I don't think my house batteries are charging while driving

[DarkVader]

I'm trying to troubleshoot and determine whether or not my house batteries are being charged by my engine while driving. Problem is my house batteries are not holding much of a charge anymore. I'm pretty certain at this point that the batteries charge while on shore power ONLY IF the inverter is on. Here's what else I know:

1. the batteries will charge and hold for at least a few hours when plugged into shore power and the inverter is turned on
2. the voltage at the batteries are around 13-14 volts when plugged into shore and inverter on (though this depends on what stage of charging it's in)
3. voltage at terminals are around 11.2 volts when plugged into shore but inverter off
4. after sitting a week the batteries died. I drove it for about an hour and parked it for a few hours. I did not check voltage at this time. Later started it up and voltage was 3.3 volts while engine running. inverter being on or off didn't matter, wasn't enough voltage. I feel the 1 hour trip should have gotten the voltage up higher than 3 volts, even if the batteries are really bad.
5. chassis batteries hold charge just fine and are not in any way being depleted, and so the alternator should be okay
6. There is a button on the dash which allows you to start the engine using the house batteries. I guess you hold it down while starting the engine. It appears to do nothing as the voltage measures at the house batteries does not change at all when the button is held down.

What are some common points to look at in this case? It also has a small solar panel that was original and it constantly says 12.5 volts while it's sunny. I don't think this is charging the battery at all either, but don't really know how to be sure. I read about the battery isolator online, perhaps this isn't working? But why would the isolator be charging the chassis batteries but not house batteries? Some guidance is appreciated!

[OldWEB]

First off, are all the battery terminals clean. I mean the actual connection part has to be shiny lead colored, not a dull lead color. Remove each connection and clean to the shiny lead (and copper - if used), a 'coating' will form between the connections that prevents a proper charge going thru.
The other question is how old the batteries are?

[rffowler55]

It sounds like you may have a couple of issues to track down: 1. Some of the inverters have a built-in charger, and not knowing your system setup, may be the primary source for battery charging outside of the alternator. If this is the case your inverter may need to remain on, check your inverter manual. 2. As previously stated above clean all of the cables to the batteries and inverter. 3. Charge the batteries to 100%, disconnect all sources of power except the batteries and with a volt meter check the batteries while under a load, google how to perform if needed. This will show if the batteries can be ruled out as the issue. 4. Doubt it is the alternator since you are not having an issue with the starting battery but using a volt meter to confirm this on the alternator would not take much time.

I strongly suspect the batteries since they are not retaining a charge.

[Ljwt330]

Couple of points.


First, if you don't have a manual for the inverter, look on line and find it.


Second, you should not have to have the inverter ON to charge your house batteries. Your inverter has dip switches on the back. Switch #4 should be OFF. This switch ties the charger function with the inverter function. Normally, when the inverter is OFF, the charger continues to charge the batteries once AC is detected. The remote panel is what you use to control the inverter functions and turning the inverter OFF at the panel should allow the charger to continue its function, but only if the dip switch #4 is OFF. Check that out on your inverter.

Your batteries are probably too low to receive a charge from the alternator. You can connect a separate charger and give them a charge and try again. If you can get the inverter/charger to produce voltage, connect to AC and let them charge fully.


I suspect the solar charger is wired to your chassis batteries, not the house batteries, so that voltage will not be available to the house bank.


The dash switch combines both house and chassis battery banks together. You need to keep the switch depressed for about thirty seconds or more for voltage to transfer. However, since your house bank is so low, you will be draining the voltage from your chassis bank. Again, that switch is basically to boost a low chassis battery so the vehicle can start and begin charging through the alternator.


I also agree with others that your house bank may be bad. Fully charge the bank and test each cell with a hydrometer.


Here is a link to the manual for your inverter, in case you don't have one.
https://www.xantrex.com/documents/Di...series%201.pdf

[wolfe10]

Since you know the batteries are shot, replace them and THEN troubleshoot both alternator and inverter/charger charging systems.

[donr103]

Great comments above.. just change out house batteries.. make sure you use a cell phone with camera and flash and record each connection before you touch them.. and review to make sure it recorded.. while coach batteries are out.. clean each connection with round wire brushes inside Eyelets.. do outside.. leave new batteries out and unconnected.. then go under hood.. disconnect negative on chassis battery and clean.. now the aux start relay does 2 things.. it should not be called aux start.. it can be used to start.. but what it mainly does.. is turn on after chassis battery reaches at a preset volts to then send eng alt, current to coach batteries.. it does this by a small black box. Real close to aux start relay.. I believe if you find the aux start relay and you will see 2 large battery cables and look closely and you will see two smaller 18gauge wires that activate it.. 1 goes to dash Switch and other to small black box.. here is the point... the wires get very corroded over time and need cleaning.. deep cleaning.. I use starting fluid or electric contact cleaner.. no smoking.. no sparks.. use cell phone with camera and flash and record each connection before you touch them.. then you have to pull each one off and wire brush the lugs and eyelets.. and reseal.. only then can you even begin to replace coach batteries and negative on chassis battery.. next you and confirm if the aux start relay, which really should be called combiner, relay. Because it combines both coach batteries and chassis battery when charging off eng alt, or when you depress the dash Switch.. after all that.. get someone to listen at the relay and you depress the dash Switch.. it should click, oh just a thought.. do this before you touch anything.. have helpers push dash Switch and you listen see if it's clicking.. 99% of just needs very good cleaning.. but you may have to start with replacing the relay.. easy.. when you are cleaning there should be some part numbers on it, record them.. also.. on the little black box.. very top.. there are some part numbers, record them.. for the most part I am talking about GM chassis but some cross over.. if new relay does not work, then next is little black box, if you want, and you know relay is old... just replace while there.. they are cheap.. buy the best upgrade you can afford and just change it out while cleaning.. the relay really takes a pounding.. it's on all the time when driving.. most rv'ers carry spares.. they burn up that often.. think about how big all those batteries are and how much load goes though that relay and how often you start and stop rv.. so I would if I were you.. . replace batteries and relay.. hope that helps some.. as always good luck and let us know what you did

[TriMoot]

Yes, good comments all, especially taking pics of all connections. I even drew a schematic to make sure I knew exactly where everything went.

I recently replaced all four of mine due to the PO never checking the water level. It took TWO GALLONS to fill all four of the batteries, so you might even check that.

But even after filling the batteries with distilled water and traveling 2500 miles all the while getting charged by the engine and generator, they still couldn't handle the microwave popping popcorn...Microwave kept shutting down. I think once the metal plates of the batteries are exposed they don't ever really come back.

So now the question...which batteries do you choose, and how many do you have? And if you have only two for the house, is there room for two more? If so, that would be great!

Also, I bought a 16 ton battery Cable Lug Terminal Crimper Crimping Tool, wire & ends, and made all my own cables. Worked really well. (This was on my old RexAir).

Also, while you're at it, you might even remove the tray (if you have one) and prep and repaint it. (Again, did that on the RexAir and NEED to do that on the new one). Then it's just a matter of checking the water and connections for corrosion once or twice a year.

Easy Peazy.

[DarkVader]

I don't want to spend hundreds on batteries if driving is not charging them. like I said, plugging into shore power absolutely for certain charges the batteries, as they hold a charge for a few hours before dying. With that said, I am wondering why driving around for an hour did not change the voltage of the house batteries. I suspect that the isolator might be bad, I just don't know where to find it.

All of you have mentioned very good points, but they are going beyond the problem at hand. I simply need to know why the alternator doesn't provide any voltage to charge the house batteries, even though shore power can charge the batteries. A bad set of house batteries certainly doesn't help, but I suspect the problem will be the same once I buy a new set. I'd rather not get to that point if I can solve the issue now.

All terminals are clean and yes the alternator is obviously working properly. I am going to check today to see if the batteries charged at all after being plugged into shore with the inverter off. Normally I must keep the inverter on in order to charge them. If not, I'll get the voltage of the house batteries to around 12v and see what happens with the engine on.

[Ljwt330]

Originally Posted by DarkVader

I don't want to spend hundreds on batteries if driving is not charging them. like I said, plugging into shore power absolutely for certain charges the batteries, as they hold a charge for a few hours before dying. With that said, I am wondering why driving around for an hour did not change the voltage of the house batteries. I suspect that the isolator might be bad, I just don't know where to find it.

All of you have mentioned very good points, but they are going beyond the problem at hand. I simply need to know why the alternator doesn't provide any voltage to charge the house batteries, even though shore power can charge the batteries. A bad set of house batteries certainly doesn't help, but I suspect the problem will be the same once I buy a new set. I'd rather not get to that point if I can solve the issue now.

All terminals are clean and yes the alternator is obviously working properly. I am going to check today to see if the batteries charged at all after being plugged into shore with the inverter off. Normally I must keep the inverter on in order to charge them. If not, I'll get the voltage of the house batteries to around 12v and see what happens with the engine on.

I understand your point completely regarding replacing the batteries, but you have more than one issue. You should try to eliminate possible failure points in a logical order. There are several steps to take before you have to deal with the batteries.

My thoughts.


Issue 1, your charged house batteries only hold a charge for a short period.

Issue 2, your AC inverter only seems to charge the batteries when it is ON. That is not typical.

Issue 3, your house batteries do not appear to be charging from the alternator.

All three of those issues could be from bad batteries, but not necessarily.


Issue 1. If you fully charge the house batteries, either by a remote charger or the inverter, and then they drain rapidly, that points to bad batteries. Fully charged means ~12.7 volts after charging has stopped for about an hour. It can take up to 4 hours + to charge the bank. Cost, zero $. If you are charging on AC via the inverter and it is ON, as you describe, as soon as you disconnect the AC, the inverter will be drawing power from the batteries and may also be inverting to a connected device. That will draw down your newly charged batteries if you're not careful.


Issue 2. Addressed in previous post. Still, measure the voltage at the inverter/charger output to the batteries when charging to see if you are getting adequate voltage. Cost, zero $.

Issue 3. Very well may be the isolation solenoid or controller. Keep in mind, the alternator charges the chassis batteries first, then switches to house. One hour of driving may or may not be enough to fully charge the house bank, especially if it was low.

[l1v3fr33ord1]

DarkVader-

Most folks on iRV2 don’t own a coach like yours. Nor do they know it’s history, as prior owners may have changed the factory design. So, it’s difficult to help you beyond offering ideas that occur “in general.” Some of them have been decent suggestions.

If you want to move ahead, including finding out how your coach is wired and what equipment it has, start by opening all the compartments and following the wire bundles. I have done that, even though I have what are supposed to be factory wiring diagrams.

It would not surprise me if you found a failed diode isolator between the chassis and house battery banks. And house batteries that need replacement.

You have the best chance of proving those guesses correct or incorrect, though.

[OldWEB]

You seem hell bent on going yer way, so let ME say that for the chassis alternator to provide a good charge to the house batteries requires the house batteries be securely grounded to the frame. This is assuming that all other components like the isolator (if you have one installed) are in working order. So check the grounding of both chassis and house batteries (or at least a Neg. cable running between the two).

Find the isolator (do you know if you have one?), they are easy to check and clean. Also mentioned, is there H2O in the batteries, even 'sealed' batteries can be opened, just be careful on that one.

Also you mention the house batteries can be 'dead' in a few hours. Unless you have a load on them, this should NOT happen. With disconnecting my house and chassis batteries, they will still have 12.7V after a long and cold winter hibernation.
Can you also confirm if you have a BCC?? Here is a newer unit that has one, with good pictures!
https://www.irv2.com/forums/f54/what...or-363834.html

[twinboat]

If you have what's circled in red, that's the battery isolator. Could be bad.

If you don't have something looking like that, look for an isolation solenoid, looking, like the item circled in blue. It could be bad.

Seems like your batteries are junk. Fixing the charging issue won't change that.

[DarkVader]

Like I said, I'm already aware my batteries are no good �� I'm trying to figure out why the alternator seemingly does absolutely nothing to the house batteries, yet shore power will charge them enough for a few hours. I appreciate that 1. Everyone is trying to help with all the issues at hand and 2. Each problem may be connected or related to each other.

I can't seem to find an isolator anywhere. But I did see a bunch of solenoid separators, as seen in the pictures. Why do I have so many?

[DarkVader]

I believe I figured it out, at least somewhat. There is an aftermarket solenoid wired between the chassis solenoid and coach solenoid. This aftermarket one is controlled by an on off switch in the cabin which I could never figure out. This solenoid, when switched on, connects the chassis batteries to the coach batteries. I looked all over and could not find anything else that allows the coach batteries to be charged by the alternator. There is no physical connection between the coach batteries and neither the alternator nor the chassis batteries, except for this solenoid. So I can conclude that the only way to charge the coach batts while driving is to turn this switch on. Strange that it is manual however....