flooded v. sealed batteries [RE-wrenches]

[Bruce Geddes]

Hi All,

Joel wrote:

> Hi Matt,
>
> In general, L16s and forklift batteries are just big golf cart batteries.

I disagree.  L16's yes, they are big golf cart types but traction cells are
a different story.  I use T105's in mobile homes due to the weight but in
off grid houses exclusively traction cells.  Down here (New Zealand) I deal
with Exide for their Powerlift traction batts.

To prove the point look at the cycle ratings.

Trojan L16 600-700  cycles to 80% D.O.D.
Trojan T105 500-600 cycles to 80%
Exide Powerlift 1500 cycles to 80%

The thing to watch out for is the capacity specs.  Most renewable power
batteries are rated at C20.  Traction cells are rated at C5.  Golf cart
batteries are C20.  BP Solar rate their PVstor at C100.

C5 x 1.295 = C20 (close enough).

Most "purpose built" renewable batteries are variations of the traction
cell.  The antimony content of the grid is reduced to reduce gassing and
this is not too bad as the renewable battery is not expected to cycle
anything like the traction battery.  I don't find the extra cost for purpose
built batteries justifies the difference.  Downside for traction batteries
in difficult locations is that they link with big lead straps that are
sweated on to the posts.  A bit tricky to apply but boy does it make for a
great, trouble free intercell connection!  No corrosion or volt drop.
Purpose built types have a different post, usually with leads and bolts.

In temperate climates the flooded lead acid battery is the best compromise
in cost, performance and lifespan.  If the ambient temperature is around 30
degrees celcius or higher industrial NiCd will give better life for the
cost.  Downside is that NiCd is less charge efficient and higher self
discharge.  Some of you may be able to use NiFe which is less efficient
again than NiCd and has self discharge in the order of 3% per day.

Sealed lead acid has its place also.  A flooded battery has greater ability
to dissipate heat as electrolyte is in contact with the case over a large
area and will generally outlast a sealed battery in equal installations.
They can also be pushed a bit harder on charging and discharging.  A sealed
battery will outlast a poorly maintained flooded battery though.  I use
sealed batteries in places where maintenance is likely to be overlooked or
at extended intervals (holiday homes).  Of course with the encapsulated
electrolyte a sealed battery can be installed indoors more easily than a
flooded.  This may be an advantage in very low temperature environments.

So what is the "best" battery?  That depends on a number of factors like
environment (temperature), cost priority, skill of the installer (welding
versus bolts), acess to different types, etc.  No one battery is ideal for
all situations.  Everything is a compromise and it depends on what weighting
you give to each factor.

Bruce Geddes
PowerOn
info at poweron.net.nz
www.poweron.net.nz

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael_welch at sbcglobal.net

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
--^----------------------------------------------------------------