M1078A1 cab and chassis electrical upgrades including AC

[hike]

Looking at the way we hope to use our M1078A1, an middle aged couple traveling with a dog or two in a land yacht, we hope to have a robust cab and chassis electrical and HVAC system separate from a habitat system. For many years we have camped and backpacked at more remote corners of the western US and hope to do much more with a habitat on our vehicle.

To the cab and chassis system we plan (need?) to add AC, GMRS, GPS, usb charging, stereo, power door locks, windows, and mirrors, backup and side cameras, map lighting, ecetera.

Concerns are the existing Niehoff 12/24v 100a alternator and LBCD as both appear expensive and may be difficult to replace while on the road. Our unit was purchased from a broker with 4 new batteries, though they are not AGM and only have 450cca. These batteries will likely get us through the habitat build out though will be replaced prior to any long trips, maybe sooner. The auto disconnect is also of some concern, though a new unit was installed right after purchasing our vehicle.

We welcome everyone's thoughts and suggestions.

Alternator: replace with 24v 200a (Prestolite A0014740JBH or similar, this unit has a J180 attachment that likely will require modifying the bracket, though it is a similar diameter and length to the Niehoff 12/24v 100a unit)
– requires adding 24/12v DC to DC converter (Victron Orion 2412v 70a already installed between PDP X1 and X2);
Batteries: two 12v 1150cca 100ah in series (Napa BAT9837 or similar).

@Ronmar has shown the existing electrical system operates well on two batteries even without replacing the undersized alternator. With the addition of a 24v 200a alternator a second 24v battery bank could be added to run additional accessories, including all electric AC and provide back up batteries if needed for cold starting. Replacing the LBCD with a smart battery combiner accomplishes this goal well and eliminates a potentially expensive and difficult part to locate.

LBCD: replace with a smart battery combiner (Victrom Cyrix-ct 220a or similar);
– rewire the feed to IAH relay and add a voltage sensor connected to the dash indicator light;
– add a second two 12v 1150cca 100ah in series (Napa BAT9837 or similar) to run non-essential accessories.

Add a Victron Smart Battery Protect 220a between the non-essential loads and second battery bank to insure the batteries are not depleted while engine is off.

Such accessories could include an electrical roof top 24v AC (Nomadic X3 24v AC or RedDot E-6100) drawing 55a to produce 12,480btu, along with power door locks, windows and mirrors, back up and side view cameras and screens. Stereo, Sirius and GMRS radios. GPS and usb chargers for tablets, phones, laptop, handheld gps. Anticipated 24v load would be between 100a - 150a.

An electrical AC unit offers plusses and minuses. On the plus side with a larger alternator it eliminates yet another added load from a compressor (minor plus), allows AC use while the engine is off, and potentially being wired into the much large habitat system in the future. On the minus side it is less than 15,000btu and the Gen2 RedDot dash units provide over 30,000btu? Our 2,600 sqft house has only 48,000btu of cooling so, 30,000 sounds like more than we need, but I could be wrong as the house is much better insulated than the cab will be even after we insulate it.

It sounds complicated, though it uses much of the existing wiring while replacing items that are either difficult to locate while traveling, more expensive than needed, or underrated for the potenial loads in a straight forward, easy to maintain way.

NOT USED Here is the simple schematic in progress REVISED BELOW in post 19:



Thank you for your comments and suggestions. We are looking forward to making it better–

 

[Keith Knight]

I’ve done a lot of what you wanting to do and tried posting it on my thread on here.
Keith’s M1078A1 Project Overland

 

[hike]

I have read a lot of your thread and obviously need to do more. Thank you—

 

[Keith Knight]

I keep considering an alternated upgrade. But mine has done everything as is. It’s hard to justify when everything is working. I could upgrade to the 200 amp and it could fail as well.

 

[hike]

I keep considering an alternated upgrade. But mine has done everything as is. It’s hard to justify when everything is working. I could upgrade to the 200 amp and it could fail as well.

Right. And you have a mechanical AC compressor so how much DC load do you really have?

 

[Ronmar]

I would not put any form of disconnect between the alternator and the batteries/load. HardWire it in like you show the starter.

it is considered poor form and dangerous to disconnect the load from a running alternator. The electrical section in any automotive service manual usually includes this caution… The LBCD and disconnect relay used on the LMTV is the only place that I have seen something like this done EVER in 40 years of playing with power systems, and I don't think is was a very good idea. They could have done it better, like dropping the control power and collapsing the field first, then disconnecting the batts and re-flashing the control power to get the alt back online with just the truck loads connected…

It takes a little bit for the alt field to collapse, longer on a brushless as it has to collapse first one field(fixed), then a second(rotating) to remove output. This can cause a massive voltage spike(can be over 100V), because the field collapse doesn’t begin until the alt sees an over-voltage and commands a reduced field, the greater the load and field, the greater the spike. I believe Neihoff got away with this by incorporating a large bank of capacitors into the LBCD to try and catch and absorb the alternator voltage spike. Not a very good design IMO…

 

[Keith Knight]

So I drive it often enough and the solar keeps the truck batteries topped off. While driving, rarely at night, AC/Heater blower motor which is typically turned to low speed is also got two phones charging and a garmin gps, power windows that are just a few seconds, oh the biggest draw is probably the two Victron Orion-Tr Smart 12/12-30 isolated DC/DC chargers that charge the house batteries while driving.
I’ve never put an amp meter on it to determine what it’s actually drawing.

 

[GeneralDisorder]

I've got the Red Dot gen 2 system in my truck and it works great. I also have a 24v DC unit in the habitat and it...... blows cold air. Admittedly the habitat is a dark color and aluminum - the awnings help and I've got real big windows to assist with ventilation. The reality is it's really only useful for sleeping at night when direct sun isn't fighting it and I I don't plan to seek out climates that are crazy hot - the truck can drive itself to more hospitable environments.....The cab is a lot of glass and even with insulation it's a pretty ugly environment for an AC. The Red Dot is pretty powerful but you get up around 100+ degrees outside and with all that glass it's still tough to keep it much more than 25 degrees cooler than ambient. Half the power? Nah I wouldn't want to modify the cab for that - plus without the heat/defrost integration it's not going to super charge the defrost which is like half the benefit of having AC. And the 24v units draw a LOT of amps - mine is near 40A quite a lot of the time. It's a very power hungry appliance. The engine driven compressor by comparison - the C7 doesn't even notice it's there. I'm much more likely to be driving THROUGH a hot environment to get somewhere I actually want to be so having ultra powerful AC for the cab is high on my list - plus you really can't understand how awesome the defrost works with the dry air provided by the AC till you experience it.

 

[hike]

I would not put any form of disconnect between the alternator and the batteries/load. HardWire it in like you show the starter.

it is considered poor form and dangerous to disconnect the load from a running alternator. The electrical section in any automotive service manual usually includes this caution… The LBCD and disconnect relay used on the LMTV is the only place that I have seen something like this done EVER in 40 years of playing with power systems, and I don't think is was a very good idea. They could have done it better, like dropping the control power and collapsing the field first, then disconnecting the batts and re-flashing the control power to get the alt back online with just the truck loads connected…

It takes a little bit for the alt field to collapse, longer on a brushless as it has to collapse first one field(fixed), then a second(rotating) to remove output. This can cause a massive voltage spike(can be over 100V), because the field collapse doesn’t begin until the alt sees an over-voltage and commands a reduced field, the greater the load and field, the greater the spike. I believe Neihoff got away with this by incorporating a large bank of capacitors into the LBCD to try and catch and absorb the alternator voltage spike. Not a very good design IMO…

Thank you. With leaving the existing disconnects in I didn't think about moving them to the ground side.

I am going to have to go back to the LBCD schematic. I recall folks are cutting out the LBCD disconnect function, connecting 12v and 24v loads to 12v and 24v bats, respectively, I assumed that drops the capacitors out of the circuit?

 

[aw113sgte]

Thank you. With leaving the existing disconnects in I didn't think about moving them to the ground side.

I am going to have to go back to the LBCD schematic. I recall folks are cutting out the LBCD disconnect function, connecting 12v and 24v loads to 12v and 24v bats, respectively, I assumed that drops the capacitors out of the circuit?

Yes if you connect the loads directly it eliminates the function of the capacitors.

 

[Ronmar]

Well the caps are built into the LBCD, so removing it removes the caps.

i would NOT put the disconnects on the ground side. Again, you do not want to disconnect the alt from the batteries while still leaving it connected to the rest of the electrical system.

the issue with ground side disconnects on a dual volt system is it can still allow a 12v circuit between 12 and 24 which can reverse power the 12v circuits. But that only applies if you are drawing 12v from the batteries. Deriving 12v from a 24-12 converter fixes that potential issue as removing ground powers down the 24-12 converter…

 

[hike]

Okay. Now I am feeling like I am working a 'flux capacitor' obviously I don't know the electrical as well as I wish.

Reroute the manual disconnect before X1 leaving the batteries, alternator and starter all direct wired to each other. The LBCD is gone, so nothing to activate the auto disconnect, though best to drop it and reroute the 1008 wire for the engine compartment and left knee switches?

Does that allow the batteries to take the place of the LBCD's capacitors? I still want to understand that 'flux capacitor' thing
Edit: or by adding the 24v 200a alternator and Victron battery combiner (Cyrix) the overload issue is managed by the Cyrix, only charging the second bank once the first is fully charged and their draw drops to allow the second set's draw to be added?

 

[hike]

I've got the Red Dot gen 2 system in my truck and it works great. I also have a 24v DC unit in the habitat and it...... blows cold air. Admittedly the habitat is a dark color and aluminum - the awnings help and I've got real big windows to assist with ventilation. The reality is it's really only useful for sleeping at night when direct sun isn't fighting it and I I don't plan to seek out climates that are crazy hot - the truck can drive itself to more hospitable environments.....The cab is a lot of glass and even with insulation it's a pretty ugly environment for an AC. The Red Dot is pretty powerful but you get up around 100+ degrees outside and with all that glass it's still tough to keep it much more than 25 degrees cooler than ambient. Half the power? Nah I wouldn't want to modify the cab for that - plus without the heat/defrost integration it's not going to super charge the defrost which is like half the benefit of having AC. And the 24v units draw a LOT of amps - mine is near 40A quite a lot of the time. It's a very power hungry appliance. The engine driven compressor by comparison - the C7 doesn't even notice it's there. I'm much more likely to be driving THROUGH a hot environment to get somewhere I actually want to be so having ultra powerful AC for the cab is high on my list - plus you really can't understand how awesome the defrost works with the dry air provided by the AC till you experience it.

Thank you. I understand your comments and they are well thought out.

What brand 24v unit did you install in your habitat?

I have thought a lot about the defrost. Recently tested it during our low teens cold snap with my wet dog riding shotgun. I learned that these trucks need to warm up before being driven for several reasons, the -10 even says so; I should have some sort of radiator cover in cold weather, especially with the EcoHubs; and at the right operating temperature our defrost works well. With an AC at 78° pulling out moisture it will be even better. Not as good as a Gen2 pulling out water then heating the same air, but better than a '65 mustang in a Utah snow storm. You have helped me greatly on issues and I appreciate your thoughts. You always make me think.

Our 2,600 sqft home in the Texas hill country has 48,000 btu's and lots of windows, perhaps we do not require as much cooling as you all? Over 12,000 btu's sounds huge for 48 sqft, through I can run this though our HVAC sizing software we use for a home. Always making me think—

 

[Keith Knight]

I’m running a 12,000 btu mini split AC with a heater(only for back up heat) after 14,000 miles the mini split has performed great even when it’s over 100 degrees. And you can’t beat the whisper quite operation of it. Just wish it could blend hot and cold for the cold damp mornings to keep the humidity low. But have found running the diesel Eberspacher hydronic heater on low and running the AC does a great job at keeping the humidity low.

 

[hike]

Okay. Now I am feeling like I am working a 'flux capacitor' obviously I don't know the electrical as well as I wish.

Reroute the manual disconnect before X1 leaving the batteries, alternator and starter all direct wired to each other. The LBCD is gone, so nothing to activate the auto disconnect, though best to drop it and reroute the 1008 wire for the engine compartment and left knee switches?

Does that allow the batteries to take the place of the LBCD's capacitors? I still want to understand that 'flux capacitor' thing
Edit: or by adding the 24v 200a alternator and Victron battery combiner (Cyrix) the overload issue is managed by the Cyrix, only charging the second bank once the first is fully charged and their draw drops to allow the second set's draw to be added?

Continuing to think about this system. With two separate 24v 100ah battery banks connected through a combiner is there any need for the LBCD or existing autodisconnect next to the battery box?

A 28v 200a (5,600watts) alternator, provide 12v at PDP X3 with Victron 24/12 70a DC to DC converter

Charging normal M1078A1 loads
2- 12v 100ah batteries in series (24v 100ah or 2,400watts), cab and chassis battery bank connected to existing M1078A1 electrical system;
running the truck and chassis 24v 30a (720watts);
56% of alternator capacity.
Something must go terribly wrong to overload the system, making the LBCD and auto disconnect extra baggage adding complexity and expense to the system. Reconfiguring the system this way eliminates the need for the LBCD and auto disconnect (next to the battery box on the A1).


Add a second battery bank
2- 12v 100ah batteries in series (24v 100ah or 2,400watts), to run added accessories.

Charging normal M1078A1 and added loads
Two 2- 12v 100ah batteries in series (24v 100ah or 2,400watts each, 4,800watts combined);
running the truck and chassis 24v 30a (720watts);
99% of alternator capacity.

Add a smart battery combiner to create two separate 24v 100ah systems, (M1078A1 bank always connected to alternator and added loads bank connected by battery combiner) and manage charging each. Prioritize the M1078A1 bank to keep starting batteries charged and running the basic truck systems fully powered. Battery combiner allows second battery bank to assist during start, if needed.

Battery combiner specs, using 230a unit:




Double voltages for 24v system

Using the battery combiner's parameters if the alternator sees voltage less than 26v it remains open, not charging the second battery bank for additional loads. Once the voltage rises over 26v one the first bank and typical loads it connects the second battery bank and added loads. The lower the voltage the longer the delay before connecting, allowing the alternator to 'rest'. Once connected the parameters allow the combiner to disconnect the second battery bank. During low voltage events the disconnection is quick, high voltages allow for more charging before disconnect. In the event of a voltage spike over 32v the second bank is disconnected immediately. The first bank is always connected.

With two separate 24v 100ah battery banks connected through a combiner is there any need for the LBCD or existing autodisconnect next to the battery box?

 

[Ronmar]

The design of the LBCD with the capacitors was as you mentioned, to provide a “load” for the alternator in the event it commanded a disconnect of the batteries. Think of it like one of those runaway truck ramps with the loose sand and gravel. It catches the trucks(alternator) energy when the brakes(batteries) are not there to do so because of a disconnect. That way the rest of the cars on the road(rest of your electrical system) doesent have to absorb the trucks runaway energy…

 

[GeneralDisorder]

Thank you. I understand your comments and they are well thought out.

What brand 24v unit did you install in your habitat?

I have thought a lot about the defrost. Recently tested it during our low teens cold snap with my wet dog riding shotgun. I learned that these trucks need to warm up before being driven for several reasons, the -10 even says so; I should have some sort of radiator cover in cold weather, especially with the EcoHubs; and at the right operating temperature our defrost works well. With an AC at 78° pulling out moisture it will be even better. Not as good as a Gen2 pulling out water then heating the same air, but better than a '65 mustang in a Utah snow storm. You have helped me greatly on issues and I appreciate your thoughts. You always make me think.

Our 2,600 sqft home in the Texas hill country has 48,000 btu's and lots of windows, perhaps we do not require as much cooling as you all? Over 12,000 btu's sounds huge for 48 sqft, through I can run this though our HVAC sizing software we use for a home. Always making me think—

It's a $400 Chinese 24v mini-split. Works well for what it is - blows 40 degree air a decent rate. I just don't think it would work as good or integrate as well as the Red Dot.

I should have said "defog" - the air drying for defrost becomes less necessary the lower you go in temperature - so that at the very frozen end of the spectrum you don't need to worry about fogging - you just need a radiator cover to get enough heat and you're good to go. It's at it's worst for fogging here the PNW when it's like 50 degrees outside and been raining for weeks. Get in the truck with wet clothes and a wet dog - you get a lot of fogging of the windows and the relatively warmer environment holds a ton of moisture (higher dewpoint). This is where I live and what my environment is like for months out of the year and I daily drive my truck so it may be more important to me than others but I'm also keenly aware of that situation from a daily driving perspective both before and after the Red Dot install. I just don't think a less powerful roof or cab wall mounted unit would do this job and it would be really annoying to have ice cold air blowing on me and the dog when I'm already wet to even attempt to try to dry the air going into the heater on recirc operation. In my case I can't put it on my roof since I have the HIMARS hatch up there so that would mean the back wall but I'm also keeping my spare carrier and all that since my truck is a factory 1079 van...... regardless the Red Dot leaves all that roof and wall space open for something else since it neatly fits into the location of the stock ugly heater. Also has much nicer controls......

Is your resistance to the Red Dot based on price or difficulty of installation? I can understand both concerns since it's definitely 5x to 10x the cost (dpending on what 24v unit you are looking at) and a lot more work but I can't come up with any real con's other than those - it's going to beat the looks and performance of a 24v unit and the 24v setups use so much amperage you really aren't going to run them for long with the truck off. In any case it's a diesel and they don't use much fuel at idle and in the military we always just let them run - we rarely shut them down if we are driving - SOP is to leave them running even when fueling.

 

[hike]

It's a $400 Chinese 24v mini-split. Works well for what it is - blows 40 degree air a decent rate. I just don't think it would work as good or integrate as well as the Red Dot.

I should have said "defog" - the air drying for defrost becomes less necessary the lower you go in temperature - so that at the very frozen end of the spectrum you don't need to worry about fogging - you just need a radiator cover to get enough heat and you're good to go. It's at it's worst for fogging here the PNW when it's like 50 degrees outside and been raining for weeks. Get in the truck with wet clothes and a wet dog - you get a lot of fogging of the windows and the relatively warmer environment holds a ton of moisture (higher dewpoint). This is where I live and what my environment is like for months out of the year and I daily drive my truck so it may be more important to me than others but I'm also keenly aware of that situation from a daily driving perspective both before and after the Red Dot install. I just don't think a less powerful roof or cab wall mounted unit would do this job and it would be really annoying to have ice cold air blowing on me and the dog when I'm already wet to even attempt to try to dry the air going into the heater on recirc operation. In my case I can't put it on my roof since I have the HIMARS hatch up there so that would mean the back wall but I'm also keeping my spare carrier and all that since my truck is a factory 1079 van...... regardless the Red Dot leaves all that roof and wall space open for something else since it neatly fits into the location of the stock ugly heater. Also has much nicer controls......

Is your resistance to the Red Dot based on price or difficulty of installation? I can understand both concerns since it's definitely 5x to 10x the cost (dpending on what 24v unit you are looking at) and a lot more work but I can't come up with any real con's other than those - it's going to beat the looks and performance of a 24v unit and the 24v setups use so much amperage you really aren't going to run them for long with the truck off. In any case it's a diesel and they don't use much fuel at idle and in the military we always just let them run - we rarely shut them down if we are driving - SOP is to leave them running even when fueling.

Unfortunately, so far I have yet to find a 24v heat pump for the habitat that I would install. That is likely pushing us toward adding a large DC to AC inverter /charger (Victron Quattro or Multiplus) to run a 110vac or 220vac LG or similar to heat and cool the habitat. We have have these 220vac LG units in our home and they work well. I understand @Keith Knight has a 3000va Victron Quattro which I believe would deliver about 15amps at 120vac. If we can stay away from adding AC power into the mix that would be my preference. A well built 24v minisplit in a small R17 space would likely be plenty.

Defogging is more difficult in moderate humid environments. If we could find a Gen1 or Gen2 unit and all the bits and pieces replacing the existing heater/defroster would be on the list. I have been watching Waterloo's site. Gen1 units, wiring kit, hose connection kit, no compressor kit, no condenser units. MME has a private label unit I $6,000? installed, though I didn't care for the fit and finish, and they may not be the quality of shop I prefer. Yes, the cost, complexity of installation and ability to repair and replace are all considerations.

Running the diesels is a common practice. My brother and I owned a sizable Caterpillar fleet in the '80's and '90's. Back then we participated in some testing of fuel use idling versus starting. The results were that idling more than 3 minutes consumed more fuel than restarting. Today's electronically controlled engines are even more efficient starting and sipping fuel. Perhaps, the timing is different today? Being able to run the AC in the cab while the engine is down 10-30 minutes is a goal for us. Not a big deal, though nice, quiet, hopefully more efficient. With separating the battery banks from the accessory batteries the start batteries are protected, the alternator is protected, and the cabin will be more comfortable. With 24v 100ah agm battery power a 24v AC unit should be able to run almost an hour leaving 60% charge.

What are your thoughts about replacing the Niehoff dual with a 24v 200a alternator, adding a battery combiner to manage the loads; and removing the LBCD and auto disconnect from an A1 unit?

Thanks for the thoughts, we are still looking for the right answers. If you know another source for a gen1 or gen2 unit please share–

 

[hike]

REVISED Schematic concept 1.3

Corrected (hopefully) wiring for
1– existing manual disconnect next to battery box;
2– deleted LBCD controlled remote disconnect next to battery box.

Still working on best connections for
a– wire 1471 (TL507) wire from 24vbattery side of LBCD to IAH solenoid;
b– wire 1853 from LBCD "B" voltage sensor for dash warning light;
c– wire 1005 from LBCD controlled disconnect "D" to remote disconnect and start (left knee switch and engine bay switches);
d– add a manual disconnect switch between second battery bank and battery protect.



Thank you to @Ronmar @GeneralDisorder @Keith Knight @aw113sgte I am learning so much from you all here and in other threads–

 

[MatthewWBailey]

REVISED Schematic concept 1.3

Corrected (hopefully) wiring for
1– existing manual disconnect next to battery box;
2– deleted LBCD controlled remote disconnect next to battery box.

Still working on best connections for
a– wire 1471 (TL507) wire from 24vbattery side of LBCD to IAH solenoid;
b– wire 1853 from LBCD "B" voltage sensor for dash warning light;
c– wire 1005 from LBCD controlled disconnect "D" to remote disconnect and start (left knee switch and engine bay switches);
d– add a manual disconnect switch between second battery bank and battery protect.

View attachment 916175

Thank you to @Ronmar @GeneralDisorder @Keith Knight @aw113sgte I am learning so much from you all here and in other threads–

Flux capacitors! Also, if you go over 88mph in your 1078 you will time travel, or at least feel
Like you are!

I like the idea of the victron doing all the 12v Power tasks in your diagram. If I ultimately drop the dual voltage alt, then I'll do this too, and just have a 12v battery bank (2) to back up the victrons. Pretty easy alteration. There not much 12v load in my 1078 truck.

I've deleted the lbcd entirely and pulled the control cable from the disconnect. Aside from my continuous 14v leg high volt issue, which is looking like a ground connections issue more and more, I've not had a shutdown obviously since the dang thing isn't in there. I drove 400 miles without it and felt relief. Odd concept, that lbcd, since the batteries are also "capacitors" from an electrical sense, and very large ones. Why "save" and alt from overload and then risk blowing the trans computer in the process? When I had the 14v ovco on the alt and it shut down, the electrical system just went back to 25v and 12.5v off the batts and stayed there. I wonder how far I could drive with the 12v stuff all off on just 4 full batteries?

I suppose adding the lbcd back in there passively , just to have the caps back, is an added layer of "transient" (per neihoff) protection but idk where a transient would come from if there's no disconnection from load. Seems like it's just horse feathers. But Mine is still sitting on the bench and It rings out 100% per the neihoff static testing guide so if someone wants a free, used, homeless lbcd, they're welcomed to it. I have a box and packing paper all ready to go.