Help With Victron DC to DC Charger

trevor.aaron

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Jun 19, 2021
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Looking for some help with a few questions around a Victron Orion-Tr Smart Isolated DC to DC Charger (12/12 30A or 12/24 20A)

Setup:
1986 VW Vanagon
Alternator: 90A Bosch
Alternator is in the back of the van
Starter battery is in the front of the van, on the passenger side
Our battery bank and solar setup will be in the middle of the van, underneath a passenger bench

Questions:
1. Can you install this to charge from the alternator? Or is it better to run this from the starter battery? Seems easier to run this from the alternator

2. Wiring from Alternator/Starter Battery - this one has been hard for me to understand... if my DC to DC Charger is 30Amps, should I wire for 30amps and fuse 50Amps? Or do I need to step it up even higher since the Alternator is 90Amps, and or the Starter battery could be even higher? My inclination is to wire this at 4AWG (about 5ft one direction from alternator to where we plan to install the DC to DC charger)

3. Fusing from Starter Battery - Depending on the answer above, what fuse would you recommend? My inclination here was 4AWG wire and to use a 50A fuse

4. Wire and Fuse from Charger to Battery Bank - this should only be a few feet at max, and the max amperage if we chose a 30A charger is, 30A. 50A fuse and 8-10AWG ought to do it. Any recommendation on type of fuse here, and am I not thinking about a critical element here?

5. 30A DC to DC charger shouldn't overheat my alternator? I'm going to measure the Amperage at idle to verify this, as well as test/calculate the load from my van (likely only lights and radio, we don't have anything else in the van that I'm aware of), but from what I can read online, you should plan for 1/3 of your alternator load for a DC to DC charger.

Thanks in advance!
 

mikefitz

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Can you install this to charge from the alternator? Or is it better to run this from the starter battery? Seems easier to run this from the alternator
The alternator is (I hope) connected to the starter battery with a heavy duty cable, so it will not matter where you connect the Orion. If the alternator connection is nearer, use that. Use a 50A fuse as near as practical to the alternator termination. On reflection the battery may be easier to access and fit fuse, route the cable and such. You decide what is easier.
The connections on the Orion accept 6AWG as a maximum, use that or 8AWG for the cable to the alternator.
8AWG to the battery. If its lithium battery a at 12v a MRBF fuse 50A may be OK.
The Orion can take more than 30A from the vehicle system depending on system voltages, I have measured up to 35A.
Your alternator should be good for this level of current.

An 86 VW should not be too demanding on power for vehicle stuff. I would guess 25 - 30A maximum.

Mike
 

MisterSandals

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Just a FYI since you have a smallish alternator… Victorian makes that Orion unit in an 18 amp model that for some reason is harder to find while searching.
Amazon has it for $164.


Sorry no linky.

Victron Energy Orion-Tr Smart 12/12-Volt 18 amp 220-Watt DC-DC Charger, Isolated (Bluetooth)​

 

trevor.aaron

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Jun 19, 2021
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Thank you both! I should have mentioned, the battery bank is 2x100Ah Lithium batteries, 12v, so your MRBF recommendation should work out. A few more questions for you all if that's alright:
  • Should I fuse higher than 50A from DC Charger to Lithium Battery Bank? 50A MRBF you mentioned should be fine, but I'm happy to go higher if that's safer
  • Fuse Type from Alternator to DC Charge - 50Amps is what I think should be safe, but as far as type, will ANL work?
  • Any advice on how exactly to hook up to an alternator? Any rules of thumb (other than double checking the wire is connected to the starter battery is heavy duty as is, per your suggestion mikefitz)?
 

MisterSandals

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Should I fuse higher than 50A from DC Charger to Lithium Battery Bank
Your fuse is to protect the wire. Size your wire properly and size the fuse for 125% of that. Don’t start over thinking this.
Your Orion can charge at its rated amps. Amps, voltage and length of wire determine the wire gauge.
 

trevor.aaron

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Thanks MisterSandals! Great point indeed! I've been using the BlueSea wire and fuse charts so, point is to trust those. Do you have advice on what type of Fuse to use? The chart gives me what types I can use in terms of Amperage, but I'm not sure what is best in the case of a DC to DC charger.
 

mikefitz

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but as far as type, will ANL work?
any type of DC rated linkfuse at 50A, ANL or Midi
Any advice on how exactly to hook up to an alternator?
There will a high current stud on the rear of the alternator with a thick cable. With the ignition off this should read the same volts as engine battery. There could be a practical problem of adding a second cable at this point due to the stud location and the 'plastic' collar around it, see picture.
It you trace the thick cable it should run to a connection point on the starter motor, you may be able to connect there. The fuse holder mounting point needs to be considered.
The cable will have to be routed so as to withstand the vibration and movement of the engine and be protected against chafe and heat. Due to possible problems and access, as suggested in my first post, connecting to the battery will be more practical.
alternator.jpg
Mike
 
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