassis batteries would not charge on shore power or Gen. problem was corroded contacts in Isolation relay.
as understand my charging system will charge the house batteries first when they are sufficiently charged it will then allow the chassis batteries to charge.

if you have charging current on house batteries and activate the boost function you should see that voltage on the chassis batteries if not suspect the isolation relay.

It has something to do with different charging characteristics on the house batteries (deep charge slow release) and the chassis batteries ( high current demand on starting) If you do not see charging voltage at chassis batteries while running on the alternator may be poor connections or alternator problem.

[Jeff753]

Originally Posted by Lakescepter

2004 HR Scepter ISC350 Onan 7.5. Chassis batts are not charging from altenator, generator or solar. House batts are staying charged, with gen running have 14.68-74 at house batts but only 11.68 at chassis batts. any ideas where to look would be appreciated have no wiring diagram for system.

Bad battery switch? But then it wouldn't start would it. Does it have a battery isolator?


Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[Lakescepter]

OK: here we go. charged chassis batts externally to 12.3v. turned on chassis disconnect and read 12.3 at B+ on back of alternator on batt sense terminal on alternator. started coach and ran at high idle and voltage at B+ on alternator read 11.78v. I assume from this test that all wiring between batts and alternator is good. From this indication is bad alt. The only caveat to this is with 12.3v showing on chassis batts still needed boost from house side. Thoughts please. Want to make sure before getting new alt.