Hi All,

Now aiming to setup a van for offgrid use. Having completed our previous camper setup (12V solar, MPPT, DCtoDC, 240V charger, AGM battery) I am considering a new approach to the van. 

I was hoping to find out if anyone is using a 48V LiFePO4 DC setup with 240V inverter/bypass & solar input. 

Based on my calcs to be able to use most everyday van electrical items it appears to require around min 4.8kw battery storage. Dc to dc chargers will also be limited by alternator performance & chargers available for 12/48. I am thinking a min 1kw solar input for charging. I am considering the Victron route as previously their products have never let me down. Happy for any other suggestions. 

I have also factored into the equation some items can be substituted with gas to reduce power consumption requirements. 

Look forward to the responses,

Cheers.

I am building a new OKA motorhome.
I spent some time weighing up the options of 12V vs 24V vs 48V for the house batteries. There are some minor cost savings and some minor weight savings going to higher voltage, but at the end of the day I have decided to stay with 12V and keep the high current cables as short as possible.
LiFeP04 about 480Ah (@12V nominal).
The vehicle will have no gas. Gas is heavy (counting the bottles), expensive and sometimes hard to get.
Hot water and central heating will be 240V (from the inverter), diesel, or waste heat from the engine.
Cooking will be an induction cook top. Fridge freezer will be domestic inverter motor 240V about 220L.

Solar will be light weight, as much as I can fit - about 2.1kW. there will be nothing else on the roof to get in the way of the solar.

You can not have too much solar.

430W of the solar will be like this......

Cheers,

Peter

Hi Mick, there has been plenty of discussion on this Forum and information regarding what you propose. I cannot help you with your proposed 48V battery system.

Most have decided to continue with 12V systems, which keeps things simple, and yet efficient, at the same time.

For mobile camping you will find that the 12V system will be the most convenient. Other systems, like 48V, may be best suited to domestic off grid set-ups.

My setup consists of 3 x 135AH (405AV) lithium batteries, 80A Epever solar controller, 4 x 250W (1000W) solar panels, with provision to input external portable panels and a 3000/6000W inverter.

The inverter has a remote on/off switch located in the kitchen area and the inverter can be plugged into the normal 240V external input socket, allowing 240V to all power points and appliances, including the aircon.

My stove, van heater, instant hot water and fridge are connected to gas. The inverter supplies 240V to all cooking appliances including microwave.

I have tested the aircon operating for four hours and the solar controller assisted greatly in keeping up amps input. I have never depleted the batteries during daylight hours, even though I have tried.

If you search solar, lithium & inverter posts on this forum there is extensive information from members relating to what you propose.

I am building a 2021 Fiat Ducato L4H3 (longest and highest available in Oz) van for permanent full time living and have gone down the 48V LiFePO4 route. I purchased raw 280Ah cells and BMS from China to make a nominal 13.44kW battery running into a 5kVA Victron inverter/charger (70A charging when hooked into the grid) with 1.2 kW of domestic solar panels on the roof.

The 48V system runs the inverter for 230V appliances including a Truma Saphir underbunk air conditioner for keeping the dog cool during the day (I am hoping that he will also let me use it at night if it's a bit hot) and will use the Cerbo GX relays to divert excess energy when the battery is full to the 40L hot water tank element. The hot water tank will also heat via a pumped loop and heat exchanger off the vehicle cooling system when driving.

I then also bult a 280Ah 12V batttery as many of the items available for mobile living are still only available in 12V, this can charge from a 60A DCDC Renogy charger or a Victron MPPT fed by either a 12V solar blanket or the 48V battery (relay controlled).

There can be weight and cost savings in going 48V, but at this point in time these will probably be offset in finding ways to run the inevitable 12V equipment (voltage converters or a secondary battery system like me) that you will have to purchase.

I will be the first to admit that the tiny home on wheels that I am building for full time living is technically complicated and over engineered, so why have I done it??.....For the same reason that my Staffy licks his equipment, because he can.

The point that I am trying to make is that if you are a techno nerd like me and have a masochistic need for problem solving, jump on the 48V bandwagon. If you want a more simple straightforward build with big fat cables then go 12V.

Either way, good luck, and see you down the road.

Thanks all for the detailed responses. Early stages at the moment going through the process of pros/cons. The biggest thing will be the weight compromise & water carrying requirements (as Peter has mentioned previously)
I am assuming everyone is paralleling the solar units to maintain the <50VDC.

Are there stand out 12V items that can not be replaced by 240V?

@ Peter

- Agree with can't have enough solar (& utilising any excess)
- What size DC to DC charger do you use for the larger battery capacity? Did you upgrade the alternator? I guess the main source of charge is solar anyway.
- I will read up on the standards. I was considering the boot (depending on weight balancing) The large capacity of a Lithium battery (& what can happen) is always in the back of the mind.
- I like the setup Peter. Do you find if you want to go day tripping & packing up or having the bigger rig is of any inconvenience vs unhitching & taking the car? Have you ever lost your perfect spot to someone else?

@ Richard
- Will check out for more info within the forum. Thanks.
- I was also planning on using the Victron multi as the main supply to the van & when shore power is connect can utilise bypass feature / charging.
- Not sure if easy controller (With MPPT) or multipass is the way to go with separate solar regulator & Cerbo.
- I also like the idea of redundancy energy sources (just in case)
- What is your A/C electrical wattage?
- Any reason you went multiple batteries vs 1 large capacity?

@ John

- I will be looking at the domestic solar panels again also. Better performance / warranty / output guarantee & $/w.
- Are you using a DC to DC at all or pure solar input?
- Like the idea of utilising the excess energy for other benefits. Cerbo seems a useful unit.
- Would you rate the Truma? After looking at other various models the specs seem ok.
- Had to look up Masochistic. I try to avoid pain but somehow end up there.

Cheers!

Are there stand out 12V items that can not be replaced by 240V?

Our diesel central heater/hot water system is the most significant. Its pumps are from 12V (or 24V???) and heating can be from the engine or from diesel or from the 240V inverter). And led lights and water pumps are 12/24V. It is useful to have the house at the same voltage as the truck.

What size DC to DC charger do you use for the larger battery capacity? Did you upgrade the alternator?

We charge direct from the standard 85A alternator on the rare occasions when we might need more than the solar. At 14.4V it will initially give us 70A into the batteries (plus the solar). That reduces as the SOC increases.

I will read up on the standards.

You have to buy a copy. 

Do you find if you want to go day tripping & packing up or having the bigger rig is of any inconvenience vs unhitching & taking the car? Have you ever lost your perfect spot to someone else?

We can pack up and be on the road quicker than you can unhitch. But we rarely camp with "competitors" (unless it is a one night stand) because we usually go to places they can not go. There is always a stunning spot 1km further. 

Many people have been within a couple of km of this spot, but very few visit, let alone camp here. Guess where we are.

Cheers,

Peeter

Ondway2grey wrote:

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Thanks all for the detailed responses. Early stages at the moment going through the process of pros/cons. The biggest thing will be the weight compromise & water carrying requirements (as Peter has mentioned previously)
I am assuming everyone is paralleling the solar units to maintain the <50VDC.

Are there stand out 12V items that can not be replaced by 240V?

@ Richard
- Will check out for more info within the forum. Thanks.
- I was also planning on using the Victron multi as the main supply to the van & when shore power is connect can utilise bypass feature / charging.
- Not sure if easy controller (With MPPT) or multipass is the way to go with separate solar regulator & Cerbo.
- I also like the idea of redundancy energy sources (just in case)
- What is your A/C electrical wattage?
- Any reason you went multiple batteries vs 1 large capacity?

Cheers!

-- Edited by Ondway2grey on Wednesday 13th of March 2024 09:19:36 PM

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Not sure what advantage you aim to achieve with 48V system over 12V system to mobile off-grid use.

I find that my 12V system is simple and efficient.

Solar panels 4 x 250W (1000W) in parallel array fitted to van roof. Connected to controller with solar purpose cable.

Epever MPPT 80A solar controller with interior monitor, connected to batteries with 8B&S cable.

LiFePO4 batteries 3 x 135AH (405AH) in parallel array. Connected to multi fused distributor, 12V charging points & Anderson plugs with 8B&S cable.

Inverter 3000W/6000W. Located within 0.5m of batteries & connected with 6B&S cable.

Tug power engine bay to rear Anderson plug 6B&S cable.

Van drawbar Anderson plug 6B&S cable to DC>DC charger and 12V fridge input.

All items bought smart by shopping extensively & seeking good quality products at lowest prices. 

If you decide to go the 48V path, please post a list of all components and solar/battery arrays.

Good luck with your research.

Ondway2grey wrote:

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- Out of curiosity do you know what load (A) the alternator charges under normal use?

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 About none.  A diesel needs no power to run, so all that is needed is for lights and fans.

Cheers,

Peter

Ondway2grey wrote:

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Thanks for the replies & detailed info, much appreciated.


@ Richard

- Good point on the advantage. Will need to compare systems with weight / cost / quality (and getting replacement parts if/when needed)
- Agree with this point. " All items bought smart by shopping extensively & seeking good quality products at lowest prices."
- I have a pop top & not to keen to mount things on the roof. I like the solar portable to park the van in the shade & let the electrons flow.

- Did you have a rough weight estimate on your electrical setup? (Panels 4 x 8kg, Controller Epever 6kg, Batteries Voltax 3 x 13kg, Inverter PSW 3000/6000W 6kg).
- What size amps DC to DC charger? (20A).
- Do you use a shunt with load monitoring device? (Yes, 200A).
- I have noticed 48V server batteries seem to have a good capacity & warranty. (Batteries 3 x $449.00, 12 months warranty, still performing like new after 4 years).