Can I have two b2b??

U

unclestinky

Joined
Nov 21, 2021
Posts
79
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56
Location
Dorset, UK
Funster No
85,531
MH
Pilote V600G
Exp
Since 2020
Hi
My Pilote pvc has a Dolphin 25/18amp b2b fitted as standard. This is a dual output unit that has 25amp outlet to the leisure battery and an 18amp outlet dedicated to the fridge (in my case compressor).
I am fitting a Votronic 50amp b2b that I removed from my previous m/h.
I have already got the required cables for the Votronic unit.

Can I leave the Dolphin b2b in place and fit the votronic separate or should I keep it simple and remove the Dolphin b2b?

Thanks
 
I have but, I am no expert. Ongrid power solutions fitted a new victron orion as part of a larger upgrade and left my factory fitted schualt insitu
 
If they have similar charge profiles, i.e. they raise to the same target voltage at each stage, then it should be ok. Although you might find one switches off before the other when the battery nears full. It shouldn't be an issue.

I assume you're going to lithium with that current? Is the Dolphin lithium aware?
 
When I changed my lead acid batteries to Lithium I fitted an extra B2B so I have two Victron 12-12-30 smart B2B’s and they work well. This was before the Orion XS arrived, otherwise I would have fitted one of them.
 
I've just got a 30a Votronic that splits the load with the fridge. Only 175w of solar. And a large 280Ah lithium battery. We tend to drive every other day for an hour. Often stay places off grid. But we'll get to a hook up every 7-10 days. I'm a relatively low electricity user. But I've never had the battery get below 50% before I we stay somewhere with EHU, and that's to do a load of cloths washing. I'm always tempted to get more solar or get a bigger B2B, but I just don't have a use for it.

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Guigsy said:
If they have similar charge profiles, i.e. they raise to the same target voltage at each stage, then it should be ok. Although you might find one switches off before the other when the battery nears full. It shouldn't be an issue.

I assume you're going to lithium with that current? Is the Dolphin lithium aware?
Click to expand...
I’m fitting a Fogstar 300ah when it arrives. The Dolphin does have lithium profile.
 
unclestinky said:
I’m fitting a Fogstar 300ah when it arrives. The Dolphin does have lithium profile.
Click to expand...
My intention was to remove the Dolphin, fit the Votronic and wire the fridge directly to the leisure battery (fused).
Some suggested on a similar thread I read, leaving both in place would be beneficial. My concern was this may make the system unnecessarily complicated.
 
If you remove the existing B2B you gain bugger all 25 + 18 = 43

I would suggest you leave in situ for your compressor fridge, 18 amps and disable the 25 amps battery charging, which will be taken over by the 50 amp unit

Guaranteed no conflict, gives all 50amps to charging, with built in redundancy should the Victron unit fail, reinstate the original charging supply
 
eddie said:
If you remove the existing B2B you gain bugger all 25 + 18 = 43

I would suggest you leave in situ for your compressor fridge, 18 amps and disable the 25 amps battery charging, which will be taken over by the 50 amp unit

Guaranteed no conflict, gives all 50amps to charging, with built in redundancy should the Victron unit fail, reinstate the original charging supply
Click to expand...
I think the gain is more, as the compressor fridge would not draw the full 18amps.
However, I do like your suggestion as like you say I will have a back up.
Thanks
 
unclestinky said:
I think the gain is more, as the compressor fridge would not draw the full 18amps.
However, I do like your suggestion as like you say I will have a back up.
Thanks
Click to expand...
Have you tried with just the Dolphin? Are you actually running out of charge? You don't need to get the battery to full every day. 😁
 
We have the schaudt 25a battery booster that runs fridge and charges battery when on. I've got the new 50a victron b2b sitting ready to go. Was going to get off grid to install it but was thinking do it myself but can't see how to disable the charging from the schaudt (some people mentioned relays but beyond my skill grade) so thinking it may be OK just to leave as is?
 
Guigsy said:
Have you tried with just the Dolphin? Are you actually running out of charge? You don't need to get the battery to full every day. 😁
Click to expand...
I had the voltronic and a 280ah on my previous m/h. I found the balance of usage / charge about right.

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I asked Udo Lang at Schaudt about using a second B2B alongside the Schaudt WA121525. He said to wire the second B2B directly to the batteries and leave the WA121525 working through the EBL as originally installed.
 
I have a 25amp Schaudt B2B fitted as standard. I am about to upgrade to a OPS280 from Offgrid and include a new 50amp Votronic wired directly to the 280. I am thinking that I will retain the Schaudt for redundancy and disconnect the supply fuse. The D+ signal from the Schaudt will move to the Votronic - BUT - can I split the D+ to feed both the Votronic and the Schudt? If so I could pull the Schaudt into use if I ever get a super low battery..
 
TrudeandDall said:
I have a 25amp Schaudt B2B fitted as standard. I am about to upgrade to a OPS280 from Offgrid and include a new 50amp Votronic wired directly to the 280. I am thinking that I will retain the Schaudt for redundancy and disconnect the supply fuse. The D+ signal from the Schaudt will move to the Votronic - BUT - can I split the D+ to feed both the Votronic and the Schudt? If so I could pull the Schaudt into use if I ever get a super low battery..
Click to expand...
Does the schaudt run your fridge when moving? Ours does so can't just disconnect it.
 
unclestinky said:
My intention was to remove the Dolphin, fit the Votronic and wire the fridge directly to the leisure battery (fused).
Some suggested on a similar thread I read, leaving both in place would be beneficial. My concern was this may make the system unnecessarily complicated.
Click to expand...
If you wire the fridge directly to the leisure battery water ever current the fridge take you will lose in charge to the battery.

I would do what eddie says most sensible option.

I have a new van due any day it comes with a Schaudt 25 amp B2B buy the time the fridge has gobbled 14amps bugger all left for 400-500 ah of Lithium I plan to fit. Also don't like the Lithium charge profile on the Schaudt.
So the plan is to to use the Schaudt unit just to power the fridge with the fridge supply switched via a relay using the D+ to switch the relay. Then fit a 50 amp Victron B2B for the batteries. That way both circuits will be independant.

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Lenny HB said:
If you wire the fridge directly to the leisure battery water ever current the fridge take you will lose in charge to the battery.

I would do what eddie says most sensible option.

I have a new van due any day it comes with a Schaudt 25 amp B2B buy the time the fridge has gobbled 14amps bugger all left for 400-500 ah of Lithium I plan to fit. Also don't like the Lithium charge profile on the Schaudt.
So the plan is to to use the Schaudt unit just to power the fridge with the fridge supply switched via a relay using the D+ to switch the relay. Then fit a 50 amp Victron B2B for the batteries. That way both circuits will be independant.
Click to expand...
Yes I agree, wasn’t an option I had considered, but sounds the most sensible.
Thanks
 
TrudeandDall said:
No. We have a compressor fridge that runs from the battery. The Schaudt just charges the battery.
Click to expand...
Therefore the B2B is effectively running the fridge. The B2B will be supplying 25 amps to the battery but the fridge will be using 15 amps so battery only left with a 10 amp charge.

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Lenny HB said:
Therefore the B2B is effectively running the fridge. The B2B will be supplying 25 amps to the battery but the fridge will be using 15 amps so battery only left with a 10 amp charge.
Click to expand...
It is true that the B2B runs the fridge, but this is indirectly, as it draws directly from the battery and it does not run all of the time.
 

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