Leisure Battery Not Charging

[Sean]

Oh Dearest Knowledgeable Souls of the Wildcamping Forums;

I come again seeking your ever so knowledgable answers! Last night whilst reading my book my lights all went out. This morning I got my multimeter out and started investigating.

I have ZIG Cfg-8 and when this is switched to onsite my leisure battery is 11.38v and when on touring goes up to 11.40v. Similarly my main battery is 12.58 onnsite and goes down to 12.52v when on touring. This all makes sense(I think).

However when I turn the motor on my main batter jumps up to 14.1v and the leisure remains at the same power. Irrespective of which switch position the zig board is on.

So my guess is that perhaps the relay control switch has gone bung? Does that make sense and if so -what is the best way to test this? Finally if this does turn out to be the case - where can I get one quickly (e.g not over the web as I'm wilding with no fixed abode). I'm in Portishead now and heading to the new forest so anywhere in the south-west area is fine.

Thanks
Sean

 

[888dee]

very similar to a problem I had which was eventually traced to a failed scotch lock type connector on the control circuit although there were other problems in the installation on mine.

anyway, fault finding, the voltage on the L battery should match the 14-odd of the M battery when the motor is running,

I'm not familiar with zig units so not sure if it has separate split charge relay or it's built into the unit... in both cases the 1st thing to check is if the increased voltage is available to the zig with the motor running.

if the SCR is separate then find that and test all of the input to that, again with the motor running, if I've got this right there should be 2 14v inputs (one for the control circuit and another for the load), if both are present then check the output at the relay, no output point at a fault in the relay, output suggests a wiring fault between the SCR and the zig.

if you don't have 2 14v inputs suggests more than likely a wiring fault and again more than likely on the control circuit, time to go looking for dodgy scotch locks


in the other case, SCR is built into the zig, again check the inputs, there should be 2 14v inputs, the load and the control circuit, the main fault with mine turned out to be a failed scotch lock joint on the control circuit, see a recurring theme here? Good Luck!!

 

[guerdeval]

Firstly can I say I'm totally impractical, but, from what I've been told by an expert and assuming your Zig does the same as my hymer, the voltage you're showing when you start the engine is the rate at which it is being charged and not an indication of the condition of the L battery, if its no good then it will still only give 11 volts or so despite having 14 volts shoved into it, as a layman it sounds like the starter battery is fine but the leisure battery is buggered, I should stress that if you have a meter you're well cleverer than me, just trying to help.

 

[AndyC]

Zig CF-8 manual here

AndyC

 

[Sean]

"the voltage on the L battery should match the 14-odd of the M battery when the motor is running," - Is this also true if the leisure battery is dead?

 

[888dee]

I believe so as this voltage is presented at the battery regardless of whether or not it can store those peskie electrons.


had another thought though, did you say the lights just went out or dimmed then went out?

just going out would suggest a break in the circuit but as to whether a battery can go open circuit like that I don't know...

 

[Sean]

Hey 888dee - thanks for quick reply and helpful pointers.

DIM'ed then went out. For the big halogen (18W) this took a matter of seconds... for the smaller ones they're still going but rather dim.

 

[888dee]

dimming would suggest a loss of charge rather than a fault developing in the circuits, unless a short circuit? is there a breaker on the circuit? do the lights work normally with the engine running? if they are would go back to my original fault finding suggestions above, good luck


shame you're not nearer and I could have had a look

 

[oldiebutgoodie]

Oh Dearest Knowledgeable Souls of the Wildcamping Forums;
I have ZIG Cfg-8 and when this is switched to onsite my leisure battery is 11.38v and when on touring goes up to 11.40v. Similarly my main battery is 12.58 onnsite and goes down to 12.52v when on touring. This all makes sense(I think).

However when I turn the motor on my main batter jumps up to 14.1v and the leisure remains at the same power.
Thanks
Sean

This all points to a dead leisure battery and dying main battery. A fully charged battery will read 12.7v+.
11.38 is very dead.
12.58 is not very healthy.(possibly a candidate for desulphating?)

I wouldn't be running halogens if I were wilding fulltime 18w will soon zap your reserves - a led replacement will take less than 1w.

 

[mildred]

Battery Voltages

Morning all!

Some time ago I came across the appended data - I remember validating it at the time but did not make a note of the original source. However I have used it to some good purpose with many batteries. It's worth noting that you should never, evah, run a battery down to below 40% if you want to keep it healthy and that you're unlikely to get better than 80% efficiency in recharging, storage and use - which puts quite a hard perspective on claims made by solar and other green solutions. LED lighting has to be the way to go ...

I'd strongly suggest the use of a cheap digital multimeter and its inclusion in your toolkit - together of course with learning how to use it!

The table below also gives Volts per Cell - be careful when making measurements between adjacent cells - specifically not to bridge the plates in a cell with your probe and also not to use probes that will contaminate the electrolyte. Acid splashes aren't nice either! Also these are the voltages of the battery itself - not the voltages measured whilst charging and also after the battery has lost its surface charge - either let it stand for an hour or turn on headlights or some other high consumption item for a couple of minutes, switch off and then measure the voltage.

State of Charge - Whole 12V battery Voltage - Volts per Cell

100% - 12.7 - 2.12
90% - 12.50 - 2.08
80% - 12.42 - 2.07
70% - 12.32 - 2.05
60% - 12.20 - 2.03
50% - 12.06 - 2.01
40% - 11.90 - 1.98
30% - 11.75 - 1.96
20% - 11.58 - 1.93
10% - 11.31 - 1.89
00% - 10.50 - 1.75


Safety Update:
Do not attempt to measure the voltage of individual cells unless you know what you are doing; guarding against shorting out the plates in a particular cell, introducing metallic contamination and acid splashes.
The design of some batteries make it impossible to get at individual cells anyway - you can only measure across the whole battery.
Repeat - Individual cell voltages are for experienced experts only!

 

[Sean]

AHH HAA SUCCESS!!

Thanks for all your help. I found that it was a 25amp fuse in the engine bay next to the battery that was gone. The confusing thing was that 4.5v were still coming down the line - so either this fuse was partially working (it crumbled when i pulled it out - it is a 20 year old vehicle) or some other forces beyond my comprehension were at work.

Big thanks to mildred and 888deee for your help.

Cheers
Sean

 

[888dee]

good news sean

 

[baldeagle690]

Hi Mildred

Could I assume that if I fully charged a battery using a quite fancy charger that tells you when the battery is fully charged it would show around 12.7v. If I checked it a couple of days later and it had dropped a bit then it's knackered assuming it's not connected to anything? I know it can be a bit more complcated than this but looking for a basic idea.

Cheers

Baldeagle

 

[jogguk]

Could I assume that if I fully charged a battery using a quite fancy charger that tells you when the battery is fully charged it would show around 12.7v. If I checked it a couple of days later and it had dropped a bit then it's knackered assuming it's not connected to anything? I know it can be a bit more complcated than this but looking for a basic idea.
Cheers
Baldeagle

Sort off as a rough guide Although provided you are talking std batteries with removable plugs a cheap battery hydrometer (giant eye dropper thing)would give a better indication and alert you to a failing cell more easily.

John

 

[Deleted member 3011]

be careful when making measurements between adjacent cells - specifically not to bridge the plates in a cell with your probe and also not to use probes that will contaminate the electrolyte.

I may have misunderstood Mildreds instructions but please DO NOT try measuring by poking meter probes down through the electrolyte to contact the plates. Vet dangerous. Just use the 12V figures. The volts per cell are given for use when a battery is made up of individual 2V cells with external connections or 6V batteries in series.

 

[Deleted member 3011]

Hi Mildred

Could I assume that if I fully charged a battery using a quite fancy charger that tells you when the battery is fully charged it would show around 12.7v. If I checked it a couple of days later and it had dropped a bit then it's knackered assuming it's not connected to anything? I know it can be a bit more complcated than this but looking for a basic idea.

Cheers

Baldeagle

Yes, but only a little bit more complicated.

You fully charge the battery and then leave it disconnected for at least 6 hours. Then you measure the voltage (with no load connected and no charging current in either). The real state of charge can then be inferred by referring to the table Mildred gave. Note that the figures will be different (sometimes a lot different) not only for different battery types, but even for the same type from different manufacturers so it is only ever a very rough guide - but of course much better than the usual traffic light indication on most chargers which are no guide at all to the state of the battery. Repeat - NO guide at all.

Then if you leave the battery disconnected, that measured voltage will slowly drop over a period of weeks for flooded-cell lead-acid batteries in hot weather (can lose up to 30% per month) - or months for some types ie AGM where the losses can be less than 5% per month.

Biggest problem is ensuring there is no phantom loads on your battery and the only way to be sure is to physically disconnect the battery.

If you fully charged the battery (IE charger took it up to 14+V and then dropped down to float voltage (around 13.7V) which should mean it is fully-charged) and it was below 12V when you checked it after the 6 hour wait time(for "surface charge" to dissipate) then you could infer that the battery is generally unwell, or that one cell had shorted out.

As a check, connect a 5 Amp load across the battery (a car headlight bulb).
A healthy fully charged battery will show the battery voltage dropping perhaps 0.1 or 0.2V immediately and then slowly over several hours to about 11.8V when the battery will be down to 50% and the test can be terminated and the battery recharged. If it drops immediately to anywhere near 12V and then rapidly over say an hour or less to say 11V then the battery is likely to be close to giving up and in any case is useless as a house battery. If it is due to sulphation, then it may be possible to recover some of its capacity, but it may not be worth the trouble.