CTEK D250SA - Two leisure batteries?

kn0bby

Senior Member
T6 Guru
Anyone know if you can run two leisure batteries off a CTEK D250SA?

Thanks
 
Great response! Fantastic detail. Cheers.

Spent some time looking last night and couldn’t see.

Doesn’t look like it’s going to be an option for me. I’ve only have room for one battery to be permanently fixed in place. I use another leisure battery in a portable battery box for my trailer. It would fit perfectly in front of the drivers seat while away. Was going to use an Anderson connector to connect it into the system when needed.

Connecting in series would have been simple. Not too sure about parallel with an external connection.


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Trailer in action..
 
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you kinda could join them together . (as you said) ( in a temporary configuration)

provided they are same Ah and chemistry etc . . .

but what will happen is when you plug the second one in . . . .

if its a lower voltage than battery #one, battery #one will drain itself into battery #two as they will try to equalise them selves.

so you could end up with two half flat batteries . . . from one full & one empty

plus it will take twice as long to charge !!

cable distance and quality of the link between the two will play a part.

as will the Anderson connector, that will start to get warm above 40A.


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what your suggesting is roughly the same as connecting jump leads to connect your battery box to the Aux battery...

yes possible, but proceed with caution.

and remember the ctek is 20A charge max (5hrs to recharge a 100A battery) (10hrs to charge 2x100a batteries)


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To join your battery box to the existing, get this type of thing. - fit this to the van aux battery. then connect ur battery box in when you need it.

just remember the points above, and keep an eye out for any heat build up in the cable or connector if the battery is low. - just unplug a lets cool off.

one the batteries have equalised voltage it will be fine.



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add at 50A MIDI fuse to it.


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.

with some of these . .



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and some of this . . . . .




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there are other options . . .

like a second dc-dc charger,

battery combiner,

etc etc

but all cost more than the simple cable solution above.
 
maybe look ay adding a battery monitor to each battery . . . .

like a BM2 . . .


.
 
have a look at this link

 
Thanks for all the advice..

Thought the batteries where the same size but double checked tonight.. The one in the van is 110ah AGM and the battery box is an 85ah AGM.. Doesn't sound like a wise option to mix them.

Ordered a BMV-712 to keep a closer eye on how much power I am using..
 
At least they are Both AGM... stats good... just capacity is a bit off...

Maybe give it a go once you fitted your BMV.

I've done the same when camping and a flat 2ndbattery... I meeted out a 45A flow to the flat battery..... so you need proper decent fat cable.
 
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