chassis alternator charges house batteries?

[stanbriggs]

2007 Fleetwood Providence 40E. Newbie owner.
when parking my RV for more than a couple of weeks I keep finding the house batteries completely discharged. while investigating why this was happening I saw in the owners manual that the chassis alternator is supposed to be charging the house batteries when the engine is running.
can anyone confirm this?
thanks,
Stan

[d23haynes57]

Yes, it should. But how would that help when parking it for a couple of weeks? Are you connecting to power? The house batteries should be getting charged when plugged in. If not, then you will need to do some extra steps to turn off all loads probably having to disconnect the batteries for storage.

[stanbriggs]

dennis,
good observations.
my question would not help when i'm parked for a couple of weeks (no trickle charging available).
my question was around why i can start the engine but do not get any house battery charging.
thanks for the confirmation. i guess i'll need to take it in for service with a group that understands class A RVs.
thanks,
stan

[NoviBill]

Originally Posted by d23haynes57

Yes, it should. But how would that help when parking it for a couple of weeks? Are you connecting to power? The house batteries should be getting charged when plugged in. If not, then you will need to do some extra steps to turn off all loads probably having to disconnect the batteries for storage.

^^^ This ^^^

If you are not plugged in and don't have solar, your batteries will be drained by a few parasitic loads that are always on. The main one being the propane and CO detector (that should be replaced every 5-8 years for your safety).

Most motorhomes have a batter disconnect (red switch just inside door) that disconnects the house batteries compltly (or nearly so) and allows the RV to sit for months without draining the battery.

[PS89]

The main one being the propane and CO detector (that should be replaced every 5-8 years for your safety).

I've seen this time and time again as a power consumption problem and the concern is way overblown. If the detector is the common Atwood unit, they only draw about 40 mA. That's less than 1 AHr per day. De[ending on the capacity of the battery bank, the detector should not deplete the batteries for many weeks or months.

As for replacement interval, the manufacturer's specific recommendation should be followed. As noted, that typically runs between 5 and 7 years of operation due to degradation of the detector's sensor element.

[chuckftboy]

Then there is the question of how old are the house batteries? While new batteries may hold charge for 6 months or longer when new, 3 or 4 year old batteries will deplete much faster when not in use.

[nickrides]

Stan

If your house batteries are going dead after a couple of weeks You have some Parasitic style draw/
YouTube " Finding a Parasitic battery draw"

Plenty of info there.
You'll need a VOM
Some parasitic draws are very hard and sometimes impossible to find
Let me tell you how I know this
Sometimes installing a master cut off switch is the only solution to these impossible fixes.
Cheap and easy to install.
Nick

[stanbriggs]

I would have thought that turning the main and auxiliary systems to off would prevent any draw. No?

[Lt Dan]

Originally Posted by stanbriggs

Attachment 437233
I would have thought that turning the main and auxiliary systems to off would prevent any draw. No?

Not necessarily. On some coaches the inverter is wired directly to the house batteries and do not go through the house disconnect. If that's the case with yours, the inverter will drain the batteries in a matter of days.

As for the alternator not charging the house batteries, you should have a merge/boost solenoid or BIRD charging system to charge the house batteries. That system is apparently not working correctly. I had the same issue with our Itasca and it turned out the merge solenoid was defective.

[YC1]

Owning an RV you need a voltmeter, tools, and a check book. Often all three at the same time.

A voltmeter is a must and will answer your first question as to weather the house batteries are getting charged while the engine is running.

Grab a note pad and your voltmeter and being by measuring each battery and then also measure them as they are built in their bank. That is, the engine may have two batteries. Knowing the voltage on each with the negative leads off will give you some sense as to the batteries potential. Same with the bank of 6 volt batteries.

Once you have logged these measurements and cleaned those wires and tightened them as you go very carefully after taking several pictures to ensure you don't leave a wire off, begin the overall test.

Measure those two banks of batteries, the engine and the house batteries without being connected to shoreline, generator or engine running. Solar can throw a twist into the measurements but lets set that aside for know as the measurement you take with no charging systems running will tell us that.

Now start your engine and take those voltage reading again. NOT separating batteries but measuring across the engine bank and the house bank. You can get lots of simple diagrams to give you an idea of where to measure.

The engine batteries should be seeing 13.7 ish, and the house batteries as well after a couple of minutes of warm up time. There can be delays built into the charging systems.

Lets assume you see both banks getting charged. Shut the engine off and repeat the test with the generator running. Hopefully you will see both banks getting charged.

With this test you can probably assume shoreline power will give you the same results.

Now for the dead batteries. You need to find any battery cutoff switches that are very large and likely in or near the battery banks. Any remote (switch) is unlikely to give you the real isolation you need for storage.

Check your owners manual again and see if they suggest this. Those manuals are huge and there will be a test some day. Well, there already is. So read the book with your notebook close by and pretend you are trying to get an A on the next test.

There is a lot to learn with these beasts and I have give you some generalized information. Your Snow Flake will be different for sure.

[Random01]

I have Fleetwood RV and remote switch cuts off propane detector and converter, all the parasitic draws, perfectly fine for storage.
If batteries get low after a couple of weeks (assuming they were charged up well prior to that) sounds like bad batteries, parasitic draws like detectors usually wont take them down that fast, test them. See voltage drop after they get charged up and get load tester too. As mentioned above,you also should see a voltage between 13.4 and 14v on your battery bank when engine is running means batteries are being charged. Clamp amp meter can be used to check how many amps are going in.
If your start your engine after house batteries got low, it will usually take a while to truly charge up batteries, hours of drivng really, running engine for few mins would only give them a very small boost. Portable solar charger is a good thing to have if you don't have onboard solar system. Trickle charger for storage (they deliver may be 1amp) and I dyi-ed cheap one delivering up to 20 amps and use it with my folding portable solar panels as I camping full time.

[Persistent]

Looking at it from a different perspective:

Lead acid batteries must be stored fully charged for long life. Significant time stored discharged will cause "sulfation".

Fully charge for 14 to 18 hours with a high quality charger. This removes all normally deposited sulfate.
Fully recharge before battery terminal voltage drops below 12.4 volts. This prevents accumulation of sulfate crystals on the plates.

Many RV's have a switch near the entry door that disconnects 12 volt appliances. Some have two switches. One for house batteries and one for chassis batteries. Using these switches you may get 1 to 3 weeks before house battery terminal voltage drops below 12.4 volts. Crystals begin to accumulate.

There are possible 12 volt appliances that stay powered when the door switch is "OFF". The propane detector is often one of them. This is usually referred to "parasitic draw".

While the engine is "OFF", the two battery sets are electrically isolated. So engine start battery may work fine, while house battery continues to discharge.

To get longer times before needing a recharge, install a disconnect switch in the positive cable of the house battery, near the battery. Flooded cell lead acid batteries in good condition may last up 6 months. AGM batteries may last up to 12 months.

[Random01]

As I mentioned, in Fleetwood RVs at least, which I have, aux battery disconnect switch disconnects propane detector and anything else that is not negligeable. But you can just disconnect negative cable (after disconnecting battery switch) to observe battery discharge behavior if you don't trust your battery disconnect switch cutting off everything. I had stored house batteries for a few months on end without ill effects by using factory auxiliary battery disconnect alone, on Fleetwood RV. Typical parasitic draws should not discharge a good, charged up battery over 2 weeks.
As to de-sulfation, there are chargers with repair mode available, certain higher voltage is used in that mode. The problem they got to run for a while but not everyone got access to shore power, but one can take the battery out, bring it home and run repair chargers, which have questionsble success with bateries already gone bad.

[stanbriggs]

Would I be correct that I can trickle charge the auxiliary batteries by applying 12V charge across aux 2 negative and aux 1 positive?
Drawing is attached.