# Autotrail Electrics



## enjohn (May 2, 2008)

Hello, I am hoping someone may be able to help me an electrical problem on my 2009 Autotrail Apache. I have two 110ah Elecsol batteries, kept regularly charged via two Solar Panels unless on a site with inclusive electrics. I have had the batteries for just under a year and have used them at rallies with only solar charging without any problems. However, whilst at the Peterborough show in April my batteries started running down quicker than I had experienced before. The only difference was that I was running a Sky Plus box via a 150w inverter.

The discharge from each appliance I recorded separately via a battery monitor and these were as follows: Sky Box connected to the inverter 2.7 amps - TV 2.2 amps - Lights 3.0 amps giving a total of 7.9 amps constant drain. With no appliances on the monitor showed a discharge that fluctuated between 0.01 and 0.02 amps. In addition the hot air blower from the heating, which wasn't constant was 1.0 amps. The only other discharge was the occasional burst of the water pump. The monitor was showing that the batteries were full charged before these appliances were turned on. After approximately 4.5 hours the Inverter's alarm started, which from previous experience in a van with only one battery some years ago meant that there was not enough power for it to continue. When I checked the battery monitor it showed that during the 4.5 hours the charge had reduced to 50%. Now I realise that the figures I have listed may not be that accurate, but I would not have expected the batteries to have lost a possible 110ahs after such a short time.

The battery wiring, the charger, the battery monitor and solar panels have all been checked and a 'drop test' under load and an 'Amp Drain' test carried out professionally. Everything has tested positive. Can anyone help me with this one please? Am I missing something, are there any other tests or checks that could be carried out? Has anyone else had a problem with their Autotrail losing power as quickly as it appears I am? Apologies for the length of the post but I have tried to give as much information as possible. Your help would be very much appreciated. Thank you.


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## clive1821 (Mar 27, 2010)

If the Battery was new and at a temperature of 25c 110ah that is the max that would be available, at say 10c the battery would only give you at best 60ah made up of 20% off for the losses of the battery and the rest due to the temperature so with 60ah actualy usable you would get 6 hours of life with the current you are taking.... The battery losses increase with age..... My current usage is quite a lot, about 10amps... But I have 2 x 230ah batteries to help me..... Hope that makes sence to you

The standing 10 to 20mA loss is nothing to worry about, just the consumption of the control panel etc... There are ways to reduce your load but we'll leave that for another day... :wink:


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## enjohn (May 2, 2008)

Hi Clive and thanks for your reply. Unfortunately I do not fully understand the figures you have given me. I only understand the very basic I'm afraid. Apologies if I am asking obvious questions, but when you are talking about the temperatures are these of the batteries or the air? Also if I have 2x110ah batteries why do I only have 110ah available? Sorry if the answers are obvious but my knowlegs is very limited. Thank you. Regards, Nick


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## clive1821 (Mar 27, 2010)

It's just a rule of thumb I use and it's the air temperature around the battery which is then the battery temperature..... There is a large decrease in battery capacity as the temperature falls, for example your car battery usually fails in the winter due to the temperature showing up the internal cell resistance etc there's various articles on line just google it and articles on this site if you want all the technical reports


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## gaspode (May 9, 2005)

Hi enjohn

Clive is quite correct, the storage capacity of your batteries will reduce quite dramatically at lower temperatures, to get the rated capacity you'll need to be at 25deg+.

I'm a little suspicious about the current you say your TV draws, I'd expect most 16" TVs to draw around 3amps+ unless they're the very latest most efficient models, but leaving that aside you still have quite a heavy constant load at almost 8 amps.

I suspect that your batteries aren't actually fully discharged, just that the terminal voltage has dropped because of the 8 amp load you're applying. You'll find that under an 8a load your battery terminal voltage might be getting near to 12v after 4 hrs use but if you disconnected the load the terminal voltage would very quickly rise to 12.5 or higher. The nub of the problem is the inverter which will have a very sensitive input voltage sensor, usually set just above 12v (at the inverter that is - not at the battery terminals where it will be higher) once the inverter input voltage drops below that figure the inverter will drop out.
Try switching everything off for a couple of minutes and you'll probably find that the inverter will start up quite happily for a while because the battery voltage has recovered to above the cut-out threshold.

The answer is to use 12v appliances wherever possible but it might also be worth making sure the wiring to the inverter is of a heavy guage and as short a run as possible to avoid losses. Also consider putting in some LED lighting, 3 amps sounds quite a lot for lighting in modern terms, you should be able to light an average van on LEDs for less than 1.5 amps. Maybe you also need to turn your Sky+ box completely off when not in use, Sky boxes are notorious for high standby currents.

Pumps can draw a fair current but only intermittently - but they will cause the inverter to cut out when they operate if your battery voltage is getting on the low side.


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## enjohn (May 2, 2008)

Thanks Gaspode for you reply. I already have LED lights, but they are much longer than our previous ones. Although they give a good amount of light with so many LEDs they appear to use a lot more power. Having said that, they do have a dimmer on them which reduces the draw. I have got a Freesat box that I will use instead of the Sky box to save on power, but am not quite sure what type of 12v lead I need. The transformer for the box reduces the voltage down to 12v and a 2amp input. I assume that I will need a 12v - 2amp adapter to ensure that the input is 2 amps? If so can you suggest a reliable company I can source it from?

Thanks again, Enjohn


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