[orbit1957]

On 698 I have two battery disconnect switches, one for the inverter bank and one for the house. Without wiring diagrams it appears each of the two banks are dedicated. My question is why would these two banks be isolated from each other? I am contemplating installing a contactor that would merge the two banks. This would allow all the battery capacity to be utilized as needed to supply all electrical DC demands. Thanks for any feedback and suggestions.

[HoosierDaddy]

Are these two battery banks in addition to your engine start batteries? My Newell has a merge solenoid that is activated when the battery merge switch is in the proper position. It merges the engine batts with the house batts. I also have a seperate set of batts that can be merged or disconnected from the house batts with a manual switch.

[johnkosir]

712 has 2 sets of batteries 1 for engine and 1 for house and inverter

[Richard]

Check carefully the wiring to ensure what you think is accurate. Newell has done this several ways over the years. For a long time they provided a disconnect switch for the house batteries, BUT the inverter was wired direct. That could give you a nasty surprise if you didn’t know it, and thought you were shutting down the inverter by turning the switch off. They then moved to adding a separate switch from the inverter.

Why two switches. One of them will isolate the house batteries from the battery merge diode and the solenoid diode. One will turn off the inverter. There are some circumstances where you might want to do one or the other.

Don’t assume anything about the red wiring. One year I took the time to disconnect all the big red battery cables and ring them out. It was NOT as I thought it was.

[TJ Clark]

Richard can you expand on "One of them will isolate the house batteries from the battery merge diode and the solenoid diode." I am not understanding what this means.

[orbit1957]

Yes I have a total of three disconnects. One in engine compartment and the other two switches in question located in the 6 pack battery bay. Three batteries are wired for inverter and three for the house with dedicated disconnects on the ground leg. I have confirmed that the two circuits inverter/house are isolated from each other. Sequencing the two disconnects by leaving one on and the other one off and vise versa. It is logical that what Richard says makes sense. My thinking it would also be useful to have the capability to merge the inverter/house batts especially if one or the other becomes depleted.

[TJ Clark]

Do all 6 pack batteries feed the inverter?

[Richard]

I can just speak of the coaches with two house battery switches that I have laid hands on.

One of the house battery switches connected directly to the inverter. So the charger part of the inverter would be disconnected via this switch.
All six batteries were connected in parallel and fed the inverter and the 12V loads.
The second house battery switch was for all the 12V loads and also provided the connection to the engine charging.

This is where some explanation of the how the late nineties / early 2000 coaches were configured. In the engine bay, in the right rear electrical compartment the alternator wiring is run to TWO devices in parallel. One is a NOCO diode box that allows the alternator current to flow automatically to both the chassis and house batteries. Because it is a diode based system, it does not allow current to flow in the opposite direction, meaning the diode box will not allow the house and chassis batteries to connect with one another. The center post on the NOCO is from the alternator, it has one post for the chassis batteries and a second post for the house batteries.

In parallel with the NOCO is the merge solenoid that allows you to manually connect the house and chassis battery systems. If the batteries are merged, the battery banks are essentially one, meaning the alternator charges both, the inverter charges both, and any load drains both. So if you merge them, and run the inverter all weekend it will also drain the chassis batteries. The merge solenoid is UNLIKE the NOCO, it allows current to flow both ways. Newell routinely tells people to leave the batteries merged, I routinely tell them it’s a sure fire way to find yourself in a no start situation.

This setup gets a little more complicated if you have replaced your house batteries with Lithiums. It is complicated because the standard NOCO battery isolator does not play well with Lithiums because of the difference in charge voltage between Lithium and Lead Acid, and because the internal resistance of batteries using the two different technologies is very different. So, in my case the NOCO did nothing to charge the house batteries when I changed to lithium. However, the merge switch still works as it always did. There are differences of opinion on charging lithiums with the alternator. I am not going to do it except in an emergency with my standard Leece Neville setup. It’s a sure way to fry the alternator. If you have the monster 50DN, or you a device for limiting the charge interface between the two banks, then have at it.

I am not disputing what Orbit is saying about the way his bank is wired. Who knows how any of our machines are wired after a succession of owners. Someone may have wired it that way on purpose

[TJ Clark]

What lithium units are you using? How many AH total for the house? How do you charge the house storage?

[Richard]

I am using a home made bank that Forest Olivier built almost ten years ago from Balqon cells. It’s a 1000 aHr. I charge it with the Magnum 2812 inverter/charger. If I boondocked a lot, I would add a second charger since the Magnum only puts out about 130 amps at full blast and the batteries would easily take a higher rate of charge.