Mobile power solution build - Expedition vehicle

TeddyandJ

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Joined
Feb 8, 2018
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71
Part way through a powerwall build into a 2012 Mercedes Sprinter Van.

24v 3.5kw (7kw goal)
640w solar (4x 160w)
Backup 12v AGM charged from alternator

Current tally 420 cells at an average 2400mah. 7S60P. Still hunting for about 100 more laptop packs to get to 7kw.


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Looks like you're off to a good start!
What are your plans with the van? :)
 
wimpie007 said:
Looks like you're off to a good start!
What are your plans with the van? :)

Primary goal is to tour Australia with my lovely lady later this year. The concept of heading out to the middle of nowhere, cooking breakfast, drinking hipster coffee after a hot shower is rather appealing. Especially so if it's done without gas or firewood. It will end up as my daily driver (motorcycle as backup to get around parking issues).

I started collecting for the power wall thinking I was going to build a container house out on a remote property, but when I considered what could be done in a slightly smaller space, I decided to skip the buying stupid amounts of land and just park anywhere.

I found another 60 laptop batteries today, so once testing is done, 7S80P is happening :)
 
Why a van instead of an RV like type of vehicle? Good plan, none-the-less :)
 
Awesome John! Thats quite some capacity you are going for. I am planing a similar project, I also have the short/high 144 Sprinter. 2x 320W panels? I just installed the maxxair roof fan, so I will only fit a single 320W panel. Am thinking about a 2.5-3kw goal right now. Am very curious to follow your build, are you documenting this somewhere? Thanks for sharing.
Merten
 
Korishan said:
Why a van instead of an RV like type of vehicle? Good plan, none-the-less :)

Hi Korishan,

This is also going to be my daily driver, so it was important that it "fit" in standard car parks (it actually does... just). As a van it just looks like a van from a casual glance. The concept of stealth camping is a little interesting. I may even do it one day.

The other factor was cost. Any sort of pre-designed RV would be well over my budget. Instead of a $45k build, it would be approaching $145k... Just not doable. Plus, RVs are uuuuuuugly :)
 
pacificmeister said:
Awesome John! Thats quite some capacity you are going for. I am planing a similar project, I also have the short/high 144 Sprinter. 2x 320W panels? I just installed the maxxair roof fan, so I will only fit a single 320W panel. Am thinking about a 2.5-3kw goal right now. Am very curious to follow your build, are you documenting this somewhere? Thanks for sharing.
Merten

Good choice on van :)

I made sure to do most of the measuring before anything else and ordered rails instead of roof racks for more flexibility. I went for 4x160W instead of the larger panels, so I would be able to tetris into odd shape combinations if needed. I went for the fantastic fan over the Max Air because of its smaller footprint. Since the 160W panels are only 1200x550mm and the centre mounted fan just 400mm wide, they fit along each side with only 20mm overhang (still less than the curve of the main body). I'll even be able to have a rear fan above the bed for cross flow.

The other design option if it looks terrible would be mounting 3 sideways behind the fan for 480w. There's 2200mm to work with there, so still no worries even including cross beams.

I'll add a build log somewhere soon and link it. Right now it's just going to facebook....
 
Scored 3 boxes of laptop batteries on eBay last week.
100 batteries in total (~600 cells).

20 look to be stupidly old, many cells testing at 0v, but roughly half have great cells. So far testing at 2200mah average. The mountain of plastic has begun.

Without counting chickens, it's possible I'll see 7S100P within a month.
 
Nice and enjoy. Most of mine were 0v and the majority are still good after a couple cycles.
 
Nice to see but I don't get why you need such large capacity?

I've got a renault traffic camper van with 100watt solar, a split charger and 180ah lead acid battery and it charges itself fully all day and I can run the fridge and TV all evening and have loads of juice to spare the next day. And this is in England! :)

Anyway i'm interested how you get on, as I've wanted to upgrade mine to lithium ion at some point. Are you using any battery balancers or inverters? I have considered a 1000 watt inverter just to run the microwave, as the fridge and tv already run on 12v sockets.
 
Great stuff good to see more nomadic powerwalls! We are shooting for 100% solar; I really hate having propane with me.
 
Yea to go totally Electric will require more power. I have No hot Water and Limited AC needs for my off-grid Camper and I have 4.6kWh currently and it runs great. Charging with 200W of solar works a treat as My usage is weekends only in the summer (4 days F-M) and there are 3 days of charge with no usage.
 
zag2me said:
Nice to see but I don't get why you need such large capacity?

I've got a renault traffic camper van with 100watt solar, a split charger and 180ah lead acid battery and it charges itself fully all day and I can run the fridge and TV all evening and have loads of juice to spare the next day. And this is in England! :)

Anyway i'm interested how you get on, as I've wanted to upgrade mine to lithium ion at some point. Are you using any battery balancers or inverters? I have considered a 1000 watt inverter just to run the microwave, as the fridge and tv already run on 12v sockets.

Howdy,

Apologies for the long absence on here. Bout of illness has hampered more than just progress.

I'm going a little overkill on the power to set it up for full off grid electrical. Induction cook top, microwave and espresso machine are the big usage items. Math and testingsays average usage is justover 2kw per day.To make sure I'm good for a few days of rain, going a little overkill is good piece of mind.

The other side is reducing draw per cell for safety/ cell life. I'm running a 3000w inverter so the lady can use a decenthairdryer (2100w). Spreading that across 7S100P brings themwell under half C :)
 
Hello John,

I am wondering if you are going to put your batteries in a "module" or case or how you were going to package them when they are in your van?
 
Riplash said:
Hello John,

I am wondering if you are going to put your batteries in a "module" or case or how you were going to package them when they are in your van?
Hi Rip,

The work continues. Just scored another 400+ cells to test (thanks Nathan and Kyle).


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First cells nudging 3400mah :)

I've changedmy mind on the fit out /housing and install a few times, but a few things remain constant. The battery, charge controller and inverter (and maybe BMS) will all be mounted below the fixed bed with battery able to be serviced from the rear doors.

Current plan is tobuild 60P expandable modules and stack them in a way that a pair of 120mm computer case fans can provide guaranteed airflow (regardless of how full of crap the van may be)

I considered a light steel box to mount it all in, but then working on the packs and checking fuses would be more difficult. Instead I'll likely frame it in wood and metal brackets with each of the 7 packs mounted verticallywith room for 3 modules per pack. Risk is low with low top voltage, a BMS and fuses, so that's pieceof mind when sleeping. It's certainly less risky than propane.... Would a sheet metal box do anything anyway? Greater chance of a short maybe make the cells run hotter...

I have a sheet of perspex to shield the entire build from the rest of the storage area. Coloured LED lighting always an option :)

Anyone have a link to a high resolution power symbol? Could be cool to etch the perspex...
 
Only a few days away from finishing testing, cleaning the last of the cells. All up I count about 1100 @1500+ most are around 2300-2700. Have only had to redo the shrink wrap on about 200 :)

I'll be taking the best 960 which will hopefully have a lower cut off somewhere around 2000mah. This will be separated into 8 packs by grouping cells in 100/50mah increments and filling each pack with the same number of each capacity. When each group is not divisible by 8, the remainder will be something something something averaged and spread even across the packs. Hopefully that gets each within an acceptable margin.

Why 8 packs for 24v? It's going to be in a van , something of course will go wrong when away for a lovely weekend or in the middle of nowhere, so I'll be building 7S120P + a spare 120P that will stay fully charged, but disconnected from the main pack unless needed (I'll have a separate charger maintaining it at top voltage ~4.05v). I plan to use a decent BMS, so hopefully swapping in a pack with a slightly different voltage in will balance out without catastrophic failure. By having it at the top voltage, the BMS will start discharging it to match the other cells rather than dragging all the others down to meet it. If I go with Batrium, I'll add a few more long mons on the spare pack to help with swift correction. Once an offending pack is fixed, it will go back in, so the average health of cells should stay roughly even across the packs. The only other option I came up with was 7S60Px2, but this had it's own challenges and honestly wouldn't fit the space quite as well.

Next steps:
-Run an IR tester (from Aliexpress) across all of them. Discard any over 150.
-Test voltage drop on the newer half (first half already done)
-Solder/tin the newer half that pass
-Separate into 8 equal packs (7S +1 hotswap)

Waiting on:
-6AWG busbar copper wire

Future John's problems:
-Turn metal storage box into fancy battery storage whiz bang power wall container
-Spend stupid amount of money on BMS (Probably Batrium)

Thoughts? Suggestions? Eeeek?

J
 
The idea of a extra pack is great. I could have used one this weekend when I had some issues with cells going bad and needing to take down the entire wall to repair.

Looks good
 
Idea for the extra pack came when I was watching TV. Happy my storage has a few extra disks for redundancy. It was one of those, ohhhhhhh sort of moments.

Don't think it would be so great in an expandable wall, but in a fixed capacity, it might just be worth the effort. Hopefully though, I never need to use it out on the road :)

Also, Wire arrived today! It's all coming up millhouse.
 
Progress!

Voltage and IR test found about 60 suspect cells. Have put them aside for retesting. Those that pass will be put to a different project.

960 cells 3200-1800mah sorted evenly into the 8 packs. A little lower than I wanted, but still overkill for the project.

Have started hideously soldering them into submission. 5 packs down. 3 to go. Slowly getting neater and quicker. Getting that silver puddle just right is pretty satisfying. Bought an 80w iron last week, probably should have gone the 120w. This one takes a moment between cells to fully heat back up. Certainly works better than my rework station or butane iron.
 
Nice progress. What made you go with square packs instead of the usual long/narrow ones? Is it because that makes it fit the van easier?


Hey now, I see a Ryobi badge in the bottom right corner of that pic. Why you hiding that tool. Proudly plant that thing out in the open so we can all see it ;)
 
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