Battery advice please

[Travis]

Hello
I have a zig unit with a leisure battery about a year old, only used about 10 times and a 3 month old van battery. Last week or so I went to Glastonbury and used the fridge only (no internal lights or sink). I made sure that zig switch was leisure battery only. The fridge worked for 5 days and kept my beers ice cold (is that a long time?).

Each day I turned the bongo over and plugged in my phone in the ciggie lighter and let the engine run for 10 minutes to top up the phone. I also used the central locking with my key fob about 6 times a day.

Anyway on the 5th day I noticed when I woke up that the central locking was sluggish and when I tried to turn the bongo over the battery was almost dead (it had a little juice in it). Luckily there were loads of people near so I was able to use some jump leads.

One guy said that the constant use of the electronic locking and also the turning over of the engine each day may have drained the bongo battery. Someone also suggested that the power taken from the battery to start the bongo will not be replenished by running the van for 10 minutes and in fact charging a phone at the same time will actually drain the battery even though the engine is running.

Can someone help me is the above true or is the zig wired wrongly considering the fridge lasted 5 days. Hope you can help as I do get paranoid about the battery and have been warned not to turn the engine over and just trust the battery.


Cheers Travis

[missfixit70]

10 minutes isn't enough time just ticking over (@20 minutes just to recharge what it took from the battery I think) especially when you add in the self closing door mechanism, using the central locking etc, you'd be better running it for an hour or so, once over that period, maybe with some revs on it? Or using a solar panel to keep it topped up.
Was the fridge still working when it wouldn't start? this would point to the LB being ok if it was.
Difficult to say for sure without being there & checking voltages of course.

[Travis]

Cheers the fridge was still working. I was wondering if the zig was wired up wrongly and drawing power from the van battery. I guess the phone didn't help either ?

[missfixit70]

Don't think the phone would have made a huge difference TBH.

[g8dhe]

Fully agree, the phone makes no significant difference at all. I've always allowed at least a 20 minute RUN (revs 1500 or above) to replace the charge used for starting and put just a little back in to last for say another week or two for an idle battery. Our old car (sold at last today ) we were using that regime on and still the battery would need a proper charge up every three months to keep it happy.

[roofraisers]

Our fridge lasted for 4 days at Glasto & then stopped working, the LB battery voltage was about 11.7 volts and the engine battery around 13 volts. The Bongo was run for about half an hour & that was enough to get the LB voltage up to run the fridge for the remaining day.( The beer was long gone but we couldn't have warm milk on our cornflakes!!)

If you have a volt meter, I would suggest running the fridge at home if the Bongo is parked up for a few days & measure the voltage across both batteries (may be twice a day) & make some notes. If the zig unit is wired correctly, then the LB voltage should fall & the engine battery remain high.
If the voltage on both batteries falls at the same time & they continually show the same voltage when they are measured, that would tell me that the fridge is drawing power from both batteries & that they are still connected together... ie the zig unit is not isolating the batteries when it should.
When the Bongo is running the battery voltages should be the same when you measure them as NOW the batteries should be connected together as they are receiving charge from the same alternator.

Nigel

[madmile]

Exactly what nigel said .
Also, if you do actually have a zig unit (a lot of people use it as a generic name for control panels), then there is a switch to 'on site' or 'touring'. If you have a seperate split charge relay, then there should be no need to have it 'touring' as this will connect both batteries and they will charge and discharge as one.
If it is 'on site' then the split charge relay if connected solely between the batteries, will do the charging, and when it disconnects as you turn the engine off, the leisure battery will be the only battery powering your fridge.
By the way - 5 days for a fridge on a leisure battery is very good, and if it was connected wrongly then the fridge would have stopped working as well as the central locking etc.
If your unsure about it though, feel free to pop over and I will check the set up for you.

Cheers
Ed

[Travis]

thanks everyone, I have a quiet weekend and will give Nigel's idea a go.

Ed if it doesn't work I will take you up on the kind offer.

I have an actual Zig and left the switch on touring as I only thought you put it on site if you have a hook up, I didn't realise it effected the batteries if there was no hook up. So I will charge them both up on "touring" and on the weekend park up put to "on site" and then check the voltage.

Thanks once again

[Travis]

Well I had a free weekend so I thought I would try the test. I went to halfords and looked at the battery testers the cheapest was £30. So I got a nice little one from e bay with a digital readout for £9.99. I turned the fridge up high and tested both batteries every hour. At first they read as so Main 12.8 leisure 12.6. After four hours the main was 12 and the LB was 11.4. So it looked like the zig was not doing it's job. In the morning I checked again and the main was 12 and the LB 12. Was there a third battery very strange. Anyway throughout the day batteries dropped and raised from 11.1 back to 12. At about 4.00pm 24 hours later the fridge stopped working. This morning I checked both batteries and both read 12. Got in the bongo turned him over and nothing. Battery appears flat. I am plugged into the mains now and will try later. Any ideas? I think the e bay tester may be wrong so I might get a proper one today.

Update...

Went to Halfords to get the £30 tester but the nice man said dont bother as all batteries will show 12 volts what ever the charge,,I am confused now

Ed if the offer is open I would like to book the bongo in with you for a couple of hours soon.

[francophile1947]

A reading of 12V means a fairly flat battery - should be around 12.8V.
Man from Halfords talks rubbish, but what would you expect All you really need is something like this http://cgi.ebay.co.uk/ANALOGUE-MULTIMET ... 2c507a3f43

[roofraisers]

The bottom line is, both battery voltages has fallen when the fridge was used, so the batteries are not being split when the engine isn't running. Could be a faulty split charge relay.....

A reason that the voltages went up slightly at the end of your test is that if the fridge wasn't actually running when you measured the voltage (because it had reached it's cold temperature on the thermostat), the fridge wasn't pulling a load off the batteries & the battery voltage had recovered slightly.
It's a bit like you running until you feel tired, you stop & get your breath back so don't feel too bad...... until you start running again.

Now that the batteries are at this level of discharge, they will both need charging individually & for a period of probably a couple of days to get them fully charged to enable you to get the best from them. A point to check maybe, when using the zig unit to charge the batteries, do both batteries' voltages increase together, ie are they doing the opposite to your discharge test.

Nigel