[Doug Musick]

I'm switching my house batteries to Lithium.  Trying to figure out the best way to install protection for the Alternator if I leave it hooked up to the house battery bank.  I know the low charge resistance of the lithium batteries will cause the alternator to burn out.  What I don't know is the best way to deal with it and how to actually do it.

For now I am leaving my house system as a 12v system to simply the install and to keep the price down. I will continue using my existing inverter and won't need a DC to DC inverter to feed the 12v house systems and can hook them up directly to my 12v bus bar.

So my questions:

How and where is the alternator usually wired into the house system on Newells or your Newell?

What equipment would you recommend I install to protect my alternator? And details on how to install said equipment.

Or do I even need to hook the alternator up to the house battery bank?  What are the cons to disconnecting the house side from the alternator completely and only using it to charge the engine batteries?  I know some of them but I'm sure your collective wisdom can enlighten me.

[RobSC]

I've seen Wakespeed units on boats and motorhomes.

https://www.wakespeed.com/product/ws500-...regulator/

[Richard]

The connection point on your coach between the alternator(chassis batteries) and the house side is the merge solenoid. If you have the large blue diode isolator, but I don’t think you do, the situation gets a little more complicated.

This is where you are going to have to do some homework on your specific coach.

In the electrical box in the engine bay, find the merge solenoid. Determine if the merge solenoid is automatically energized when the ignition switch is on. If it is, then you will have to disable that circuit. By keeping the merge solenoid inactive, the alternator will be isolated from the house batteries. Manually activating the merge solenoid would allow you to charge the batts from the alternator.

When you stare at that solenoid, the house is one side terminal, and the chassis is on the other side.

There are other ways as you have already mentioned. My OPINION, and it’s not the gospel, is that trying to charge lithiums from the alternator on a Series 60 unless it has a 50DN alternator is a problem going somewhere to happen. I have been running a lithium setup for 10 yrs now without ever charging from the alternator. We go pedestal to pedestal normally, and usually with the gen running the AC units. Others have different needs with regard to boondocking and energy management. It depends a lot on how you plan on using the coach.

[Doug Musick]

I am normally plugged into shore power except when driving, and then if it's warm out the gen is on to power the AC and thus everything else. When not hooked into shore power and with the generator off, my house batteries have plenty of power to cycle the aqua-hot blowers and pumps, fridge, water pumps, microwave etc. for 8 or more hours. With the increased capacity of the Lithium batteries, I should be able to boon dock/drive for about 16 or more hours without any other power source. In cool weather it would be nice to occasionally boondock for several days, but it just isn't feasible with all the creature comforts in the Newell without a Gen or an impressive solar array to keep things charged up.

I'm leaning to just inactivating the solenoid as you described, maybe leaving it wired and installing a manual on/off switch on the house side of the solenoid in case I need to merge because of a dead bank (either one) so I can start the Gen or Engine if needed in a pinch. That would eliminate the risk of the merge solenoid switch being accidentally bumped by me or my grandkids, and accidentally burning up the alternator.

I'm sure I don't have a blue diode isolator, at least not in the engine bay electrical box with the chassis wiring and remote start. I'll look again tonight.

[BusNit]

I installed solar panels which theoretically on paper produce 3600 watts. I can get around 2900 tops for a few hours. I did not integrate the engine alternator to my lithium's since as Richard said, it is a problem waiting to happen. If I decide I need engine driven charging, I would add a second specific high amp alternator made for Lithium charging curves. I separated two of my house batteries for the generator and two for the engine start. My merge solenoid will separate the generator from the engine or use all four batteries. They are not tied into the lithium bank. Generator power will run the inverter which will in turn charge the battery bank. Shore power for the same. Solar panels will also jump in if needed when on generator or pedestal. Gotta love Victron equipment. Still learning to use it. For maintaining the lead acid batteries I have a single stand alone victron 25 amp battery charger for the generator batteries but would need to leave the merge solenoid on to keep the engine batteries maintained. Power comes from the 120v side of the inverter/battery bank to run it. I may add a second victron battery charger for the engine batteries so I don't have to use the merge solenoid when parked. It too will run from the lithium battery bank/solar/inverter as needed.

[folivier]

When I first installed my LiFePO4 sytstem that Richard is now enjoying I added a Balmar external regulator. It took a bit of tweaking to get it set right for the 1000 amphours. I found that the alternator would throw a belt before it would overheat. After getting it set up correctly it worked fine for charging the LiFePO4 system.
Balmar has updated their regulator for LiFePO4's and now has an app for tweaking the settings. The one I used had a magnet to change the settings. https://balmar.net/application/rv/
On my Foretravel I added 3 BattleBorn 100amp batteries and used a Victron 30amp DC to DC charger which replaced the isolator. It worked fine but limited the charge to 30amps which kept the alternator happy.

[Doug Musick]

No blue diode isolator in the engine bay electric compartment. Although the merge solenoid has many wires connected to the input and output sides, however only one big one (4/0) on the in and out terminals, which should be the alternator and the and the house battery bank lines. I'll try tracing the other lines when I have a little more time. One of them was still good size, probably an 8-gauge wire. So, I'm really curious to see what it is feeding or pulling from.

If I install a DC-to-DC charger, what would that schematic look like?

There should already be a wire going from the alternator output somewhere (maybe at the alternator or maybe a splice near the engine batteries) that goes to the house batteries. Do I simply break that line and put the DC-to-DC charger in the middle and that's it?

[Richard]

Doug,

If I read your comments correctly, and you know reading is not a strong suit of mine, then you are looking for two things. One, to be able to merge the chassis and house side for emergency start. Two, to be able to charge the house side safely without frying the alternator.

If that is correct, it may be even easier than you proposed. Here would be the steps.

Determine if the merge solenoid is automatically closed when the ignition is on. If so, disable that feature. There may be multiple trigger wires to the solenoid. If so find the one that is hot when the switch is on. If the merge has other triggers then they may be the dash switch activated ones. If so, you are home free.

Second, determine of the heavy cable terminals on the merge solenoid is house, and which is battery. Label for posterity, or when you reach my age and have CRS. If you want to use a DC to DC, you would simply wire it across the two heavy terminals. Of course it’s one directional so you have to know which side is house and which is chassis.

One thing to keep in mind when wiring up a DC to DC setup, or any other connection between house and chassis is you may not totally disconnect the voltage with the manual disconnects. It is always good to confirm with a Voltmeter that the circuits are dead.

[Latitude 28]

Doug,

If I read your comments correctly, and you know reading is not a strong suit of mine, then you are looking for two things. One, to be able to merge the chassis and house side for emergency start. Two, to be able to charge the house side safely without frying the alternator.

If that is correct, it may be even easier than you proposed. Here would be the steps.

Determine if the merge solenoid is automatically closed when the ignition is on. If so, disable that feature. There may be multiple trigger wires to the solenoid. If so find the one that is hot when the switch is on. If the merge has other triggers then they may be the dash switch activated ones. If so, you are home free.

Second, determine of the heavy cable terminals on the merge solenoid is house, and which is battery. Label for posterity, or when you reach my age and have CRS. If you want to use a DC to DC, you would simply wire it across the two heavy terminals. Of course it’s one directional so you have to know which side is house and which is chassis.

One thing to keep in mind when wiring up a DC to DC setup, or any other connection between house and chassis is you may not totally disconnect the voltage with the manual disconnects. It is always good to confirm with a Voltmeter that the circuits are dead.

Doug, In this scenario that Richard talks about, if you would want to charge "Bi-Directional" this DC to DC charger can do the trick....https://www.sterling-power-usa.com/SterlingPower12voltto12volt-40ampbatterytobatterycharger.aspx

[folivier]

Sterling makes good stuff but if you're already committed to Victron then their DC>DC charger integrates nicely. That's Victron's biggest feature is their integration.