Daryl wrote:
On 3/22/2013 6:09 AM, Keith W wrote:

Battery energy density MJ per kilogram

Lithium-ion battery 0.720
Alkaline battery 0.671
Nickel-metal 0.28
Lead-acid battery 0.17

The reason the AGM isn't used in larger applications is that it cannot
be recharged as it is being discharged.

Hmm ISTR that my car alternator can charge the battery and
run the lights at the same time so I'd love to know what scenario
you had in my mind there

You left out a slew that use
Deep Cells.


Feel free to add them in.



IT does the job if you keep it over 50% just like clockwork and
can last at least 2 to 5 years without going below 50% charge if you
keep them above freezing and below 100 degrees (the same as the
Lithiums). I use AGMs on a daily basis and my battery provider says
I am the hardest on batteries he's ever seen. I am getting ready to
do another build that uses the heavier Deep Cell which is designed
to put up with my punishement. But the AGMs are more rugged than
the Lithiums that I also use.

Nacads also work but for about one run into town before they
overheat. Ever seen a Nacad blow up? IT's pretty anticlimatic. They
burst and make a mess out of everything around it. And it's
caustic. Same goes for a Lithium except they will go into flame
and feed the flame until all the liquid is used up. I have never
had a case break open on an AGM. I've crashed em, dump em, drop
em, used them for Rocky Mountain Offroad, and more.

I can see that the Deep Cell Sealed Lead Acid should be as tough and
have a longer run time but they are twice as heavy.

Which is something of a problem for aircraft

Just leave out that 1 six pack of Tomato Juice to make up the
difference. It's not a real problem where an extra 10 pounds is
really going to make a difference for something the size of the 787. An
added 10 pounds for safety sake is very important.



Its going to be a lot more than 10 pounds.



The lifespan of
the Deep Cell the way I use batteries should be as high as the
Lithium and cost less. But the weight means only my 3 wheelers will
use them. They just don't make 10 to 15 amp deep cells. But they
do make a very solid 35 amp at twice the weight and size of a 12
amp AGM. I am just not sold on Lithiums and I am certainly not sold on
Nicads. The Airline Aircraft Industry can use the AGMS and have
less problems, almost the same run time as the lower Lithium Mag
batteries and save a bunch of money.


Airbus use NiCads ,the Boeing 737, 747 (pre-800) and 777 use NiCads
, they disagree
with you.

Nicads are old technology. The AGM batter is much newer. When they
were designing the 737, 747 and 777 the AGMs weren't available. Single
Airplanes use the AGMs and that is more critical for weight
and safety than the big birds are.


AGM batteries have been around for at least 25 years and Boeing
have used them in military aircraft includng the AV8B so that
idea wont fly. They were certainly around when the 777 was
being designed.

I use all these batteries in transporation every day. I am a dealer
in the AGMs and the Lithiums as well as the motors and kits. I can
also get you a good deal in Deep Cells but the shipping would be a
killer.

I can buy them locally and have done so for use in towed caravan
installations.

Keith