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Not all batteries are created
equally!
Batteries are the core if
not the heart of your alternative energy system. Be sure to start with the right stuff! Batteries,
next to generators
are the component that are most often skimped on, but make or break your
system. The damage to batteries are the single most often cause of failure within an
off-grid system. Batteries may be the most expensive component within your
system.
When it’s time to
purchase or change batteries remember that all batteries are not created
equally. Batteries are purpose constructed; they are optimized and constructed for specific applications and therefore
the wrong type of battery will perform worse.
If the battery you are looking to use off-grid is also rated with cranking
amps, the battery is not a true deep cycle battery but a compromise
formulations such as used for RV and boating applications.
Quality is a decisive
factor in performance. Fresh batteries in good condition offer all of their rated
runtime and recharge cycles. Improper battery types, batteries with
inappropriate design or aging batteries, which have been discharged and
recharged many times, accept less of a recharge over time which results in
shorter runtime.
Because the depth of discharge
is significant off-grid batteries should have heavy plates. If you're
purchasing a solid brand name product you can actually compare batteries by
weight comparison. Heavier equals more lead and is better.
Initial vs. Lifetime
Battery Cost
Canadian Tire, Wal-Mart, Sears and others sell "deep cycle" marine battery for
as low as $60 which may seem
like a good deal. After all, they are deep cycle batteries! However, the
use to which you will put these batteries will kill these batteries within
two to three years. Your cheapest alternative is an
industrial battery such as used in battery powered floor cleaning equipment.
If you are starting off on your own and expect to make mistakes and
think you might damage or destroy your first batteries start with these as they
are designed for a similar usage-charge cycle. Otherwise, allow us to
recommend quality batteries built to last many years in an off-grid application.
We deal with a number of manufactures and will find the most appropriate battery
for you at your location and application. All batteries age over time.
Battery aging is considerably slower if you charge your batteries before they
are half depleted. This is called 50% depth of discharge and will provide
4X the cycles vs. deep discharge.
Adding Batteries
If you intend to purchase what you can afford now and add more batteries later,
think again. Mixing old and new batteries is never a good idea. Batteries age
over time. When several are connected as single battery bank the batteries act as and are
treated as a single battery by your equipment. The limit of the battery
array are the
oldest, weakest battery within the array. Batteries within a battery bank should
be identical in age and model. If your system is set up and configured to work with
several battery banks a new, separate, battery bank can be set up with different batteries.
However this gets complicated!
What happens, and why is it
that the new battery that's been added that fails first? As mentioned in the
previous paragraph, your charging (and discharge) systems see your battery bank as one battery.
Within the battery bank the new battery which is much more chemically and
electrically active and will overcharge before the 'old' batteries come up to
full charge.
During the discharge cycle the new batteries will discharge and over-discharge before the
others. This over-cycling will quickly age
or destroy the
new battery. There are are other reasons such as differing output
and resistance between batteries but the above example loosely defines the
issue.
Follow the link 'Battery
Replacement' at the
left side of this page.
We've become battery
experts over time, there's a LOT to batteries and battery maintenance! It
is our hope that our information assists you and prevents early battery failure
within your system.
Caution:
Inverters consume power while they wait for a load to come
on. Most inverters are
equipped with an automatic shut off feature that reduces the amount of standby
power required while dormant. This is frequently called "sleep mode," or
"standby," or "power saver" or... An inverter, even in the sleep mode continues to consume battery power!
Even an inverter that is turned off consumes power as the capacitors within will
consume power. Don't leave your inverter in a
situation that can drain your batteries flat. It is best to turn off the power
to the inverter over the winter for this reason.
ALL Lead acid batteries self
discharge over time. At moderate temperatures self discharge can be as much as
5% per month. In colder Canadian winter temperatures self-discharge is
considerably slower. Always store you batteries with a full charge!
Suggestion: Most
inverters and some solar charge controllers have a low voltage disconnect
feature. Because batteries should never be taken down as low as the
factory default settings on these devices we strongly suggest you raise cut-off
level to less than 75% discharge. (Voltage will vary depending upon the type of
batteries and the nominal voltage of your battery bank.) Also, if you
don't need it on, turn the breaker to the inverter off if you don't have an AC
fridge.
Each time a battery is
charged or discharged some of its life is consumed. Some processes take more
from the battery than others. The harder your battery is charged or
discharged more your battery life is worn away.
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