EBL B2B sanity check

[ian27]

to those who've done this before, can I ask for a sanity check please.

My EBL and WA121545 are wired as below, this is as per one of the standard schaudt schematics.

van came to me with a nackered lead acid, I have swapped it for a lithium.

in order to avoid the WA 121545 boosters 40A charge looping the through the B2B relay inside the EBL (having learned from others on here there is a risk of burnout) I propose to rewire as below... as far as I can tell, I just join the boosted output + to the leisure + (assume all done with appropriate cabling/fusing/terminals, its just the logic that I'm sanity checking). WA121545 takes care of isolating this from starter + whilst D+ is not active ?

side note I'll remove the D+ input from the EBL as it will no longer do anything. My fridge's D+ is through a separate standalone relay and its high current power feed is direct off the leisure.
thanks
Ian

 

[Lenny HB]

The WA 121545 can be set to an output current of up to 70 amps so you might want to look at your cable sizing and fuses, depending on cable length possibly 25 mm2 or 35mm2 cable and 80 amp fuses.
I'm not a fan of Schaudt B2B's with Lithium as on the Lithium setting they output a constant 14.4v and don't shut down when the battery is charged.

 

[ian27]

thanks. I'm assume as you didn't comment on anything else that my plan is indeed sane and similar to how you did it?
right now just want to be able to use what I have, and the loop through the EBL seems rather pointless.

the alternator side of the starter in mine is fused at 50 and cabled at 16mm, so no benefit to upgrading the other side's fusing/cabling yet. as/when I want more charging power I will get an auto-electrician to sort out the alternator side , swap the B2B to something else with a better lithium profile , uprate the cabling / fuses etc.

 

[LithiumConvert]

Which version EBL? -- it makes a huge difference. they have different version numbers for a reason.

Edit: Sorry I have just seen the 31 in the diagram.

 

[LithiumConvert]

Our 2022 Hymer Exsis came from the factory with an EBL 30 and the Schaudt WA121545
and no battery connections to the back of the EBL - Both connectors are empty.

The 121545 B2B circuitry complete by-passes the EBL and there is no D+ signal to the EBL
The fridge is fed direct from the leisure battery with its own D+

The EBL 30 charges both batteries through other connections on the front of the EBL
and takes the supply for the habitation electrics from the leisuure battery charging circuit.
Your diagram does not show how the EBL is going to charge both batteries - or even either battery.

But, your basic concept is a good starting point

My primary comment is that you have a 50 amp fuse feeding the EBL which is much bigger than is required.

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