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New Van Build - Design Check

culbyem

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Joined
Nov 29, 2022
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Hi everyone. I've recently started planning a new build that's much more complicated than my last van and could use some input from people smarter than I am.

Mainly, I'm curious if my wire gauges are appropriate and my fuses are correctly placed and sized. I've tried to do my best to use the online calculators and amp charts, but I'm sure there's some nuances to electrical systems that I'm not familiar with.

Also, if there are any other quality-of-life design considerations that I'm not thinking of.

I apologize my diagram isn't the most detailed, I'm used to drawing network diagrams, not electrical diagrams.

A few details that may/may not be helpful:
- Solar panels: 2x 200W 12V Rich Solar
- SCC: Victron100/30 MPPT
- Batteries: 2x 206Ah 12V SOK
- Inverter: Giandel 2200W
- Transfer Switch: Go Power! TS-30 30A
- AC Charger: EG4 12V 15A
- DC Loads: Puck lights, Maxxair fan, 12v ICECO fridge, mobile device chargers, Water pump
- AC Loads: Induction cooker or electric kettle (not simultaneous), laptop charger, maybe a TV.

Thank you so much. Your input is greatly appreciated.
 

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  • Solar System.pdf
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2200 ac watts / .85 conversion factor / 10 volts low cutoff = 258.823529412 inverter amps

Your batteries are rated for 100 amps continous per battery or ~200 amps in aggregate.

Suggest you go with a decent inverter/charger instead discreet inverter, charger and transfer switch.

There a lot of other things.
 
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SOK 206Ah is rated 100A discharge, 50A max charge, ( 40 A recomended).
2200 watt inverter at max power will take with a 12v system almost 200 A, taking Into account efficiency and losses.

Induction hobs may be rated higher than 2200 watts, and control of heating power is by modulating the input power, thus there is a higher power needed even when the burners are set to a low heat power.

The system may be marginal using both burners on a dual hob.

Regarding the circuit diagram it's probable the batteries will deliver short term over 200 amps, a higher battery fuse would be preferred, say 250 amps. More ideal would be an individual MRBF fuse on each battery positive, 150 A. Blue Sea, https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A.

Cable protection needs to be at the power end, thus all fuses or breakers as near as possible to positive buss bar, using a Lynx power in is a neat solution. (change MPPT breaker for a fuse, it can be disabled via the app if required).

Fuse in the solar feed is not required . Fuse needed for the feed cable to DC fuse box.


Once you have AC power distributed in the van ideally you need protection, RCD / RCCB / GFCI.
This needs an inverter with neutral to PE bond at the inverter and van metal connected to PE. Battery negative also to van metal.
Inverter case to and battery negative to van metal, needs cable one size down on Inverter feed cable. This ensures protection under inverter AC and DC internal faults.

As suggested an inverter charger with built in transfer switch and automatic neutral bonding when off grid simplifies instalation. (assume you are in 110v , 60Hz land)
 
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2200 ac watts / .85 conversion factor / 10 volts low cutoff = 258.823529412 inverter amps

Your batteries are rated for 100 amps continous per battery or ~200 amps in aggregate.

Suggest you go with a decent inverter/charger instead discreet inverter, charger and transfer switch.

There a lot of other things.

Thank you for the advice. Is something like this what you're referring to?
Victron Multiplus Compact 12/2000/80-50
 
Thank you for the advice. Is something like this what you're referring to?
Victron Multiplus Compact 12/2000/80-50

That would be an excellent choice.
Its 2000VA which is ~1600 watts at 25C but it has significant surge capacity.
 
SOK 206Ah is rated 100A discharge, 50A max charge, ( 40 A recomended).
2200 watt inverter at max power will take with a 12v system almost 200 A, taking Into account efficiency and losses.

Induction hobs may be rated higher than 2200 watts, and control of heating power is by modulating the input power, thus there is a higher power needed even when the burners are set to a low heat power.

The system may be marginal using both burners on a dual hob.

Regarding the circuit diagram it's probable the batteries will deliver short term over 200 amps, a higher battery fuse would be preferred, say 250 amps. More ideal would be an individual MRBF fuse on each battery positive, 150 A. Blue Sea, https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A.

Cable protection needs to be at the power end, thus all fuses or breakers as near as possible to positive buss bar, using a Lynx power in is a neat solution. (change MPPT breaker for a fuse, it can be disabled via the app if required).

Fuse in the solar feed is not required . Fuse needed for the feed cable to DC fuse box.


Once you have AC power distributed in the van ideally you need protection, RCD / RCCB / GFCI.
This needs an inverter with neutral to PE bond at the inverter and van metal connected to PE. Battery negative also to van metal.
Inverter case to and battery negative to van metal, needs cable one size down on Inverter feed cable. This ensures protection under inverter AC and DC internal faults.

As suggested an inverter charger with built in transfer switch and automatic neutral bonding when off grid simplifies instalation. (assume you are in 110v , 60Hz land)

I saw that with some induction cookers. The one I was looking at actually draws lower power at lower heat levels.

Thank you for the suggestion about the fused bus.

I unfortunately did not depict grounding or gfci outlets on my diagram, but they will be in the install.

And yes I am in US so 110v/60Hz.

Thanks so much for the advice.
 
That would be an excellent choice.
Its 2000VA which is ~1600 watts at 25C but it has significant surge capacity.

Thanks again for the recommendation. Does this look like a better design? @mikefitz I tried to incorporate your pointers as well.

2 quick questions.
- Would the inverter charger be connected directly to the positive battery terminal or would it be connected to the distributor bus?
- Since the charging amperage for the inverter/charger I linked above is 80A, but the recommended charging amperage for the SOK batteries is 40A (50 Max), would I throttle the AC charger amperage to like 65A, or would it need to be 40A? Or can it stay at 80?

Thanks again.

Sidenote, as far as inverter power usage for an induction cooktop, I'm looking at one of these which has a power setting or a temperature setting, so I'm hoping that the 1600W output of the Multiplus 2000 would suffice.

 

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  • Solar System - Updated.pdf
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Thanks again for the recommendation. Does this look like a better design? @mikefitz I tried to incorporate your pointers as well.

2 quick questions.
- Would the inverter charger be connected directly to the positive battery terminal or would it be connected to the distributor bus?
The lynx power-in is both a fused positive and un-fused negative busbar.
The inverter/charger connects to the lynx power_in.
- Since the charging amperage for the inverter/charger I linked above is 80A, but the recommended charging amperage for the SOK batteries is 40A (50 Max), would I throttle the AC charger amperage to like 65A, or would it need to be 40A? Or can it stay at 80?
The max suggested charge current for a single battery is 70 amps.
I would use that so as to stay within spec even if one battery is offline.

Thanks again.

Sidenote, as far as inverter power usage for an induction cooktop, I'm looking at one of these which has a power setting or a temperature setting, so I'm hoping that the 1600W output of the Multiplus 2000 would suffice.


That is pushing it a bit far.
The output wattage of the cooktop is 1800 watts.
Since this is an inductive load, the apparent power from the inverter's point of view will be higher.

Can you get a lower draw cooktop?
 
Here is a video that will show you how to fuse the branch circuits of the lynx power-in.

This video will show you how to get another branch circuit.

This human readable textual representation is how I would do your system.
Hint the dc_legend block explains all the atoms in the dc_domain block.
 

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  • culbyem.txt
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I did a bit of googling on the power factor of induction cooktops and it seems they can be pretty close to a power factor of 1.
But still your 1800 watt induction cooktop is above the continuous rating of the inverter/charger and potentially could be run for extended periods.
Also your batteries are pushed to the limit to deliver 200 amps so I'm going to stay with my suggesting to get a lower draw induction cooktop.
 
The lynx power-in is both a fused positive and un-fused negative busbar.
The inverter/charger connects to the lynx power_in.

The max suggested charge current for a single battery is 70 amps.
I would use that so as to stay within spec even if one battery is offline.



That is pushing it a bit far.
The output wattage of the cooktop is 1800 watts.
Since this is an inductive load, the apparent power from the inverter's point of view will be higher.

Can you get a lower draw cooktop?
Yeah I could definitely find a lower draw cooktop. I was just trying to find one that I could use on lower power when totally disconnected, but have more when on shore power.

And thank you for the txt file. To make sure I'm understanding it correctly though, you're saying that you would parallel connect the batteries through the Lynx instead of directly to each other? I guess that makes sense with the individual mrbf fuses for each positive terminal.
 
To make sure I'm understanding it correctly though, you're saying that you would parallel connect the batteries through the Lynx instead of directly to each other?
Yes.
Each battery should have equal length wires so that they have equal path resistance.
The benefit is fault tolerance.
A battery can die or be taken offline and the system will still work with limited capacity.
 
You can use the 1800 watt cooktop but it may shut down the system if set to its highest setting.
 
Yes.
Each battery should have equal length wires so that they have equal path resistance.
The benefit is fault tolerance.
A battery can die or be taken offline and the system will still work with limited capacity.
I have already purchased a smart shunt. How would you suggest I connect that with the 2 batteries being split? Maybe a separate set of bus bars to consolidate the batteries that then connects to the Lynx?
 
I have already purchased a smart shunt. How would you suggest I connect that with the 2 batteries being split? Maybe a separate set of bus bars to consolidate the batteries that then connects to the Lynx?
revised topo
both batteries connect to the line side of the shunt
load side of shunt connects to lynx
 

Attachments

  • culbyem.txt
    1.4 KB · Views: 17
revised topo
both batteries connect to the line side of the shunt
load side of shunt connects to lynx
I can't tell you how much appreciate all of your input.

I've updated my diagram and made a few adjustments based on components, etc. Does this seem like it will work?
 

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  • Solar System V3.pdf
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Should be a double pole disconnect between the panels and the solar charge controller

multiplus grounding lug should go to the lynx bar.
if the multiplus has an internal short to ground its a huge amount of current over a non-deterministic path

6 awg can be fused as high at 100 amps
The fuse protects the wire not devices
 
The dc distribution is a special case and that is why it gets a 100 amp fuse on 4 awg.
 
Came here to back up that trying to run inductive load off one SOK 206 can drop the voltage below the battery's BMS threshold for protection, causing it to abruptly fall to zero output.

That said, to wake up those SOKs you need to attach a charger. 20A has worked for me, such that if you don't have shore power and you have a 20A DC-DC installed, you can simply crank the engine. Couldn't speak to chargers of other amperages; haven't used any of them.
 
Came here to back up that trying to run inductive load off one SOK 206 can drop the voltage below the battery's BMS threshold for protection, causing it to abruptly fall to zero output.

That said, to wake up those SOKs you need to attach a charger. 20A has worked for me, such that if you don't have shore power and you have a 20A DC-DC installed, you can simply crank the engine. Couldn't speak to chargers of other amperages; haven't used any of them.
Thanks for the insight. I'm planning to have 2 batteries and tbh, inductive loads will not be the norm. I'm just hoping to be able to run a lower-powered cooktop if needed. I've also started looking at alternatives to induction cookers.
 
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