View Full Version : Merge Switch

07-10-2009, 02:57 PM
Hello to you all, After replacing the batteries, installing a batteryminder, and fixing air leaks as well as a whole bunch of little stuff, my '87 is running like a champ! My question is about the merge switch on the dash. When I'm going down the road, what position should the merge switch be in? I leave it in the neutral (center) position. All batteries are new in the coach. When I'm plugged in, do I leave it in the neutral position. What I do understand of that switch, is that I can use it to steal power if I need it. Is it used for any battery charging application? Is the up(forward) position engine batteries or coach batteries? I need a 101 lesson on the merge system! Thanks guys, Jennifer

07-10-2009, 04:49 PM
i am not the expert some of the others are, but know enough to be dangerous.

1. when the key is on, the batteries merge no matter what position the switch is in. that way when you are driving, both sets of batteries are being charged.

2. i don't know if there was any consistency on which way the switch was installed except the middle position is always UNMERGED.

3. either up or down, the result is the same. all batteries are merged.

4. the only difference between up and down is what set of batteries is powering the merge solenoid to actually merge the batteries. that way if one set or the other is low and cant power the solenoid, the opposite set will power the solenoid.

5. when staying without external power, i would recommend keeping the merge switch OFF so you can run down the house batteries and still get the DD to start, and or your genny.

6. a number of us also use a battery desulfider that newell puts on all of their new coaches to allegedly extend the life of the batteries. they are called powerpulse and are made by pulsetech



07-10-2009, 04:52 PM
Thanks Tom, I have a Battery Minder installed as well. Thanks for the info it is helpful. My instincts were right as far as leaving the switch in neutral. Jennifer

07-10-2009, 05:02 PM
Jennifer, sounds like you are getting your Newell in great shape.

First, I would recommend replacing the merge solenoid in the rear 12 volt panel (likely behind a door on the rear of the coach). Newell recommends replacing these every couple of years. Make sure you use a solenoid with a constant rating rather than a starter type solenoid that is only meant for being activated for a minute at a time.

The merge system should operate as follows:
Engine off, merge switch off: chassis batteries and house (coach) batteries are isolated. If the coach is plugged into shorepower or the generator is running, the battery charger (likely an old battery boiler/single stage charger unless it has been replaced) will keep the house batteries charged but the chassis batteries will start to discharge slowly.
Engine on, merge switch off: chassis batteries and house batteries are both charged by the alternator and if the generator is running by the generator's alternator.
Engine off, merge switch on (either position): chassis batteries and house batteries are both charged by the shore power or generator. If the generator is off and no shore power is available, both the chassis batteries and the house batteries will run down together (bad!!).
Merge Switch Up/Down Positions: on most non-Newell coaches, the merge switch is powered by the house batteries. This assumes that your chassis batteries don't have enough charge left to start the coach and that you have enough charge on the house batteries to activate the solenoid to tie the two battery banks together to get the coach started. The two position switch Newell uses does this in one position (up position I believe but I haven't verified that lately and someone may have reversed the wires on a particular coach). However, Newell provides the second position in case your house batteries are really drained down so you can power the merge solenoid off the start batteries to tie the two battery banks together so you can start the generator which is powered off the house batteries.

Now, assuming that the merge system is functioning properly and that you have added the BatteryMinder to the chassis batteries and your coach is plugged in, both banks of batteries will be charging so you would keep the merge switch in the Off position. I use a Trik-L-Start unit to keep the chassis batteries charged while on shore power rather than the BatteryMinder. When driving the merge switch would again be in the Off position.

With the BatteryMinder on the chassis batteries and the coach plugged in, both sets of batteries will stay charged, although the house batteries will be overcharged with the original battery charger. You would only need to activate the merge switch if for some reason the start batteries didn't have adequate charge to start the coach or the house batteries didn't have adequate charge to start the generator. These situations are unlikely UNLESS you leave the coach unplugged from shore power for several days or weeks depending on what you shut down inside the coach.

I would STRONGLY suggest that you replace the battery charger if it is an original single stage charger. Either an Iota or Progressive Dynamic or Xantrex 3 or 4 stage charger will make your batteries last longer. A good multi-stage battery charger will be less expensive over the next 6 years than damaging your house batteries with the single stage charger.

Hope I haven't beat this horse to death.

07-10-2009, 06:55 PM
Hi Michael, Great info! I have already replaced the merge solenoid. It's one of the first things I did when I was having troubles with the generator. The battery minder is hooked into the house batteries. Would it be better hooked into the chassis batteries? I'm still unclear..perhaps its the friday fuzz in my brain today.

Engine off, coach plugged in to shore or generator running, = merge in neutral.

Engine off, merge on, both sets of batteries will run down together.

If I am plugged into shore or the generator is running, will all batteries get charged or just the house batteries with the switch in neutral?

If the engine is running, the alternator is charging the chassis(engine)batteries regardless of what position the switch is in.

Yes I have the old style battery charger. I am looking into getting that changed. I don't want an inverter/charger, just a charger. I have 6 deep cycle marine, monster,expensive, heavy batteries in this coach. The previous owner added a few extra to run an additional inverter for the microwave/convection oven.

I will reread you reply and work it out in my brain. Let me know if any of my re-iterations on what I think you said are not correct. Thanks again and again, Jennifer

Richard and Rhonda
07-10-2009, 07:20 PM
If I am plugged into shore or the generator is running, will all batteries get charged or just the house batteries with the switch in neutral?

Only if you have a battery minder or trickle charger that diverts a small amount of current to the chassis batteries. If you don't have one, and your chassis goes flat, you can flip the merge switch and the chassis batteries will get charged.

If the engine is running, the alternator is charging the chassis(engine)batteries regardless of what position the switch is in.

Yes, but the house batteries are being charged also, because turning on the ignition key merges the batteries.

This can freak you out when you put in your new charger and run the gennie while driving. The first stage charge will be above 14 volts and above where the regulator on the alterator cuts off, so while the charger is in bulk mode >14 V you will actually see the ammeter showing discharge on the chassis batteries. I spazzed out the first time it happened. When the bulk charge is over and the charger automatically goes to a lower voltage setting the alternator will pick up again and the ammeter will tilt in the charging direction.

07-10-2009, 08:09 PM
Thanks Richard. The generator certainly adds excitement to the equation. I now try to remember to turn off the charger on my ProSine before I start the engine and generator since my ProSine will actually get an over-temperature error if I am running the charger while the generator and the engine are running. Doesn't happen otherwise.

Jennifer, yes, the battery minder would be better on the chassis batteries and put a multi-stage battery charger in place of your existing charger, since you don't want an inverter/charger.

With that setup, as long as you keep the Newell plugged into shore power, you should never have to move the merge switch from the OFF position.

Wally Arntzen
07-10-2009, 11:13 PM
Jennifer, I have a Truecharge 20+/40+ muti-stage battery charger that I got at campersworld that works perfict. It can charge 3 banks of batteries and only charges the bank that needs charging. When your parked or have your coach at home and pluged in it only charges the the bank that is using power. If your living in the coach and using power it will charge as needed and the engine batteries will be charged at lower intervals due to no or less usage. It can be mounted horizantally or vertically and have mine on the back wall of the bay where the power cord is located. It can be used for any type of batteries and has a switch to change from flooded "wet" or sealed lead-acid batteries.It can be set to provide the correct charging cycle for sealed lead acid batteries using gel technology or AGM (absorbed glass mat) technology.
I don't recall what I paid for it but I think it was in the $350.00 area. It works great and I highly recomment it.
I also commend you on the effort and determination you have put into getting your coach road ready.