Double Battery whilst camping

Wookie_66

New Member
I have a diesel heater straight to battery which is usually fine for the hour blast I need. However going away with the gf in the cold so going to be on longer. Wondering if I can get away with buying another car battery or even a leisure battery and linking jump leads to the 2 to give myself extra ah. So then when disconnect I hopefully still have power to start van after a few days. I also have a booster to jump start if take it to far.
 
The big danger with 2 batteries connected as a bank is they should be exactly matched (identical batteries and age) if not one will be lower voltage and drain the other.

If the batteries are at different charge levels when connected you will get quite strong current flow as the lower charge level one draws current from the higher charged one until the voltages equalise.
 
I have a diesel heater straight to battery which is usually fine for the hour blast I need. However going away with the gf in the cold so going to be on longer. Wondering if I can get away with buying another car battery or even a leisure battery and linking jump leads to the 2 to give myself extra ah. So then when disconnect I hopefully still have power to start van after a few days. I also have a booster to jump start if take it to far.

I'd take that 2nd battery just as a spare. If trying to preserve battery charge/life have the engine running if possible when starting AND stopping the heater as this is where you get a huge drain because the glow plug is used to light (start) and burn off excess diesel (stop).
 
The big danger with 2 batteries connected as a bank is they should be exactly matched (identical batteries and age) if not one will be lower voltage and drain the other.

If the batteries are at different charge levels when connected you will get quite strong current flow as the lower charge level one draws current from the higher charged one until the voltages equalise.
I understand the basics but I would have thought overall it would last longer and hopefully protect the van battery from completely dying and if it did I would be in the same situation as if I didn't have it but would have had the heater and lights on for longer? I would not be putting an empty battery on the van battery and if was half level it would be hit and miss if I had been driving van for the day.
 
I have a diesel heater straight to battery which is usually fine for the hour blast I need. However going away with the gf in the cold so going to be on longer. Wondering if I can get away with buying another car battery or even a leisure battery and linking jump leads to the 2 to give myself extra ah. So then when disconnect I hopefully still have power to start van after a few days. I also have a booster to jump start if take it to far.
A different approach; buy a trickle charger, outdoor extension lead, an extender with fused 230v outlet and stay at a campsite with electric hookup?
Check out @Dellmassive How I done it threads for recommended trickle charger rating.
Use above to keep either van battery or second battery topped up, whilst keeping the separate?
 
A different approach; buy a trickle charger, outdoor extension lead, an extender with fused 230v outlet and stay at a campsite with electric hookup?
Check out @Dellmassive How I done it threads for recommended trickle charger rating.
Use above to keep either van battery or second battery topped up, whilst keeping the separate?
Can't find the post but got the idea. Ehu to battery charger
 
Can't find the post but got the idea. Ehu to battery charger
I found this one;

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

Post #59 shows a 5A Noco trickle charger.

Also check out;

 
12volt EHU is a better plan if you want to support a single battery van, a lot less bulky too and safer than croc clips that might shift in the night and suddenly discharge 800A of starting current on a short while you sleep...

I made mine up to charge through the trailer socket:

https://www.t6forum.com/threads/trailer-socket-12v-ehu-how-I've-done-it.45009/

If you do want to do this at least fit a fused Anderson connector to connect batteries together safely, jump leads is just asking for a short and likely a fire.
 
12volt EHU is a better plan if you want to support a single battery van, a lot less bulky too and safer than croc clips that might shift in the night and suddenly discharge 800A of starting current on a short while you sleep...

I made mine up to charge through the trailer socket:


If you do want to do this at least fit a fused Anderson connector to connect batteries together safely, jump leads is just asking for a short and likely a fire.
Hi @roadtripper
Thank you for sharing above.
It looks very well and comprehensively written.
I’ve had a quick look through and your solution would be very useful for us with our very lightly converted day van, which we occasionally spend the night in and can often go a few weeks without use.
Andy
 
I’ve had a quick look through and your solution would be very useful for us with our very lightly converted day van, which we occasionally spend the night in and can often go a few weeks without use.
That's pretty much my use of the Caravelle too.

Nothing wrong with a fused quick connect for your choice of charger on the starter battery either and many find you can tuck the charger in there under the bonnet and run the cable out fine just like an EHU cable, but if you have a fully wired trailer socket I quite like the neatness of it.
 
I found this one;

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

Post #59 shows a 5A Noco trickle charger.

Also check out;

I brought a cigarette lighter adapter today for my noco5 (just so happened to have one) and liked it up to my old small river. I'm just wondering if there's a better way to use dc to dc as there is alot of energy wasted converting it to AC out of the ecoflow and back to DC.
Might have to upgrade to the river max.
 
I was going to suggest a power pack and charger as another option, if you already have the power pack and charger then that's a good thing to try.

As the lithium battery in a power pack is a very different thing to your (I assume) AGM van battery you are going to need some conversion. Although nominally "12v" you can't just connect them.

Actually there isn't a huge difference between Inverter+Charger and a DC-DC converter as both will use switch mode techniques. A dedicated DC-DC charger may have less losses but is likely only worth the expenditure if you are fitting a second battery.

Your best bet is to not leave it trickle charging but to use it to top the main battery up to about 80% where charging efficiency drops off. I think on the NoCo that's when the last green segment starts flashing but isn't solid.
 
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