[technomadness]

Hello all. Just joined.

I would like to build an EV truck in the long term, but in the short term the project is to make an electric camper out of a Ram ProMaster, and live in it full time.

The RV industry is not innovative and so I’ll be cutting some new ground here— for instance I intend to use an incinolet incinerating toilet— so no carrying around a big tank of poop!

Anyway, I have worked with Lithium Iron Phosphate batteries way back in 2007 (built a BattleBot powered by A123 sample cells).

Things have advanced a lot and I’m looking to build a rather large (by my terms but probably small compared to others in this forum) system.

So I’m looking to build a pack of around 48V with a capacity of 12kwh.

I am looking for something stable, reliable and maintainable, and to be capable of putting out around 50A sustained, but most usage would be much less than that. Low maintenance is ideal.

I am concerned about cell balance and so would like something with a built in BMS- but I’m willing and able to build my own pack if there is a good source of cells (eg a company with a steady supply not random eBay purchases) AND a bulletproof BMS to keep them balanced.

I am willing to spend real money on this, so not trying to cheap out. Budget about $12k, though it seems DIY should be closer to $6K... just haven’t found a good solution.

Best answer I have so far is to buy 8 Battle Born lithium iron batteries and put them in a 4s2p configuration.

I have seen an DIY EV supplier that has larger pre-made packs, but not a lot of info about how they work/ how to use them.

I’ll be charging with a large solar array and the vehicles alternator, probably a second alternator (so a source for a good alternator for a 48v system would be great.). Can get a generator if needed and sometimes I’ll have 3600 watts of shore power.

Hmmm, occurs to me that maybe a nice feature would be to add a Tesla charging port and be able to fill up the pack at an EV charging location? That would be great!

I have an electronics background, so very strong knowledge on the fundamentals but not a lot of experience with the current state of the art.

Rest of the rig will run off of 120V AC from an inverter and at this stage I’m leaning towards Victron for solar controllers, inverter/charger and the like.

Any suggestions? And thanks in advance!


PS- there’s a lot of work in this project building out the interior of the van and the like. In a few years I’d like to replace the gas engine and make it truest all electric, but right now fossil fuels are the only practical way to heat an RV in very low temperatures—- and more importantly I need to keep the project scope down to something achievable in the short term.

 

[technomadness]

Also if there’s an obvious good “build your own pack with BMS” resource, please feel free to point me to it. I’ve found Little in my googling, it seems this stuff is still pretty new.


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[brian_]

I don't understand the plan yet: it looks like various 120 V AC coach loads will run via an inverter from this 48 V 12 kWh battery, but what is to be operated directly from it at 48 V? Not primary vehicle propulsion (that's the gas engine), and not typical RV devices (such as lighting, ventilation, plumbing, etc. which are 12 V DC).

Has 48 volts been chosen to suit the availability of an inverter, perhaps intended for solar installations?

 

[brian_]

I am concerned about cell balance and so would like something with a built in BMS- but I’m willing and able to build my own pack if there is a good source of cells (eg a company with a steady supply not random eBay purchases) AND a bulletproof BMS to keep them balanced.
...
Best answer I have so far is to buy 8 Battle Born lithium iron batteries and put them in a 4s2p configuration.

The Battle Born batteries are 4s LiFePO4 units with a BMS... essentially a module. I get the desire for the BMS, but having 8 separate BMS seems awkward; the Battle Born products are really intended to replace a single 12 V lead-acid battery. The BMS of each Battle Born unit operates independently, so you can have several of them, but as far as I know there's no central monitoring or display. I hope you can find a suitable BMS which can handle your whole battery, not just one module of it.

 

[brian_]

In a few years I’d like to replace the gas engine and make it truest all electric, but right now fossil fuels are the only practical way to heat an RV in very low temperatures—- and more importantly I need to keep the project scope down to something achievable in the short term.

RVs are relatively poorly insulated, simply because insulation is bulky, but also because they have a lot of surface area for their volume. They are also used for extended periods, compared to a car. I don't think energy stored in a battery will make sense for heating an RV in cold weather for a long time.

Are you committed to a gasoline engine, rather than diesel? If you choose diesel, you can also use the diesel for space heating and water heating. This assumes that you are cooking electrically - if you need propane for cooking, you might as well heat with it as well. There are other issues with the gas or diesel choice, but this is one which is unique to RVs.

 

[brian_]

Hmmm, occurs to me that maybe a nice feature would be to add a Tesla charging port and be able to fill up the pack at an EV charging location? That would be great!

Why Tesla?
Since Tesla's Superchargers do not permit charging of anything other than a Tesla car (and even they need a subscription), if you use a Tesla vehicle port you will always be using it with an adapter to one of the non-Tesla connection types.

 

[technomadness]

I don't understand the plan yet: it looks like various 120 V AC coach loads will run via an inverter from this 48 V 12 kWh battery, but what is to be operated directly from it at 48 V??

There is a very high efficiency AC unit designed for solar that runs directly from 48 volts. Most of the rest will be 120v stuff.

Likely I think 24v might be better because there’s better support for it from my victron supplier, and my solar panels will be 24v. (Four 280 watt panels, each with their own mppt controller.)

The real energy users will be 120v anyway- Computers, microwave, the incolet etc.



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[technomadness]

The BMS of each Battle Born unit operates independently, so you can have several of them, but as far as I know there's no central monitoring or display. I hope you can find a suitable BMS which can handle your whole battery, not just one module of it.

I agree. That’s why I’m here posting for suggestions. If someone knows a good supplier of CALB cells and a good BMS to go with them then that’s great. Or something like the battle born batteries but in 24v, great.



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[technomadness]

RVs are relatively poorly insulated, simply because insulation is bulky, but also because they have a lot of surface area for their volume.

Are you committed to a gasoline engine, rather than diesel? If you choose diesel, you can also use the diesel for space heating and water heating.

This van will be very well insulated, I’m building myself in large part because of the terrible insulation on off the shelf RVs.

Not planning to use the battery for heating mostly, though may have a heat pump type AC and use that when temperatures are not really cold— but below 50 degrees I will want a furnace.

The people who make diesel hydronic heaters also make gasoline fired ones and I plan to have one of those installed.

I love Diesel engines in theory, but not since the new regulations in 2010. The sprinter was the platform I was originally considering but it’s shape is suboptimal (too narrow) and it’s emissions control system is too high maintenance— and in this application I’ll often be a long way from someone who can repair it.

The pentastar engine is an older design and reliable, and every RAM dealer in the country, and most random car mechanics, can work on it. Plus the promaster allows me to sleep across the width, allowing a much better van layout.

Since this is a self build, I intend to not have a propane system aboard, but will likely have a small propane grill for cooking outdoors that uses the green cylinders.

 

[Kevin Sharpe]

If someone knows a good supplier of CALB cells

EV West and EVTV can both supply CALB cells in the US. However, that's a very expensive solution today. OEM batteries from Nissan Leaf or Chevy Volt are MUCH cheaper.

a good BMS

Take a look at Wolf's work (here)

 

[technomadness]

Why Tesla?

Since Tesla's Superchargers do not permit charging of anything other than a Tesla car (and even they need a subscription), if you use a Tesla vehicle port you will always be using it with an adapter to one of the non-Tesla connection types.

Ah I didn’t know that. I do love the idea of being able to stop at an “electric gas station” and fill up the battery.

Can you link me to a primer on the types of vehicle charging ports and details of where they are located?

Is it even possible to fast charge my pack from one of these locations?

I will likely have a 50 amp RV style shore power connector and a 100 amp battery charger built in... Victron makes one that can take two different sources of power.

What voltage are vehicle charging ports at? Other than Tesla is there a network of them? I’d gladly pay to use them—- paying $0.15 /kWh even is cheaper than checking into an RV resort for hookups.


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[Kevin Sharpe]

Can you link me to a primer on the types of vehicle charging ports and details of where they are located?

Have a look at Open Charge Map

 

[technomadness]

Have a look at Open Charge Map

So many charging points! Amazing.

Does someone make an off the shelf EV system that supports charging from these ports? So I can have the charge cable, charging controller and battery all be configured correctly?

If so I’m guessing the challenge would then be finding a way to tie solar and the engine alternator into charging it as well.


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[john61ct]

If people start using these - usually subsidized - electric charging stations for non-vehicular usage, there will be a backlash and greater rules enforcement.

They are there to encourage and facilitate EVs, not for recharging our House banks.

 

[Kevin Sharpe]

If people start using these - usually subsidized - electric charging stations for non-vehicular usage, there will be a backlash and greater rules enforcement.

They are there to encourage and facilitate EVs, not for recharging our House banks.

Just like charging your EV at an RV hookup you'll find energy vendors will adapt... usually they start by charging a fee for the electricity

 

[Kevin Sharpe]

Does someone make an off the shelf EV system that supports charging from these ports? So I can have the charge cable, charging controller and battery all be configured correctly?

The simplest way to do this is to buy a wrecked EV... you can pick up a damaged but drivable Nissan Leaf for 2500-5000 USD and that contains everything that you need.

 

[brian_]

There is a very high efficiency AC unit designed for solar that runs directly from 48 volts. Most of the rest will be 120v stuff.

Likely I think 24v might be better because there’s better support for it from my victron supplier, and my solar panels will be 24v. (Four 280 watt panels, each with their own mppt controller.)

The real energy users will be 120v anyway- Computers, microwave, the incolet etc.

That makes sense. Thanks for the answer

In general, once you get away from 12 volts (so you will need a DC-to-DC converter to run the 12 volt equipment), a higher voltage is better for wiring... but equipment availability is key, and if you can avoid converting the solar panel output that would be good.

 

[brian_]

Since this is a self build, I intend to not have a propane system aboard, but will likely have a small propane grill for cooking outdoors that uses the green cylinders.

This isn't an electric issue, but it would be good to avoid the little disposable cylinders - they're very expensive and wasteful. There are good refillable one-pound cylinders from Manchester, but you're unlikely to find anyone set up to fill them. U-Haul offers cheaper refillable one-pound cylinders, but only in some areas. If you can set up a ventilated locker for a bulk cylinder (5-pound to 11-pound, if you can't fit a 20-pound), you'll save cost, hassle, and waste.

Since you will have propane, you can get a camp stove or single-burner tabletop stove, for more cooking outside and less power consumption.

 

[brian_]

So I can have the charge cable, charging controller and battery all be configured correctly?

Yes, but one caution: no one uses 24 V or 48 V in a road-going EV, so the charging stations are not set up for it. A station which provides 120 V AC or 240 V AC could work just like your equipment for charging at a powered campsite, but the DC fast charging setup is intended to provide the high voltage needed by an EV battery; I'm only guessing, but I doubt it could handle such a low-voltage battery... check, anyway.

 

[brian_]

If people start using these - usually subsidized - electric charging stations for non-vehicular usage, there will be a backlash and greater rules enforcement.

They are there to encourage and facilitate EVs, not for recharging our House banks.

Just like charging your EV at an RV hookup you'll find energy vendors will adapt... usually they start by charging a fee for the electricity

As a taxpayer without an EV, I'm subsidizing other people so they will use electricity (produced by burning coal and natural gas here) instead of burning gasoline. Since the alternative to this big battery is mostly burning propane (for cooking and heating) and burning gasoline (in a generator), I don't really see a problem with this use of my money. The subsidy is nonsensical to me either way, and what little logic it has works either way.

I haven't heard of any campground changing their power policy or pricing due to EVs, but that may be a local issue... there are almost no EVs here, and it's hard to imagine them using campsites to charge. Campgrounds do change power pricing by season: in areas where people are in them long-term over the winter and short-term in the summer tourist season, the winter monthly rates do not include power (it is metered and charged) but the summer daily rates do include power with no limit.

Of course this is an issue, and is a reminder of how completely unworkable "free" EV charging is in the long term.