Bongo Fury

I've had my Bongo for over a week now and I'm getting to grips with the base van and the previous owner's modifications. It's a 2001 2.5TD 4WD Aero. Warning: this is a long post as I try to get my details and thoughts down.

So, the previous owner explained that it had a leisure battery, which he disconnected when standing 'to save it'. I noticed that all the things he said were fed from the leisure battery still worked when disconnected. When I quizzed him he said it would because the leisure battery would help to start the van. This since rang alarm bells.

What I found under the bonnet was that I have two batteries with an Altec voltage sensing charge relay between them, and a small fuseboard beside the relay which patches into the original cabin fuseboard to cover lights, sockets, radio and blinds. The charge relay wiring was incorrect with a red cable connected to the -ve terminal of the leisure battery instead of +ve. In fact, on further inspection the +ve sensing fuse was removed so the voltage sensing charge relay is doing diddly squat.

More notable was the 'fat' red cable to the +ve terminal of the leisure battery, which I now know is a parallel circuit for the Cold Start option (I also have the engine switch, which confirms it). This is why he said the leisure battery helped start the car and why there's no separation of circuits between batteries despite the second fuseboard and patching.

I read in the forum, the Cold Start option has potential for problems, which I'll touch on later, but it appears to me to be a hindrance.

I read that leisure batteries are deep discharging and shouldn't be used to start a car. I also read that these kinds of batteries don't like being charged all the time by the alternator and can dry out. I then read that the parallel circuit means if the leisure battery is low, it will draw from the starter battery and flatten it. All this sounds really undesirable.

It seems to me that I need one or the other - parallel Cold Start OR voltage sensing charge relay - and I really feel like I need the latter. What do others do in this instance? Can someone give me guidance on where to go from here?

My thoughts:
1. Retain the parallel charge circuit but fit an isolator so I can decide when the leisure battery is connected and gets charged. I would forgo the circuit patching, but would I need to change back to a starter battery?
2. Remove the parallel charge cable and rewire the voltage sensing charge relay circuit correctly splitting out the circuits too. I think this is my preferred option, but how would I terminate the parallel cable to make it safe or where would I need to disconnect it from altogether (the alternator)?
3. If I remove the parallel cable, how does that affect the exhaust valve 'engine' switch, would I need to remove that too?
4. With the problems/considerations associated with the Cold Start option what do I need to keep an eye out for? Is there anything I need to remove/replace?

Thank you

I’m no expert with the electrical wizardry however in your photos it appears you have a 70amp as the starter battery. I think that’s too small for a 2.5D. I’m not sure why there is a red cable going to the negative on the leisure battery? Maybe previous owner didn’t have any black left but doesn’t look right. Plus, it appears to be routed directly over the leisure positive terminal and looks like it could easily short.

I’d be minded to revert to a standard split charge system and get the biggest amp starter battery that will fit.

Other regular forum members have a far better understanding of these systems than i do so I’ll leave the rest to them. Hopefully you get it sorted.

I haven't taken the cables out of the kopex but there is one 6mm red sensing cable going to the starter battery +ve and a 6mm red charging cable going to the leisure battery +ve. The 6mm red cable going over the top of the leisure battery is the fuseboard output (I think) which should also go to the +ve. It's deliberately marked with black heatshrink. Every wiring diagram I've seen for a voltage sensing charge relay circuit has two cables from the leisure battery +ve and only ground to the -ve. All of that wiring is wrong to me.

Perhaps the smaller battery would have been fine with two in parallel for the Cold Start option.

(Oh and these photos show the wooden spacer blocks around the starter battery and missing tie down bolt from the battery clamp. Pretty sure that's an MOT fail. I've fixed that already.)

Good job on the starter battery clamp I’d not noticed that. I’d also suggest getting some battery terminal covers. In a worst case scenario it’s possible the bonnet could make contact and arc across the un protected terminal posts.

I searched more deeply into the forum and the two options have come up a few times.

This one is suggesting the opposite. Retaining two starter batteries and parallel alternator change cable. All circuits run from them both and as long as it's not more than a night's camp they should be ok. Starter batteries don't like to be drained though and leisure batteries don't like to start.
https://www.igmaynard.co.uk/bongo/forum ... php?t=6482

This post refers to changing to a split charge leisure battery and recommends removing the parallel starter cable. viewtopic.php?t=69008.
Some people insulated with old bike tyres and taped up but I feel this is unsafe.

I guess I'll be tracing the parallel charge cable and disconnecting from both ends.