# What's best battery setup... 2 small or 1 large?



## Bazbro (May 9, 2005)

So... taking all things into consideration and batteries of similar quality and configuration, what is best - 1 large battery or 2 smaller ones; say, 1x 160ah battery versus 2x 80ah batteries?


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## listerdiesel (Aug 3, 2012)

If they are identical 80AH batteries in parallel, then marginally you'd be better off in performance with 1 X 160AH, as two in parallel rarely give the same performance as when singled up.

Usually, the choice is driven by space considerations more than anything else.

Industrially, batteries aren't parallelled that much, and if they are there tends to be steering diodes for discharge and charge current paths.

I'd go for the single.

Peter


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## Penquin (Oct 15, 2007)

In our case it has to be the two small as there is not enough space for one large - they fit under the driver's and passenger's seats and can only be a certain size - we had to search hard to find the best replacements and found

http://www.tayna.co.uk/Leisure-Batteries-C45.html

to be excellent; ordered two after discussing our needs on late Tuesday morning, arrived by courier here in France before lunch Thursday - outstanding service IMO.

Dave


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## andrewball1000 (Oct 16, 2009)

Barry, I prefer two separated by a mechanical switch (1,2, both, off). Gives you more variations on charging and use. Also when one is flat you can switch to the other.


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## raynipper (Aug 4, 2008)

I'm no expert here but most up market RVs stateside use 4 or 6 golf cart Trojan 6 volt batteries for the leisure side.

Ray.


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## airstream (Jan 7, 2009)

*6 volt*

Hi,
2x6volt "genuine" deep cycle ie Trojan, US Battery, Rolls
Buy em once look after them and they will last for ever 
Ray


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## nicholsong (May 26, 2009)

Ray(airstream)

I have been considering 2X6v traction/deep-cycle and have just looked at Trojan website and was bit confused by their designations.

I want 2x6V to give 220AH, in our terminology - please what is their equivalent? It has to be wet cell because I use a Sterling B2B charger.

Also Trojan do not have a dealer in Poland so are there other equivalent manufacturers I could look at?

Thanks in advance.

Geoff


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## teemyob (Nov 22, 2005)

*traction*

I too like the idea of Traction batteries. But the problems is how to vent them as they do not have central vents like some Varta semi traction for example.

I think you can get batteries delivered from tayna to Europe.


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## nicholsong (May 26, 2009)

Trev, thanks

When you say no 'central vent' do you just mean that each filler cap is vented or there is no vent (surely there must be venting)? One could still vent the battery 'box' - sole-use underfloor compartment in my case.

Tanya do not seem to offer traction batteries.

Geoff


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## airstream (Jan 7, 2009)

*trojan etc*

Hi Geoff,

I vent my Trojans using the sealed battery box etc

These are what I have in my van

http://www.batterymegastore.co.uk/product/TE35/

Trojan are the one of the biggest suppliers of golf cart batteries in the world so I am surprised that they are not in Poland

As this type of battery is used on boats and Poland has a large boat building industry it may be a place to start

Trojan, US battery and Rolls all make a similar battery range

Good Luck

Ray


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## teemyob (Nov 22, 2005)

*vent*



nicholsong said:


> Trev, thanks
> 
> When you say no 'central vent' do you just mean that each filler cap is vented or there is no vent (surely there must be venting)? One could still vent the battery 'box' - sole-use underfloor compartment in my case.
> 
> ...


Sorry, Yes they are vented from the caps.

By central vent, I mean that the Varta Semi traction is vented from the side and you can fit a tube that then runs out under the vehicle habitation area.

http://www.tayna.co.uk/Trojan-Batteries-6-Volt-S1188-1.html

http://www.tayna.co.uk/US-Deep-Cycle-Monobloc-Batteries-C100.html


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## teemyob (Nov 22, 2005)

*http://www.motorhomefacts.com/ftopict-131950-tayna.html*



nicholsong said:


> Ray(airstream)
> 
> I have been considering 2X6v traction/deep-cycle and have just looked at Trojan website and was bit confused by their designations.
> 
> ...


An Experience of International Shipping from Tayna


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## airstream (Jan 7, 2009)

*Banner?*

Hi again Geoff,

I have just noticed that the Trojan distributor in the Czech Republic is Banner Batteries who are also in Poland?

Ray


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## nicholsong (May 26, 2009)

Ray and Trev

Thanks for answers and links.

Ray, I had just found Banner in Poland - on Trojan's website. I had looked at 'Distributors' but they have another link 'Dealers'. The Banner address is in Katowice where I live - handy.

What were Tandy's delivery charges to France - probably a bit more to Poland?

I can get quotes from Tandy and Banner.

I am still a bit undecided whether to change mine because they are performing OK using EHU at home only and the B2B on the move. Only doubt I have is the age of the existing batteries - I have had the MH 3 years and because the previous owner only had it fr 5 months he did not know how old they are, so am wary to go on long trip. I tried to get them drop-tested in UK in Spring but all the workshops said they are not allowed to use them now. Maybe I can try here.

Geoff


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## teemyob (Nov 22, 2005)

*assume*

I assume there will be no problem charging 2 x 6v from a 12v charger?

TM


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## nicholsong (May 26, 2009)

*Re: assume*



teemyob said:


> I assume there will be no problem charging 2 x 6v from a 12v charger?
> 
> TM


Trev

Cannot see why there would be as when wired in series there are effectively 6 cells in a line just like a 12v battery.

Other MHF Members use 2x6v and I assume they have standard 12v chargers.

But I would like an expert to confirm that before I bought them.

Geoff


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## listerdiesel (Aug 3, 2012)

At that level, 2 X 6V wouldn't be a problem.

It's when you get into long strings of cells or batteries that you start to get cell/battery balancing issues.

Peter


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## airstream (Jan 7, 2009)

*Charge*

Hi Geoff,

!2 volt charger is all thats required - standard charger you can charge up to 13% ish of ah @ c20 rating or advanced 3 stage type charger 20% is fine

I use a marine 3 stage charger on my 245ah battery

If alone and on gen set I charge at around 40amps max - I can go to 50 amps if required (my charger is adjustable) but as I never drop below 50% depth of discharge I really dont need the higher charge rate but it does keep the gen set running time down

If on hook up I restrict the charge to around 10 amps as no need to rush things and if, as in some areas of Europe hook up has restricted amps I can reduce as required

Regards Ray


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## nicholsong (May 26, 2009)

Peter

Thanks for that.

Out of interest why are these traction batteries 6v ?

Geoff


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## listerdiesel (Aug 3, 2012)

nicholsong said:


> Peter
> 
> Thanks for that.
> 
> ...


They are not true traction batteries per se, but probably for use in small pedestrian-controlled sweepers and things like that.

A true traction battery has discrete 2V cells which can be swapped out if they fail, or in the case of Nicads they will be 1.2V per cell.

There is an issue with using traction batteries, in that they need to be gassed every now and then to stir the electrolyte, more as a result of topping up than actual usage.

Traction chargers are pretty crude affairs, for years they just whacked a charge into the battery on a timed basis, regardless of the state of the battery at the start of charge. This meant that gallons of water was broken down into hydrogen and oxygen, and topping up became a weekly ritual.

Nowadays things are a little bit better, but we don't sell into the traction market, we only do controlled chargers for things like railways and utilities. If you screw up on charging a Turbostar carriage, there's a few hundred thousand pounds worth of electronics in there to destroy.

Here is a battery tray off a typical carriage, 110V for the on-board systems and 24V for the engine starting:










These are all Nicad cells.

Peter


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## nicholsong (May 26, 2009)

Peter

Thanks, I am learning a lot today.

Geoff


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## listerdiesel (Aug 3, 2012)

Like many subjects, Batteries are very wide-ranging and are used across many industries.

Our main products are high-output chargers for the railways and utilities, a typical charger for a train would be 110V 50A DC output for those like the InterCity 125 and similar, 110V 200A for Virgin Voyager shore supplies or 29V 100A or 200A for DMU's.

In all cases, the voltage quoted is the actual charger output voltage.

We don't do consumer electronics, I even have to buy my own charger!

Peter


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## coppo (May 27, 2009)

We have x2 6volt Rolls(6FS 220), wonderful batteries, use 280w of solar, Dometic Tec 29 and a Sterling B2B to charge.Never used hook and lived in it all winter.

Normal 12v van charger is fine.

Paul.


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