Connecting leisure and vehicle batteries

[Alshymer]

Hello
I have a lithium 100AH battery connected to 2 solar panels.
As our vans are not moving very much, as a temporary measure could one take a cable with crocodile clips on it from the Lithium to the vehicle battery Lead/Acid to keep it charged up?
Best wishes to all.
Alshymer

 

[Fisherman]

Hello
I have a lithium 100AH battery connected to 2 solar panels.
As our vans are not moving very much, as a temporary measure could one take a cable with crocodile clips on it from the Lithium to the vehicle battery Lead/Acid to keep it charged up?
Best wishes to all.
Alshymer

I am no expert on this but I felt I have to give a response in case you damage your battery. Any connection between a solar panel and a battery has to be controlled by use of a controller. A direct connection without a controller will overcharge your battery causing damage. I am sure that wildebus will give good advice on this. He knows much more about these things than I do. Hope this is helpful.

 

[Deleted member 47296]

This will show an elaborate version of what you are wishing to do. http://www.motts.org/BRIDGING FUSE.htm Make sure you put a fuse onto the connection so that if you forget it's there the fuse will blow if you try and start the engine. Also, I would not insert the fuse until the croc clips are in place so that if you accidentally touch metal that is earthed you will not cause either the fuse to blow or an unfused wire to arc.

For a more permanent solution Wildebus has currently got some straightforward bits of kit available.

He may also be able to advise on how to modify your current system easily.

 

[maingate]

Yes you can but put a 10 amp fuse in the wiring for safety (in case you switch on the ignition without disconnecting).

 

[QFour]

Why don't you just disconnect the vehicle battery. Problem solved. Our Laika has a solar controller with dual battery output so it always charges the habitation battery first and then charges the vehicle battery.

 

[Alshymer]

Why don't you just disconnect the vehicle battery. Problem solved. Our Laika has a solar controller with dual battery output so it always charges the habitation battery first and then charges the vehicle battery.

Hello
I have a lithium 100AH battery connected to 2 solar panels.
As our vans are not moving very much, as a temporary measure could one take a cable with crocodile clips on it from the Lithium to the vehicle battery Lead/Acid to keep it charged up?
Best wishes to all.
Alshymer

 

[Alshymer]

Thanks for your replies.
The leisure battery is connected to the solar panel by a controller.
I just wondered whether by doing this whether the Lithium and lead acid batteries connected in parallel would produce a conflict.
Regards
Alshymer

 

[wildebus]

Thanks for your replies.
The leisure battery is connected to the solar panel by a controller.
I just wondered whether by doing this whether the Lithium and lead acid batteries connected in parallel would produce a conflict.
Regards
Alshymer

It partly depends on how well your solar controller is configured.
A Lithium Battery will generally charge at a voltage level that is not recommended a standard Lead Acid battery to taken to.
When the solar is not running, the Lithium Battery will be 'resting' at a notably higher voltage than the Starter Battery, so there will be a constant draw from the Lithium to the Starter when the two are connected.
When you have a physical connection between the two batteries, there is nothing to prevent a parasitic draw on the vehicle (starter battery) side of the electrics that could -potentially - drain the leisure battery (lights left on for example - door step courtesy lights is a key example of a slow but constant draw if they stay on).

In short, using a direct connection from a Lithium Battery to a Lead Acid Battery is physically possible and it wil seem to work just fine, but is not recommended and is not something I would do in other than the very short term (talking maybe just a day, not weeks)

You must have spend well over £1,000 on your Lithium Battery and solar charging setup - maybe worth using something more suitable then two pounds worth of wire and fuse to keep it protected, don't you think?

 

[witzend]

Hello
I have a lithium 100AH battery connected to 2 solar panels.
As our vans are not moving very much, as a temporary measure could one take a cable with crocodile clips on it from the Lithium to the vehicle battery Lead/Acid to keep it charged up? Best wishes to all. Alshymer

YES but I,ve a similar setup and use this http://www.motts.org/BRIDGING FUSE.htm[/URL
Always be aware of advice from sales men

 

[Okta]

I have a lithium leisure battery but decided against doing what you were thinking of doing. I was told not to mix the two different technologies. The lithium sits at a higher voltage than the lead acid and I thought direct linking wouldn’t do either of them any good. I don’t have solar but my Efoy fuel cell does the same job of keeping the leisure battery topped up. I had a spare Sterling battery maintainer from a previous motorhome which I now use. However, being fed from a higher voltage battery meant that it would have been on permanently, which in turn would mean using more Efoy fuel than necessary. I bought a £14 12v time clock and set it to power up the battery maintainer for just 1 hour every day.

This setup works very well. The leisure battery gets charged with a proper lithium profile and the engine battery gets charged with a lead acid one. They are kept safely separate and both are maintaining proper voltages. A lithium battery can deliver a mighty current without a significant voltage drop and I had visions of something getting fried.