Choosing the best leisure battery

[Lonesome-Whizkid]

I've just finished reading an article on leisure batteries and feel the need to ask a few questions regarding them. Since im learning, I may get things wrong from time to time.

Ok, First Question?. Are starter batteries designed to be charged very quickly and deep cycle batteries designed to be trickle charged over a length of time like 24 hours?

Second Question?. Does anyone use two 6 volt traction batteries connected in series as it's supposed to be a good combination and i also see you can buy them as large as 225Ah, Would that be right? Would that 225Ah be for one or two batteries?

Third Question?. Can someone please explain to me the difference in batteries connected in series and connected in parallel?

Fourth Question?. Why are leisure batteries so expensive, I've got a chart in front of me here and they start from 84 pounds and go to 440 pounds and being advised to get the biggest you can as it prolonges the life of the battery by only discharging it to 50% and even lasting longer if limiting discharging to 20%?

Fifth Question?. Tipically, How long would one expect to get from a life expectancy of a battery? 3 to 5 years if cared for??? :silly:

Sixth Question?. What does it mean when refering to a battery charge at 70 cycles or 700 cycles? What is a cycle???

Sorry for so many questions.

 

[Gozza]

For questions one and two, there will be others much cleverer than me along soon!
Three - If you wire the two battery positives together, and the two battery negatives together, you will have effectively one battery with higher capacity, this is parallel. e.g. if you wire two 6v, 100 Ah batteries this way, you will have one 6v 200Ah battery (approximately). NEVER do this with batteries of different voltages!
If you wire the two batteries with the negative of one to the positive of the other, then use the pos and neg terminals which you haven't connected, to connect to the circuit, this is series and will give you the equivalent of one battery with the voltages added together - e.g. two six volt 100AH batteries in series give you one 12v 100AH battery. NEVER do this with batteries of different capacities!

Question 4: I've never heard that advice, but as soon as you start staying on "no mains electric" sites you'll need more capacity than you think, so do consider that. As with everything else in life, the cheap ones have been made with cheap materials and won't be very good, the most expensive ones will probably be overpriced for what they are.

Question 5: three to five is probably a good guess but it depends how well you follow the manufacturers instructions for care of them.

Question 6: A cycle is a discharge followed by a recharge of the battery, and is a measure of how old the battery is and how much use it's had. Older batteries will have lost some of the capacity they had when new, even if well cared for, so a batt that's done 700 cycles will probably have very little capacity left, compared to one that's done 7 or 70.

Don't worry about asking lots of questions - that's how we learn, and everyone one the fori=um once knew nothing at all!

 

[paws]

Gozza says" cleverer people will be along soon ...for Q 1 and 2."
Well I'm not clever but I'll give you a rough steer on them...

1 Starter batteries are designed to start engines....(where a high load but for a short time needs to be delivered). The starter battery is then (usually) immediately recharged by the engine's generator (on a car that's usually the alternator) The alternator will provide a high rate of charge, initially, but this will rapidly "tail off" as the battery is recharged. The charging voltage will often be around 14.4v the current (amps) can be initially quite high sometimes around 50 amps or more, but rapidly reduces eventually to just a trickle.

2 Traction batteries (don't even go there!) They are not suitable for caravans (far too heavy) unless used by an expert for a specialised purpose. It is most unusual to have two 6 volt batteries coupled in series, on a caravan as 12v batteries are generally more suitable, cheaper and readily available.

225 Ah is a huge capacity..... (about twice the maximum capacity that most folks use on their caravans)
The weight of such a beast would be considerable, and its size far too big to fit into the average size caravan's battery locker.
( look up the size and weight of such a beast and then compare this with the "payload" that your caravan provides... there wouldn't be much weight allowance left in your payload, for even a small bottle of beer!)
All the best
Regards
paws

 

[ProfJohnL]

Hello Whizz,

As you have discovered there are several different type of batteries, and choosing the right one relies on understanding on how you need it for.

I think its easier to deal with your questions in a different order to the way you have presented them, as some points feed into other answers.

As a general points all types of rechargeable batteries will wear out over time. Each type of battery has different characteristics So its important to read the manufacturers information on how to use, charge and store them to maximise their useful working life.

There are many different ways to describe the life characteristics of rechargeable batteries, but some manufactures or standards use the multiple cycle method you ask about in Q6. Wikipedia tell us:

"A charge cycle is the process of charging a rechargeable battery and discharging it as required into a load."

So as a battery ages its abilities to be fully recharged and to deliver the current to a load will deteriorate. By checking its performance at the 70th and 700th charge cycle, a life span characteristic can be described for the type of battery. A the performance of a poor quality battery will deteriorate more quickly.

Q1 Starter batteries can recharged quickly, and that tends to happen because as soon as the engine is running, the alternator provides power to recharge the battery. It happens that starter batteries deteriorate faster if they are left discharged. Leisure batteries can also be recharged quickly (not quite as quick as starter batteries) but they are more tolerant of being used over long periods and being charged at a slower rate. Trickle charging is an option provided its through a smart charger.

Q2 You could use two 6V batteries connected in series to give 12V, however whether traction batteries are a realistic proposition in a caravan I am not certain. Traction batteries are bigger and heavier than the equivalent capacity of leisure battery. The extra weight will eat into the available payload in the caravan, also they are designed for industrial uses and may not have the gas-off venting systems you should have in a caravan.

Q3 Gozza has coverd this point

Q4 Let me ask you a question, Would you expect your car to last longer if you drove it with your foot to the floor all the time or if you were more gentle on the throttle? I hope you expect better life if you're gentle. The same applies to the chemicals in the batteries. Use them at full whack all the time, and they will deteriorate quicker. So a big battery will be less stressed than a small one for the same job.
Why do prices of everything vary? Its the way supply and demand operates, small niche products cost more to produce than mass market products. Not all batteries are made exactly the same, some will use better components and chemicals than others, Some will have certain special features, and that usually cost more. Branded goods usually carry a premium price (look at designer clothes!)

Q5 If you look after the battery properly then 5yrs should be easily achievable, but as you may have gathered from the previous points it does depend on getting the right battery type, and taking care of it. Some people I know have had over 7 years, and they claim the battery is still fine. but others I have know have had only 1 year because they didn't look after it.

 

[JTQ]

My view on selected question:
Ok, First Question?. Are starter batteries designed to be charged very quickly and deep cycle batteries designed to be trickle charged over a length of time like 24 hours?
A: “starter” batteries have to be suitable for quite fast recharging, it is the nature of the task they are there for. The technology needed for deep cycling batteries can mean they are damage by fast charging; in certain cases dramatically. There is a large ground of products in between. Marine batteries are often required to both start engines and serve “hotel” loads over prolonged periods, so are a compromise product in that centre ground.

Second Question?. Does anyone use two 6 volt traction batteries connected in series as it's supposed to be a good combination and i also see you can buy them as large as 225Ah, Would that be right? Would that 225Ah be for one or two batteries?
A: I for many years used a 12 volt Varta “traction” battery in my caravan, superb unit for our needs but very expensive and heavy for its capacity rating. Unless your usage needs its special features it is not cost effective.

Fourth Question?. Why are leisure batteries so expensive, I've got a chart in front of me here and they start from 84 pounds and go to 440 pounds and being advised to get the biggest you can as it prolonges the life of the battery by only discharging it to 50% and even lasting longer if limiting discharging to 20%?
A: Real ones are expensive because they need a lot of lead, to create strong twist resisting grids, to take the densely packed lead pastes and tight dividers. Plus, they are specialist products. You are in territory where quality costs, but remember it is also a high margin business so you need to purchase at the best discount; most unlikely a reseller like a caravan accessory outlet.
What you are buying is the ability to take deeper levels of discharge without as much damage as with cheaper technology products. So you need to ask,” do you need that ability?”; if only creaming off 20% between charges then a cheaper technology, ie starter battery will do.
Your understanding that minimum discharging prolongs life is exactly right, just some cope better than others.

Fifth Question?. Tipically, How long would one expect to get from a life expectancy of a battery? 3 to 5 years if cared for???
A: 5 years is easily obtainable in our type of use, but to do so, it is paramount to “promptly”, but at moderate rates, recharge after using it. Leaving them discharged is a killer with both depth of discharge and duration of not being fully charge powerful influences. Quality for purpose also comes into it.

 

[bertieboy1]

The reason 6 volt batteries have a higher Ah rating is that at 6 volts the current taken by a load is double that taken by a 12 volt battery.
eg. 12watt bulb - at 12 volts current = 12W/12V = 1amp. at 6 volts current = 12W/6V = 2 amps.
My first car was a volkswagon beetle and it had a 6 volt battery rated at somewhere around 80Ah.

 

[ProfJohnL]

The reason 6 volt batteries have a higher Ah rating is that at 6 volts the current taken by a load is double that taken by a 12 volt battery.
eg. 12watt bulb - at 12 volts current = 12W/12V = 1amp. at 6 volts current = 12W/6V = 2 amps.
My first car was a volkswagon beetle and it had a 6 volt battery rated at somewhere around 80Ah.

Hello Berti

I understand what you are trying to say, but you've got slightly mixed up with your terminology.

The Ah (Amp/Hour) rating is a fixed quantity rating relating to the total charge capacity of a battery. It is not affected by the load you apply it. The load determines the rate at which capacity will be will be used up.

Most lead acid batteries are constructed from multiple cells usually rated at 2V each, and each cell will have its own Ah charge capacity. If we were to assume each cell had a capacity of 10Ah, you could connect 6 cells up all in series to give 12V and then add the cell Ah capacities together to get 60Ah. You could take 3 cells and connected them to give 6V but you would only have 30Ah capacity. However if you did the same with the 3 remaining cells then connected the two banks in parallel you would still have 6V but will have increased the capacity to 60Ah. So size for size batteries will retain the same Ah capacity regardless of how they are internally connected.

Your example of the bulb is ambiguous. You should have made it clear the it wasn't the same bulb being used on 12 and 6V, but different bulbs each rated at 12W but designed for 12V and 6V respectively.

 

[Lonesome-Whizkid]

I never did pay attention in physics class. really wished I had now as it's actually easy enough to understand.

 

[Lonesome-Whizkid]

So let me get this right, Batteries connected in parallel doubles the voltage and batteries connected in series doubles the ampers? Is that right or is it vice versa?

 

[WoodlandsCamper]

vice versa hmy:

 

[Damian]

Two in parallel give same voltage but more A/Hours. IE 12/100 + 12/100 =12/200
Two in series gives double the voltage but same A/H rating.iE, 12/100 +12/100 = 24/100
BUT,the two batteries MUST be exactly the same

 

[Lonesome-Whizkid]

So, I've not to concern myself with batteries connected in series unless its 2 X 6 volt batteries?

And to connect two batteries in parallel its negative to negative and positive to positive? With an earth on the chassis?

Can I ask, What is the purpose of joining two leisure batteries together in parallel if say there both 12 volt 110AH.? Once there linked together will they be charged together aswell.?

 

[colin-yorkshire]

hi, LW,
1. is correct.
2, yes, but several considerations have to be borne in mind ie, weight, location of extra battery assuming there is only one battery box, length/size of connecting wires and how the connections are to be made ie, first battery connected to van electrics, and second as extra capacity (like a spur) or earth to first battery power take off from second one,
personally I have no idea why one would go to all that trouble when the means of recharging one battery are so elementary and simple to achieve,
3. yes of course they would however as the total capacity is now doubled they would take twice as long to charge up.

 

[Wilbury]

Hi,
Do not forget that with batteries in parallel unless the electrical and mechanical characteristics are identical thay will not charge or discharge at the same rates which means that you may end up having to charge them individually.
Rgds

 

[WoodlandsCamper]

There's no sense in having 2 batteries connected together in a caravan. If you are off-grid then have 2 and use them one at a time (hopefully charging the unused one somewhere whilst the other is in use). Sites without hookup quite often provide battery charging facilities.

 

[Lonesome-Whizkid]

Ok, thanks.

 

[Len_Cuff]

Ok so I've a battery advertised at 110 (actually apparently 96) and it has performed fine - so far. As you only use it once before if recharges either by towing or electric it works fine.

 

[ChrisUK]

our Numax 110AHr has done 6 seasons, each of which included a 2 month stay Off EHU using a solar panel. This weekend we are off on another 2 month stay and hopefully the battery will still be OK.

When not caravanning it is kept in the garage with a CTEK charger connected which probably helps with battery life. I am aware it will not last for ever, but being mean I keep pushing it (my luck that is!).