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Wiring dual batteries with diode battery isolator, where to put the shunt(s)?

B

Bart23Sept

Member
Hi all,

Setting up an electrical system to run dual batteries and dual electric fuel pumps. Have a battery diode isolator to protect batteries from each other but how would the shunt or shunts for the ammeter be incorporated into the system?

I have the Victron Arogodiode battery diode isolator, if there's a more suitable option for an aircraft I'd be happy to hear about it.

Thanks!
 
I would think that your shunts would be on the electrical system and would read the battery being selected, as long as you are only using one at a time.
-Marc
 
Plummit said:
I would think that your shunts would be on the electrical system and would read the battery being selected, as long as you are only using one at a time.
-Marc
Click to expand...
I was hoping to read the amps upstream of where the dual batteries are paralleled. Is that possible?
 
I’m not familiar with the isolator you mentioned but I noticed from its website that it says it’s probably not the best option for a new electrical system design. I recommend you read the Aeroelectric Connection (http://aeroelectric.com/Connection/R12 Searchable Merged Chapters.pdf) if you haven’t already and make sure you fully understand your needs and the best way to design for them. The author includes drawings for many different system designs and you can use those as a starting point for your own design.

As for shunt location, it depends on what amperage you want to measure (bus, alternator, battery). There are a lot of opinions about this. I want to monitor my battery usage so I measure the amperage on the positive lead of each battery using Hall effect sensors. If you use shunts make sure they are rated for whatever amperage you are measuring.

If you want to measure at a different point then we would need to see your system schematic to see how to achieve your goal.
 
I overhauled the electrical system earlier this year before flying the plane and now am switching over to dual electric fuel pumps so the system is being modified to include a second battery. I'm leaning away from the diode isolator I shared in the first post since the 2nd battery will only power the second fuel pump in an emergency and the added complexity of the isolator won't be necessary.
 
I like to monitor B lead amps for each alternator with a shunt on each. That will give you the fastest way to understand the health of your alternator(s). I also monitor voltage as a way to confirm output of the alternator(s) but that will lag a little from amp monitoring. Since my EFIS has inputs I also monitor amp loading on my primary bus. FYI, I run a modified Z-14 bus architecture.
 
You mentioned you overhauled the electrical system. Did you create a schematic at that time that you can share? That will help us give you better advice.

In the meantime you might want to check these out these links. I assume you have a single alternator. If not Google the Z-14 electrical system. A variation of that is what I went with for better redundancy than dual batteries alone, which could be useful for you if you’re going with electronically dependent ignition and fuel injection.




 
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