Solar system for Electric Bus

[eSkoolie]

Hi all,

I’ve got an electric school bus I’m converting to a motorhome. I think I have a rough idea of the system that I want but I’d like some advice/opinions on if you think it’ll work and how to possibly make it better.

The bus has 105kW (400v) of Traction batteries and an onboard AC charger that takes up to 19.2kW @ 240v. I currently don’t want to mess with the high voltage system directly so my idea is to charge the bus via the onboard charger, directly from solar and a split phase inverter, after my 48v house batteries are full. Below is the proposed system:

2018 Lion Electric School Bus:
400vdc 105kW Traction Battery
12vdc Accessory Battery
J1772 L2 240vac Onboard Charger (max 80a)

Input:
48vdc 3.3kW Solar
240vac 50a Shore power (occasionally)

Solar storage:
48vdc 200ah (9.6kW) LiFePo4

Output:
120v (for appliances)
240v (to charge Traction Battery)
12vdc (for lights and to charge Accessory Battery)

The inverter I’m looking at is the MPP LVX6048. My plan is to output @ 240v split-phase to a breaker box and pull 120v for the appliances from there. Not sure where I’ll pull the 12vdc from right now but that’s a low priority.

I’m know I’m not going to get a quick charge for the traction batteries, it’ll still take days, but it’s all icing as far as I’m concerned!

What do you think? Possible?

?

 

[Hedges]

I'd like to use one of these, connected directly to 400V battery and fed from PV.
The issue would be getting BMS communication with inverter.

https://files.sma.de/downloads/SBSE-US-DS-en-23.pdf

 

[billvon]

I'd like to use one of these, connected directly to 400V battery and fed from PV.
The issue would be getting BMS communication with inverter.

Either spoof the CAN bus or connect directly with an inverter that doesn't need BMS communications. We did that (spoofed the CAN bus) with a Solis 6kW.

 

[Hedges]

Got an inverter to suggest that doesn't need BMS connection ... and will work with his 400V battery?

 

[justinm001]

Definitely possible and seems like the best solution for now. Although you'll be losing 10-20% converting from DC to AC to DC I believe.

I'm hoping to do a conversion to EV on my bus at some point.. hoping Prevost makes a conversion kit for it. Whats your Kw/mile? I'm hoping mine will be 1.5 but I've seen 1-2 as average and I think the Tesla Semi is 1.5ish.

You could do 48 to 12 charger or just a 120 to 12 charger and take the conversion losses if not a big load. 120 to 12v chargers are like $30 and it's always good to have just as a backup.

 

[eSkoolie]

I'd like to use one of these, connected directly to 400V battery and fed from PV.
The issue would be getting BMS communication with inverter.

https://files.sma.de/downloads/SBSE-US-DS-en-23.pdf

Looks like it’s not meant to be used off-grid?

 

[eSkoolie]

Definitely possible and seems like the best solution for now. Although you'll be losing 10-20% converting from DC to AC to DC I believe.

I'm hoping to do a conversion to EV on my bus at some point.. hoping Prevost makes a conversion kit for it. Whats your Kw/mile? I'm hoping mine will be 1.5 but I've seen 1-2 as average and I think the Tesla Semi is 1.5ish.

You could do 48 to 12 charger or just a 120 to 12 charger and take the conversion losses if not a big load. 120 to 12v chargers are like $30 and it's always good to have just as a backup.

I’m right at 1.5—105kW gives me about 70 miles.

I understand I’ll be losing from the conversion although I don’t think there’s much I can do about that? Also the high idle consumption on these units. Wondering if there’s another way…

 

[Hedges]

Looks like it’s not meant to be used off-grid?

It is meant to be used with specific supported batteries.

It is marketed for on grid and grid-backup. It is the replacement for their Sunny Boy GT PV inverters, adding battery input as well.
I think it would work with no grid (always "backup")
The problem is lack of documentation regarding BMS CAN-bus communication protcol.

Previously their offering was Sunny Boy Storage (high voltage battery inverter, apparently a modified Sunny Boy for battery instead of PV), plus Sunny Boy, plus auto-transformer and transfer switch.

Smart Energy should work as an off-grid system. Don't know the surge rating yet. SBS 6kW model had anemic 9kW surge.
But I though if there was a way to make it work with foreign batteries, it would be ideal. It would provide MPPT PV charging, and programmable rate of draw from AC input for charging. Also gives you 120/240V house power.

I expect to use it for upcoming grid-tie PV systems, possibly adding their recommended batteries to make a listed ESS for my sister.
For myself, I wish I could use with a DIY battery. I haven't learned what BMS protocol SBS needs either.

You may find some Chinesium high-voltage AIO which have enough documentation on battery to use them.

 

[time2roll]

Hi all,

I’ve got an electric school bus I’m converting to a motorhome. I think I have a rough idea of the system that I want but I’d like some advice/opinions on if you think it’ll work and how to possibly make it better.


What do you think? Possible?

?

Yes looks good. Probably need 16 amp EVSE to feed power to the main charger and yet limit the power.

Leave room to double+ the 48v battery if needed.

Does the bus have air conditioning?

 

[justinm001]

I’m right at 1.5—105kW gives me about 70 miles.

I understand I’ll be losing from the conversion although I don’t think there’s much I can do about that? Also the high idle consumption on these units. Wondering if there’s another way…

victron seems to be the lowest idle consumption since LF also Victron would allow you to turn on the MPPT but turn off the inverter based on rules, and 2 outputs of the inverter means you can use 1 for the L2 charger and other for appliances then have separate rules (assistants) to control either.

Ideally you'd find some 48 to 400 dc to dc charger, even better if it was 2 way so you could pull from the chassis batteries. Use the 48V 10kW as a buffer 20-80% then the 400v 105kW as additional storage and let it drain to 50% or 25% if boondocking. Just enough charge to get to a shore charger if needed. A DC to DC charger efficiency would be like 95% instead of 80% but thats going to be something special and likely custom.

Thats my plan with a backup 12V inverter and additional 400v huge removable packs but i'm a good 5 years out

 

[rustythorn]

you might want to consider pairing two 120VAC victrons for split phase 120/240. this is my plan for my EV RV. not only are the victrons more efficient but the powerassist option will give you faster charging options. for example, i'm looking at two 120 VAC multiplus II 48/3000/35-50, which gives me 4.8 kw system. if i plug a 7.2 kw [240 VAC 30 AMP] public charger into my system i can then output 12 kw thus charging the EV much faster. granted i this requires me to drain my house battery but solar will extend that window. same thing is true for any grid power. a standard 120 VAC 15 AMP outlet will allow me to charge at 6.6 kw. your EV is a little bigger so maybe two 5000 VA multiplus II?

 

[justinm001]

you might want to consider pairing two 120VAC victrons for split phase 120/240. this is my plan for my EV RV. not only are the victrons more efficient but the powerassist option will give you faster charging options. for example, i'm looking at two 120 VAC multiplus II 48/3000/35-50, which gives me 4.8 kw system. if i plug a 7.2 kw [240 VAC 30 AMP] public charger into my system i can then output 12 kw thus charging the EV much faster. granted i this requires me to drain my house battery but solar will extend that window. same thing is true for any grid power. a standard 120 VAC 15 AMP outlet will allow me to charge at 6.6 kw. your EV is a little bigger so maybe two 5000 VA multiplus II?

I think the Mp2 3000 is only 50amp in/out so you can only powerassist to 50amps on each leg. I think 5000 are 95a. I went with Quattro 5000s as they're 100amps plus 2 inputs and outputs.

 

[eSkoolie]

Yes looks good. Probably need 16 amp EVSE to feed power to the main charger and yet limit the power.

Leave room to double+ the 48v battery if needed.

Does the bus have air conditioning?

None currently. Looking at adding a mini-split down the road.

 

[eSkoolie]

you might want to consider pairing two 120VAC victrons for split phase 120/240. this is my plan for my EV RV. not only are the victrons more efficient but the powerassist option will give you faster charging options. for example, i'm looking at two 120 VAC multiplus II 48/3000/35-50, which gives me 4.8 kw system. if i plug a 7.2 kw [240 VAC 30 AMP] public charger into my system i can then output 12 kw thus charging the EV much faster. granted i this requires me to drain my house battery but solar will extend that window. same thing is true for any grid power. a standard 120 VAC 15 AMP outlet will allow me to charge at 6.6 kw. your EV is a little bigger so maybe two 5000 VA multiplus II?

IIRC, Will Prowse did a video back in Dec with two Victron Multiplus II set up for split-phase 240v and was limited to 20a (4.8kW) charging his Tesla? Seems low for the $$$ outlay. Of course, will last a lifetime…

I appreciate the Victron suggests and I would totally go that way if I could afford it! Alas…

 

[rustythorn]

IIRC, Will Prowse did a video back in Dec with two Victron Multiplus II set up for split-phase 240v and was limited to 20a (4.8kW) charging his Tesla? Seems low for the $$$ outlay. Of course, will last a lifetime…

I appreciate the Victron suggests and I would totally go that way if I could afford it! Alas…

yep the paired multiplus 3000 is 20 AMP at 240 VAC for 4800 watts. the MPP LVX6048 is 6000 watts or 25 AMP at 240 VAC. paired multiplus 5000 would be 33 AMP at 240 VAC for 8000 watts.

however, as i pointed out only the victrons allow you to combine grid and battery for greater power. so the paired multiplus 3000 plugged into the grid or portable battery [eg solar generator] will give you from 6600 watts to 16800 watts, were as, the LVX6048 will never get above 6000 watts

it all boils down to what your use/application will to be, however, an EV RV will have much more complex use/application considerations than an ICE RV. where do you plan to charge, how fast you need to charge, etc... do you plan on using campgrounds? campgrounds can have lots of different power options 15, 20, 30 or 50 AMP at either 120 or 240 VAC. level one charging only goes up to 20 amps [if you can even find one] so if the campground has 30 or 50 amp 120 VAC you will not be able to use it to charge unless you have a victron setup

 

[eSkoolie]

yep the paired multiplus 3000 is 20 AMP at 240 VAC for 4800 watts. the MPP LVX6048 is 6000 watts or 25 AMP at 240 VAC. paired multiplus 5000 would be 33 AMP at 240 VAC for 8000 watts.

however, as i pointed out only the victrons allow you to combine grid and battery for greater power. so the paired multiplus 3000 plugged into the grid or portable battery [eg solar generator] will give you from 6600 watts to 16800 watts, were as, the LVX6048 will never get above 6000 watts

it all boils down to what your use/application will to be, however, an EV RV will have much more complex use/application considerations than an ICE RV. where do you plan to charge, how fast you need to charge, etc... do you plan on using campgrounds? campgrounds can have lots of different power options 15, 20, 30 or 50 AMP at either 120 or 240 VAC. level one charging only goes up to 20 amps [if you can even find one] so if the campground has 30 or 50 amp 120 VAC you will not be able to use it to charge unless you have a victron setup

As I understand it, all 50-amp service in the US is split-phase 240v (common household) so I’d be fine with a NEMA 14-50 to J1772 EVSE.

 

[time2roll]

As I understand it, all 50-amp service in the US is split-phase 240v (common household) so I’d be fine with a NEMA 14-50 to J1772 EVSE.

I recommend this one (40 amp) that should work in most conditions if power needs to be limited etc. I have the 30 amp and works perfectly.

Adjustable 12 to 40 amp 120v or 240v

 

[rustythorn]

I recommend this one (40 amp) that should work in most conditions if power needs to be limited etc. I have the 30 amp and works perfectly.

Adjustable 12 to 40 amp 120v or 240v

does it allow you charge at 30 amps on 120 VAC?

 

[time2roll]

From the link:

On a standard 120V outlet, you can set it to the the 12A setting. When charging at a 20 amp outlet, it is recommended to set it to 16A. When charging at a 30 amp outlet, it is recommended to set it to 24A.
Call us: 1-385-355-3873

 

[rustythorn]

From the link:

On a standard 120V outlet, you can set it to the the 12A setting. When charging at a 20 amp outlet, it is recommended to set it to 16A. When charging at a 30 amp outlet, it is recommended to set it to 24A.

with that period after 'settings' it can be interpreted two ways. i know that it sounds like it should run higher amps on 120 VAC but unless they explicitly say so or someone has experience doing so i'm going to be skeptical.