Burstner solar connections

Wildebus posted about a stand alone device that will charge the EB once the LB is full. Maybe that's worth a look?

Edit for link:

Protecting your Starter Battery

Just about everyone have their Campers and Motorhomes parked up for likely the next 2 months and quite possibly longer. But just like a parked-up car, the Starter Battery will start to flatten when not used. Various ways to deal with this ... If you have a VSR split-charge system, this will...
motorhomer.com motorhomer.com
 
St3v3 said:
Wildebus posted about a stand alone device that will charge the EB once the LB is full. Maybe that's worth a look?

Edit for link:

Protecting your Starter Battery

Just about everyone have their Campers and Motorhomes parked up for likely the next 2 months and quite possibly longer. But just like a parked-up car, the Starter Battery will start to flatten when not used. Various ways to deal with this ... If you have a VSR split-charge system, this will...
motorhomer.com motorhomer.com
Click to expand...
I've now fitted one myself actually! works very well :)

As an aside, we are probably doing to do some reprogramming so it can also provide a bit of a "boost mode" to the Starter Battery for those folk who, for example, like to sometimes listen to the cab radio with the radio off so as to transfer extra power from the Leisure Battery for a set time when there is a need (as determined by the owner).
 
Yeoblade said:
i just used one of these:
Ebay CBE b2b

not had a problem as long as there is solar power, Eb charged too. Trevscoda sings its praise too.View attachment 56072
Click to expand...
I wonder how 'intelligent' it is?
Votronic make a very similar item for the same money and you may be interested to see what it looks like inside ...
www.t6forum.com

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

As you can see below...100% charging with everything off. The graph shows that I have just been for a drive and has been charging. Very accurate....drove to Tesco.....showing the rise in charge, levelled off whilst in shopping, then charging on way home, pretty pleased with it now.
www.t6forum.com www.t6forum.com
about £2 worth of components.

A lot of these units work on basic voltage differentials between the two batteries - so as long as the Leisure Battery is around 0.7V higher than the Starter Battery, the unit will turn on and a current will flow from LB to SB. That can generally work as a Starter Battery is not typically below 12V and a Lead Acid battery is usually only above 12.7V when on a charger (they will be higher for a while after charge, but when in use for a small time, the voltage drops of course).
So when all is good, those units are fine, UNLESS you have Lithium Batteries, where the voltage settles much higher and so there can be a constant transfer between LB and SB as the differential is over 0.7V and can remain so until the Lithiums are virtually drained.
Also, if a fault occurs on a battery which creates a big drain (or if something is left on that is sucking the battery down), as the SB keeps dropping, the >0.7V difference means that the LB - whether Lithium OR Lead-Acid - can get sucked down as well.
This graph shows how a battery can go bad for no apparent reason - Look at the voltage (blue) line dropping as the battery fails from around 2:00AM
1599131595582.png
Now if you had a simple battery maintainer like the Votronics, potentially like the eBay one (I don't know the details of that but I suspect it is similar), or the wonderful 'Clive Mott' system that some like to promote, the effect of this fault occuring on a Starter Battery would be to drain the Leisure Batteries to such an extent that they could likely be damaged beyond further use.
I personally would not fit one of those units in my van if I were given it for free unless I could be sure it would disengage at low voltages (and I mean be sure, not just base the decision on a description in an eBay listing backed up with no data or tech sheet)
 
wildebus said:
I wonder how 'intelligent' it is?
Votronic make a very similar item for the same money and you may be interested to see what it looks like inside ...
www.t6forum.com

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

As you can see below...100% charging with everything off. The graph shows that I have just been for a drive and has been charging. Very accurate....drove to Tesco.....showing the rise in charge, levelled off whilst in shopping, then charging on way home, pretty pleased with it now.
www.t6forum.com www.t6forum.com
about £2 worth of components.

A lot of these units work on basic voltage differentials between the two batteries - so as long as the Leisure Battery is around 0.7V higher than the Starter Battery, the unit will turn on and a current will flow from LB to SB. That can generally work as a Starter Battery is not typically below 12V and a Lead Acid battery is usually only above 12.7V when on a charger (they will be higher for a while after charge, but when in use for a small time, the voltage drops of course).
So when all is good, those units are fine, UNLESS you have Lithium Batteries, where the voltage settles much higher and so there can be a constant transfer between LB and SB as the differential is over 0.7V and can remain so until the Lithiums are virtually drained.
Also, if a fault occurs on a battery which creates a big drain (or if something is left on that is sucking the battery down), as the SB keeps dropping, the >0.7V difference means that the LB - whether Lithium OR Lead-Acid - can get sucked down as well.
This graph shows how a battery can go bad for no apparent reason - Look at the voltage (blue) line dropping as the battery fails from around 2:00AM
View attachment 56081
Now if you had a simple battery maintainer like the Votronics, potentially like the eBay one (I don't know the details of that but I suspect it is similar), or the wonderful 'Clive Mott' system that some like to promote, the effect of this fault occuring on a Starter Battery would be to drain the Leisure Batteries to such an extent that they could likely be damaged beyond further use.
I personally would not fit one of those units in my van if I were given it for free unless I could be sure it would disengage at low voltages (and I mean be sure, not just base the decision on a description in an eBay listing backed up with no data or tech sheet)
Click to expand...
I guess it is similar to the one you cite, (I was hoping it had a mini computer in it controlling all the electrons:) )
I don't have lithium batteries, all lead acid, so no problem there.
Actually I did have a problem over winter /lockdown, I left it for 6 months and the S battery went flat beyond recovery, so a new SB was needed.
It was 8 years old and over winter the solar would be minimal to keep the system fully charged, It will only charge the SB when the LB are full and I guess that didn't happen.
 
The more I look at it the more I agree. I think the option of a dual controller which has a trickle charge for the SB. A second controller will probably do the job but needs to be ‘tunable’ to give the lower charge rate. The problem is that the 100w panel only has a little power to share at the best of times and dual controllers can share it more efficiently.
 
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