240v hook-up and charge controller

[MidLifeCrisis]

I've got a T25 with a Zig (the wife has a T4 with a somewhat more auto zig ) and both, as I understand it, only charge the leisure battery when on mains hook-up.
So the question is, if I connected on of these voltage sensitive switching relays between leisure and main, would it then top off the main when the leisure achieved a full charge? (both batteries are actually car batteries, leisure standard size, main heavy duty), and would this cause a problem with the existing split system when running?

Sorry to but in.

Martin

Don't see why that wouldn't work - you'd have to connect the voltage-sensing-relay unit backwards (i.e. with its input coming from the leisure and the output going to the main) but I don't see why that wouldn't work ok;
However the Zig is pretty wheezy as a charger (I think it is max 4 or 5 amps) so it might struggle to ever get both batteries nicely charged unless it was connected for a 'long' time!!

Do you want this so you can maintain the charge on the batteries at home as I wouldn't necessarily see the need to charge the main batt while out and about (the alternator should take care of that)?

Finally it wouldn't cause any problems that I can see with the original split charge - I think you'll find when the split charge relay kicks in, the voltage-sensing relay will then kick in also (as it sees the increased voltage through the split charge relay) - so effectively the batteries will be linked up by two cables which is no bad thing!!

[MartinR]

Thanks for that. You're right of course - when moving around regularly it probably wouldn't be needed, but the T25 is a bit of a project, and as it's too high for the garage, the enthusiasm over winter is a bit low, so it can be parked up for some time. I've been caught by leaving the manual zig on touring and had one of these new fangled radios run battery down a bit, so thought that this would allow the zig to work as a trickle charger for both.

Might give it a go, though with no urgency.

Thanks

Martin

[MidLifeCrisis]

I've been caught by leaving the manual zig on touring and had one of these new fangled radios run battery down a bit

There was some talk about this a while ago and the consensus seemed to be that it was best to completely disconnect the main battery from the Zig so that this couldn't take place - as there is no real good reason why you would ever want to run the Zig off the Main (that's what the leisure is there for of course)

Or perhaps have a disconnected plug at the Zig that can be connected in an emergency but not just by accidentally flicking the 'touring' switch (which is just too easy to do when scrabbling round in the dark trying to switch the zig on)

[Budgie7]

[quote="ghost123uk"]@ Budgie7, yes, as long as you have one of those "voltage sensitive" automatic split charge relays. Wire your mains charger to the main battery and as soon as the voltage rises above about 13 Volts (which it will quite quickly) then the relay activates and so the charger then charges your leisure battery [/
Put my charger onto the main battery and waited and yes the relay did click and started charging the leisure battery, thanks ghost,

[ghost123uk]

@ Budgie7, yes, as long as you have one of those "voltage sensitive" automatic split charge relays. Wire your mains charger to the main battery and as soon as the voltage rises above about 13 Volts (which it will quite quickly) then the relay activates and so the charger then charges your leisure battery

Put my charger onto the main battery and waited and yes the relay did click and started charging the leisure battery, thanks ghost,

You’re welcome

[Budgie7]

Hi , connected the charger to my main battery and the relay started clicking continuously on and off to charge my leisure battery, is this right ?,
also later in the day when the main battery was about 14 volts the clicking stopped. again is this right .
Am I right in thinking that when the batteries get to about 14 volts does the relay then switch itself off again and presumably when the leisure battery drops below a certain voltage does the relay switch itself on again. Thanks for any help

[ghost123uk]

Hi , connected the charger to my main battery and the relay started clicking continuously on and off to charge my leisure battery, is this right ?, also later in the day when the main battery was about 14 volts the clicking stopped. again is this right .
Am I right in thinking that when the batteries get to about 14 volts does the relay then switch itself off again and presumably when the leisure battery drops below a certain voltage does the relay switch itself on again. Thanks for any help

I am afraid that non of the above is right

Time for a bit of an explanation, then the reason why your relay was switching on and off. These "smart" relays work like this. When there is no charging going on, that is, no charger is connected and the engine is not running, the batteries voltages sit at around 12.8 Volts. However, when you connect a charger, be it a mains one, or the engines alternator, the voltage on the main battery quickly rises to around 14 Volts. The smart relay senses what the voltage is and as soon as it gets over about 13.2 Volts, it then knows there must be a charge happening, so it switches on, connecting the leisure battery into the circuit so it too gets charged.

Note, the relay does not automatically switch off when a battery is charged. This is not a problem.

What is happening to you when the relay is clicking on and off may now be clear. It is caused by your leisure battery being too flat, or your charger being too weedy. You connect the charger, the voltage on the main battery rises, the relay senses this and switches on. BUT, as soon as that leisure battery gets connected, it "sucks" so much power into itself that the charger can't keep up and the voltage drops. The relay senses this voltage drop and thinks the charging has stopped, so it switches off. The overly heavy load of the leisure battery is now gone, so the voltage rises, the relay switches on, the heavy load of a flat leisure battery, coupled with a charger that is not powerful enough, causes the voltage to drop, the relay turns off and the now reduced load causes the voltage to rise again, the relay turns back on, but the................................. you see what is happening

The solution is to charge your leisure battery separately this time and don't let it get so flat in future, it is very bad for them.
You may also consider a beefier charger.

[Budgie7]

Thanks ghost, I understand now and it makes sense. I will keep an eye on my leisure battery and make sure it doesn't loose to much power. I have one of those fancy voltage display things, do you think it is worth having that connected to my leisure battery , so I can always see at a glance what my battery is doing, thanks again
Barry

[ghost123uk]

I have one of those fancy voltage display things, do you think it is worth having that connected to my leisure battery , so I can always see at a glance what my battery is doing, thanks again

Yes Barry, that is a good idea. Check it though by putting it on a battery, noting what it says, then putting a multimeter onto the battery and noting what voltage that gives. Reason is I have seen some of those voltage display things that are quite inaccurate. If yours is, then just note what the difference is and remember to add or subtract to get the correct reading. With luck yours might be close enough of course. The minimum voltage you should ever let a battery fall to is 11.5 Volts. You can buy a thing called an "LVD" (Low Voltage Disconnect) that automatically disconnects your leisure battery should the voltage fall too low, Here is one = http://www.ebay.co.uk/itm/12V-PROGRAMMA ... 3f46abc0e0" onclick="window.open(this.href);return false;

[Budgie7]

Hi again, yet more problems. The oxford battery charger that I was using has just switched itself off, for no apparent reason, and will not work again. So I dug out my old smartrite charger, Connected it up to the starter battery and listened, but no clicking from the relay, except when I switch the charger off. What is happening or what am I doing wrong. ?

[ghost123uk]

Two things to do that will help I.D. what is wrong.

1 - Without any charger connected, measure the voltage on both the starter battery and the leisure battery and post them both here.
2 - Hook up the charger to the main battery, turn it on, wait 5 mins, now measure the voltage on the starter battery and post it here.

[Budgie7]

Me again,
1- voltage at the starter battery is 12.9, voltage at leisure battery is 12.8
2-after 5 mins connected voltage is 14.5
This time relay is clicking on and off

[CJH]

Those voltages seem healthy enough.

This time relay is clicking on and off

Do you mean it is clicking on and off while the charger is (constantly) connected, or that it clicks on when you power the charger and off when you turn it off?

If the former, try to measure the voltage on the starter battery while this is going on. As per Ghost's description, I'm guessing you'll see the voltage rise when the charger connects (causing the relay to click 'closed' and connect the leisure battery), then fall when the leisure battery connects (causing the relay to 'open' again and disconnect the leisure battery). The voltage readings when the relay closes and when it opens might help us here.

Is your relay one of the adjustable ones, like this? If so, it's possible that the relay could use some adjustment, so that it doesn't open the moment the leisure battery connects.

[Budgie7]

The relay just clicks on and off constantly. Even when I am driving, all you can hear is the relay clicking away.

[Budgie7]

No my relay is not like that, but I have just bought one of those, so I might try that just in case the relay is at fault