Solar Hybrid Electric Skoolie Adventure Begins!

[miscrms]

Making good progress!



Got the solar charge controller wired in, and was able to get it up and running this morning by borrowing a string from my home grid tied setup.



Now I can start to explore the upper end of the charge range and see what these old batteries can still do. The Schneider put about 9.3kWh in on the last charge before it topped out at 64V. The Morningstar put another 5.9kWh in to bring it up to 66V, and the batteries still seem like they can go a bit higher.

Rob

[Birdarchitect26]

That inverter should charge two bat banks, aka 48V leafs and the bus batteries.
If not i could separate them via, at least, a charge controller

[Jdawgsfanasty]

Originally Posted by miscrms

Ok, not really. Not that kind of solar hybrid electric anyway, cool as that would be. But a bus electric system powered by solar, using batteries from a Nissan Leaf Electric, and recharged when needed from a Toyota Prius Hybrid.

We're just getting started on our Skoolie journey, and I thought it might be fun to start a thread so you can all see what happens when a EE who dabbles in electric cars, plugin hybrids, and home solar tries to design a Skoolie electric system (and conversion to put it in). Should be entertaining. At least to me. Some day when its all over ;)

If things go to plan (ha!) our family of five is going to take the plunge and start full timing next summer. Enough of the big city and the Phoenix summers already. Hopefully we'll be spending a lot of time out boondocking in places with trees and water, gradually rehydrating from our overlong stay in the desert. We're likely putting down a deposit on our bus this week, a 1997 Blue Bird All American RE 40' Activity bus with transit style windows, under bus storage, freshened Cummins 8.3 and an Allison MD3060.

To that end I'm hoping to design a pretty robust solar electric system to keep us functional out there. I designed and installed a 5.5kW system on our house, so I at least have some idea what I'm in for. My basic thought going forward is to try and model the design more on off grid homesteaders, whose systems are geared toward maximal efficiency, rather than traditional RVs which seem based more around convenience and presumed access to utilities.

I also have two assets to start with that I'm hoping will come in handy. One is a complete functional disassembled salvage Nissan Leaf. The other is a Toyota Prius that we will likely dolly behind the bus. At a minimum the Leaf will probably be donating its battery pack to the bus, about 15kWh of Lithium batteries weighting 400lbs and about the size of suitcase. High on my list of favorite stupid Prius tricks is the little know fact that you can tap into the High Voltage battery and draw up to about 5kW (maybe as high as 9) without any modifications, and the engine will kick on and off as needed to keep it's own battery in a safe operating range. That would at least give us a backup power source without having to worry about a generator. And when we do need to use it, it should be as efficient as the best diesel generators, with emissions approaching the best propane models.

So here's my basic plan, still lots to be fleshed out. It's pretty much all based around that big Leaf battery, most likely reconfigured to 48V. Primary charging is from solar, with options for charging from the Prius, shore power, or the bus alternator when driving. Having a way to charge the bus battery off the 48V also seems like a nice backup.



About the only piece of equipment I've looked into in detail is the Morningstar Tristar MPPT 600V charge controller which should work equally well for charging the 48V battery off the Solar or the Prius's 230VDC output. It could also handle a wind turbine should we decide to add one for overnight charging.

If I can figure out a way to keep the Leaf battery in it's original 360V configuration, there might be some other goodies I can use as well. The BMS and 3.6kW charger for sure, and possibly the electric AC compressor and coolant heater as well. But 360VDC compatible inverters seem to be a bit rare. I wonder how hard it would be to modify the 80kW drive inverter to put out 120/240V AC at 60Hz

I've also been working on a spreadsheet to start modeling our usage, to get a better sense of sizing for the inverter, solar and battery. Not much real data in there yet, but the solar output is scaled off our home system production, and the frame work is in place so we can model basic appliance usage and cycling loads like the fridge and AC once we have better consumption numbers.



Rob

There's a guy on YT who put a leaf pack in a 1964 coach!!! He shows how he tied the cells...

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[Jdawgsfanasty]

Originally Posted by miscrms

Ok, not really. Not that kind of solar hybrid electric anyway, cool as that would be. But a bus electric system powered by solar, using batteries from a Nissan Leaf Electric, and recharged when needed from a Toyota Prius Hybrid.

We're just getting started on our Skoolie journey, and I thought it might be fun to start a thread so you can all see what happens when a EE who dabbles in electric cars, plugin hybrids, and home solar tries to design a Skoolie electric system (and conversion to put it in). Should be entertaining. At least to me. Some day when its all over ;)

If things go to plan (ha!) our family of five is going to take the plunge and start full timing next summer. Enough of the big city and the Phoenix summers already. Hopefully we'll be spending a lot of time out boondocking in places with trees and water, gradually rehydrating from our overlong stay in the desert. We're likely putting down a deposit on our bus this week, a 1997 Blue Bird All American RE 40' Activity bus with transit style windows, under bus storage, freshened Cummins 8.3 and an Allison MD3060.

To that end I'm hoping to design a pretty robust solar electric system to keep us functional out there. I designed and installed a 5.5kW system on our house, so I at least have some idea what I'm in for. My basic thought going forward is to try and model the design more on off grid homesteaders, whose systems are geared toward maximal efficiency, rather than traditional RVs which seem based more around convenience and presumed access to utilities.

I also have two assets to start with that I'm hoping will come in handy. One is a complete functional disassembled salvage Nissan Leaf. The other is a Toyota Prius that we will likely dolly behind the bus. At a minimum the Leaf will probably be donating its battery pack to the bus, about 15kWh of Lithium batteries weighting 400lbs and about the size of suitcase. High on my list of favorite stupid Prius tricks is the little know fact that you can tap into the High Voltage battery and draw up to about 5kW (maybe as high as 9) without any modifications, and the engine will kick on and off as needed to keep it's own battery in a safe operating range. That would at least give us a backup power source without having to worry about a generator. And when we do need to use it, it should be as efficient as the best diesel generators, with emissions approaching the best propane models.

So here's my basic plan, still lots to be fleshed out. It's pretty much all based around that big Leaf battery, most likely reconfigured to 48V. Primary charging is from solar, with options for charging from the Prius, shore power, or the bus alternator when driving. Having a way to charge the bus battery off the 48V also seems like a nice backup.



About the only piece of equipment I've looked into in detail is the Morningstar Tristar MPPT 600V charge controller which should work equally well for charging the 48V battery off the Solar or the Prius's 230VDC output. It could also handle a wind turbine should we decide to add one for overnight charging.

If I can figure out a way to keep the Leaf battery in it's original 360V configuration, there might be some other goodies I can use as well. The BMS and 3.6kW charger for sure, and possibly the electric AC compressor and coolant heater as well. But 360VDC compatible inverters seem to be a bit rare. I wonder how hard it would be to modify the 80kW drive inverter to put out 120/240V AC at 60Hz

I've also been working on a spreadsheet to start modeling our usage, to get a better sense of sizing for the inverter, solar and battery. Not much real data in there yet, but the solar output is scaled off our home system production, and the frame work is in place so we can model basic appliance usage and cycling loads like the fridge and AC once we have better consumption numbers.



Rob

Have a look at this...https://youtu.be/sLtx-g1ex9I

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[miscrms]

Thanks, Juan and I have chatted a few times. We’re both in Phoenix, so hopefully we’ll be able to get together some time!



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[Jdawgsfanasty]

Originally Posted by miscrms

Thanks, Juan and I have chatted a few times. We’re both in Phoenix, so hopefully we’ll be able to get together some time!



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Looks awesome...I bet that's gonna be sweet...

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[miscrms]

FYI I’m posting more technical details of the battery / electrical build here:

https://secondlifestorage.com/t-Mobi...kW-Solar-Build

I’ll continue to update this thread with progress and more Skoolie specific details once we start building it into the bus as well.

Rob


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[miscrms]

Looks like I’ll be able to get about 16kWh in and out of the battery after testing. Not quite as much as I was hoping, but not too shabby for a 5+ year old battery either.

Rob


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[miscrms]

Not too much new, but I found an interesting product to try for having the option of charging the main battery from the bus 12v system / alternator. This would not be a normal operating state, but there could be times when we want to run something like the AC while driving and its not sunny. I don't think this will be a common occurrence but for the price it seemed interesting to try.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1



This is kind of a weird product, normally solar charge controllers are buck converters (convert panel voltage down to battery voltage), but this one is a boost converter. That's only useful is you have low voltage panels and high voltage battery, which would be odd. But it also claims to have a straight dc:dc boost converter mode which is what I'm interested in.

It will be connected through a 60A dc circuit breaker that will double as a disconnect. In theory it should draw up to 50A from the 12v battery / alternator and provide up to 10A into the 60V nominal house battery. That's 600W which would be about enough to run the smaller 9000 btu mini-split at max power. If it turns out to work well I'd be tempted to parallel a second unit to be able to supply enough current to run both ACs, but we'd probably need to look at upgrading the alternator if we thought we'd regularly be needing to run 100A.

I've also been working on the design of the 12V house power system. I've decided to try running a small dedicated industrial 12v DIN mount supply for the contactors since the entire system depends on the reliability of this supply.

https://www.mouser.com/ProductDetail/709-DDR-30L-12

12v dc:dc converters that can take 56-66V dc in are a little hard to find, but I finally found one that looked promising from an EV supply place. It's 50A/600W output should be plenty for what I have in mind, basically just the water pumps, some LED lightning, and probably USB charging ports. I ordered from the same vendor through eBay.

Waterproof 72V Input 12V DC-50A Output 600W Isolated EV DC-DC Converter USA Stock

The input will be fused at 15A with another of the midnight din mount fuse holders, and the output fed to a midnight 40A dc din mount breaker. I chose 40A rather than 50A as the DC breaker panel I decided to try is only rated for 45A, and I really don't expect to ever be using more than 20-30A.

Here's the marine switch / breaker panel I decided to try.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.bluesea.com/products/435..._Breaker_Panel



Rob

[joeblack5]

I have that boost charger to go from 12 to 48 volt but I think the max current is 10 amp at the input. So for 12 volt the total power is 120 watt.

later j

[miscrms]

Originally Posted by joeblack5

I have that boost charger to go from 12 to 48 volt but I think the max current is 10 amp at the input. So for 12 volt the total power is 120 watt.

later j

Interesting. The listing says it's 0-10A adjustable output current, 600W max. But for the price it wouldn't surprise me too much if that's wrong ;)

Rob

[Tootalltechie]

At 72 volts and 10 amps, the math says 720 watts. Those wires look pretty small to handle anything more.

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[miscrms]

Originally Posted by Tootalltechie

At 72 volts and 10 amps, the math says 720 watts. Those wires look pretty small to handle anything more.

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Yeah, agreed. The specs are pretty lean, not much documentation. It may do 600w at some combination of input / output voltages, but I’ll be surprised if it will do 50A in from 12v. There may well be a max input current that didn’t make it on the spec sheet. For the price it will certainty be interesting to play with though.

Rob


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[miscrms]

Well, the dc:dc converter I was looking at for the main 12v supply seems to be out of stock. It's also a generic Chinese unit, with probably questionable specs.

So I'm thinking about going with this Sevcon unit. It's only rated at 40A output, but that's probably a real 40A from a known brand and meant for vehicle use. Only downside I see is it may need extra heat sinking to run near full power for extended times. Not that we'll necessarily need to do that. So I may just give it a try and see how it does. But at the same price as the generic one it's probably a smarter choice.

Sevcon DC/DC Isolated Converter / Voltage Reducer 80 to 12V - 622/11211 (5-Pin)

Rob

[BussBry]

Originally Posted by Jdawgsfanasty

Have a look at this...https://youtu.be/sLtx-g1ex9I

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And Just like that, I am back in the market for a Prius!

I market for solar companies so I am also planning on doing my bus all solar and boondocking as much as possible. I will need to follow your info closely because I am not as familiar as I would like to be with electrical systems. But, I am getting a crash course with youtube university and the forum here.

I am not familiar with hybrids, but would this same principle apply to other hybrid cars as well? We were looking at getting a ford fusion because it can be Dingy towed behind the bus.

If we could also use it as a battery backup that would be a win-win.

[Sleddgracer]

Originally Posted by BussBry

And Just like that, I am back in the market for a Prius!

I market for solar companies so I am also planning on doing my bus all solar and boondocking as much as possible. I will need to follow your info closely because I am not as familiar as I would like to be with electrical systems. But, I am getting a crash course with youtube university and the forum here.

I am not familiar with hybrids, but would this same principle apply to other hybrid cars as well? We were looking at getting a ford fusion because it can be Dingy towed behind the bus.

If we could also use it as a battery backup that would be a win-win.

that's worth thinking about