B2B and Victron IP22 sharing cables to battery bank?

[Glandwr]

I am thinking of installing a 30amp IP22 charger hard wired to EHU supply. It will be in a cupboard close to an existing Sterling 50amp B2B. To avoid some very awkward routing and expense what do the knowledgeable on here think of the idea of using a junction to share the cable?

99% of the time only one of the chargers will be using the cable at any one time. But Sod's will mean that someone sometime will start the engine while still on Hookup. What would happen? Current cabling looks like 16mm.

 

[Thistle]

A whole bunch of scenarios spring to mind depending on all sorts of hypothetical situations but in reality the probability the batteries are so heavily discharged to be pulling the full potential 80A at the same time that you plug into to the mains and you also have the engine running should be very unlikely.

Plus you do have the ability to engage brain and prevent it from ever happening

Use the 3% column in the chart linked below to check the current capacity of your 16mm over what ever length it is.
If it’s a particularly long run then the 10% column begins to apply and the resulting volt drop down the cable will further limit the current drawn by the batteries especially if they are lead acid.

Fuse the output of the two chargers independently as usual but protect the cable itself with a suitable higher capacity fuse and give it a go.

http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg

 

[davep10000]

Not entirely relevant, but I have never had more than 42Amps out of my Sterling 50A B2B, even with heavily discharged battery. This is because the 50A rating is Amps IN to the B2B from the alternator. With inefficiencies, and the B2B output being higher than alternator voltage, you will never see 50Amps to your leisure battery.

 

[wildebus]

I am thinking of installing a 30amp IP22 charger hard wired to EHU supply. It will be in a cupboard close to an existing Sterling 50amp B2B. To avoid some very awkward routing and expense what do the knowledgeable on here think of the idea of using a junction to share the cable?

99% of the time only one of the chargers will be using the cable at any one time. But Sod's will mean that someone sometime will start the engine while still on Hookup. What would happen? Current cabling looks like 16mm.

1) no point in running extra cable if what you have in place is perfectly fine for doing the job.
2) if it is 16mm2 cable, then it can handle both chargers together if you happen to run both. You might need to check the fuses and positions though. A fuse should ideally be fitted close to the source of any power - so any chargers AND any batteries as well.

 

[Glandwr]

No danger of conflicts between the 2 chargers? Also if I go ahead what's the recommendation for the junction of the thick wires please?

 

[merl]

No danger of conflicts between the 2 chargers? Also if I go ahead what's the recommendation for the junction of the thick wires please?

There's no danger of conflict between the 2 chargers.
You could cut and crimp ring terminals and simply bolt the 3 legs together but personally I'd want the junction covered to prevent accidental shorting. Something like this.

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If you search you should be able to find smaller units with less connections but still with a plastic cover.

ANL fuse holders match which you'll probably need too.

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Fuse Type: ANL. ANL Fuse Holder. 1 x ANL Fuse Holder. 1 x ANL Fuse. Connecting fasteners designed to securely hold fuse in place for ultimate performance. Fits 0 4 8 10 Gauge. Rated Current: 40/50/60/100/150A.

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[Nabsim]

No danger of conflicts between the 2 chargers? Also if I go ahead what's the recommendation for the junction of the thick wires please?

You may get the mains charger dropping back when it sees the battery rise from the B2B but it won’t cause any problems. I run 2 x IP22 chargers and they reduce amps when running together