Van - 12v, 14kwh lifepo4. Help needed for diagram review.

[Aero]

Hello,

Long time reader First post.
I'm in the process (although a bit slowed down by covid) to sell my place, so my campervan would be my only "house".

​

Vehicule​

I bought a Knaus Boxlife 600 MQ (a brand more known in Europe)
The campervan is built on a Promaster 159" wheelbase high roof.

Autonomy​

As the van will be my house, I would need enough power to be able to work every day if needed.



I've tried to come up with a realistic idea of how much I would need daily.
According to my latest estimation, that would be 1300Wh/day.

Best case scenario would be if solar could be enough to be stationnary for days (even in winter cases with low amount of sun).
I don't know if that can be achieved though because I would need quite a lot of solar panel in winter according to simulations I made. (Take center of France as location)

For scenario #10 below (only solar, no alternator), In winter, I would need around 800WP of solar panels to have 7-10 days of autonomy.

Solar​

To complicate things further, for solar, I have to build around existing roof window and vents.

In blue are existing window.
In white is the bathroom vent.
In black is an existing 120W solar panel.



There is also an awning on one side.


Tilting solar or sliding may be an option.

Batteries​

Regarding batteries, I was thinking about putting lifepo4 at the same place there is agm batteries for now.
It's the wooden box on the left over the arch wheel. It houses one 90AH AGM batteries and the electronics and panels for 220V and 12V.



To get an idea of the space needed for the batteries I did a few sketches.

- 7200WH 600AH 12V with GBS Lifepo4 100AH packs

- 7200WH 600AH 12V Winston 100AH cells

Questions​

• Is my thinking logic and process good?
• Is few days autonomy achievable considering my constraints?

 

[Aero]

It looks my screenshots got resized and are barely readable. I'll see if I can improve that.

 

[HaldorEE]

How much power will you need for ventilation fans?

The battery box is big enough to store a sizable LiFePO4 battery pack, especially if you add shelves to permit more than one layer deep. Are you thinking of commercially packaged batteries or building you own pack from individual cells? Individual cells would make it easier to fit more battery capacity and permit you to customize the battery to your needs.

Are you going to be relocating often or will you tend to stay put for longer periods. If not constantly relocating you might want to investigate tilting panel mounts to maximize your solar input.

 

[HaldorEE]

You might want to add a small inverter based generator to deal with prolonged cloudy periods.

 

[HaldorEE]

A data point on the DIY battery. A 7160 WH battery made from eight of the EVE 280 AH cells would cost approximately $1000 to build here in the USA including a BMS, fuse and terminals. This is 20% of the cost of a comparable battery pack made from commercially built "drop-in replacement" batteries.

There looks to be room for double that battery capacity (14 kWh) in your battery compartment. It might be a good idea to build in more battery capacity since your actual power usage needs are still speculation.

 

[Aero]

Hello HaldorEE and thanks for your questions.

I've added pictures of 3D sketches in my first topic related to batteries.
I was thinking about going the DIY route, building packs with lifepo4 indivual cells. Don't know yet which one would be the most suited.
I've read topics here about the feedback from people buying from china on aliexpress.

I don't intend to stay stationnary, but would enjoy the luxury of being able to stay at one spot if I particulary enjoy it. Especially at remote place where moving just to get energy may not be convenient.

 

[Aero]

There is no power needed for ventilations fans as there are none on the windows.

If possible, I'd like to avoid using and inverter generator.

 

[HaldorEE]

There is no power needed for ventilations fans as there are none on the windows.

If possible, I'd like to avoid using and inverter generator.

Your roof vents are not powered? The weather must be very mild in France. Ventilation and cooling is a big part of most people's power budget here.

Your approach is how I would do it. Focus on need first then figure out what it takes to get there. Don't hesitate to discard the solar panel you currently have on the roof. You don't want mixed panels (capacity or voltage) and the best option for you may be something in a different size (to make the most of the roof space you have).

What are you going to be doing for hot water? Will you have a shower?

 

[HaldorEE]

These are the batteries I am using.

4pcs Rechargeable Batteries Solar System Lifepo4 3.2v 230ah 280ah Battery 300ah 302ah Cells Battery Lifepo4 - Buy Lifepo4 280ah battery Lifepo4 300ah lifepo4 Product on Alibaba.com

4pcs Rechargeable Batteries Solar System Lifepo4 3.2v 230ah 280ah Battery 300ah 302ah Cells Battery Lifepo4 - Buy Lifepo4 280ah battery Lifepo4 300ah lifepo4 Product on Alibaba.com

www.alibaba.com

Eight of these will give you 7168 WH.

 

[HRTKD]

I would use the maximum depth in that cabinet. Wider cells may have more Ah and use the space better. The battery that HaldorEE posted above is the same Ah that I'm using. It looks to be similar size also.

On the roof, don't be afraid to put a panel OVER the vent. If it isn't a vent that produces heat and the vent can't raise up, then to make best use of the space on the roof, put a panel over the vent. You may have to come up with taller panel mounts, but that's a small price to pay for more roof real estate.

 

[Aero]

Your roof vents are not powered? The weather must be very mild in France. Ventilation and cooling is a big part of most people's power budget here.

Your approach is how I would do it. Focus on need first then figure out what it takes to get there. Don't hesitate to discard the solar panel you currently have on the roof. You don't want mixed panels (capacity or voltage) and the best option for you may be something in a different size (to make the most of the roof space you have).

What are you going to be doing for hot water? Will you have a shower?

Yeah i'm quite surprised also to see that almost all of commercial campervans I've seen here in europe do not have fan powered window ventilations.
I've seen some at fairs have AC, but they are a very small fraction.

I was planning on discarding the existing panel indeed.

For hot water and heating, I've a Truma Combi 6D (diesel).

 

[boondox]

Well thought out beginning! Really good to see a decent energy audit as a starting point.

A few thoughts: You will want some fan powered vents. Cooking generates things not good to breath and a lot of moisture. When out and about I use the fan when cooking or if it is hot, otherwise I just open the vent.

No matter how awesome the solar power system you have is there will be times it won't charge your batteries. Not only on cloudy/rainy days but what if you park in the shade? The first thing I look for in a campsite is shade and wind protection if I can get it. So some alternate method of charging the batteries is essential. I have a 50 amp DC/DC charger from the alternator and since I have very low power consumption (I am camping, not living in the van) that works for me. Running the engine for 20 mins a day or so will top me up. If I was living in the van I would have that plus a generator so as to have a redundant back-up. I live off the grid at home and have two generators and two inverters all ready to rumble so that it is very unlikely I am ever completely out of power.

Great start to your build, looking forward to riding along and watching your progress!

 

[Aero]

I added Lishen 272AH batteries to the sketch to get an idea.

They seem very similar in size and specs to the EVE ones you seem to be using.

Had a look at the prices online for those. They seem to be around 120-130USD / kwh, shipped to France.
Maybe even less with the group buys.

What would be the ideal wiring for 16 cells ? 8S2P?

I'm reading that 24V system may be more interesting.
Because of wire gage, among other things

 

[HRTKD]

If you want 24v then 8s2p would be the way to go. Keep in mind that stacking the batteries requires a good amount of room. The height of the battery is just the minimum height. You need room for big cables, bus bars between the terminals, the BMS and also room to work on the battery. Also, 8s is 90 lbs of battery!

It looks like 8s is going to be very cramped in terms of length and height. Will it work? It depends on how creative you are with the space. If you have access to that cabinet through the top - not the door - that would make it much easier.

 

[Aero]

Well thought out beginning! Really good to see a decent energy audit as a starting point.

A few thoughts: You will want some fan powered vents. Cooking generates things not good to breath and a lot of moisture. When out and about I use the fan when cooking or if it is hot, otherwise I just open the vent.

No matter how awesome the solar power system you have is there will be times it won't charge your batteries. Not only on cloudy/rainy days but what if you park in the shade? The first thing I look for in a campsite is shade and wind protection if I can get it. So some alternate method of charging the batteries is essential. I have a 50 amp DC/DC charger from the alternator and since I have very low power consumption (I am camping, not living in the van) that works for me. Running the engine for 20 mins a day or so will top me up. If I was living in the van I would have that plus a generator so as to have a redundant back-up. I live off the grid at home and have two generators and two inverters all ready to rumble so that it is very unlikely I am ever completely out of power.

Great start to your build, looking forward to riding along and watching your progress!

Thanks boondox for the kind words.

Not my van but the same kind of roof window. I can open windows all around but no fan powered ventilation.
I've cooked in it by it was mainly in summer.



I was also looking at DC/DC charger as a way of charging when solar is not usable.
Tried to get more infos about the alternator I got installed on the vehicule but couldn't get much except the basics: it's a 150AH recharging a 12v battery.
At first I was thinking I would use that at Idle if power got low. I then learned that it's not really recommended to idle diesel motors for long time.

If I were living off-grid, a very well insulated generator would be a solution for backups. But after reading many topics on the pros/cons of generators, I've decided to not go that route.

 

[boondox]

Ah, I missed that it is a diesel. It is indeed true it is not a good idea to idle for long periods of time. What I don't know is how high you need to get the engine RPM's in order to help with carbon build up or if that is possible.

I hear you about not wanting a genny. I wouldn't want one either. But I do believe that somehow you need to get an alternate charging source. I think it will be tough to live on solar alone.

 

[Aero]

I would use the maximum depth in that cabinet. Wider cells may have more Ah and use the space better. The battery that HaldorEE posted above is the same Ah that I'm using. It looks to be similar size also.

On the roof, don't be afraid to put a panel OVER the vent. If it isn't a vent that produces heat and the vent can't raise up, then to make best use of the space on the roof, put a panel over the vent. You may have to come up with taller panel mounts, but that's a small price to pay for more roof real estate.

I was considering many options.

One of them was a sliding panel.

Similar to this from Orion Designs but with 2x500W Yangtze panels

 

[Aero]

Ah, I missed that it is a diesel. It is indeed true it is not a good idea to idle for long periods of time. What I don't know is how high you need to get the engine RPM's in order to help with carbon build up or if that is possible.

I hear you about not wanting a genny. I wouldn't want one either. But I do believe that somehow you need to get an alternate charging source. I think it will be tough to live on solar alone.

It may be unavoidable at the end. But for now I've still hope I can do without. ?

I was also considering an alternative way of recharging. One that may not be very common.
Charging on EV chargers. The ones you can pay to charge.

Similar to
https://diysolarforum.com/threads/charging-camper-on-ev-charging-ports.6575/

Accessing J1772 (Level 2) EV Chargers to charge Van/RV lithium system

I've been thinking about this for a while, with a couple of false starts over the past year and a half, but I think I finally have the necessary pieces to make this a reality for my van system (DIY lifepo4, 24V configured as 3 parallel 8S batteries, total of 6.2kwh, Overkill BMS for each 8S...

diysolarforum.com

 

[Aero]

If you want 24v then 8s2p would be the way to go. Keep in mind that stacking the batteries requires a good amount of room. The height of the battery is just the minimum height. You need room for big cables, bus bars between the terminals, the BMS and also room to work on the battery. Also, 8s is 90 lbs of battery!

It looks like 8s is going to be very cramped in terms of length and height. Will it work? It depends on how creative you are with the space. If you have access to that cabinet through the top - not the door - that would make it much easier.

It was just to get a rough idea. If I wanted to optimize space, I would indeed probably need to remove the existing wooden box, and make a custom one.
I don't have an inverter yet so that would also need to go there.

16 cells would sum up to 186 lbs.

Fortunately on the opposite side, I got the clear water tank. But it might indeed be unbalanced.

 

[HRTKD]

I was considering many options.

One of them was a sliding panel.

Similar to this from Orion Designs but with 2x500W Yangtze panels
View attachment 28517

That's a slick system.