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Beginner installation questions

Asinnobooks

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Joined
Oct 10, 2021
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Hey everyone! We're installing the system on our first van and have a couple of questions that we can't find answers to elsewhere. Really hoping you guys might be able to help.

  1. We need to ground our house batteries, our DC-DC charger and our 1100W inverter to the vehicle chassis. Is it possible to ground the all at the same point with 3 lugs on the same self-tapping screw into the bare metal of the van?
  2. We're one stud short on the positive bus bar for everything we need to attach. Is it possible to connect 20A MPPT and 30A DC-DC to the same stud?
  3. We're using breakers as fuses; they have BAT LINE and AUX LOAD written on them. When using these between MPPT and Battery/busbar, or between DC-DC charger and Battery/busbar, should the batteries be connected to the AUX LOAD side as that is the direction current will be travelling?
  4. When grounding the house batteries, should the cable come directly from the negative battery terminal, rather than the negative busbar where everything else is connected?
  5. Finally, how should we size the fuse/breaker for the cable coming out of the starter battery for the DC-DC charger? We can't get a handle on how many amps will be leaving the starter battery.
Sorry for the long post. We're really stuck with these things and hope you guys might be able to help!!

Thank you, thank you
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1: yes, up to 3 things at a time on lugs/bolts
2: Yes, as long as the wires are good you can have 3
3: Links to the breakers? Anything in the manual?
4: Same same, it all goes to the same place. As long as all the parts end up connected somehow you could do battery -> chassis and busbar .-> chassis and the net effect would be the same as battery -> bus bar -> chassis
5: That fuse is going to be 120% of whatever the max draw of the charger is. If it's a 30a charger then you'll want 36a, or 35 if that's what's available in stores.

Someone please correct me if I'm wrong on any of those.
 
Thank you very much for your responses - massively helpful!

3. https://www.amazon.co.uk/gp/product/B08MTDQSJ5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
These are the breakers we've been using. Nothing in the manual.

5. For the DC-DC charger, the manual calls for a 60A fuse for the external battery protection, which I assume is the house battery rather than the starter battery. I'm wiring it up with the 60A breaker (the one linked above) between the DC-DC charger and the busbar, and then was planning to put a 50A breaker between the starter battery and the DC-DC, as that is all I have available. Is that unwise?
 
So are you using the house batteries to charge the starter battery or the other way around? Either way it'll be a 60a fuse on either end if that's what the manual calls for. Assuming you're using 60a rated wire.

Traditionally the text goes right-side-up and the power comes in from the bottom and out the top.

I'm trying to figure out what the DC-DC charger is for.
 
Fuses protect wires. If breakers are labeled "bat-load" they are directional. don't use on dc-dc charger or other B2B chargers. In fact you will find no DC breakers in my arsenal.
My negative is Battery -> shunt -> BusBar -> all other device negatives plus one to the chassis. No more than two cables to one stud on the BusBar. The device case lugs connect to the closest point, chassis or BusBar. I use chassis connections with no more than two cables to a bolt. The chassis connection must be quality. Coast guard allows three cables to a stud.
 
So are you using the house batteries to charge the starter battery or the other way around? Either way it'll be a 60a fuse on either end if that's what the manual calls for. Assuming you're using 60a rated wire.

Traditionally the text goes right-side-up and the power comes in from the bottom and out the top.

I'm trying to figure out what the DC-DC charger is for.
Using the starter battery/vehicle alternator to charge the house batteries whilst driving, as well as solar panels - running on Victron Orion 12/12 30 and Victron MPPT 100/20 respectively.
 
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