Bongo Fury

Calling all Mazda Kitchen Cube owners (and auto-electricians )!
I've been having problems with my leisure battery in the cube draining over a couple of days (the battery is a 65AH starter battery which I am "using up" but it also did this with the original battery, which is why I stuck the 65AH one in).
Basically what happens is: After sitting for 2-3 days the battery monitor decides that the voltage level has dropped too low & disconnects the battery from the consumer unit - i.e the red LED comes on & lights etc stop working. If I now drive the van around to charge the battery, but don't reset the red LED, then the van will sit for a couple of weeks without any large drop in battery voltage (I have a voltmeter permanently fitted).

Deciding to investigate with my ammeter today, I disconnected the battery & reconnected it with my ammeter between the battery positive terminal & the positive lead. With the red LED on the outside of the cube glowing the rewading was 0, as expected. With the red LED reset, I get a reading of 0.16Amp. I guess that this is the current used by the system to monitor the battery condition.

My question is, is this the usual drain from the system, or is my unit malfunctioning? I do have a spare charge monitor unit from another cube, but it's going to involve a bit of work to swap it, so I'd rather check other owners readings first if possible. It may of course be my battery that is goosed!

Also, has anyone fitted an isolator switch so that the monitoring system can effectively be switched off if the van is left sitting for a while.

Finally I've noticed that gizmos that you can buy to plug in between your coolbox & battery, and which cut power to the CB if battery voltage drops too low, automatically switch it back on when the battery is sufficiently charged. Does anyone know if the Mazda system could be modified to do this as well? My unit has never had the LED cover which acts as a switch & it's a pain to fiddle around with a screwdriver to switch it back on every few days!

I don't have one of the Cube's but a drain of 0.16 Amps is way too much if everything is Off. That's consuming nearly 4A/Hr each day. Sounds like there might be a faulty switch, try putting your ammeter in place of each fuse and see if you can locate which circuit is drawing the power when it is apparently off.

Thanks Geoff I'm planning on checking the other fuses once the battery is fully charged again. I still suspect the charge controller itself though since the switch bank/consumer unit has been changed since I got the van. The drain problem has been there since I got it, but originally i assumed that it was down to the original LB being goosed.

There is a mains operated relay that is supposed to switch the charging over from the vehicle (Ancillaries ON) to the charger itself when the mains is on. I wonder if that relay has failed with its contacts s/c and is drawing a current back thru itself and another relay that is connected directly across the charger 12 Volt output, they form the reset and monitoring circuit in conjunction with a third relay.

I think I know the relay you mean Geoff - I was looking over a spare set of Cube electrics I have this afternoon. If it's not too difficult to get at I might try swapping the relays over tomorrow. Thanks for the hint.

It sounds as if you're well up on the way the Cube electrics work. Any thoughts on how straightforward it would be to bypass the whole charging system & switch to a "standard" split-charging set-up?

Never seen one, just looking at the circuit diagram (there are a couple of modules with no circuit however)! It looks simple enough from the electrical point of view, but often the physical layout makes life difficult at times.

Is the circuit diagram for the cube on the Bongo Fury shop CD? I woonder if it's possible to disable the monitoring circuit & still leave the charging system intact...

Yes it is indeed on the CD. But as with most vehicle manuals its more wiring diagram as opposed to circuit diagram - lots of modules are blank boxes!
It should be possible to convert but the problem as I say is that there is one module that has the S/B un-switched being fed into it, but no circuit within the module itself, and this feeds back into the switched S/B it also has a switch (reset?) as well so a trifle difficult to say what the best option is, the module might even contain a Voltage Sensing relay but I am reluctant to guess ...another factor is that I have no idea what the internal charger is rated at, again nothing to help on the circuit either as its another empty module with just connections shown. My own inclination would be to alter it to match something like the Zig Marque 1 unit here

Thanks for your input Geoff. Investigations continue...