# Loss of 12v whilst hooked up



## AndrewandShirley (Oct 13, 2007)

Our 12v system keeps cutting out even when we are plugged in to the mains.

The system indicates we are taking out more than we putting in.

We only have 10 small flo lights on, (factory fitted on two switches) three of which are on their last legs and need new tubes. Could this be the cause?

We have checked and atm we only have the lights on and nothing else.

Thoughts.


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## pieterv (Feb 3, 2009)

Check your 12V charger (e.g. fuse), although if with flo lights you mean fluorescent, do take into account that they can take a fair bit of current.


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## clive1821 (Mar 27, 2010)

Just worth a thought a 12volt flo light can take 2amps times by say 10 all one in one go would be 20 amps which is a lot depending on your battery and the current supplied by the mains charger if less than 20amps for example would start discharging your battery.... It's hard to recommend an answer as I can't grasp how your set up is working


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## gaspode (May 9, 2005)

First thing to say is - don't fit new tubes, buy some LEDs to replace your flourescent fittings. The small tubes are usually 8watts so if you have 10 on, thats 80watts = at least 8amps when you take losses into account (or if they're twin tube fittings double that figure), quite a significant load if used for any length of time. By using 10 LEDs instead you could reduce that load to around 1.5 amps.

Second thing is check your charger output, you shouldn't be getting the 12v cutting out if you're on hook-up, battery voltage should be at least 13v with the load you mention when the charger is switched on and hooked up to mains.

Third, how old are your leisure batteries and what's their voltage when charged and lights on? If it's much lower than 12.5 you may have a dud cell which is preventing the batteries charging properly. Have you checked the acid level in the batteries recently?


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## AndrewandShirley (Oct 13, 2007)

Thanks Gaspode

New tubes
We have been looking for replacements but could not find any we liked at Shepton but its on the list.

Charger output
Had an electrical surge whilst in Morocco that knocked out a number of units. This we may have a damaged one. Due to be checked out when we get back in a couple of weeks.

Leisure Batteries
Am checking age of the single battery tomorrow and we have already planned to upgrade to two.
The voltage when charged and the lights on indicate a negative draw e.g. everything off 11.7 +6a (usually 12.9) but with flo's on 11.6 -3.1a

Have never checked the acid level in the battery another job for tomorrow, now whats the Spanish for "Distilled Water"?
(Agua destilada of course)


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## tikki (May 13, 2005)

Hmmm. We may have the same problem here!

Last night, on mains hook up with loads of 12v lighting on, TV & sky box supplied from 12v, not mains, turned the tap on & TV & Sky box shut down.
I briefly disconnected the mains hook up and had no power whatsoever!
This morning I had a good look around the twin battery installation & the myriad of fuses in that area and found that one of the fuses had not blown but, had melted the holder & itself completely into a nice green blob!
This had originally been part of a block of 3x30 amp fuses and was the only one I hadn't replaced with the larger 'Maxi' fuse which isn't as susceptible to overheating.

I briefly connected the cables directly without the fuse and everything worked fine. Tomorrow when we get home, I'll replace the melted fuse unit with a Maxi fuse! 

The other 2, one of which supplied the fridge, had overheated on long journeys and melted the fuse housing but not actually blown the fuse.

I still don't know why the standard fuses can't cope with the heat but the Maxi fuses can?

Hope this helps in some way

Chris


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## GEMMY (Jun 19, 2006)

Why are you lit up like a Christmas tree?

tony


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## gaspode (May 9, 2005)

AndrewandShirley said:


> We have been looking for replacements but could not find any we liked at Shepton but its on the list.


Have a word with Saul at Aten Lighting, http://www.atenlighting.co.uk/home.php?cat= They're the ones I always deal with and I've found Saul to be the best authority on LED lighting, I think he'll also give a discount for MHF members.


AndrewandShirley said:


> Had an electrical surge whilst in Morocco that knocked out a number of units.


That sounds ominous, that's what you get for using foreign electrickery. Make sure the indicator lamp is lit on the charger, if not check the internal charger fuse and hope it's not something more serious.


AndrewandShirley said:


> The voltage when charged and the lights on indicate a negative draw e.g. everything off 11.7 +6a (usually 12.9) but with flo's on 11.6 -3.1a


That sounds wrong. With a battery level of 11.7v I'd expect a charge current much higher than 6amps, if the charger is working OK I'd suspect a dud cell in the battery. If you can borrow a hydrometer, test the specific gravity in each cell of the battery before you top up the acid, if you find that they differ to any degree it's the battery.


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