Before ordering cables & fuses: final technical review of 24V Victron campervan schematic

DIY
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1

Hello,

Before ordering the final cables, fuses and protection devices, I would appreciate a technical review of the attached schematic.

System:

  • VW Crafter campervan
  • 24V Victron NG Lithium 200Ah
  • VE.Bus BMS NG
  • MultiPlus II 24/3000/70-32
  • Lynx Distributor
  • Orion XS 1400
  • SmartSolar MPPT 100/30
  • Cerbo GX MK2 + GX Touch 50 Flush
  • Orion-Tr 24/12-30Non-Isolated
  • Smart BatteryProtect 12/24V-65A

The overall architecture is fixed.
I am mainly looking for feedback on:

  1. Fuse ratings
  2. Cable sizing
  3. Protection placement
  4. Grounding / bonding
  5. Any safety-critical issues

I am NOT looking for alternative system designs or different component recommendations.

If you spot anything incorrect or non-compliant, please indicate the specific connection and your proposed correction.

Thank you.

electrical block diagram
electrical block diagram1511×1007 249 KB

2

Two Quick Questions: What’s the AGM battery for? Why not use a fuse and disconnect switch instead of the 60A breaker?

3

Starter battery id guess. But i would also use a fuse on the Orion XS input, or at least a quality MCB like a BlueSeaSystems.

I would be very cautious with connecting the LTE modem directly to the busbars. Theres nothing protecting the SmartLithium against complete discharge. Even after the VE.Bus BMS has switched off all the loads, the LTE is still connected to the busbars and can keep draining the battery.

Some key connections are missing, but maybe thats intentionally left out for schematic clarity. GX to BMS to MP is a VE.Bus. MPPT and Orion XS to GX is a VE.direct each. BatteryProtect to BMS is an ATD wire. These are not optional since they protect the SmartLithium in the event of an issue. Remember that SmartLithiums do not have a contactor or FET/IGBT disconnect internally, they can not physically switch off. The protection is done through the BMS and its coms or ATC/ATD contacts.

A 75/15 would have done it as well, 24V x 15A is 360W while campervan mounting usually means the panels lays flat on the roof, so its almost guaranteed to never bring its rated output. I dont see the need for a PV isolator with just 48Voc but thats up to you.

4

Just to be clear, those questions should be posed to your reputable and experienced systems installer; you’ll get a lot of opinions here that will likely be valuable, but the purpose of the Community is not to provide compliance review, as noted in the Community Guidelines, particularly because safety regulations in Belgium are not necessarily the same regulations as exist elsewhere in the world.

If you need to find good installers there are no shortage of them, and dealers as well, where you are; you can find them through Victron’s “where to buy” map, which lists both installers as well as dealers and distributors, many of the latter of which can give you recommendations for local installers to be sure to steer you straight and in compliance with your local regulations.

5

Hi
Thanks for the disclaimer. I know I’m asking as a DIY’er in a DIY forum.

Some well known camper builders are not in your 'where to buy" list.
Do you have a partner program with public labeling so we can be sure how safe (and legal) everything could be?

Thanks.

6

This is my current version. (Happy to share the final design as a draw.io file later on.)

image
image1434×967 228 KB

I’m aware that I still need to verify the specifications of the cable sizes, connectors, fuse ratings, and devices before installing everything. The cable sizes and fuse ratings will be adjusted during the design process.

7

I don’t personally, no - I’m not Victron, nor is this an “ask Victron” forum, we’re all just system owners, installers, enthusiasts, etc. Victron is a manufacturer only, so beyond the “where to buy” list (and even including the list), it will be up to you to evaluate the suitability of the potential installers with whom you choose to contract. I certainly always recommend discussing this with your authorized Victron distributor before, during, or post-purchase as well; there’s a very good chance they have a short-list of local recommended installers too, and likely to be vetted since it’s fully within their best interests to make sure that the components they sell you are going to be installed correctly!

8

Theres no need for the two ATC lines. Both the Orion XS and the MPPT are connected over VE.Direct to the GX, so they are already BMS controlled.

You could keep those connections, just in case, if thats what you want, but i would connect the ATC to the MPPT remote On/Off instead. That BatteryProtect on the MPPT output might not live long in its function as a charger disabler. BPs are strictly unidirectional, so powering the MPPT up from the battery might already be enough of a reverse current for the BP to break.

9

Why are you using different cable sizes for the positive and negative connection to your 12v fused loads?

10

Hi

From the manuals and pictures of the available connections, everything seems like the Victron SmartSolar MPPT 100/30 (SCC110030210) has no remote On/Off (L/H) connections and can’t be monitored and controlled together via de VE.Direct connection.

Apparently when connecting the VE.Direct to the Cerbo GX MK2 (BPP900450110), it can be monitored but not On/Off controlled.
When connecting the VE.Direct (via a “VE.Direct non-inverting remote on-off cable” ASS030550320) with the VE.Bus BMS NG (BMS300200300) Allow To Charge, you can’t monitor the MPPT with the Cerbo GX.

Matt’s Van gives the same advice if you want to do both monitoring and controlling:

The Orion XS 1400 still has both VE.Direct (for monitoring) and H-connection to control Allow To Charge.

“That BatteryProtect on the MPPT output might not live long in its function as a charger disabler. BPs are strictly unidirectional, so powering the MPPT up from the battery might already be enough of a reverse current for the BP to break.”
–>> Do I just need to switch IN and OUT connections?

Thank you.

11

Hi Derek.
That was not my intention.
Thanks for pointing that out. I will definitely adjust it.

12

Any MPPT connected over VE.Direct participates in DVCC, same as the Orion XS. Then the battery decides on how it wants to be charged. No need to also use the ATC as well.

Asterisk five under the table

Solar Chargers, Inverter/Chargers, Multi RS, Inverter RS and Orion XS do not require wiring. All other loads and chargers must be wired and controlled via ATC/ATD.

True, my bad.

Then it will live even shorter. They cant handle reverse currents. Maybe the few mA that the MPPT uses itself when no PV voltage is available is not enough to cause damage to a BP. The main issue is, that a BP can fail open or shorted.

If it fails open, you notice right away, the MPPT will not be able to charge anymore.

If it fails shorted you will only notice once it should switch off, and it doesnt anymore.

Also stated in the video that Orions can pass current in both ways is also not true. The Orion XS models are able on the hardware level to do that, but that function was so far not implemented in the software. Every other Orion does not feed anything back to the input.

Ive only skipped thorugh the video, but theres more false stuff, like the Lynx Distributor LEDs, they only work if you also have a Lynx BMS or a VE.Can Shunt, they dont work on their own.

A PV isolator and an MCB on the PV? Hes installing a 20A MCB and then expects that to trip on 9A of shirtcurcuit current of the panels? That MCB never trips.

Mounting electrical stuff on flammable material.

Id also like to know where the two PE connections run off to, as those are somewhat vital to the security of the whole thing. Forget everything else, if those are not done correctly it might be deadly. Ive got to stop watching that video. Good luck with your build

13

Hi

Right before reading your last post, I read the DVCC parts on this page: 11. DVCC - Distributed Voltage and Current Control
Mainly the differences with BMS v1 <> v2 <> NG were important.

The VE.Bus BMS NG is not mentioned in the table on that link.
It is on your link. Thanks for suiting this out!

I’ve deleted the “Allow To Charge” cables and the Battery Protect.
And added some (too long :wink: ) texts.

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If you or someone else have remaining remarks. Feel free to share, thanks.

14

Ive fallen into this trap myself a few times. When searching for DVCC, you get results from any of the GX device manuals, and you have to pay attention as to which GX devices manual you are currently looking at. My DVCC link goes to the Ekrano GX while yours is from the CCGX, which is a fair few years older than the NG stuff. Easy trap to fall into, sadly.

15

And I should better use this link specific for the Cerbo GX: https://www.victronenergy.com/media/pg/Cerbo_GX/en/dvcc—distributed-voltage-and-current-control.html

Maybe also a difference between the MK1 and MK2…

I’ll use the Cerbo GX MK2 (BPP900450110 or BPP900451100).

I’ll read it tomorrow :slight_smile: .
Thanks.