Split Charge Wiring Advice

[jims-terrano]

Hi guys, I’m in need of some advice please. I got a CTEK 250SE battery to battery charger. It’s actually for my VW camper but same thing will work on a Terrano. Here’s a link to the unit, unfortunately this video also shows a pass through unit which I don’t have.
https://youtu.be/kTRiqyzK9zA

My question is about the negative connection on the charge controller. Both the two batteries are grounded to the body of the vehicle, the second battery is earthed with 10mm cable that comes with the kit.
Now I totally understand that the controller goes between the two batteries connected with 10mm cable for obvious reasons. However, the earth for the controller should it be 10mm or something thinner. My way of thinking is that the controller is only using a small current to run the device so will not need 10mm cable.

Thanks

 

[Lazy-Ferret]

Hi guys, I’m in need of some advice please. I got a CTEK 250SE battery to battery charger. It’s actually for my VW camper but same thing will work on a Terrano. Here’s a link to the unit, unfortunately this video also shows a pass through unit which I don’t have.
https://youtu.be/kTRiqyzK9zA

My question is about the negative connection on the charge controller. Both the two batteries are grounded to the body of the vehicle, the second battery is earthed with 10mm cable that comes with the kit.
Now I totally understand that the controller goes between the two batteries connected with 10mm cable for obvious reasons. However, the earth for the controller should it be 10mm or something thinner. My way of thinking is that the controller is only using a small current to run the device so will not need 10mm cable.

Thanks

This one has made my brain hurt trying to work it out...

The problem is, the way these battery to battery chargers work is effectively a Switch mode power supply. What they do, is take the input DC, chop it into a high frequency, convert it, then smooth it, and spit it back out. To be safe, I would take the negative in and out in 10mm, but you only need enough wire to reach from the terminals, to a bolt on the body local to the charger.

 

[solarman216]

I agree with Clive, I had given this some thought, but decided that the manufactures knows, he is not going to waste heavy cable for nothing, and once Hz comes into it who knows, you Jim should know of all people that when it comes to transmitting on some frequency's they only use tube as the feeder wire as the signal only goes on the outside area of the conductor, how mad is that? Rick

 

[jims-terrano]

Hadn’t thought about it like, of course that’s exactly how it works. It’s basically working as an inverter bringing voltage up by around a volt or so. Will sort that out later.