# Battery maintenance



## j20ands10 (Sep 16, 2010)

Ok had the MH since september last year and have worked out we can last about 48hrs without EHU.

I think we should be lasting longer but never want to push the batteries too much.

Can some either explain or point me in the direction of a good / reliable source of information on what i should be measuring to make sure I am not over doing the batteries. is it amps, volts, amp/hrs

I have
2 x 100mah batteries
600w inverter
6amp? Main charger connected to the batteries.

The previous owner added a volt meter with a clever push button to so its not draining any power  

We just run the fridge and the required lights from 12v 

We have chatted about buying a generator but don't think we do enough rough camping to warrant one. Nor will it actually help, it would take say 12hrs to charge my 12v system....not sure I could put up with that.

Thanks in advance


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## BillCreer (Jan 23, 2010)

Hi,
What you have seems fairly typical of what others use with two good sized batteries. Most people, you'll find, run their fridges from gas as they consume a lot of electrical power.
There are plenty of postings on this forum that will answer any questions you have about alternative charging sources if you search.


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## JeanLuc (Jan 13, 2007)

j20ands10 said:


> We just run the fridge and the required lights from 12v


Assuming you have a Dometic / Electrolux absorption fridge (silent) and not a compressor fridge, I would be very surprised if it runs on 12V battery power when you are stationary. In most (if not all) installations, the switching relays are set up to connect the 12V supply only when the engine starts and power normally comes from the engine battery, not the leisure ones. (I am aware there is some connection to the leisure batteries for AES fridges, but this is not about powering them as I understand it.)
12V supply is designed only to maintain the temperature whilst you are travelling. When stationary, the fridge runs on gas or 230V mains if hooked up, 12V doesn't work.

Given your battery set-up, I would expect to be able to last 5 days (maybe more) in summer and 2-3 in winter depending on temperature. The biggest single drain on battery power in winter (apart from running a big inverter for extended periods) is the blown air heating system. We have lasted 3 days in winter at temperatures well below zero with the Truma heater running 24/7, but the batteries died on the third evening. That is with 2 x 110 Ah.


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## wilse (Aug 10, 2007)

This was similar to an issue we had.

In short we got 1 night with a few lights and TV for couple of hours plus heating.

In the morning the voltage of the batteries was very low.

To cut to the chase, I got the batteries properly tested [NOT load tested with a hand held device] the report showed the batteries were below 50% usuable, yes they worked, but we always seemed to muller through the power.

I would recommend a test. It cost me £5 per battery.

Out of interest if you have no solar, how ofter is the van sat around? As your battery could be slowly draining.

How often do you hook it up?

I replaced my batteries and all is good now, we've done two days [longest yet] with all the trimmings on, and still had plenty of juice left.

PS, have you got LED/Halogen/Fluorescent lighting?

w


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## barryd (May 9, 2008)

We have 1 x 110AH battery and no solar or genny. we last 5-6 days in summer and maybe 3-4 in winter.

Led lights
No inverters
Small low power TV
Never ever use the blown Air heating (dont see the point of it really)
Fridge Gas
Fire gas

However, I think the battery must be getting on for 4 years old. Ive never even looked at it let alone maintained it. I presume its maintenance free to last this long. How long do they last?


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## j20ands10 (Sep 16, 2010)

*more infor*

Thanks for the input just to confirm a few things:

The fridge is a compressor type no option to run it on gas (i was under the impression these a very efficient )
No blow air heating just a standard gas heater
Lights are fluorescent - looking into led ones. currently 9w compared to 1.5w on led does not take a genius to workout which would be best.

I think our biggest killer is the inverter I am now looking at a 12v to 18v convertor for charging the laptop rather than the current 12v to 240v to 18v which again does not take a genius to work out which is more effective.

The batteries were both new september gone, the van is used at least once a week and over the winter when the roads were too bad it was on EHU and the charger put on every 2 weeks or so making sure they stayed above 12v. Before we go away the van is used (driven) and or the charger put on for 48ish hours also put fridge on to chill it down.


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## j20ands10 (Sep 16, 2010)

after 2 nights /3 days away without using the inverter our battery state started at 100% and ended at 60%.

So between not running the inverter and also putting one of those cheap wired outdoor/indoor thermometers in the fridge to prove it was cold enough on 3-4 and did not need to be on 6 things are looking good for a week away without the need of EHU.


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