ZIG CF8 auxiliary battery charging

[CJH]

Hi folks

New member here. I've owned my 1982 T25 Viking conversion for about three weeks now, and have been camping in it for the last two of those weeks. I've got various things to ask the forum, and I'm going to start with a question about the factory-fitted ZIG CF8 unit. Having camped for just a couple of nights without a mains hookup I was surprised to find my new 80AH auxiliary battery had gone flat. I have the fridge connected directly to the auxiliary battery, so I know it's this that flattened the battery, but I had expected that driving about for the day between those two mains-less nights would have put some charge back in the auxiliary battery. I've done a few tests with my multimeter since we got home, and it seems that the auxiliary battery isn't being charged from the engine.

So my question is, under what conditions should the auxiliary battery get a charge from the vehicle alternator?

As per the ZIG instruction manual the vehicle battery is connected across terminals 1 & 2, and the auxiliary battery is connected across terminals 3 & 4. When I'm connected to the mains (and the "Touring/On-Site" switch set to "On-Site") my multimeter shows over 14V across the auxiliary battery terminals, so I know it's getting a charge is this scenario. But with the switch set to "Touring" and the engine running I was expecting to see a charge from the alternator, but all I'm seeing is the battery's self-voltage (just over 12V after a short while on the mains charger). Across the vehicle battery I can see the alternator's input (around 13V) when the engine is running (with a bit of gas to get the revs up a bit). Even after a full day's running yesterday, the auxiliary battery hadn't been charged at all after going flat the previous night.

So am I wrong to expect the ZIG unit to allow my alternator to charge the auxiliary battery? If not, under what conditions should it do so? I don't have any other form of split charging, and in fact the ZIG manual suggests disconnecting any other split charger. The manual specifically says that in the "Touring" position the auxiliary battery should get a charge, so I assume that there's either a fault with my ZIG unit, that the wiring's been tinkered with some time in the last 30 years, or the conditions have to be just so.

All suggestions gratefully received.
Chris

[CJH]

Oops - my mistake. It looks like the wire from terminal 2 to the vehicle battery +ve terminal has been disconnected. I assume that the only route from the alternator to the auxiliary battery is via the vehicle battery, and since that route is currently broken then there's no way for my auxiliary battery to charge from the alternator. I'll fix that before bothering the forum any further!

Chris

[billybigspud]

Fit a split charge system then you wont forget to switch that switch. Well annoting when you forget and have no charge in ya leisure battery.

[billybigspud]

Fit a split charge system then you wont forget to switch that switch. Well annoting when you forget and have no charge in ya leisure battery.

[MidLifeCrisis]

Also, running your fridge off the leisure battery is always going to flatten that battery fast (even if your leisure battery is charging correctly and you are driving around quite bit).
I think those fridges can pull up to 8-10amps so in theory your leisure battery isn't going to be able to power it for much more than a few hours before it is effectively flat (note that you'll never get the full 80Ah out of battery).

Vans are usually wired so that the fridge is only powered on 12v while the engine is running - the 12V to the fridge is usually run through a relay that is triggered by a wire from the alternator. When the engine isn't running the fridge should be switched so that it is running on gas or 240V mains (if you have those options). What sort/type of fridge is it?

Info on fitting a split charger (to charge the leisure batt direct from the main batt) is in the Wiki - hit the 'Wiki' button at the top of this page, then search for 'split charge' for more information than you'll ever need/want!!

(Further note: once you have a split charge system in place, most folks disconnect the connection from the main battery to the Zig so that there is no chance of flattening the main battery by accidentally leaving the switch in the 'touring' position when parked up)

[CJH]

Thanks folks

My fridge is a three way (Electrolux RM122), but in the few days I had the van before we took it away for a holiday I removed the gas connection since the fixed copper pipe was very dented and corroded. It may well have been sound, but I had no means to test it and no time to replace it. So I jury rigged a direct (fused) connection from the leisure battery, to be used only in emergencies. I knew the current draw would be high, but I hadn't banked on it being quite so high, and I'd assumed that driving around would top up the battery. I'll now get the gas connection replaced, and wire up the 12V supply to run from the vehicle battery via a relay.

Since getting back I've now read various threads that recommend the split charge option. The ZIG manual gives a strong steer away from this option, stating that "the relay type of split charger causes the major problem that current is only available from the vehicle battery when the ignition switch is on, thereby preventing the use of the vehicle battery to assist the life of the caravan battery". But I guess that's the main advantage. I completely agree that when you're camped away from a mains hook-up it's a lot easier to manage with a flat leisure battery (which is anyway designed to cope with deep discharge) than it is to recover from a flat vehicle battery. So I'll check out that Wiki page and install a relay type split charger and disconnect the vehicle battery from the ZIG. However, on the night when I realised that our leisure battery was flat we had no lighting, so as an emergency I used a jump lead to connect the vehicle battery +ve to the leisure battery +ve cable (disconnected from the leisure battery to avoid the batteries trying to equalise, and I disconnected the fridge feed of course!). I knew that running the two 8W fluorescent tubes and a strip of LEDs upstairs for a couple of hours would only pull a few amp-hours from the vehicle battery. With a split charge relay I still won't have a way to use the vehicle battery for 'emergency' lighting. I might look into fitting a switch so that I have the option of the new split charge facility OR the ZIG-preferred method of having the vehicle battery in the circuit.

[MidLifeCrisis]

To be fair - once you have the 'split charge' in place you'll never need to touch the 'On-Site/Touring' switch again (as it'll always be in 'On-Site' positin) ..... so .... if you trust yourself you could leave the main battery connected to the Zig and use that switch as your 'Emergency Override' - I just like to idiot-proof my stuff so that the idiot (Me) can't mess things up ....

[CJH]

Ah yes, that makes sense.

I've just been reading through the Wiki, and I've seen your piece on the intelligent relay. Since I need to do the wiring for both the fridge and the leisure battery, one of these Smartcom relays seems like the best bet. One question though - if I'm "on-site" and charging from the mains, I guess the charging voltage at the vehicle battery terminals will go over the Smartcom trigger voltage, so the relay will connect. Since both batteries will already be getting a charge from the ZIG at this point, connecting them via this smart relay shouldn't be a problem I guess. Are there any other issues to worry about in this situation? The fridge 12V supply would be live I guess, but on-site I'd have the fridge set to 240V anyway.

[MidLifeCrisis]

The Zig will only charge your Leisure battery - it won't charge the Main battery (whatever switch position you have set).
Have a look at the schematic of the Zig here;

You'll see that setting the switch to 'On-Site' connects the mains transformer to the Leisure Battery.
Setting the switch to 'Touring' connects the main battery to the Leisure but disconnects the mains transformer connection.

[CJH]

Thanks - that's a useful diagram. OK, so in the "on-site" position there's no problem with the smart relay turning on. What about in the "touring" position? In the event that I use the "touring" position in an emergency, and forget to switch back to "on-site" before driving off (this is going to be confusing!), this will connect both batteries to the alternator, but the smart relay will also be switched on. Is there a problem in this? What happens for instance if the voltage on the output side of the smart relay goes to 13V (courtesy of the direct connection to the alternator) before the relay switches on?

I've bought all the bits to do the wiring now. The Ring spec sheet says to use 44/0.33mm2 cable rated at 27.5A, and a 15A fuse. The Wiki mentions a 30-40A fuse (and by implication a higher rated cable, say 50A). I found it really difficult to get 50A cable and connectors rated to match, and ended up buying 30A cable and Maplin's yellow eyelet and spade connectors. These don't have a current rating, but will accept fatter cable than my 30A cable, so I expect they're up to it. But my question is what kind of current is likely to come from the alternator in the worst case (or from the vehicle battery if the leisure battery is flat)? Is 40A really necessary, or can I trust Ring's spec sheet when they say to use a 15A fuse?

[MidLifeCrisis]

Other people on here have strong opinions on the wire gauge/fuse sizes to use for the split charge system.
The Wiki is the current best advise on what to do (and some do more than that even).

The issue is that a very flat leisure battery can draw a fairly large current initially which can blow fuse/melt wire if the lower gauges are used ..... obviously the higher the gauge the better in terms of safety and efficiency .....
I would have thought that a 15a fuse might blow quite regularly if you drain your leisure significantly.

Ultimately as long as the fuse is lower rated than the wires then the systems is 'safe' it just might get annoying replacing that fuse on a regular basis (and obviously you won't necessarily know its blown until you discover that the lesiure hasn't charged during the last drive ......)

Not very helpful I know but this is really a case of bigger is better ...

You can get cable from these guys if needed (and just about anything else you might need/want/crave);

http://www.autoelectricsupplies.co.uk/p ... ategory/11

[CJH]

Thanks again. I've installed everything this afternoon, and it seems to work. I've gone with 30A cabling and 25A fuses for now. So as you say, the fuses are protecting the cabling, and I'll watch out for blown fuses. There's a 25A fuse between the battery and the smart relay input, a 25A fuse between the relay output and the auxiliary battery, and a 15A fuse between the relay output and the fridge. If these prove to be a problem I'll have to upgrade the wiring before going for larger fuses, but I'll try and get a bit of experience with this setup first. Recabling would be easy, as the relay and my new 4-way fuse box are mounted under the driver's seat, so all the cables are short. The longest cable is the one from the relay to the auxiliary battery under the passenger seat.

The smart relay didn't work initially, as it's set to switch on at 13.5V and off at 13.2V. My initial measurements showed that my main battery currently only gets up to 13.2V when the engine's running, so by trial and error I've tweaked the smart relay's adjuster so that it switches on at 13.15V and off at 12.75V. I suppose these values might depend on the state of charge of the battery and any other loads, such as headlights etc, so for now I've repurposed a redundant dashboard warning light to show me when the relay is on, just to get experience with the settings. I'm actually a bit annoyed that there is this potential for the smart relay to be mis-adjusted. I'd almost prefer a couple of dumb relays now, using a reliable ignition-controlled live.

I took the time this afternoon to remove the front mat, the lower dashboard and glovebox, the floor between the seats and the seats themselves, so that I could get a good look at all the wiring, as there were quite a few unused cables dangling in each of the battery boxes. I've removed quite a bundle of redundant wiring. There was one pair of wires I couldn't identify though, so I've left them in place for now, even though they're not connected. They're a yellow and a blue wire, entering the main battery box through a hole in the floor of the battery box. They run under the van to the front, and are tied up behind the radiator grille. They're too thin to be for fog lights (I think). Is there anything else that would use these wires as standard? If they're for some sort of aftermarket device that's no longer fitted I'll just get rid of them.

[MidLifeCrisis]

Those yellow/blues wires are probably something aftermarket as the vast majority of the wiring runs direct from the fusebox - if it doesn't go anywhere then its prob safe to remove.

Agree re those Smart Relays - I was always a little nervous of them (and also installed a guide light as you have) - I found them a little unnerving as after a drive they can often stay 'activated' for a while as the voltage decays on the main battery from the higher alternator voltage to the slightly lower battery voltage - so it often meant that I left the van with the relay still activated and had to 'hope' that it would eventually switch off (not very relaxing! although there is no prob real danger in the batteries staying connected when there is no drain on them ..... but it still made me nervous) I ended up switching it for standard relay(s).

[ghost123uk]

Couple of points from me.

Firstly when you say

it's a lot easier to manage with a flat leisure battery (which is anyway designed to cope with deep discharge)

Please note that this is a common misconception about normal leisure batteries. They will be damaged if they are allowed to go more than 60% flat, ie when the voltage falls much below ~12 volts. If you ever allow them to go totally flat, by leaving summat on all night like a fridge, they will be seriously impaired and will never be anywhere near as good as before. Here is a table courtesy of http://www.caravantalk.co.uk" onclick="window.open(this.href);return false; =



Many folk (including me) use a thing called a LVD (Low Voltage Disconnect) that cuts off the leisure battery when the voltage falls too low LINKS HERE

Also, your charging voltage is too low at 13.2 volts. It should be 13.8 minimum and 14 or even 14.5 volts for modern batteries. You might well need to replace your alternators voltage regulator / brush pack = about £15 and 15 minutes work. HERE is one - - - Here is another (from Brickwerks) Disconnect the main battery before working on your alternator !!

[CJH]

Thanks both. I'll definitely look into an LVD. Before I get a new voltage regulator for my alternator though, can you confirm that measuring the voltage across the main battery terminals is the correct way to measure the output of the alternator? I can't see another way to do it, but it seems like the battery might be acting as a bit of a sink so I won't get a true reading.

Chris