How to add 2nd (portable) leisure battery to current Euro 6/CTEK 250 System

[RikParr73]

I currently have a Euro 6 engine with CTEK 250SA set up, using a single 110ah LB and 110w solar panel. All is working fine. I want to add a second leisure battery that I will house in a portable tool box that I can connect to the system in the van to either simply charge it or to add additional capacity if needed (when off grid using the crx50 fridge etc). Hoping it will just be a case of connecting a cable to each + and - and hooking up to the portable battery as/when, or do I need to be aware of anything? Any advice appreciated. Thanks, Rik.

 

[VanDamMan]

I currently have a Euro 6 engine with CTEK 250SA set up, using a single 110ah LB and 110w solar panel. All is working fine. I want to add a second leisure battery that I will house in a portable tool box that I can connect to the system in the van to either simply charge it or to add additional capacity if needed (when off grid using the crx50 fridge etc). Hoping it will just be a case of connecting a cable to each + and - and hooking up to the portable battery as/when, or do I need to be aware of anything? Any advice appreciated. Thanks, Rik.

Hi @RikParr73 … I’ve a similar system…from my leisure battery I’ve added a + and - to an Anderson plug…then setup my mobile battery box…you will need both batteries to be same size and chemistry ( mine both 110a AGM ) for safety inline fuse…Now the bad bit …the box is heavy…but on a plus side and can also charge the battery box at home ..I use my Ctek battery charger….my system is very low tech…Oh …and don’t forget to use battery type cable….
ps …if you want any more detailed help I’m sure @Dellmassive can oblige…

pps.. If you buy a Battery box rather than a tool box all the connection are pre-made…but not all boxes are equal…I wanted 2x 12v sockets..a battery charge indicator ..and terminals to connect the charger..

 

[RikParr73]

Hi @RikParr73 … I’ve a similar system…from my leisure battery I’ve added a + and - to an Anderson plug…then setup my mobile battery box…you will need both batteries to be same size and chemistry ( mine both 110a AGM ) for safety inline fuse…Now the bad bit …the box is heavy…but on a plus side and can also charge the battery box at home ..I use my Ctek battery charger….my system is very low tech…Oh …and don’t forget to use battery type cable….
ps …if you want any more detailed help I’m sure @Dellmassive can oblige…

pps.. If you buy a Battery box rather than a tool box all the connection are pre-made…but not all boxes are equal…I wanted 2x 12v sockets..a battery charge indicator ..and terminals to connect the charger..

View attachment 124401View attachment 124400

Hi and thanks, this is exactly what I am looking for! I will prob use a toolbox with wheels to get around the weight issue. The anderson plug/socket was also a missing part of the puzzle so thanks for that too mate. I can crack on now. Cheers!

 

[VanDamMan]

Hi and thanks, this is exactly what I am looking for! I will prob use a toolbox with wheels to get around the weight issue. The anderson plug/socket was also a missing part of the puzzle so thanks for that too mate. I can crack on now. Cheers!

Idea…. Buy a collapsible camping cart….so can be used for other stuff..as well as moving battery box around…..nothing worse than trying to lug all last nights washing up to the wash point…

 

[Dellmassive]

@RikParr73

as @VanDamMan said above.

that's fine, but make sure its the same battery chemistry and type/size.

preferably the exact same battery.

also try to have both batteries at similar SOC when you connect them. (as large currents can flow between a flat and full battery)


normally 50A Anderson connectors are used to connect batters together.

remember to fuse all battery connection.

so you need to fuse the outgoing leisure battery POS terminal.

and also the 2nd battery terminal.


more info on building a battery box here:

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It --

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It -- It's about time that I got this long-overdue project sorted out. The missing parts are on order and completion is in sight . . . . . . . . ready for the Post Pandemic 2020 Camping Trips (Hopefully) This is where it started. p1...

www.t6forum.com

....


the CTEK D250 has around 20A charge current, so that's ok for two battery's together.




remember that if the second battery is low and you plug it in to the vans leisure battery . . . . current will flow from one to another until they equalize . . whether the CTEK is running or now.

the 50A Andersons will start to get hot above 40A so bear that in mind.

also make sure you use decent fat battery cable for the interlink. and make sure its fused at 50A or below ( depending on the size if the interlink cable )


.




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[RikParr73]

@RikParr73

as @VanDamMan said above.

that's fine, but make sure its the same battery chemistry and type/size.

preferably the exact same battery.

also try to have both batteries at similar SOC when you connect them. (as large currents can flow between a flat and full battery)


normally 50A Anderson connectors are used to connect batters together.

remember to fuse all battery connection.

so you need to fuse the outgoing leisure battery POS terminal.

and also the 2nd battery terminal.


more info on building a battery box here:

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It --

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It -- It's about time that I got this long-overdue project sorted out. The missing parts are on order and completion is in sight . . . . . . . . ready for the Post Pandemic 2020 Camping Trips (Hopefully) This is where it started. p1...

www.t6forum.com

....


the CTEK D250 has around 20A charge current, so that's ok for two battery's together.




remember that if the second battery is low and you plug it in to the vans leisure battery . . . . current will flow from one to another until they equalize . . whether the CTEK is running or now.

the 50A Andersons will start to get hot above 40A so bear that in mind.

also make sure you use decent fat battery cable for the interlink. and make sure its fused at 50A or below ( depending on the size if the interlink cable )


.




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Kit List And Stuff -- How I Done It & What I Use --
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VIP Membership | VW T6 Forum - The Dedicated VW Transporter T6 Forum
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For Sale - Summer-weekend-t6f Limited Edition External Stickers
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Thank you very much for the reply. I was going to use 16mm cable for the interlink. Sorry, just to confirm, should I put a fuse on the pos of the portable LB between the battery and pos and pos of the socket I will be putting in the box to connect to the van LB? I will ensure both batteries are similar SOC. I have just started reading through the thread you linked me to, looks very interesting, I may want to pick your brains some more, but will try to keep the questions limited! Thanks again.

 

[Dellmassive]

@RikParr73

16mm2 should be ok for the 50A max the Anderson connector can take.

BOTH sides of the link need fusing.

BOTH battery POS terminals need fusing.

ALL battery POS connection need fusing

so

LB POS -->Fuse -->Anderson plug ------ Anderson plug -->Fuse -->2nd LB/Battery Box


More info here:

Diagrams, Schematics & Wires -- How I Done It --

Diagrams, Schematics & Wires -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

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https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it --

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it -- id like to build a thread showing what's possible as regards to seat base builds. lets post a collection of our electrical installs, be it in the seat base or rear conversion. just EHU or SCR/VSR, charger, DC-DC...

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[RikParr73]

@RikParr73

16mm2 should be ok for the 50A max the Anderson connector can take.

BOTH sides of the link need fusing.

BOTH battery POS terminals need fusing.

ALL battery POS connection need fusing

so

LB POS -->Fuse -->Anderson plug ------ Anderson plug -->Fuse -->2nd LB/Battery Box


More info here:

Diagrams, Schematics & Wires -- How I Done It --

Diagrams, Schematics & Wires -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

www.t6forum.com

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it --

Seat Base Electric + EHU + Solar Install + Charger + DC-DC -- How We Done it -- id like to build a thread showing what's possible as regards to seat base builds. lets post a collection of our electrical installs, be it in the seat base or rear conversion. just EHU or SCR/VSR, charger, DC-DC...

www.t6forum.com

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That's great, again many thanks for your help mate, appreciated. Best start getting my goodies list ready

 

[RikParr73]

Hi

So i've been going through your build guide (thanks for that) and working out what I wanted from my system. I am going to re-do the van side of things first and for now just have a direct link from the portable LB to the van using Anderson connectors as you suggested. I have drawn up a wiring diagram to reflect what I will be doin, I am very limited with my knowledge so if anyone could confirm if it looks safe/ok, want to be sure fuses are right size and location. Happy to receive suggestions/comments At a later date I will want to add a portable solar panel to the portable unit, just wary that CTEK has max open circuit of 23v - would adding another in parallel be ok? I've been advised to check there is a diode in case 1 panel stops working and prevents charge going to any faulty panel and setting on fire?! Many thanks.

 

[Dellmassive]

That looks OK

I was wondering about the second battery NEG connection being direct to the battery.

But that should be OK... as the shunt will be set to the 1 battery anyway.

Just remember all POS connections must be fused. And fused as close to the source of the power as possible.

Note.

The ctek to busbar needs a fuse.

The battery POS to busbar needs a fuse.

 

[RikParr73]

Yaay, got it right lol!!! Thanks for confirming. All noted about POS connections. When complete I will open a new thread about the solar. Thanks again.

 

[Dellmassive]

take a look at my battery box build . . . it might give you some more info .. .

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It --

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It -- It's about time that I got this long-overdue project sorted out. The missing parts are on order and completion is in sight . . . . . . . . ready for the Post Pandemic 2020 Camping Trips (Hopefully) This is where it started. p1...

www.t6forum.com

.

 

[RikParr73]

take a look at my battery box build . . . it might give you some more info .. .

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It --

12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It -- It's about time that I got this long-overdue project sorted out. The missing parts are on order and completion is in sight . . . . . . . . ready for the Post Pandemic 2020 Camping Trips (Hopefully) This is where it started. p1...

www.t6forum.com

.

Yes, I've been working with that to get extra info - great thread!

 

[RikParr73]

Yes, I've been working with that to get extra info - great thread!

Sorry, what amp fuse should I use from LB to POS bus bar? I'm not using any inverter just crx fridge, lights, stereo head unit, USB ports and Planar heater.

 

[Dellmassive]

that depends on the thickness of the cable, and how many amps you will be pulling max.


so assume 30A max draw.

over rate the cable to 50A.

then down rate the fuse to 30A.