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Hi Forum!

Our family is eagerly waiting for our crew van to be built and in the meantime I've been lurking and studying up. I finally have my electrical system planned out and wanted to get some feedback from the more experienced van converters. I have pre-purchased some of the parts during sales and etc, so most of these items have been secured. Would love feedback on the system, any pointers or advice, and suggestions! Something to note is that this is not for living out of, it will serve as our mode of transportation and sleep in 2-3 day increments broken up by motels, friend's houses and etc. Our travel will be at most a week at a time.

Battery: BigBattery's 170Ah Lithium x2, (Has integral 300a serviceable fuse, will go 1/0AWG to shunt/bus)
Solar Panels: 100w Renogy x 2 (200W total, wired in Series), 20a fuse and 10AWG
Charge Controller: Victron 100/20 MPPT, 20a fuse and 10awg
Inverter: Xantrex 2000 SW (1800w Inverter) 250a fuse 1/0AWG to bus
DC/DC Charger: Victron 12/12/18amp Charger, 6AWG 60a fuse
DC Distribution Block: Blue Sea block, it's 100a but will probably fuse to 30a as loads are under 25a max. 16awg or 10awg?
Bus Bars: Blue Sea 250a 6stud bus bars. x2 for neg/pos)
Shunt: Victron Smart Shunt (the one you just have bluetooth for)

Loads:
AC: Some short duration heavy AC loads. (Coffee/kettle/induction/Bosch Elec WH)
DC: Lights, Water Pump, electric mattress heater

Some noobie questions I have:
If the run from my shunt to my bus bar is very short (6-8") do i need another fuse? Since the batteries have fuses integrally, would I need another one past the shunt to the bus bar?

How low can I discharge my batteries? The website says the BMW cuts overvoltage and undervoltage but I am a bit confused as they don't say how many ah are usable.

I've read a lot and have been more confused with each read on the dc/dc charger. Several sources say w/ lithiums they can damage the alternator. I will be tapping from the starter battery so is that a good enough buffer? I don't understand the risks here.

The Inverter has a recommended fuse size of 250a, a max operating amp of 200. Each single battery is 175a conti w/ 300a max for 6seconds. If i parallel these batteries onto a bus bar, does that deliver the 200a the inverter may need? I don't plan on going over 1500w so I doubt this would be a regular thing...

How do you wire the shunt for batteries in parallel? Does the monitor read the two as 1? Will there be any unbalanced charging or discharging or will they keep each other balanced naturally?

Thank you ahead of time for your consideration!! Excited to learn and start a build thread when the van arrives!!
 

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Welcome!

Everything sounds pretty good.

I don't think a fuse/breaker from the shunt to the buss bar is needed if you have one from the batt to the buss bar.

You discharge your battery by running loads. I'm not sure I understand this question.

The DC>DC charger will manage the draw from the vehicle charging system. Sounds like it will be 20A max. Most people look to charge their bank faster in the neighborhood of 50A to shorten charge times.

Running your bank in parallel will add your amperage capacity so it sounds fine.

The shunt only sees the voltage and current as a single battery bank. If they are wired together they will charge and discharge in sync.

Are you planning on making use of a shore charger?

Again, welcome and congrats on the new van!
 

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Fuses protect wires. The fuse at the battery will not only protect the wire to the shunt, but the entire length of the wire even after the shunt. So no fuse after the shunt is necessary.

All batteries are rated for capacity. The usable amount for LiFePO4 is generally accepted to be around 80-90% of total capacity. Actually, it is all "usable" it's just that the batteries will last longer if not completely discharged. It sounds like your BMS will protect against over discharging them (low voltage cut off). If you feel the need, once you get things running you could apply loads until the BMS shuts the battery down and look at your amp meter to see how much you got out of it.

I'm not sure how a B2B would damage the alternator, unless it was drawing too much current for the alternator to handle. Since your B2B is only 18 amps, there is no danger of that.

With two 170 AH batteries connected in parallel, you have created a single 340 AH battery. This is more than sufficient to handle the loads your inverter will impose.

As long as you are getting a lot of sun, you will have quite a bit of power (example: 200 X 8 = 1600 watt/hours) available to recharge your batteries. Without sun you will be depending upon the wimpy 18 amp B2B which would mean a lot of driving to recharge. 300/18 = 17 hours.
 

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Here is a handy on line tool for calculating wire size. Just input the current and round trip wire length and it will suggest an appropriate wire.


Powering a 2 kW inverter takes ~ 250 amps, so you might want to double check the rating of your bus bar and wire size. I would have expected closer to 3/0 than 1/0.

It is a good idea to use bus bars that are rated for ~ 2x the expected current or risk getting pretty warm. You can try those and see if you are satisfied. If not, there are 600 amp versions.

200 watts of solar will only keep up with an RV refrigerator in very sunny locations. In this area that is a trickle charger.
 

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Suggest a larger DC-to-DC charger like the 50A Kisae we offer.
It will charge your batteries much faster when you are driving.
If you can get by with a 1000 watt inverter then your battery
power will last longer. Insta-pot mini and 800 watt coffee maker
will work fine with a smaller inverter. Makes cables smaller
and whole electrical system becomes easier/less expensive
to implement.

All the best,
Hein
DIYvan
 

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Discussion Starter #7
Welcome!

Everything sounds pretty good.

I don't think a fuse/breaker from the shunt to the buss bar is needed if you have one from the batt to the buss bar.

You discharge your battery by running loads. I'm not sure I understand this question.

The DC>DC charger will manage the draw from the vehicle charging system. Sounds like it will be 20A max. Most people look to charge their bank faster in the neighborhood of 50A to shorten charge times.

Running your bank in parallel will add your amperage capacity so it sounds fine.

The shunt only sees the voltage and current as a single battery bank. If they are wired together they will charge and discharge in sync.

Are you planning on making use of a shore charger?

Again, welcome and congrats on the new van!
Thanks Vanpackr!! Amazing how much knowledgeable people are on this forum!

I do not plan on using a shore charger, (yet) Thank you for clarifying the battery questions and shunt!
 

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Discussion Starter #8
Fuses protect wires. The fuse at the battery will not only protect the wire to the shunt, but the entire length of the wire even after the shunt. So no fuse after the shunt is necessary.

All batteries are rated for capacity. The usable amount for LiFePO4 is generally accepted to be around 80-90% of total capacity. Actually, it is all "usable" it's just that the batteries will last longer if not completely discharged. It sounds like your BMS will protect against over discharging them (low voltage cut off). If you feel the need, once you get things running you could apply loads until the BMS shuts the battery down and look at your amp meter to see how much you got out of it.

I'm not sure how a B2B would damage the alternator, unless it was drawing too much current for the alternator to handle. Since your B2B is only 18 amps, there is no danger of that.

With two 170 AH batteries connected in parallel, you have created a single 340 AH battery. This is more than sufficient to handle the loads your inverter will impose.

As long as you are getting a lot of sun, you will have quite a bit of power (example: 200 X 8 = 1600 watt/hours) available to recharge your batteries. Without sun you will be depending upon the wimpy 18 amp B2B which would mean a lot of driving to recharge. 300/18 = 17 hours.
Thank you for the answers! I am getting that my B2B charger maybe insufficient. I will have to see how it works, i may wire another in parallel if it becomes a major issue. The reason I felt it may be enough is that most of our travels will likely be very long road trips w/ 4-5 hrs on the road daily.
 

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Discussion Starter #9
Here is a handy on line tool for calculating wire size. Just input the current and round trip wire length and it will suggest an appropriate wire.


Powering a 2 kW inverter takes ~ 250 amps, so you might want to double check the rating of your bus bar and wire size. I would have expected closer to 3/0 than 1/0.

It is a good idea to use bus bars that are rated for ~ 2x the expected current or risk getting pretty warm. You can try those and see if you are satisfied. If not, there are 600 amp versions.

200 watts of solar will only keep up with an RV refrigerator in very sunny locations. In this area that is a trickle charger.
What a great tool, I will for sure reference this as I start measuring everything. Just to be clear, the inverter is called a 2000SW but it's actually 1.8kw if that makes a difference.

Also, that's very good to know on the bus bars. I am hoping that none of my electrical loads will be max simultaneous so I'm hoping to stay well under the 250a rated at the bus bars. The 600a versions seemed to be very much more expensive and have only 4 studs.

As far as the low solar and b2b charger, my philosophy was to keep usage low but always not be worried about running out. I calculate our average electrical usage to be around 95ah with somewhat liberal use. (We will not have a fan or fridge) so I am hoping to get at least 3 days out of the batteries w/ zero charging. I am hoping that w/ the two charging sources I can recharge on the longer drives we'd see.
 

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Discussion Starter #10
Suggest a larger DC-to-DC charger like the 50A Kisae we offer.
It will charge your batteries much faster when you are driving.
If you can get by with a 1000 watt inverter then your battery
power will last longer. Insta-pot mini and 800 watt coffee maker
will work fine with a smaller inverter. Makes cables smaller
and whole electrical system becomes easier/less expensive
to implement.

All the best,
Hein
DIYvan
Thank you for your suggestion Hein, I think there is a consensus on my DC/DC charger being undersized. I wanted to stick to victron because of the common controls ecosystem i would have. The desire for a larger inverter comes from trying to avoid propane all together w/ an induction cooktop. Most of the heavy duty cooking will be on the fire! :)
 

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DC/DC Charger: Victron 12/12/18amp Charger, 6AWG 60a fuse
I'd go with the Victron 30A version Orion-Tr Smart DC-DC Charger Non-Isolated 12/12-30 (360W) - $220. If have have a Transit 2020 with dual batteries connect to the CCP2 on the base of the driver's seat. If you only have 60A CCP1 use the Isolated version of the charger which has the engine running detection mechanism to turn it on/off. If you want more alternator charging you can wire 2 of the Victron DC-DC chargers in parallel for 720W of charging.

Ford does not recommend connecting directly to the starter battery for 2020 models because of smart regenerative charging/load shedding and start-stop UNLESS you control the charge "using load-shed signal and Third party switch". See section 4.5 in 2020 Ford BEMM. The CCPs exist exactly for use for charging from the Transit electrical system.

Loads:
AC: Some short duration heavy AC loads. (Coffee/kettle/induction/Bosch Elec WH)
DC: Lights, Water Pump, electric mattress heater
No vent fan, fridge or air heating or cooling?
 

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Discussion Starter #13
I'd go with the Victron 30A version Orion-Tr Smart DC-DC Charger Non-Isolated 12/12-30 (360W) - $220. If have have a Transit 2020 with dual batteries connect to the CCP2 on the base of the driver's seat. If you only have 60A CCP1 use the Isolated version of the charger which has the engine running detection mechanism to turn it on/off. If you want more alternator charging you can wire 2 of the Victron DC-DC chargers in parallel for 720W of charging.

Ford does not recommend connecting directly to the starter battery for 2020 models because of smart regenerative charging/load shedding and start-stop UNLESS you control the charge "using load-shed signal and Third party switch". See section 4.5 in 2020 Ford BEMM. The CCPs exist exactly for use for charging from the Transit electrical system.



No vent fan, fridge or air heating or cooling?
Ah that is very good information. I was planning on connecting to the batteries. I will look into the CCP1 studs. I do not have a heavy load yet, so I am keeping my system fairly light. My big investment was on the batteries which I feel would be a better investment than charging sources. (For now). I may add more solar or additional orions if my experience shows I'm lacking charging.

I do not have a vent fan, or fridge (plan on large cooler), and no heating/cooling besides a very nice 300watt electrical mattress pad. (120v). I am leaving wiring and space voided for a potential fan in the future. I will be traveling w/ a family of 4 and i'll need a big space for food that is unreasonable for a fridge to handle.

I'll probably have a very unique build, as I plan on using a mid-roof 148 to sleep 4 and have a tiny sink area. I only have 8' behind the second row seats to work with!
 

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I'll probably have a very unique build, as I plan on using a mid-roof 148 to sleep 4 and have a tiny sink area. I only have 8' behind the second row seats to work with!
You are definitely going to want a fan unless you plan to sleep with the doors open. That many sleeping bodies will put a bunch of moisture in the air that will condense on everything on cool nights.
 
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