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Discussion Starter · #1 ·
Having sorted out my Lidl sat. system and rf modulator (BIG thankyou to everyone who posted I don't know where I'd be without MHF). The challenge for me now is powering laptop(TV), rf modulator and sat. box, looking at the options I think that running an additional battery in parallel is fraught with complications:-

1- leisure battery sited under passengers seat so not possible to replace with larger battery and to get another battery to run in parallel would get in the way

2- the charging system is either gel or lead acid , the living area battery is a gel

3- to match present gel battery 85 amp/hr. is rather expensive , cheapest quote so far is £100.

A little lateral thinking poses the question - Why not have a separate battery that could be charged independently. The only downside that I can see to this is will the supply on campsites be enough to power the battery charger ?(Optimate). I would welcome anybodys thoughts on this (be gentle with me as electrics do tend to baffle me Thanks
 

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Hi Mike

Easy to supply a battery charger from site, my 30 Amp charger only needs under 1 amp from mains, a little Ctek isnt going to use that much.

Optimate isnt that a winter trickle effort (have not got time to look up now)
 

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Hi Mike,

We have an 85A/H Gel habitation battery, so a similar problem to yours.

Solution: I've put a 110A/H (Lead Acid) battery under the passenger seat which is left on charge whilst on the drive with an Optimate (And can also be charged if it we're on a site's hookup).

To this I have a cheap multimeter connected to monitor the state of the battery and a 600w (1400 peak) invertor, isolated via a double pole switch.

This solution gives me independent 240v without the risk of flattening the habitation battery and can easily be accessed if additional 12v is required.

Ian
 

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The easiest way to charge three batteries is to fit a split charge diode block. You basically connect it to your alternator, then connect the batteries to it via individual terminals. This block prevents batteries drawing current from other batteries, thus keeping them isolated from each other. This system does away with the split charge relay.

To use the two leisure batteries for the Living accommodation, fit a two way switch so you only draw power from one battery at a time.
 

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Hi Steve

That could prove disasterous with a gel battery (the Diode) could lead to a dead gel battery in very short order
 

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Rest In Peace Mike, 1944-2017.
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fjmike said:
A little lateral thinking poses the question - Why not have a separate battery that could be charged independently. The only downside that I can see to this is will the supply on campsites be enough to power the battery charger ?(Optimate). I would welcome anybodys thoughts on this (be gentle with me as electrics do tend to baffle me Thanks
Hi Mike

This is exactly the approach I have taken in our van. We have an Autosleeper Executive which is great but when it comes to storage space we do need to be economic in what we carry. So I have a normal 85 amp/hr Leisure battery plus an extra 65 amp/hr battery which is used solely for our entertainment system.... Lcd TV and Dvd player. We do not watch an excessive amount of Tv or Dvds but when the battery is at 50% capacity the Lcd TV just shuts down ( very convenient as it does not harm the battery), this is about 3 days use, 8-12hrs or so, never actually timed it. When this happens if we are staying on without any hook up we limit our TV to just the news and weather running from the normal leisure battery.

I use a Ctek 3600 charger to charge on a hook up and at home to maintain, rotating it between the three batteries as necessary. I also have an accumate charger which is a stable mate of the Optimate you mention, both of theseare Ok for maintenance but the charge rate is very low and a full recharge to the TV battery is much quicker with the Ctek.

One other often neglected option for power that I use if necessary is the vehicle battery. I can run the TV, Dvd or laptop from the vehicle battery via a simple battery protector from Maplin , this cuts off the power to any appliance fed from the battery leaving enough power to start the engine. Note that my cigar socket is wired on, with ignition off!

http://tinyurl.com/8r5mq <<<link to maplin page for battery protector


We have just returned from a 5 day break over the Bank Holiday we stayed put for 5 days without a hook up, watched loads of TV computed a bit and ran all the normal things and had power to spare when we set off for home.

Another tip if you are using a charger (Ctek, or Optimate) that connects by the "tamiya type connectors" is get some of them from maplin and you can use them to connect/disconnect all your varous systems/batteries, including the charger.

http://tinyurl.com/88fru <<<link to maplin page for DIY tamiya connectors, buy the loose ones as the polarity of the wiring on the pre wired ones is reversed when compared to the Charger . ( :lol: sorry about that Jabber)


Mike
 

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Discussion Starter · #7 ·
Thankyou all for the replies , what iI will do is buy a cheapish charger and probably a lead acid 110 amp/hr battery . then when we are up a mountain stage of the Tour de France with everything fully charged should give us a reasonable amount of viewing time. Mike , is it the LCD TV that gives you the 50% capacity shutdown or did i miss something?
 

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fjmike said:
Mike , is it the LCD TV that gives you the 50% capacity shutdown or did i miss something?
Hi mike

What happens is that the LCD TV backlight starts to flicker when the battery gets to around 50% capacity and the voltage has dropped to around 11.9 - 12.0 at this stage we stop using that battery. It is just a fortunate coincidence that my LCD TV does this but it is very handy since using a battery to below 50% capacity does not do it a lot of good.

Mike
 

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Hi Spykal

11.9 or 12v is very flat, the range is over about 1 volt ie if 12.8 is fully charged 11.8 is palookaville ,, 12.3 to 12.4 is about as low as you want to go, only thing thats preventing your battery dying at mo is the good charger you are using.

12.3 TO 12.4 is the rested voltage, that would equate to 12.1 to 12.2 under TV type load.

The cut outs on virtually everything that I have tested so far are way to low to save the battery.
 

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I have fitted a second battery in the locker next to where the main is located. I did consider fitting it as an additional one to us just for entertainment but in the end fitted it with one of 'Spykal's' plugs and sockets.

On my last trip away turned the charger off, I can do that because I have fitted a separate fuse, and just ran on the batteries. At the end of four days voltage was 12.9v, I measured it from a 12v socket.

I expect I shall wire the extra battery in permanently. When I fitted it I also fitted a connector for the CTEK 3600, because I believe this so much better at preventing sulphation, and in fact rejuvenates the battery. (Must plug myself in some time) When I arrive back from trips now I always do a charge with the CTEK.

The other thing, copied from Spykal, is I have made a lead to go in the cab cigarette lighter socket to charge the cab battery from the CTEK.

It all works well and gives me a versatile system in this area.

John 8)
 

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Rest In Peace Mike, 1944-2017.
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Hi George

The voltages I quoted were at the stage that the TV Starts to complain and under the load of the TV and freeview box. After resting the battery does come back up to a rested voltage of 12.04/05 indicating that the battery is around 40-50%. The only thing I have not done is check the specific gravity of the electrolyte to get a better idea of the battery condition. The battery I use for the TV is an ordinary vehicle type Lead acid which pre this duty had been used for 18 monthsor so on a car so I can't be doing much wrong, it has lasted over a year now on TV duty (say 60 - 80 nights away). If I had to replace it it is still a relativly cheap way of powering the TV. I am sure I have heard you say that an ordinary Lead acid battery is hard to beat, I agree.

mike
 

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Discussion Starter · #13 ·
This thread has thrown up some interesting points . The thing that now concerns me is how to easily / cheaply measure the battery voltage so that I'm not caning it too much
 

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Rest In Peace Mike, 1944-2017.
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Hi Mike
Get yourself a digital voltmeter:

http://www.maplin.co.uk/module.aspx?ModuleNo=37279&doy=
Maplins do them for £4.99 or often on a special at £2.99.

Then use a voltage chart to check your battery, the voltages only give an indication of the condition but over a period of time/use you will get an idea of how the battery is doing.



If you have the normal "two flat pin type"12 volt connectors in your van you can push the probes of the digital voltmeter directly into these to check the leisure battery.

Please do not try to use a meter to test any mains electricity (240 volt AC) unless you feel qualified to do so.

You can find lots of useful info on the web about how to use a meter...one place to start:
http://www.doctronics.co.uk/meter.htm#digital

Mike
 

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Hi Mike

That chart is for foriegn climes, the electrolyte is altered to account for Higher ambient temperatures. and hence the top line figure is lower.

In the UK a standard Lead acid will be about 12.8 when fully charged, Knock off 10% of charge per 0.1v pretty much as per chart, but with higher starting point.

Only problem with this system is that the voltages should be measured after the battery as sat without charge or discharge for 12 Hours, BUT it will be fairly good if the load isnt high ie say your TV is drawing 3 amps or less, when switched off for 10 mins the reading will be near enough.

What I find with most "auto Cut off's" is that they are way to low to help save the battery
 

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Rest In Peace Mike, 1944-2017.
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GeorgeTelford said:
"snipped" Hi Mike

That chart is for foriegn climes, the electrolyte is altered to account for Higher ambient temperatures. and hence the top line figure is lower.

What I find with most "auto Cut off's" is that they are way to low to help save the battery
Hi George

Re the figures on the chart ...you may well be right but I have posted this chart as a help to anyone wanting a rough guide to the state of the battery. It has helped me over the last couple of years to come to an understanding of my battery set up and my usage of them. What I suggest is, if anyone is interested in understanding the relationship between the capacity of the battery and its usage then get a meter and work with a voltage chart. Since my batteries are rarely "at rest" for long enough to test as you suggest ...we do use the van a lot so they are either on charge/maintenance or in use most of the time so a pinch of salt has to be taken with my voltage measurements...never the less the use of a digital voltage meter and my chart or your figures or in fact an old scrap pad just to record voltages will give anyone a better understanding of how the battery behaves.

Re the auto cut off: when I bought the Maplin battery Protector that I have I too was worried about what appeared to be a really low cut off voltage. So during a week back in the winter when we were at home I tested it under the conditions I would use it. I connected the TV via the cigar lighter socket to the vehicle battery. It worked just fine cutting off the power to the TV eventually after many hours use. Then without waiting for the battery to stabilise I was able to start the van. I started it several times just to make sure. After a little rest the battery....according to the battery voltage chart, was well within the safe area of the chart. If anyone else wants to use one of these devices I recommend testing it for themselves before using it when camping.

I think when talking about 12 volt power we have to remember that folks vans come in many different sizes, a small camper van with just the one battery to power the vehicle and the habitation should not be compared to a big A Class with a battery bank of several 120 amp/hr batteries. Sometimes batteries will get abused...maybe either through a lack of understanding or just necessity.

I do try to look after my batteries but even so, knowingly I do occasionally abuse them. As I see it they are a "consumable" item and although sensible usage and proper charging can prolong the battery life they still have a finite lifespan. I cant comment on any of the expensive "fancy" batteries but the humble "ordinary" lead acid battery is very good value for money and can and should be replaced cheaply before problems arise.

Mike
 

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Hi Mike, (Spykal) the system and things you use more or less mirror mine as you know, it all seems very straight forward to me to use your chart and a multimeter if necessary. Like you I have one just for the caravan. Which I tend to use probably too much.

I think it is important for Mike and others to realise that what we have put in our posts on this thread is practical, as is, and not theory, which can at times be slightly different when talking about voltages etc.

John 8)
 
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