Two batteries or one with solar panel

Budgie

Budgie

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Hi all I bought our van from new in 2015 after a month I got another banner leisure lead acid battery which matched what was already in situ and wired up in parallel, a year later I fitted 120w solar panel, all ok until a couple of months ago when one of the batteries packed up followed by the other a month later, so just over 4 years use, we rarely use hookup when using the van only when parked up at home.
After looking online some people are saying it's best to have double the solar power for whatever batteries are fitted ie , I had 2 x 110w =220w so should have solar panels of at least 440w, as I do not have room for more solar I'm thinking maybe it may be best to just have one battery then the 120 panel will be able to keep it charged up more, and therefore last longer and also save the expense of another battery.
Any advice from the experts on here will be very much appreciated.
 
Interesting what you have read there about the solar. The general rule of thumb I am familiar with and tend to work to is 1W of Panel to 1Ah of Battery - so 2 x 110Ah of Battery (assuming you mean that when you said 2 x 110W) would lead to around 220W of Solar.
Not a hard and fast rule by any means and the mix of Batteries and Solar more depends on your type of touring (move every day? stay put for a few days?) and the time of year (Summer Holidaying only? 4 season camper?) and your usage.

You could well find that your batteries get topped up well before midday in the summer even with the 1Ah=1W "rule" let alone "1Ah=2W" idea. (In my last van I had 2x 110Ah batteries, 2 x 100W panels and I was trying to think of ways to use the 'wasted' energy I could not use from the solar panels as my batteries were full by around 1PM each day).
 
The right size for a solar panel and for your battery bank depends on how much power you use.

If you use about 12Ah of power (that's 12A for an hour, or 0.5A for 24 hours, or some mixture of the two) you will want a solar panel that produces 16Ah each day to replace it (lead acid batteries are only about 75% efficient).

On average, in the UK, you can expect 3 hours "sunshine equivalent": more in Summer, less in Winter.

So you are looking for enough panels to produce 16Ah in 3 hours, which means about 5A or 60 watts. As it happens, that's about the typical output of a 100 watt panel fitted flat on the roof.

The size of battery you need depends on how long you will be using that 12Ah of power each day when it is cloudy weather. If you need to be able to go five days without sun, you need 60Ah of usable power in your batteries. So you will need somewhere between 120Ah and 150Ah of battery. This is because you never want to discharge the battery below 50% full, and the batteries will lose capacity as they age.

Of course, none of this is much help if you don't know how much power you need. But you could work backwards, working from how long your batteries last without being topped up.
 
Mine over eight years old,two 90ah with 200w solar,just remember it does not mater if you have a 1000w of panels as when you require power norm at night you will be running from the batts as no sun shine,so in effect tot up what you burn then you will know what size of batt bank you require.
 
I have 2 110 amp batteries topped up with a 100 watt solar panel batteries are 6years old seems to work well and engine when running not much lately I might add campervan
 
I too would suggest reviewing your consumption to consider size of batteries and solar panels.
Banner leisure batteries aren't maintenance free and electolyte should be checked regularly.
There's been a lot of advances in battery technology in the last few years and I'd advise a lot of research and have plenty of salt on hand when reading the NCC tables!
If you have the roof space it may be worth considering another panel if it doesn't overload your regulator.
 
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