2002 100 series duel battery relay issue (1 Viewer)

[josh100seriestas]

Hey folks

After searching the forum and other pages I plucked up the courage to ask a question here.

Our 2002 100 series (2uz auto) has developed a issue with what looks like the duel battery system.

The relay clicks randomly , sometimes while driving and sometimes when parked with the keys out of the ignition. Sometimes constantly.

Both battery's have been replaced and if I dont use the car for a while the starting battery drains to below 7 volts, sometimes 0.

Charging system checked at 14 volts, If I jump start the car it runs and drives fine, and will start, but if left over night its dead flat again.

Has anyone ever seen this before? I dont want the wife to be left stranded on the side of the road I would never hear the end of it.

 

[willyroo]

Wow three major issues, headed by WAF (Wife Approval Factor).

Firstly - welcome to 'mud, and I'm guessing "tas" means Tassie aka the fantastic place that is the bottom of Australia.

If you have a process that is causing your batteries to regularly drain below 10 volts, they're pretty well stuffed. And it's caused by the "relay" - which is either on the way out or has a grounding issue.

The initial troubleshooting would be to ask an auto electrician to have a look at the system. I'm not familiar with the use of a simple relay in a dual battery system - my experience is that the best battery management for 2 batteries in a fourby is an electronic isolator. Mine in the LX is a Redarc Smart Start, however here in Oz there are other options including the ABR Sidewinder, which worked perfectly well in my previous LC.

 

[beatle_bayly]

Welcome Josh.

Unfortunately I'd say your start battery is buggered if its been down to 7V, so further troubleshooting may be difficult.

Have you owned the vehicle for some time, and has it always worked OK until recently?

I assume your start battery is in the LH/Passenger side cradle, and the auxiliary battery is in the RH/Drivers side cradle? I'm used to HDJ100 so can't recall if the V8 has twin batteries in parallel from the factory? If so, are you sure the auxiliary battery is separated from the start battery via the VSR? Some setups keep both batts hardwired in parallel and use a VSR to isolate power to the back of the vehicle, either for a third battery, or to power a caravan etc.

Are you absolutely certain it's the relay you hear clicking, and not one of those three resetting circuit-breakers at the top of the photo?

Your relay/isolator looks like an older Redarc to me, going by the blue override wire. Regardless, these types of Voltage Sensitive Relays aren't all that smart, really just a switch, activated by sensing the voltage from the input side (the start battery).

I'd be disconnecting the start battery from the VSR and see what happens. Disconnect the cable from the start battery +ve to the VSR and INSULATE the free end so it doesn't short out. With VSR out of the picture:
- Does the start battery charge?
- Does the start battery retain charge (if not, it could be from parasitic power draw, or just that the battery is cactus). Do you have anything that is pulling power from the start battery with the engine off? e.g. caravan anderson/fridge power wire, electric brake unit, etc etc.
- does the VSR keep clicking? If so, it could be wired incorrectly, or shorting internally because it's only source of power would now be from the auxiliary battery.

If that all checks out OK, then you need to troubleshoot the VSR itself.
Disconnect (and INSULATE) the cables, and:
- check for shorting across the two main connection posts.
- check for a good earth on the small black wire
- check that neither of the large posts are shorting to the small earth cable
- grab a spare bit of wire and apply 12V +ve power to the OVERRIDE connection. The VSR should close, and stay closed. Does it close? Does it cycle on/off?

Other questions that might help troubleshoot:
-What services are connected to the auxiliary battery that are using power with the engine off?
-Are you getting any odd idiot lights on the dash (which may indicate a dodgy alternator)
-Check the electrical connections to the alternator are solid and clean
-Have you recently carried out ANY electrical work on the vehicle, or something that plugs in to the vehicle (caravan etc) ?