Leisure battery cheap cabling?

[grantw]

Would this be suitable? Seems cheap. 10m of 50mm cable. 5m in black and 5m in red.

http://www.ebay.co.uk/itm/5m-Amplif...3?pt=UK_In_Car_Technology&hash=item3f1d85bc2d

 

[Chas]

I think it's 5m in red and 1m in black.

 

[grantw]

Doh, good spot!

 

[Chris]

Welding cable is usually a better price. This is 25mm I know but honestly unless you intend to reverse the power to winch from or something 50mm is a bit OTT

http://www.ebay.co.uk/itm/Copper-We...066?pt=LH_DefaultDomain_3&hash=item2a1fb188fa

 

[grantw]

I was looking at the 25mm then noticed the 50mm wasn't that much more. So thinking about it.

Currently trying to get power to the back for a fridge and water pumps for the easter weekend with it being as cheap as possible but also expandable.

I was thinking of initially running a fused 25mm cable from the battery via a voltage sensitive relay which terminates at a distribution box. With the distribution box being earthed on the chassis. With my understanding this would keep the two starter batteries at a safe charge whilst running my fridge etc. But would also allow easy expandability once I buy a leisure battery and more cable running back to the starter batteries for a proper earth.

 

[Chris]

But the fridge will only run with the engine then? Until you get a battery that is. Your main batteries should be safe at that. 50 mm is overkill though. Harder to work with. That's why I went with welding cable as is more flexible than other spec. But I wanted to reverse the power to start, winch etc etc. If all I was doing was running a fridge, I'd probably have done it with less than 25mm. My air pumps drag 40 amps but ONLY from the rear battery supply board so I didn't have to go monster on the cable. If I had run the pumps from the front of the truck, I'd would have needed something bigger.

Chris

 

[Jon Wildsmith]

last year I used a 3rd battery in a battery box in the boot between the fridge and the back seat to power the fridge and ran a 16mm wire from the front to charge it, via a DC-DC charger i my case but a voltage sensitive relay would work as well. It was a quick fix to not having decided what to do about installing an aux battery properly and it worked very well. Haven't decided what to do this year so I'll probably end up doing the same again through not making my mind up again!

 

[grantw]

I think the VSR should only cut out once the starter batteries drop below 12.8v .. and then hopefully cutting back in at 13.7 volts once the car is restarted. I hope i'm not missing how these actually work.

Jon, when i was stalking around other posts on the subject ... you have one of those fancy (i.e very expensive) Stirling dc-dc chargers? I hope to justify the cost of something like that in the future. Possibly with proper traction batteries so they can be discharged completely.

 

[Jon Wildsmith]

you will have a 3rd battery that the VSR is connecting to the engine bay batteries though? Otherwise as Chris says the VSR will only engage when the engine is running and for a short while afterwards and then the voltage will drop to a point that the VSR disengages. I do have a Stirling DC-DC charger, yes.

 

[grantw]

the VSR should be engaged if the motor is running or not ... I think?!

 

[grantw]

Hrmm .. seems I was getting my voltages confused. Was thinking 12.8volts was an indication of the battery being around 85% charged.

 

[Chris]

Typically the VSR senses two voltages. The main battery and the aux battery. If it's not connected TO an aux battery it can't tell the drop between the two - which is uses to be intelligent. Some of these simpler VSRs I understand just sense drop to earth on the one battery so they should run most of the time with the engine. But the battery, once the engine is off, will drop pretty quickly to the point that it will deactivate the VSR. As you are pulling power from the battery, that higher float charge will deplete quite quickly I'd think. It will sense the draw and shut off. No I am not an electrical engineer, but I've had a few of these and that's how they seem to work.

I have never seen any of my chargers connect with the ignition on, but the engine not running. There has to be charge being sensed to the main battery before it will trigger.

 

[grantw]

I think this is what I'm after ...

http://www.intervolt.com/products/electronic-battery-isolator/ebi-series.aspx

Looks expensive though.

Given something like that you would have 3 batteries in the bank for their first 20%(adjustable) of discharge and then just your leisure battery for the remainder. I like the idea of this. Is there another sensible way to achieve it?

 

[grantw]

I've never seen a VSR so your observations as always Chris are greatly appreciated

 

[Chris]

Damn, that's lovely. What sort of money? I'd have one and I don't even need one.

Chris

 

[grantw]

Lol, I emailed them ... not sure will get a response though.

 

[Chris]

Being waterproof is a bonus. Not sure which model etc, but if prices are sensible I could be on for one. Or two.

Chris

 

[grantw]

I think it's too pretty to be sensibly priced.

Found these ones as well http://www.ase-supply.com/Cole_Hersee_48510_Low_Voltage_Disconnect_p/ch-48510.htm

But from that site shipping is a killer ($150 USD!!!)

 

[grantw]

I think I found what I'm after

http://www.reuk.co.uk/buy-REUK-PROGRAMMABLE-LOW-VOLTAGE-DISCONNECT-LVD.htm

If I hook that up with a 100amp or so relay I should be in business.

 

[Jon Wildsmith]

I don't know what fridge you've got but mine has LVD built in with a choice of 2 or 3 trigger levels.