Thread: Dual Battery System

they guy on the beach is an idiot.

you are getting voltage drop under load which is causing the cutout.

it doesnt have to be an earth it could be one of the positives as well. you need to measure each leg of the positve from the battery to the isolator and the load as well as back from the load to the negative and this is where it gets fun.. if you're not earthed directly back to the battery and the isolator is measuring its voltage from the body mount or any where else you've now got multiple earth paths and you're in for a world of fun. Going point to point, from one end of each wire to the other you need to see less than .1v drop under load. if you see any drop with the system turned on and not under load then you've got some proper problems.

When you do your probing, dont forget to probe at both the terminal and the cable coming out of the lug. I've seen 2v drops from the lug and the wire caused by poor crimping, and corrosion inside the crimp caused by bad insulation.

It could also be that your cut out unit is set to cut out at say 12V and then when the load comes off the voltage creeps up .3v.

when you say you checked the voltages on the battery, how did you check them? the battery may be on the way out and is dropping down under load and then recovering to just below the cut in voltage for the traxde (From memory the minimum low cut out is 10.5 and the auto hookup voltage is 12.8, Tim'll correct me on that)

edit..

I just checked the functional layout on the usi160, it doesnt do load isolation (unless tims changed it and not updated his website). How is the load hooked up to the aux battery and what are you using to do the low voltage cut out for the load

Hi Damo, do you have an ABG-25 fitted as well as the USI-160?

Or are you running your accessories power sockets straight from the auxiliary battery?

Originally Posted by Blknight.aus

they guy on the beach is an idiot.

x2

Originally Posted by Blknight.aus

when you say you checked the voltages on the battery, how did you check them? the battery may be on the way out and is dropping down under load and then recovering to just below the cut in voltage for the traxde (From memory the minimum low cut out is 10.5 and the auto hookup voltage is 12.8, Tim'll correct me on that)

Hi Dave, the USI-160 isolates at 12.0v in SHARED mode, 12.7v in IGNITION mode and 10.0v in WINCH Mode.

All modes cut-in at 13.2v

The ABG-25 isolates at the USER SELECTABLE settings of 11.6v, 11.8v, 12.0v or 12.3v, and cuts in at 12.7v

Damo's problem is a bit of a brain teaser, but I bet it turns out to be something simple but not so obvious.

Originally Posted by drivesafe

Hi Damo, do you have an ABG-25 fitted as well as the USI-160?

Or are you running your accessories power sockets straight from the auxiliary battery?

Hey Tim,

Thanks for your time on the phone yesterday as well. I didn't install the system as I am an absolute numpty when it comes to wiring, but from what I understand it is wired from the battery, to a fuse box then to the sockets.

I don't have the ABG-25

This one might be above my scope as well to finally diagnose and fix - can anyone recommend a good auto electrician in Sydney, maybe a Land Rover specialist?

Originally Posted by Damo89

This one might be above my scope as well to finally diagnose and fix -

rubbish, can that rot, this will be as simple as a dicky connection or a screwed up wiring connection. if you can draw line pictures, if you have a multimeter and you have a digital camera this will be simple.

the basic steps will be.

draw a picture of all the parts of the system laid out in a pattern you can understand. (put the batteries at the top of the page, the loads at the bottom and draw lines for wires and boxes for control units as they appear in the system.

grab your multimeter and measure the voltage at all parts of the system start at the earth of the main battery and goto all the points in the system that should have 12V, write those numbers down and call them B1+(x)V do the same from the aux battery and label them as B2+(x)v swapping X for the value on the meter.

now go start to finish on each wire and write that down as (x)Vdrop.

and thats step one to being an auto sparky.

easy.

Alright I've gone through it and come up with this diagram. Everything was tight and in good condition. Hope the diagram is not too confusing, I was a little confused with the Vdrop numbers...

On a side note, I didn't have the fridge in last night and it didn't die and has been sitting idle for almost 24 hours now. Is it a load issue after all?

I've also taken a bunch of photos of all the connections etc so let me know if you want to see them.

I'm still scratching my head.

On another note - the Anderson plug was installed to be a charging point to plug a solar panel into, still - not sure why its coming up as 0.0V. And not sure why the relay to the fuse box is coming up so low...

What is at the centre of the top red horizontal line?

Strange that you get volts there but not on the right hand plug. Is it the wiring between that and the plug? The plug itself or bad earth on plug?