Information on battery types and charging capabilities.
The following information is
kindly supplied by Sterling Power who have carried out extensive research
in to batteries and their suitability to various charging systems. The
following information is well worth taking the time to read as it will
help you choose your next battery and dispel any myths you may have heard
Frequently Asked Questions
On this page we
(Sterling) display questions that are asked of us; we hope that you
find this page useful. For any queries that may not be listed on this page,
please do not hesitate to contact us.
We are always
being asked: which is the best battery? We refer to marine or vehicle
auxiliary charging batteries
or domestic batteries. There is a lot of confusing literature about
this subject. The information in
the literature tends to be correct, but it's the parts which are not in
the literature, and the customers' assumptions that cause the confusion
and hence the problem. We will try to answer the question. In order
to save you time , we suggest you adopt the following attitude, and make
the person selling you these products answer the question below.
The key question:
I went on to the web and obtained 3 different battery type prices, these
were the first prices I came to and have no reflection on any company,
I was looking for about a 100 amp hr battery
100 amp hr leisure. normal open lead acid ( so called leisure ) £49.99
100 amp hr A.G.M = £ 175
100 amp hr Gel = £265.59
So in our mind the A.G.M. is about 3 times more expensive than the
standard one. And the gel is about 5 times more. So the question is, if
these batteries are 3-5 times more expensive than the standard one, what
do they do that is 3-5 times better? Do they last 3-5 times longer ?
Do they charge 3-5 times faster to reduce your engine running hours ?
Rather than ask us these questions, please ask the sales man, who is trying
sell this stuff for cycling, exactly what you are getting that is 3-5 times
better than standard lead acid batteries.
The brutal truth about marine leisure batteries.
1)There is no such thing as a marine battery. If you see a marine label
on a battery it is simply words and may as well say Mickey Mouse.
2)For cost and performance: Open lead acid batteries are the best. All
other batteries are a derivatives of this with variations to suit different
where there are specific problems implementing the standard lead acid battery.
E.g Gel is a standard lead acid battery, except that the acid has been
jellified. But by solidifying the electrolyte this introduces many problems
not associated with free flowing water based batteries.
3)“Most expensive is best.” This is not even close to being
true. In fact we would say the reverse is true in the marine leisure market.
When reading all the sales literature regarding gel/a.g.m, please note
that none of their curves and claims refer to standard lead acid batteries.
(They know better.) They never claim they have better performance than
standard open lead acid, this is an assumption on your side. They may claim
that they can stay on a shelf longer.
4)If a statement says that this is the best battery, the question is, best
at what aspect?
5)If the term 'maintenance free' is on a battery, then treat this with
caution. There is no such thing as maintenance free. All batteries are
basically the same, a gel, seal lead acid, and A G M they are only maintenance
free because of the reduced charging performance curves, and not because
there is something special about the battery. If you charge a normal lead
acid battery to the gel or A.G.M curves, then they would not require maintenance
either. Remember 'maintenance free' is a handicap to fast charging not
an advantage. This feature, which on the surface looks good, is, in most
cases the worst feature that you could possibly buy; as this feature dramatically
limits the maximum charging characteristics of the battery.
6)Fast charging costs water, i.e. if you want to charge you batteries fast,
don't touch a sealed/gel/agm etc with a barge pole. Fast charging will
result in a certain % water loss from the battery. If the battery is sealed
the water loss cannot be replaced. REMEMBER FAST CHARGING AND
FREE ARE A CONTRADICTION OF TERMS. You may not like this , but tough, it's
the way it is.
7)Watch the term leisure / deep cycle as it simply does not exist. The
standard so called leisure batteries are simply starter batteries with
extra support for the active lead material. This may increase the life
by 5-10 %, but does not turn a starter battery into a deep cycle battery.
True traction (deep cycle) are not available at a sensible price and
are uneconomical to use for standard leisure use. However, if you plan
to live onboard or travel the world, then do look at 6 v or 2 v traction
and build your battery bank up from those batteries, but expect to pay
about 3-6 times the price of so called standard leisure batteries. On a
daily use cycle, the standard so called leisure battery (which is a starter
battery) will last you as little as 6-8 months where as traction would
last 15 years. But on a leisure rating (2 weekends per month and about
4 weeks holiday) then you would get about 5-7 years out of a standard leisure.
That's if you charge it right using advanced regulators, and constant current
8)Battery sales companies quote battery cycles such as 6000 cycles for
the battery. This looks good on the surface, however it will be 6000 cycles
at say 10% discharge. This is a meaningless figure. All batteries have
a manufactures graph which, odds are, you will not see in full; as the
embarrassing section tends to end up on the advertising companies editing
floor. The graph will have % discharge on one side, and cycles on the other.
This graph is sometimes shown on glossy battery information, but is normally
censored at about 30-40% discharger where the figures can still show 4000
cycles. What they fail to show is the 100% discharge cycle
which at the end of the day is the only ultimate datum point. Whichever
battery performs the best at 100%
discharge will perform best
at 50% etc. The interesting fact is that they are all about the same.
That is because they are all basically the same battery. A gel and conventional
starter battery go down the same production line until one has a gel substance
put in it and the other liquid. The shock with this figure is that for
gel, sealed, or leisure, etc etc, the constant figure is about 30-60 cycles,
where as true traction with thicker plates is over 300 +.
It is however available from correctly specked commercial batteries.
So which is the best battery for standard domestic leisure use?
The job we are referring to is for auxiliary charging system on boats, camper
vans or vehicles. I am not getting into what each and every battery type is best
at, or for, as each type has a market, it just maybe not this market.
To pick the best battery for your job, then at least understand how they work.
Forget the actual chemical formulas and all the fancy terms around, the bottom
line is that lead acid batteries have been around since the 1st world war and
the basic principles have changed very little. The only thing we all agree on
is they are not environmentally friendly, but they are cheap to make, and they
will remain the best until such time as some one comes up with a solution which
can compete. Which by the way to date they simply have not.
So how do they work?
Let us understand the basics. They are all lead acid , but fall into 2 basic
groups. A starter battery and a traction battery (fork lift truck, true deep
Type 1 ( starter batteries ) A battery is simply a bucket of energy. If you wish
to get the energy out fast, to start a engine ( cold cranking rating ) then you
need a large surface area ( large plate size ) The only way to get a large surface
area into the bucket is to make the plates thin, so they can squeeze into the
bucket ( this is your starter battery, it needs the cold cranking kick, in order
to start the car, so its plates are thin to achieve this). This theory is pushed
even further with batteries which increase this surface area more, to make what
are known as high torque batteries. These deliver even higher cold cranking
by putting the plates in a 'swiss roll' configuration, in order to make them
thinner and increase the surface area. This is good for cold cranking, but has
a fatal flaw when it comes to fast charging. (the problem is, it works too well
when charging and destroys itself.)
Type 2 ( traction or fork lift truck batteries) batteries are not interested
in the cold cranking kick which is required for a starter battery, but are still
interested in the power in the bucket. So they can reduce their surface area
of the plates. The good thing about being able to reduce the surface area is
that you can make the plates much thicker. The end result is you still get the
same power from the bucket, it is simply delivered at a slower rate.
So for deep cycle, and long life, the traction batteries are by far and away
the best. But their price tends to kill them. However, if you are doing a long
journey round the world, or going away from the u.k. for 2 years + , then investing
in 2 volt or 6 volt traction batteries is a must, regardless of the cost, and
they will pay for themselves many times over. For general leisure use they
are the best, but a bit of a waste of money unless you want to keep the boat
for 15 years to get the use out of them.
So what's the end result of these two battery types?
A battery is made up of lead plates, with a lead paste on the plates. Every time
the battery is used, then so many bits per sq inch fall off the plates, if you
have a large surface area then a large number of bits will fall off. Then to
make maters worse your paste is thin so you cannot afford to lose the paste.
However, if you have a small surface area and thicker plates the same is true,
but the plates are thicker and as such you don't care so much. That's it in
very simplistic terms, and those are the differences between traction batteries
and starter batteries.
As you can see from the above 2 battery types, the plate configuration cannot
be blended. If for starting, you have a large surface area of thin plates, for
traction you have a small surface area of thicker plates. One is black and one
is white, there is no grey area. So if you are purchasing a battery and it has
a cold cranking rating, and the sales man says it is a deep cycle battery but
will also start your engine, then it is a starter battery.
What we want now is the best for general leisure.
Having understood the 2 x basic types then you need to ask yourself -what do
want from the battery?
Most people want:
1) to charge their batteries as fast as possible in order to reduce their engine
2)pay as little as possible for the above
3) get about 5-7 years use as a leisure battery, (2 weekends per month and about
4 weeks holiday per year).
If you are one of the average leisure people then stick to low cost lead acid
so called leisure. If you want to turn your boat upside down, and expect to wright
in about 5 secs, then the lead acid range with sealed removable caps would be
a good choice.
If you want to turn your boat upside down for a hour or two then a sealed lead
acid would be worth looking at. However don't expect to charge them as fast.
The best battery to use for fast charging using advanced charging
a) For general leisure use: use low cost lead acid which can be topped up with
water. So called leisure batteries
b) For long term cruising then use 6 volt traction
Avoid gel / agm for 3 reasons
1) very expensive
2) very slow charger rate
3) poor cycling numbers
Avoid sealed / A.G.M batteries for 3 reasons ( a.g.m. )