Am I correct that for this (inquisistent) case the circuit (without parts) should be like this?
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May be, may be not. On paper it looks as though it should work. Victron do not publish it and I have not seen reports where people have done it.
The concern in my mind is you have a voltage controller in the DC to DC and a current controller in the BMS that is being discussed without a buffer battery between. If the control loop settings in the two controllers do not match properly you could get voltage and current swings as there is no system capacitance to dampen responses. I doubt anybody wants to fit a buffer battery. Then again, it may be OK, the only way to know would be to try it.
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Thank you.
Yeah, Victron doesn’t publish that scheme.
But Victron publishes one for the Orion XS DC-DC:
Here it is:
Does this mean I can use the Orion XS without a BMS?
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Not if you are charging a lithium battery. You need a battery with an internal BMS or if you are using Victron Lithium Smart batteries then you need one of their external BMSs. They have several, for a simple system the Small BMS can shut down chargers and a Battery Protect will disconnect loads.
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Finally, upon considering everything discussed in this topic, I would like to ask the community to verify the scheme below:
Looks good. You show resettable breakers on the Orion and MPPT. Be very careful of using these, do not use the cheap Amazon/ ebay ones, they often trip completely wrong current. OK if they are for example genuine Blue Sea. As you have fuses you do not need DC breakers here, isolators if you really want something. The main isolator on the house battery, make sure that is good brand also, it will have 100+ Amps passing through.
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Thanks for the feedback. Will stick to that scheme.
Can I mount MPPT and DC-DC upside down? So that the terminals are at the top and not at the bottom.
Yes from a cooling point of view but less ideal from an electrical point of view, easier for dust, moisture to get into terminals or dropped metallic objects. You could consider shielding them if you do.
I’m a little late to this thread. I run a near identical system in an old Landcruiser 100. You can save some money here.
A drop-in LiFePO battery with built-in bms is cheaper than the Victron Smart BMS and Smart battery combo. The battery does not need bluetooth if you have a Smartshunt
You can opt for a Smartshunt instead of the BMV712 if you dont need the dedicated physical display.
The resettable breakers and fuses in series is overkill. More volt drop and connections for not much added utility.
A Smart Solar 100/20 will do for two panels of around 110W each. It gives you a 20A load output with selectable low battery shut-off for your DC loads and it can also be wired to shut down your inverter on low voltage.
I use portable panels and simply fold them up or lay them face down to connect/disconnect so I haven’t bothered with a dual pole DC isolator. No issues in a year of regular use. Wired in series the two panels can produce around 50V so some form of protection is advised if you can’t depower them before disconnecting.
I would add a dedicated fuse on the wire from alt/starter to the DCDC charger. Most vehicles already have a fusible link or fuse from alternator to start battery that is rated for a much higher current and will not protect the supply to your Orion XS which should be around 60A fuse for 16 sq.mm cable.