A question for those that understand batteries

[Tony x]

Hello,
I suspected last week and confirmed today that the voltage sensitive relay between the leisure battery and starter battery has failed. The relay is part of a Williton kit that I believe were well thought of but not made anymore.
Anyhow, the relay failed in that it will not connect the two batteries together.
There is also a separate relay in the wire joining the two batteries that breaks the connection when the ignition is off and makes it when the ignition is on.

I've altered the wiring to bypass the voltage sensitive connection.

My question is that now, when I start the Bongo it will be drawing power from both the starter battery and the 110ah leisure battery.
Is this likely to cause the leisure battery any harm?
The Bongo always starts easily.

Thanks

[g8dhe]

There should only be one relay in the charging path, along with two fuses, so a little confused by you saying there are two ? The original Willinton design uses the circuit below.


If you use the IG2 circuit on the ignition switch for driving the relay then the LB will not be in circuit when the Starter motor is used, best to pickup the IG2 from the lower connection on this fuse;

[Tony x]

Thanks Geoff - that's he layout of the kit that is fitted.
The second relay is an addition and part of a somewhat involved solar panel set up. If it wasn't there the batteries would be connected together almost always as there is a solar panel and controller that feeds the starter battery
In any case, am I likely to damage the leisure battery ?

[g8dhe]

If you have bridged the SCR relay out permanently then yes the LB will be providing power in parallel with the SB, so it will just appear as one larger battery, this won't be good at all for the LB. There shouldn't need to be any relay associated with any sort of normal solar panel controller.

I'd be inclined to rip out whatever has been installed and start from scratch with the wiring and units.

[Tony x]

Thanks Geoff.
It's the winter pack version with the heavier duty starter motor which wont help matters either.

[WestyK]

Just been trying to figure out your set up and think i understand what and why its been done having recently changed from a relay split charge system to a VSR based system

My guess is that it was installed as a VSR based system and probably ok but one of the side affects of the way they work (as I have found out) is if you need or want to charge one of the batteries the VSR kicks in so you end up charging both. Not ideal.

Now you say you have a Solar panel. This would do the same and switch on the VSR and try and charge both batteries which it it really doesn't need to so my guess is that the relay switched by the ignition circuit has been fitted to stop this happening.

So if you have only bypassed the VSR and still have the other relay switched by the ignition it should still work like a conventional split charge system.

Of course I agree with Geoff that if its in any way suspect then start again.

Appreciate there are a lot of ifs and assumptions here and i may be completely wrong but it makes some sense to me even if not the right way to do it.
Would still advise you get it checked out if your not sure, certainly wouldn't want them bot connected pertinently together that wont work well at all.

Hope that's some help
Ian

[g8dhe]

Not all VSR's will detect either voltage, you buy as needed personally don't think its a good idea as with Solar panel charging or EHU charging the LB if you go to start then again both batteries will be in parallel.

[Tony x]

Hi again.
There is one 30 W solar panel that goes through a controller and to the starter battery
There are two other solar panels, 190 W, going through a different controller and on to the leisure battery.
Like I say, it's a bit involved.
However, I'm confident I'll find a way for the system to work and start the Bongo as it should.
My hunch is that there will be no point replacing the voltage sensitive relay as it was almost always on - I've probably been tapping into the leisure battery to start the Bongo for some time without realising it.

[g8dhe]

Not really enough info to say why. Its controlled by the ECU so there may have been other factors coming into play. Are you sure it was the glowplug relay as there are quite a few relays down that side of the van, unless you put your hand on the relay and felt it operating it might have been one of the others even.

[Tony x]

A solution...
Having contemplated various possibilities on how to make a leisure and starter battery set up work with solar panels I've concluded that the following should work -

A relay to connect the two batteries when the ignition is on, disconnecting them when the ignition is off.

An additional timer relay to control the main relay so the two batteries remain disconnected for 25 seconds when the ignition is first turned on. You would start the Bongo within these 25 seconds.

I considered other options, diodes (might work but you'd suffer some voltage drop and you'd probably need a few), voltage sensitive relay (wouldn't work), using an ignition feed for the main relay that turns off when the starter motor is spinning (there is such wiring on the Bongo but this set up would be less versatile) and even using the 12v timed feed to the glow plugs to control the main relay (would only work most of the time)
Cheers
Tony

[g8dhe]

Why not use the normal IG2 circuit from the Ignition ?
This powers up when ON, but not during START. This means you have partial control over when the batteries are in parallel and automation to ensure that they are not in parallel when the starter motors is called for.
See below I assume your a diesel ?

Its also very easy to pickup coming off the lower contact of the fuse;

[Tony x]

Hi Geoff.
I did consider the option you mention and it was a close second and yes, it is a diesel.
The reasons I went for the timer relay were because if the leisure battery was heavily depleted then the edge might be taken off the starter battery when you turn the ignition on but prior to starting the engine (perhaps a pretty weak reason) and because I didn't realise that the ign2 circuit was so readily accessible.