I have to confess that I have never actually liked my Nat Luna split charge system. I've never thought it to be very weatherproof, the solenoid failed too and then more recently the cabin display packed up. Not a good advert. OK so the actual time bit kept working but I couldn't use the manual over-ride.
When in the Lakes last weekend the truck had been parked for 2 days whilst camping. I'd been using the lights and so on. I pulled away in the rain and the wipers were struggling to drag themselves across the screen. Because I have converted to 12v start, the DS battery powers all of the vehicle systems.
Now, the National Luna system relies on a timer to bring in the charge solenoid rather than the IBS system which uses a voltage sensing circuit. I had to drive for at least 5 minutes with lights on and wipers going plus the demister all pulling from the standing battery. Then there was a click, the dash voltmeter leapt up and the wipers took off! I'd had enough. Time to go. It's over priced, unreliable and not particularly well made.
This morning, I junked the control box and replaced it with this VSR
The reason I chose this one was because it has an extra ground terminal which when connected gives you a manual over ride. I'll stick a press to make switch in the cabin later so I can connect if necessary.
http://www.ebay.co.uk/itm/100-180-A...GING-RELAY-WITH-MANUAL-CONTROL-/222059813742?
It says it's 100 A rated but to be honest with having 6mm terminals I didn't really want to connect main battery cables to that. Sure, we all know that it doesn't need to be connected using 50mm2 welding cable but I had some concerns that the cables might be so strong that they could move and snap the terminals off. So being a cunning bunny, I just used the VSR to fire the original relay with the 10mm contacts. It's easy to wire up. No electrical mysteries.
So here's the built up unit.

The picture makes it look a bit scruffy, it's not that bad really. There is some alloy fuzz on the body of the solenoid, but it's just Morocco showing through again.
And here it is bolted into position.

I put the voltmeter on it, then connected the CTEK charger rather than run the engine so I could hear what was going on. The voltage climbed 12.9, 13.0, 13.5 click - CLUNK. Straight in. Works a flipping treat. With my big alternator the VSR triggers almost immediately so no more dragging wipers.
When in the Lakes last weekend the truck had been parked for 2 days whilst camping. I'd been using the lights and so on. I pulled away in the rain and the wipers were struggling to drag themselves across the screen. Because I have converted to 12v start, the DS battery powers all of the vehicle systems.
Now, the National Luna system relies on a timer to bring in the charge solenoid rather than the IBS system which uses a voltage sensing circuit. I had to drive for at least 5 minutes with lights on and wipers going plus the demister all pulling from the standing battery. Then there was a click, the dash voltmeter leapt up and the wipers took off! I'd had enough. Time to go. It's over priced, unreliable and not particularly well made.
This morning, I junked the control box and replaced it with this VSR

http://www.ebay.co.uk/itm/100-180-A...GING-RELAY-WITH-MANUAL-CONTROL-/222059813742?
It says it's 100 A rated but to be honest with having 6mm terminals I didn't really want to connect main battery cables to that. Sure, we all know that it doesn't need to be connected using 50mm2 welding cable but I had some concerns that the cables might be so strong that they could move and snap the terminals off. So being a cunning bunny, I just used the VSR to fire the original relay with the 10mm contacts. It's easy to wire up. No electrical mysteries.
So here's the built up unit.

The picture makes it look a bit scruffy, it's not that bad really. There is some alloy fuzz on the body of the solenoid, but it's just Morocco showing through again.

And here it is bolted into position.

I put the voltmeter on it, then connected the CTEK charger rather than run the engine so I could hear what was going on. The voltage climbed 12.9, 13.0, 13.5 click - CLUNK. Straight in. Works a flipping treat. With my big alternator the VSR triggers almost immediately so no more dragging wipers.