Bus conversion 280AH EVE 2P8S 24v 14.4kWH setup all in one or individual components?

frostyllama

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Hey guys, first post but have been lurking. Big fan of Will's videos. I've ordered and received my 16x 280AH 3.2v grade A eve cells with busbars from alibaba through Shenzhen UNIS with trade assurance for about 1600$ delivered to my door.

I have also ordered and received 2x overkill solar 100a 8s 24v BMS's

Currently I'm in the process of specking out the rest of the system. I am leaning towards a 2P8S 24v system for redundancy in case one pack fails; cell goes bad, bms goes bad I won't be left stranded without power. Will be doing a lot of boondocking. I plan on putting a minimum of 1000watts of solar on the roof. the 24v setup is capped at a continuous draw of 4800 Watts.

This will be a full time rig. The pack should be large enough to support all electric appliances for a couple of days without access to solar. The conversion will include:
- Mini split for heating and cooling
- induction stove top
- on demand water heater
- microwave/convection/airfryer
- various other kitchen appliances
- Gaming laptop with monitor
- Lighting
- Whatever else I need

I plan on using a 4000 watt inverter, and want grid and generator charging options for cloudy weather or days I can plug in.

Budget for MPPT, inverter/charger, ATS, various other fuses wiring and busbars is about 1500-2500$ Although I don't mind saving money here or expanding the budget if needed. Solar panels will have a separate budget.

I'm hung up on whether or not to build the system with individual components or just taking the easy way out and getting all in one unit. Any input or advice is appreciated.
 
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frostyllama

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Have you done an actual energy audit and determined your energy needs? If not, link #1 in my signature.
I'll do that now, just playing fast and loose with general numbers in my head for average power consumption for each device.
 

snoobler

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It really matters. You have what appear to be a lot of high demand items if all of those are electric.
 

frostyllama

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You're right.

The highest total consumption device should be the mini split and it's fairly hard getting decent averaged rates over 24 hours on the internet. Depends on a lot of factors including BTU's, SEER rating, environment, and usage. From what I was able to gather they rarely go into peak load and usually sit in an off or low load state. in a small ~80sqft well insulated space should average about 300-500 watts per hour under use. at 12 hours works out to say -6KWH a day.

I plan on supplementing with a diesel heater, generator and grid plug in. Temperate days should see lower to no energy usage.

I plan on getting a dc cooler style fridge which will use under 100 watts. -2.4KWH a day
all other kitchen appliances should be used under an 1hr per day. likely much less. -1KWH I could supplement this with propane burner if necessary.

laptop gaming setup under 100 watts 8 hrs a day. -800WH

looking at about 10.2KWH for big appliances under heavy usage. Pack should last about a day with no input.
can count on about 4 hours of solar on a sunny day at 1000 Watts +4KWH

missing water heater.

Should have frequent access to grid power >2 times a week.
I can learn to adjust and supplement or use alternatives where needed.
Only with real life usage will I be able to tell actual consumption. I'll have to work around the system constraints but I'm willing to learn and adapt
 

frostyllama

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Leaning pretty heavily on a victron multiplus 24/3000. My loads should be under 3kw most of the time and it can handle a surge charge. If I find I need more I can string a second one.

I've got enough roof space to put 2000 watts of solar which will handle my power needs much better off grid.

I'm talking to alibaba suppliers about doubling my battery bank as well
 

HaldorEE

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Leaning pretty heavily on a victron multiplus 24/3000. My loads should be under 3kw most of the time and it can handle a surge charge. If I find I need more I can string a second one.

I've got enough roof space to put 2000 watts of solar which will handle my power needs much better off grid.

I'm talking to alibaba suppliers about doubling my battery bank as well
That is a solid choice.

For 3000W plus system I might also consider a 48V battery systems. That will save on your solar charge controllers, BMS and wiring cost.

Read the data sheet. A 45A Solar controller can only handle 1300W into a 24V battery. The same controller can handle 2600W into a 48V battery. To handle 2000W at 24V will require a 70A controller (or two 35A controllers in parallel).

Also at 48V your BMS will be less of a limiting factor. FET based BMS have a hard time delivering rated current continuously, I have seen many recommendations to derate their max current 50%. I am not sure I would go that far, but I am not counting on my 150A BMS delivering more than 100A to my Inverter (a Multiplus 24/2000)

3000W at 24V is probably going to require close to 140A once you take into account losses due to conversion efficiency. A 100A BMS is going to be hard pressed to deliver much more than 50A continuously for very long. That is less than 1200W. Two batteries in parallel are going to be required to get anywhere close to the rated power that Multiplus at 24V. Unfortunately the Multiplus won't run off 48V DC which means you are going to be pushed up into the Quattro. This is a more capable device, but is also about $600 more expensive.

Amazing how quickly a simple, cheap little system can just creep into a monster on you. Same thing happened to my Ford E350 Conversion Van power system. I started out thinking I was going to be able to use something like a Bluetti, ended up with one heck of a lot more.

In my opinion you would be wise to think hard about your actual system capability needs. I predict you will end up spending $2000 more than your original estimate to do what say you are planning. And not spending enough can be more expensive than spending too much because then you get to buy stuff twice. Sometimes that is ok if you can parallel them. But if you can't that is wasted money.
 
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frostyllama

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Thanks for the feedback. Luckily I haven't purchased anything that would force me into 24v or 48v system. Was thinking about the jump. With the pack I have could run the 2 overkill's in series or buy 2 more 24v overkill's on a new set of 16 Lifepo4 cells with a 2S2P for 48v. Alternatively sell the ones I have and get a non fet based BMS specifically for 48v.

Going 48v would save some money on the MPPT and wiring but would cost more for the Victron Quattro as you say.

Decisions
 
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HaldorEE

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Thanks for the feedback. Luckily I haven't purchased anything that would force me into 24v or 48v system. Was thinking about the jump. With the pack I have could run the 2 overkill's in series or buy 2 more 24v overkill's on a new set of 16 Lifepo4 cells with a 2S2P for 48v. Alternatively sell the ones I have and get a non fet based BMS specifically for 48v.

Going 48v would save some money on the MPPT and wiring but would cost more for the Victron Quattro as you say.

Decisions
Great to have an open mind. So many people are resistant to any hint they might not have made the best possible decision. 2000W is where 24V really makes sense and 4000W is where 48V is the clear winner.

3000W is on the fence, ether 24V or 48V could end up being best. Things like what is the primary charge source (solar, alternator or shore power) can heavily influence that decision.

I think you are very wise to lean Victron. The more I learn about this subject, the more impressive they become. I don't believe anyone else has a comparable infrastructure.

For example my 100/20 Smart Solar is able to communicate with my BMV-712 battery monitor using Bluetooth. That is very cool. I can control my solar charging on the basis of battery state of charge instead of just looking at the battery voltage and no cables are required.

My Multiplus doesn't have Bluetooth so I am using the relay output of the BMV-712 to control shore power charging. The Orion-TR Smart Charger has Bluetooth, but it doesn't support Victron connect yet so it is also controlled by a relay input.

In any event, my BMV-712 is controlling all three of my charging sources. And that includes cold temperature charging cutoff. My BMS should only ever come into play if the batteries get unbalanced enough to reach a low or high cell voltage limit.
 

Dzl

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Great to have an open mind. So many people are resistant to any hint they might not have made the best possible decision. 2000W is where 24V really makes sense and 4000W is where 48V is the clear winner.

3000W is on the fence, ether 24V or 48V could end up being best. Things like what is the primary charge source (solar, alternator or shore power) can heavily influence that decision.
The only thing I would add to this, is that Marine stuff is often rated <32VDC (I believe this is because 'Low Voltage DC' is defined by the ABYC or USCG as <32V but I may be mistaken), and RV stuff is almost always available in 12V, usually available in 24V if you look hard enough, and almost rarely available in 48V, of course you can use a stepdown converter (And the RV code considers low voltage DC to be less than or equal to 24V nominal).

Also--and this may be mostly due to my inexperience--personally I am more fearful of 48VDC. From what I've heard <30V is generally considered fairly safe for humans, while 48V has greater risk/consequence.

I mention this only to give a fuller picture. I agree that once you get up towards a 4kW+ 48V starts making a lot more sense, though for me, I think of 4kW as the breaking point where either 24v or 48v is acceptable.

I think 48V makes the most sense in situations where the DC side of the system will basically just be energy storage + PV (such as an off grid cabin where all the consumers are 120VAC).

I feel each voltage has its advantages and disadvantages, and to a large extent it is about matching the proper voltage to your (1) system size, specifically inverter size, and (2) matching the proper voltage to your context and design goals.

Thinking about all the high draw loads you have, I agree with Haldor's assessment that 48V is at least worth consideration though I think 24V is an equally viable option.
 

frostyllama

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Thinking about all the high draw loads you have, I agree with Haldor's assessment that 48V is at least worth consideration though I think 24V is an equally viable option.

A lot to consider, will mull it over
 

Dzl

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That is cool. Funny you mention an e350 conversion, that's the same base for my 7.3 short bus.
E-350 is an awesome platform! With a bus body you have to be a little weight conscious especially if you have single rear wheels, but it has a great aftermarket, cheap parts, and good engine options depending on year.
 

Dzl

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Oh and as to your main question, I vote for individual components as opposed to an all in one. If Victron's AIO was available in the states I might think differently, but it isn't. And I don't think Growatt/MPP AIOs are well suited for vehicle based builds, and the convenience is not all that valuable in that context, at least to me. It is certainly nice, but it also creates a single point of failure and takes away your ability to design a system to your needs. A quality inverter/charger + solar charge controller is the way to go.
 

frostyllama

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E-350 is an awesome platform! With a bus body you have to be a little weight conscious especially if you have single rear wheels, but it has a great aftermarket, cheap parts, and good engine options depending on year.
Sure is! It's a dually. Just finished gutting the interior. Once the rain eases up I can start the window skinning and buildoutIMG_20201112_145423.jpg
 

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