# Battery/Electrical Fault



## Chascass (May 10, 2007)

When at the meet in Scotland I had a problem with the battery's ( 2 sealed 110 ah battery's fitted ) I noticed a big drop in the battery read out when on load i.e. 12.9v to 11.8v with a 80 w load, I thought I must have a duff battery, so today I tested the battery's to see which one had gone down.

Battery 1 (disconnected from battery 2) reading with multi meter at the battery before any load 12.9v, with a 60 watt load direct to battery via a 300 watt inverter 12.5v a drop of 0.4v

Battery 1 reading inside van (panel) 12.7v, with a 60 watt load via the inverter plugged into the van socket 11.6v
a drop of 1.1v

The second battery was virtually identical. it would appear that the battery,s may not be the problem.

Can anyone advise what the fault might be.

Charlie


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## Techno100 (May 8, 2010)

Sounds like they're not fully charged to begin with? ought to be reading 13.6 ish when charged.


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## Chascass (May 10, 2007)

My understanding is that when on charge (ehu) the panel should read approx. 14v and off charge after allowing the battery to settle a fully charged battery is approx 13v

The thing I don't understand is why the battery drops 0.4 v (what I would expect) when on load direct to the battery, but drops 1.1v when 
on load connected to the van.

Charlie


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## stearman65 (Nov 22, 2010)

*Battery*

I would check with something other than an inverter, a 300W inverter can be taking out more than you think. Test it with a dedicated 12v load item, lights etc.


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## wilse (Aug 10, 2007)

How long was the inverter running?

A multimeter and panel may give a slightly different reading, but not by much.

I had an electrical issue and found that my power was rapidly going after some fairly light use each evening...

When I tested them myself the panel said 13.2v [100% full!] I put a few lights on, and the voltage went to 12.4v within a few mins.

Knackered batteries. Both were in a very poor state, even though I had them load tested by a local garage.
I found battery testing company and then tested on their fancy tester... overnight... report came back, batteries couldn't hold proper charge, even thought the panel reported it was at the time.

Swapped the batteries and all in now good. Now the panel starts off at 13.7 ish.

Have you a solar panel? how often are they hooked up? How old are the batteries.

w


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## Chascass (May 10, 2007)

*Re: Battery*



stearman65 said:


> I would check with something other than an inverter, a 300W inverter can be taking out more than you think. Test it with a dedicated 12v load item, lights etc.


The thing is I'm using the inverter on both tests, at the battery and in the van, so same usage. its the drop between the 2 tests that I can not understand.

Charlie


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## Techno100 (May 8, 2010)

Have you tried plugging in in the van and measuring at the battery? It may be the panel is reading inaccurately


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## clive1821 (Mar 27, 2010)

uuummmm so you are testing correctly well done, and you have identified both batteries are still working ok..... just aside it might be a good idea to leave your load on directly on your batteries (one at a time) for say 4 hours and if your load is still working and the inverter has not tripped out due to low voltage I would reckon the batteries are ok.... when you are connected in to a cig lighter taking about 5 amps, from your plug to your fuse board and metering there would be a voltage drop more than you saw directly on the battery terminals, it may well be something to do with the metering current shunt or the cable connection from the shunt to the batteries just my view... just make sure you charger up the batteries before the test...


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## Chascass (May 10, 2007)

clive1821 said:


> uuummmm so you are testing correctly well done, and you have identified both batteries are still working ok..... just aside it might be a good idea to leave your load on directly on your batteries (one at a time) for say 4 hours and if your load is still working and the inverter has not tripped out due to low voltage I would reckon the batteries are ok.... when you are connected in to a cig lighter taking about 5 amps, from your plug to your fuse board and metering there would be a voltage drop more than you saw directly on the battery terminals, it may well be something to do with the metering current shunt or the cable connection from the shunt to the batteries just my view... just make sure you charger up the batteries before the test...


Hi Clive

I now have Battery 2 on charge (out of van) for a test tomorrow.

Battery 1 with out fully charging it I placed on test with a voltage of 12.9v which dropped to 12.5 with a load of 60 watts, after 4 hours that has dropped to 12.00v I will leave it untill it reaches 11.8.

It look like it will have to be a visit to a auto electrician

Charlie


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## clive1821 (Mar 27, 2010)

Ok it would be better to put a load of around 150watts on your inverter, and if your batteries are say 110ah if the test lasts over 4.5hours it's a good bet you battery is in good order...


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## Chascass (May 10, 2007)

Thanks Clive

I think the test will have to be over a longer period of time with a 60 watt bulb, in these days of low energy bulbs that is the biggest I can find.  

Charlie


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## clive1821 (Mar 27, 2010)

Yep you have the idea now... its not full proof but it give you a very good idea if the batteries are ok... I've got to do the same thing my self as one of my batteries I feel is not happy, I'll fiddle the next time i'm on a camp site with eletric hook up.... I use a 150 watt out door halegen lamp that seems to put a good load on the test battery but not to much of a load.... all the best


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## Chascass (May 10, 2007)

It is recommended that battery's are not allowed to go below 50% of their capacity, lets say that 50% is 11.8.

Am I correct in thinking that is when the battery is at rest and not when on load.

Charlie


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## Techno100 (May 8, 2010)

This looks like a very helpful article if the link works.
pdf download



> Check the state of
> charge using a direct
> current voltmeter -
> 12.7 volts indicates a
> ...


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## Chascass (May 10, 2007)

The article states a battery at 12.7= 100% - 12.3= 50% - 11.8= fully discharged.
If that's correct we have less to play with than I thought.

PS + it also advises that a battery should not be allowed to discharge below 80% of it's capacity. 8O

Charlie


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## Techno100 (May 8, 2010)

I have 2 different solar regulators and one disconnects the load at 10.6 volts but is programmable and the other at 11.1 by default and non adjustable. (for battery protection).
I have my inverter fed from the load terminals of my solar regulator so it has 2 chances of being switched off by under voltage (by regulator or by inverter itself). Never happened yet tho.
I've just replaced my 12 volt HD sat receiver with a 230volt one so that my TV and receiver are both off my inverter and I can monitor what is going out and in. Today the ouput of tv receiver and inverter totaled 4.2 amps with 2.4 amps going in under cloudy sky. Batteries under load showing 12.4volts but quickly back up to 13 and climbing rapidly to 13.7 from solar regulator. Under clear sky I can get a good 5 amps most of the day.

Some of that may be helpful?


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## Chascass (May 10, 2007)

I have tested the battery's and both are in good condition.

Battery 1
Charged to 13.45V after a 1 hour rest
Start of test with a 60 watt load = 13.00v, after 7 hours (checking every hour) there was a constant fall to 11.94v, at this point I stopped the test and the battery returned to 12.35v off load.

Battery 2 was very near the same as battery 1 

So now to charge up both battery's again and place in the van and see what I find when the same 60 watt load is used.

Charlie


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## wilse (Aug 10, 2007)

Not sure if this helps or not??

On my old batteries 2 x 100 amp [now binned]

I started with 13.2v on the panel [13.1 on battery terminals]
I ran a 3.4 amp load. I checked every 30 mins.
Here are my results:

start min - 160A - 13.2v
030 min - 158A - 12.5v
060 min - 156A - 12.4v
090 min - 155A - 12.4v
120 min - 153A - 12.4v
150 min - 151A - 12.3v
180 min - 149A - 12.3v
210 min - 147A - 12.3v
240 min - 146A - 12.2v
270 min - 144A - 12.2v
300 min - 142A - 12.2v

After, when off load, the voltage rose back to 12.4v

Needless to say this was both batteries. I suspected the electrobloc, but it wasn't. With a couple hours of TV and a light or two we could only just survive one night, with a 12/12.1v in the morning.

I used a battery testing company after doing my own test, the said the batteries had around 50% capacity.
I think it was checked with a machine called a Surechecker??

W


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## 747 (Oct 2, 2009)

You also need to remember that m/home manufacturers are not generous with the diameter of cable they fit and these can be long runs. This could be the reason for the different readings when the batteries are off the van.

If you consistently use a fairly heavy load from one 12 volt socket, I would recommend that you run a bigger diameter cable with the appropriate fuse fitted.


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## Chascass (May 10, 2007)

Thanks for that wilse

I did not check what amps my test was but I guess 60 watts + the inverter must be around 6 amps, but the proof of the pudding will be when I try the same test connected up to the van that's the bit I cannot understand.

Charlie

PS 747 Yes if I find a big difference that would be my next port of call


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## Chascass (May 10, 2007)

Well I have recharged the battery's 

Battery 1 Fully charged 13.3v, with a 60 watt load direct to the battery 12.95v...... a drop of 0.35v (what I would expect)

Battery 1 connected to the van panel reads 13.25v, 60 watt load direct from the van socket 12.3v.....a drop of 0.95v (I would of expected about 0.45)

Battery 2 very near identical

Can anyone one confirm that their's dose/dose not drop by this amount under a small load (starting to doubt myself) sorry if I'm getting boring 

Charlie


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