Leisure batteries - 1 large or 2 small?

[Lucky]

With only a fortnight or so before my new 2020 Fiat PVC arrives at the dealer I'm trying to narrow down my options for upgrading the electrics. When it comes to batteries I want to increase the usable storage capacity from a single 95AGM and envisage going for Gel - the dealer will take the standard AGM in part exchange.

My questions are, space permitting:

• is it better to choose a pair of batteries or one larger one?

• if a pair, do they need to be matched in capacity or can I 'squeeze' in whatever fits?

Other info if required - the PVC comes with a condenser fridge and so is electric hungry, I want to be off grid as much as possible, I have a Honda gennie if required (boo hiss), I will be maximising solar, adding a B2B, and currently don't know the make or spec of any other electrical components that are fitted.

Thanks all.

 

[Carolyn and Kev]

Personally...fit two. If one goes down at least you can get by on one! Secondly...Fridges are all 12v greedy full stop! (Odd when you think of putting a Exclamation mark after the words Full stop! Oh dear...
If you need to be off grid then solar and or a 'Genny' is the way. I know folks will hiss and boo at the 'Genny' idea but it works. The quieter the better obviously. Inverter will be a big help ...but make sure you get the correct one and that your first idea of 2 Leisure batteries are quality ones and with a good output.
There are others on here who are "Owls" when it comes to this stuff...Wise ones that is. Listen and take note of their words of wisdom...we are all learning all of the time!

Kev

 

[Jev88]

If you go for two they need to match.
Also consider 2x6V wired to produce 12V. More AH than 12V batteries it appears. Trojan t105 for example

 

[68c]

Why buy a van with a compressor fridge if you want to be off grid?

 

[Lucky]

Why buy a van with a compressor fridge if you want to be off grid?

The compressor fridge isn't by choice, but the van in question was the best compromise I found to meet my requirements. I'm now trying to address the weaknesses.

Any constructive contributions are welcome.

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[pappajohn]

If you go for a pair they don't have to be the same ah/physical size.
Your charging system, no matter if its mains charger, solar or B2B only sees it as one big battery with a combined ah rating.... IE: a 95ah plus a 110ah will be seen as a 205ah battery.
Only stipulation, they must be the same age (or very similar), voltage and type. (lead acid, GEL or AGM)

 

[Lucky]

Thanks, very helpful.

 

[Lucky]

So, two small or one large battery will charge at the same rate?

 

[pappajohn]

So, two small or one large battery will charge at the same rate?

They will charge just the same but obviously the larger the battery bank the longer to charge.
The smaller will only take what power it needs, the power will then continue to charge the larger until that too is charged.

 

[cmcardle75]

Why buy a van with a compressor fridge if you want to be off grid?

Because with enough solar and driving with a B2B charger, you can keep it going indefinitely and don't need to keep refilling your gas. It also enables you to put the fridge in a convenient place, which might not happen to be on an outside wall, nowhere near an opening window.

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[Minxy]

Why buy a van with a compressor fridge if you want to be off grid?

It is getting to be pretty standard for PVC converters to fit them now, much cheaper and also a lot easier to install as there's no gas to mess about piping to it, no external vents to cut into the side of the van etc, and thus it can be put anywhere.

 

[Minxy]

Hi Lucky, where is the existing battery? If it's under one of the cab seats you may be able to get another one of the same size in there with it to save having to find a 'home' for it, however you are unlikely to be able to go any bigger in capacity than is already fitted as you need to bear in mind not only the width and depth but the height.

As for your existing AGM, don't let the dealer px it as they'll give very little for it and charge you a packet for the replacement gels, better to wait until you get your van and then make your final decision when you can check out what will fit where as well as what the electrics will charge.

 

[Lenny HB]

I would go fo two batteries but it's not critical.
If its a Euro 6d engine it will have a B2B as it will have a smart alternator

 

[Lucky]

Understood, thanks.

Btw, is there a market for second hand but not used (if you get my understanding) AGM batteries or am I looking at giving it away to a deserving Funster ?

 

[Minxy]

Some people will definitely want your AGM battery to go with their existing one so you should be able to get a good chunk of dosh for it, just check what the cheapest price is for it online etc and do a discount for a funster, that way you both benefit.

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[cmcardle75]

So, two small or one large battery will charge at the same rate?

Assuming that they are connected by large enough cables, they will remain at approximately the same state of charge as each other. If the cables are too thin or long, you may find the battery remote from the connection to the charger charges more slowly than the other. If possible, this should be avoided using short, thick cables.

If the batteries are in a different state of repair, it is possible for the better battery to be damaged by the failing battery. By the time you notice a problem, both batteries may be shot.

 

[Millcourt]

You did not mention the make/model of your new MoHO, but you may find it helpful to have a look at a report I posted last year.......

Campscout……. First 10 weeks, plus recent Lifos/Inverter addition

Campscout……. First 10 weeks, plus recent Lifos/Inverter addition...….. In 2017 we bought a 2-year old Autocruise Accent, which had been little used (less than 3000 miles and as new internally) and enjoyed a number of trips in this. We had opted for a PVC for the small footprint and relative...

www.motorhomefun.co.uk

I took delivery of a new Globecar Campscout last July and this also came with a compressor-only fridge. Previously we have had 3-way fridges and have found that the one we have now cools much more rapidly and we have been happy with it. However, I was also concerned about power consumption and wanted an inverter for Mrs M's hair dryer and tongs. After careful measuring, I found we could fit 2 Lifos lithium batteries and an inverter under the driver's seat where the original Varta battery had been installed. Not only did this effectively double the available battery capacity, it also reduced the weight. Not the cheapest option, but with 250 watts of solar panel, we have found this to meet our need for extensive periods off-grid.

Since posting the report mentioned, I have also fitted a Schaudt B2B unit.

If you would find it helpful to speak about what I have done, please PM me and we can get in touch.

Best wishes for much enjoyment of your new PVC MoHo.

 

[Just smiffy]

I would get as many and as big as payload and space will allow...

 

[Lucky]

To summarise my understanding:

• there's little or no benefit from opting for one large battery instead of two smaller ones;

• if size dictates I can fit a mix of differing Ah batteries to optimise capacity, with no adverse effects;

• be mindful of battery height as well as length/depth when choosing where to place them;

• specify thick cables and minimise cable length;

• check how much the dealer is allowing me in part exchange for the battery supplied with the vehicle as standard - it may be considerably less than I could sell it for privately;

• moreover shop around for the best deal rather than my default behaviour of using the PVC dealer;

• as the van is a Euro 6 2020 model it might (will?) come already with a B2B - so don't buy one in advance of collection!

•.investigate 6V and lithium batteries as an alternative (although I suspect these might be more expensive solutions).

Thanks all

 

[Campervan_man]

2 matched and linked.
Some BIG batteries are a 'bit heavy' { understatement }.

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[nicholsong]

If you go for two they need to match.
Also consider 2x6V wired to produce 12V. More AH than 12V batteries it appears. Trojan t105 for example

That is true but check dimensions - they are often tall.

Also if one cell goes kaput the other 6v is no good for a 12v system.

Geoff

 

[TCG]

Have you thought of lithium batteries

 

[Lucky]

Broken Link Removed

You did not mention the make/model of your new MoHO, but you may find it helpful to have a look at a report I posted last year.......

Campscout……. First 10 weeks, plus recent Lifos/Inverter addition

Campscout……. First 10 weeks, plus recent Lifos/Inverter addition...….. In 2017 we bought a 2-year old Autocruise Accent, which had been little used (less than 3000 miles and as new internally) and enjoyed a number of trips in this. We had opted for a PVC for the small footprint and relative...

www.motorhomefun.co.uk

That's a very good read, thanks for highlighting it. I can see how your circumstances took you in the direction of Lithium. Personally I don't require an invertor so don't need to save space under the passenger seat, nor will I be constrained by payload when I update the GVM on the Maxi chassis, so I'm still in the Gel camp at the moment. Plenty more research to do before committing though

 

[autorouter]

Also consider 2x6V wired to produce 12V. More AH than 12V batteries it appears.

Don't be misled by the apparent Ah capacity, it's the Ah capacity at 6 volts. A 200Ah 6V battery in series with another 200Ah 6V battery results in a 12V battery bank with a capacity of 200Ah.

It will be approximately the same size and weight as two 100Ah 12V batteries in parallel, which will also have a capacity of 200Ah total.

 

[Lucky]

Useful to know, thanks

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