Ground Plan for Multiple Voltages?

[luvrbus]

Aren't the catastrophic fuse a delay type with the sand I had problems with mine showing some voltage but would not run the inverter.

I have a Magnum inverter and was torn between the fuse on the - or + Magnum told me on the + side or void the warranty lol for the life of me I could never figure out how they could tell were the fuse was located if you needed warranty work 

[Lee Bradley]

Just guessing but I would say the inverter has internal connections to it's chassis ground. So if your ground side fuse blows, it still has full power through those circuits.

re: Sean's comment on automotive fusible links; they are not part of the start circuit. They are in the circuit supplying power to the fuse box.  I do not support fusing the starter or alternator circuits but each to his own.   

[Lostranger]

I have a Magnum inverter and was torn between the fuse on the - or + Magnum told me on the + side or void the warranty

My Magnum is out of warranty, so....

[Seangie]

Keep in mind that the fuse I am talking about is a catastrophe fuse on the negative side of the batteries that connects to the frame.  I would still fuse all my dc devices (inverter, fridge, lights...etc.) on the positive side. 

-Sean

Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org

[Lostranger]

Keep in mind that the fuse I am talking about is a catastrophe fuse on the negative side of the batteries that connects to the frame.  I would still fuse all my dc devices (inverter, fridge, lights...etc.) on the positive side.

Got it. Fusing every load was never an issue. My original question was whether to ground the two house DC systems to the chassis or run dedicated ground loops for 24v and 12v. In the process of working through that, I discovered the concept of putting the catastrophic battery fuse on the ground side rather than the positive side. THAT was a new idea for me, but I like it.

Thanks again.

Jim

[luvrbus]

I have knew Sean Welsh and Dick Wright both for a long time it was always a interesting conversation to listen at those 2 on their ideas on generators and inverters I didn't know enough about a electrical setup to tell which party was right or wrong 

[eagle19952]

Then would someone paint a picture of this catastrophic fuse saving a bus from burning to the ground, or an example of the result of not having one...or even provide a picture of one installed.
I don't have one. never crosssed my mind that I'd need one.
Seangie even thinks it's a good idea but he doesn't have one.
Ground is ground it's all ending up in the same place no matter where you attach it. Next we'll all be pounding brass rods 8ft feet into the ground.

[luvrbus]

It saves the batteries and inverter if your lucky Donald ,100's around that don't have the high dollar catastrophic fuse just a safety valve people buy Me personally I never saw a inverter or cable burn on one most of the time the relays go out and the inverter doesn't work anyway and I had factory conversion with 2 -2012 Trace Inverters they were not fused either 

The fuse I had that was bad was a Ebay deal the guy screwed me it would test because when I open it I found the silica in the sand had melted and formed kinda of link, 50 bucks and real pissed over that deal

[brmax]

Jim can I ask what models are the inverters or components for your dc system, I thought you mentioned solar also. Just curious and interested
Thanks and good day

[Lostranger]

Jim can I ask what models are the inverters or components for your dc system, I thought you mentioned solar also. Just curious and interested
Thanks and good day

We have four Samsung, 255 watt PV panels that are rated at nominal 24v each. I wired them in two series pairs to feed 48v to a MorningStar 65 amp MPPT charge controller. From there to main bank of four 8D AGM batteries wired series/parallel for 24v. The MorningStar can be set for 12/24/48v output. (I think. Not sure about the 48v output, but 48v input is no problem.) Battery bank wired with 2/0 fine strand copper to Magnum MS4024 inverter. We probably don't need 4000 watts of inverter potential, but the price was right, and it performs flawlessly. So does the solar charging system. I used to think that all "modern" house vehicles had to depend on shore power and/or a large generator, but reading Rob Gray's build in 2011 convinced me otherwise. We've been off grid since February of last year. We have an old Kohler 4500w gasoline generator, but we've not used it or hooked to shore power in months. We do currently live without air conditioning, however. That should change before end of summer, but we'll use a tiny window unit over the bed and run it sparingly.

Even though we're living in the bus, our conversion is a work in progress. We'll be buying a Sundanzer chest-type refrigerator to operate on 24v. Current refer is propane. We have a full-size front loading Maytag washer and propane dryer. Our Rheem, propane-fired, tankless water heater is probably overkill for two people, but, again, the price was right, and it works flawlessly. We both love to cook. We'll replace the current Magic Chef propane rv range with a 30" Premier range that uses battery ignition. All lighting will be LED. We're doing as much as possible with 24v DC, but we have a few things that take 12v, and so far that has meant using a small step-down device. Our primary 120v AC needs are washing clothes, entertainment and power tools.

Our primary heat source is a small wood burner I patterned on stoves designed for yachts. We used propane radiant heaters for backup last winter, but no more. I recently acquired a ThermoKing Tripac APU. It's an older model, and I am in the process of refurbing it to use instead of the generator. It will mount over the engine where the original air handler sat. We'll use it for backup heat and cooling in the bed/bath/utility area at the rear of the bus. When it is running, it's alternator(s) will charge batteries.

Hope that's not too much of an answer. We're still learning how to live off grid, but we seem to be getting better. We have utility water at home base, so we don't have to operate a well pump.

Jim

[eagle19952]

Your rig does sound interesting....
this part i did not know was possible...

to feed 48v to a MorningStar 65 amp MPPT charge controller. From there to main bank of four 8D AGM batteries wired series/parallel for 24v. The MorningStar can be set for 12/24/48v output.

Does this reduce the charge time....what is it's advantage ??

could this be configured as
48 volt panel config to the controller
set to 12 volt output charge
into 12 volt battery bank.

[Lostranger]

Your rig does sound interesting....
this part i did not know was possible...

to feed 48v to a MorningStar 65 amp MPPT charge controller. From there to main bank of four 8D AGM batteries wired series/parallel for 24v. The MorningStar can be set for 12/24/48v output.

Does this reduce the charge time....what is it's advantage ??

could this be configured as
48 volt panel config to the controller
set to 12 volt output charge
into 12 volt battery bank.

I run 48v from the panels because it's easy to do, and it makes for lower line loss. The MorningStar will definitely provide charge for a 12v battery bank. Just select for that in the setup. 48v in with 12v out is no problem.

[Iceni John]

The big advantage of Maximum Power Point Tracking (MPPT) solar charge controllers is that they will down-convert voltage from the PV array to whatever the batteries need, but at the same time they up-convert current, so the power remains essentially the same.   Like Lostranger, I will be using the Morningstar TS-MPPT-60 controllers for my setup.   My PV panels produce about 30V and 8.5A each, and I'll run four panels in parallel to each controller which will then turn that into about 14.5V to charge the batteries, but it will push about 60A into the batteries if needed, twice the current the panels produce.   Magic!   The controllers can accept up to 150V input, such as from a large system with panels in series, and down-convert to 12, 24 or 48V  -  however, the closer the panel voltage is to the charging voltage, the more efficient the controllers run.   For my application the controllers will be running at high-90s % efficiency.

If you have Pulse Width Modulated (PWM) controllers, essentially they waste the excess voltage by not converting it into amps, so for larger systems they don't make any sense to use.   For us folk achieving total self-sufficiency from solar (yes, it can be done, contrary to what the naysayers think), squeezing every possible amp into the batteries is the key.

John

[Oonrahnjay]

The big advantage of Maximum Power Point Tracking (MPPT) solar charge controllers is that they will down-convert voltage from the PV array to whatever the batteries need, but at the same time they up-convert current, so the power remains essentially the same.   Like Lostranger, I will be using the Morningstar TS-MPPT-60 controllers for my setup.   My PV panels produce about 30V and 8.5A each, and I'll run four panels in parallel to each controller which will then turn that into about 14.5V to charge the batteries, but it will push about 60A into the batteries if needed, twice the current the panels produce.   Magic!   The controllers can accept up to 150V input, such as from a large system with panels in series, and down-convert to 12, 24 or 48V  -  however, the closer the panel voltage is to the charging voltage, the more efficient the controllers run.   For my application the controllers will be running at high-90s % efficiency.

If you have Pulse Width Modulated (PWM) controllers, essentially they waste the excess voltage by not converting it into amps, so for larger systems they don't make any sense to use.   For us folk achieving total self-sufficiency from solar (yes, it can be done, contrary to what the naysayers think), squeezing every possible amp into the batteries is the key.

John

      What batteries (type like AGM, size, how many, etc.) are you using for this setup, John?

[Iceni John]

Probably golfcart, maybe L-16, perhaps something else if I can get a good deal on them.   I made two pull-out drawers that each have space for four batteries, but because I have two separate systems running in parallel I could conceivably have different types of batteries in each drawer, provided the controllers can handle them.   I'll be charging golfcart batteries at the upper end of their 5 to 13% recommended charge rate  -  my intention is to have the batteries fully charged by midday or very soon after, leaving all the panels' output during the afternoon for heating water or running power tools etc.

I had to use two controllers because I want to keep the house system the same 12V as the chassis, otherwise life gets too complicated with different voltages.   The theoretical disadvantages of 12V for heavier loads are offset by the simplicity of having everything able to run off any source, including connecting the house batteries to the chassis in emergencies.   Simple is good!

John