Quick question. I have installed a CTEK 2050SE DC-DC charger. Its all running well with no problems. I will install an isolator switch between the leisure battery to the camper 12V electrics, but I was wondering is it worth installing a second isolator switch between the vehicle battery and the DC-DC charger? Jut thinking about when the vehicle gets work done on it to isolate the vehicle completely from the leisure battery & charging system, or is there any point in doing this? Would it just be a waste of time & money - will the CTEK 250SE be suffice to protect the leisure battery? Any input is appreciated. Thanks
Isolator Switch between Batteries and Chargers?
- Thread starter Sharra001
- Start date
It's optional,
But not common practice from what I've seen.
The supply cables need fusing as Pete mentioned.
The only downside of adding a switch in, is that every connection creates resistance and heat,... so each switch will add 3 additional connection points.... ring terminal in, actual switch contracts, ring terminal out,... you will see some volt drop. And the switch will get warm when pulling large currents due to the relatively small contact areas.
It's more common to use the main midi / maxi fuse as a point of isolation when doing work on the system.
But not common practice from what I've seen.
The supply cables need fusing as Pete mentioned.
The only downside of adding a switch in, is that every connection creates resistance and heat,... so each switch will add 3 additional connection points.... ring terminal in, actual switch contracts, ring terminal out,... you will see some volt drop. And the switch will get warm when pulling large currents due to the relatively small contact areas.
It's more common to use the main midi / maxi fuse as a point of isolation when doing work on the system.
having said all of the above,
fitting a battery isolator switch on the leisure battery side is very common practice.
(to disconnect leisure battery for storage to stop it going flat, or to disconnect when working on the system)
so start battery --> fuse --> cable --> dc-dc --> cable --> isolator -->fuse --> leisure battery
....
i run a 300A isolator my self, next to the LB under the drivers seat,
++++
and just an example of heat build up across connections and fuses, here you can see some thermal shots it took,
this one showing a fuse block,
..
this showing battery connection cables and inline fuse with a 30A charger running,
.
and this one showing an Orion dc-dc running.
fitting a battery isolator switch on the leisure battery side is very common practice.
(to disconnect leisure battery for storage to stop it going flat, or to disconnect when working on the system)
so start battery --> fuse --> cable --> dc-dc --> cable --> isolator -->fuse --> leisure battery
....
i run a 300A isolator my self, next to the LB under the drivers seat,
++++
and just an example of heat build up across connections and fuses, here you can see some thermal shots it took,
this one showing a fuse block,
..
this showing battery connection cables and inline fuse with a 30A charger running,
.
and this one showing an Orion dc-dc running.
My main experience of 12v systems is in marine use (yachts, narrowboats) and it's a surprise to me that battery isolators are so rare in campers - certainly for inland use they are required by the Boat Safety Scheme (BSS)
If I end up fitting a high current second battery I think I'll try and fit one, maybe by the starter battery to isolate the feed into the main van.
I would recommend if you want to fit one to get a decent one, probably a marine one, not something off eBay or the basic ones used in race cars.
If you choose not to I think it's wise to consider how else you can isolate in an emergency given the currents that can flow. Maybe you have an Anderson connection, maybe you have a fuse, but are they easy to access in a hurry or do they need tools to get to them? Is it worth putting a small notice where they are is others can find them quickly if you are not near the van?
As an aside the traditional approach in yachts will probably horrify you as the isolator is also the split charge system. One big dial that you set to 1 to start, move to 1+2 to charge, move to 2 when moored and engine off, move to OFF when you leave the boat. It works because it's all make before break but if anyone foolish moves it to OFF when the engine is on bye bye alternator. It's simple and robust in a harsh environment but it's falling out of favour for twin ON-OFF isolators.
If I end up fitting a high current second battery I think I'll try and fit one, maybe by the starter battery to isolate the feed into the main van.
I would recommend if you want to fit one to get a decent one, probably a marine one, not something off eBay or the basic ones used in race cars.
If you choose not to I think it's wise to consider how else you can isolate in an emergency given the currents that can flow. Maybe you have an Anderson connection, maybe you have a fuse, but are they easy to access in a hurry or do they need tools to get to them? Is it worth putting a small notice where they are is others can find them quickly if you are not near the van?
As an aside the traditional approach in yachts will probably horrify you as the isolator is also the split charge system. One big dial that you set to 1 to start, move to 1+2 to charge, move to 2 when moored and engine off, move to OFF when you leave the boat. It works because it's all make before break but if anyone foolish moves it to OFF when the engine is on bye bye alternator. It's simple and robust in a harsh environment but it's falling out of favour for twin ON-OFF isolators.
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All cable comes with an operating temperature range rating for the insulation, however you shouldn’t be approaching anything near that in normal operation.
Have a look at 12v Planet website for a very good explanation on cable sizing.
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