Re: Battery Analysis Spreadsheet.

["David Roden (Akron OH USA)" <roden@ald.net>]

From:           	Steffan Carroll <steffan@usa.net>

> Note the Long WP22-24NE,  24V 22AH SLA AGM Lead Calcium battery with an
> energy density of 114 wh/L and specific energy of 43 wh/kg.  Nothing else
> comes close.

Thanks for the references.  I checked out the specs on

     http://www.bestbattery.com/spectbl3.html

It didn't list a WP22-24NE that I could find, but it did show a WP22-
12NE.  The given specs for that battery show 41.6 wh/kg at the 20 hour 
rate.  Certainly that beats Hawkers, which are in the 33 wh/kg range at 
the 20 hour rate.  It is almost as good as a Trojan T-145 (44 wh/kg at 20 
hour rate).

Unfortunately, the 20 hour rate doesn't tell you much about how it will 
perform in an EV. 

The other page mentioned

     http://www.asiansources.com/kunglong.co

has some numbers for faster discharge on other models of the Long line.  
I couldn't find the WP22-24NE there either, but the figures quoted for 
the WP20-12 are:

	20 hr - 20 ah
	10 hr - 20 ah
	 5 hr - 17 ah
	 1 hr - 12 ah

I'm skeptical about the same rating at both 10 and 20 hours.  But if we 
calculate Peukert's exponent from the 10-hour and one-hour rates, we get 
1.29 -- pretty mediocre for an AGM.  It works out to about 1.28 when 
calculated from the 5-hour and one-hour rates.

Now look at the Hawker G26EP:

	10 hr - 26 ah
	 5 hr - 25 ah
	 1 hr - 21.7 ah

This gives us a Peukert exponent of 1.09.

Here are the specific energy figures at the one-hour rate:

	Long WP20-12: 23.5 wh/kg
	Hawker G26EP: 25.8 wh/kg

The energy density figures at the one-hour rate:

	Long WP20-12: 62.7 wh/dm^3
	Hawker G26EP: 70.3 wh/dm^3

As you push past the one-hour rate, the Hawkers will look better and 
better by comparison.  At 27 minutes, the Long is 17.6 wh/kg, and at 30 
minutes the Hawker is 23.4 wh/kg.  (The Long doesn't give a 30 minute 
rate.)
	
The figure that's conspicuous by its absence on both Long webpages is 
cycle life.  Hawker gives theirs as 400 cycles at 100% DOD (C/5).  It 
would be interesting to run some cycle life tests on the Long batteries. 
If their cycle life is comparable to Hawkers, and the cost appreciably 
lower, they might be an alternative worth considering, as long as you 
don't discharge much faster than the one-hour rate. 


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1974 Honda Civic EV 96vdc
1970 GE Elec-trak E15 36vdc