Re: (ET) Elec-trak Digest, Vol 11, Issue 160

["Robert" <euclid delhitel net>]

Don,
That's correct, my off grid L/A batteries never see 50% discharge and rarely 
see less than 80%. For those of you who don't know, batteries are rated in 
cycles. Each time you discharge and then recharge a battery you complete one 
cycle. The deeper you discharge the battery during that cycle the fewer 
total cycles you will have before the battery is no longer functional. One 
of the reasons the batteries last so long in a Prius is because the 
batteries never see a deep drain so you get a tremendous amount of cycles 
out of them.

Rob

Message: 1
Date: Mon, 19 Aug 2013 17:50:22 -0400 (EDT)
From: Theoldcars aol com
To: roberttroll hotmail com, elec-trak cosmos phy tufts edu
Subject: Re: (ET) When did they start making car batteries out of
gold??
Message-ID: <61a6 241b6aa7 3f43ed1e aol com>
Content-Type: text/plain; charset="us-ascii"

The Trojan TE35 I looked at on line appears to be flooded  battery? There
is a TE35-Gel which is a seal battery. You might want to check  and make 
sure
the TE35 is really sealed.

If I had a choice and had to use a lead battery it would a  gel. They have
more cycle life and stay in balance better. You do need a  charger that has
an algorithm for gel or you will cook them.

LiFePo4 should have four times the cycle life but I very highly doubt  this
would provide 32 years of calendar life. NiMH had a projected  calendar
life of 10 years but there are 15 year old NiMH batteries still going 
strong.
Lithium has some projecting a calendar life 10 to 15  years. This could 
vary
a lot by how deeply you cycle the pack and how many  cycles you run. I have
also heard 20 years but there is no way of knowing. Also  warmer
temperatures shorten all battery chemistries calendar life. There  are many 
factors
that affect overall performance.

I have a good friend who installed a pack of the older CALB SE 100AH  cells
in an OEM Ranger EV.

http://southtownelanes.com/electric_pickups.html

He has over 30,000 miles but has not noticed any capacity loss. Before he
used LiFePo4 his best performance using lead was 15,000 miles with
significant loss of capacity before reaching that mileage. Also lost a few
batteries during that time. The actual useable capacity was far less  and 
the cost
of the lead is 50% of the LiFePo4. So now all his use is all  costing no 
more
then he would have paid for lead at 30,000 miles. This  does not factor in
all the other advantages. He has reach his point of  payback.

When you size a lead pack you should figure not going less then 50% on
discharges for maximum cycle life. If you do your cycle life will be
significantly reduced.

What is misleading with lead is the AH claims by manufacturers. 200 amp
hours at a 5 amp load is just not how most people use batteries. With
significant loads your 200AH rated lead is really closer to 100AH. If you 
expect
to get close to the claimed cycle life with lead your use should be 50% of
that.  So 50AH of capacity DOD would be your best chance at maximum 
success.

You could do about the same thing with a CALB 60AH cell. Your cost would be
reduced by 40% of the 100AH cells and it is highly likely to still way
out last the lead pack.

What is the amp load and for how long?

Don Blazer