[ausev] Open Garage this Sat... 9am - 1pm
Roy Holder
roy at holder3.com
Thu Aug 20 15:57:43 GMT 2009
Mark,
I have gotten 3 years and 15,000 miles out of my trojan J150 batteries.
Since early this summer I can no longer make a round trip to work and home,
but I can charge at work, so they are still 'usable'. One charge a work
day most of the year(250) and 2 a day for Dec-Mar, means nearly 9000
cycles. The batteries are heating up more now during charging and venting
a little acid. Im holding off replacing them to see if LiFe drops some
more... Keeping my fingers crossed.
I draw around 100 to 180 amps from the batteries during my trips, up to 300
for brief acceleration on to 183. Car would hold 60 mph up and down hills
on north 183 untill revently, now it drops to just under 55 up the great
hills overpass. I still only use about 40-42 amps a day from the
batts(averaged 270 watthour/Mile). Max ah used during a range test was 95
when the batts were about a month old. The geo is about 2800 lbs with the
batts. About 40% overall average depth of discharge,
I dont have a 25 amp load to test the batts with, so I cant compare to
published data.
This is all DC efficiency metering, I have an inductive clamp AC amp
meter, I should make a power cord one of these days before I replace the
batteries to see what the AC efficiency is.........before and after.
how is your daily draw vs capacity?
At 11:08 AM 8/13/2009 -0500, you wrote:
>Great stuff Brian.
>This is good info to know as it’s the true picture of the efficiency of the
>system.
>We often only focus on DC efficiency, i.e. efficiency of the car that moves
>the vehicle a certain distance for a given amount of available energy. For
>example to estimate the range of a small vehicle with 10kWh of usable
>energy, one could assume an average of 250Wh/mile efficiency (or "fuel
>economy") which would give it a 40 mile range (+/-). But we don't often
>talk about the system efficiency, which includes battery efficiency and
>charger efficiency and any parasitic loads on the car while charging
>(cooling pumps for example). I think the Tesla claims a 350Wh/mile
>efficiency number taking into account all of these things. Flooded lead
>acids are less efficient than li-ion, for one reason, because they require
>an overcharge for balancing which eats into efficiency.
>
>So by that metric, your fuel economy/efficiency has been:
>Feb 389 wh/mile
>March 455
>April 543
>May 592
>June 1230
>July 874
>
>We can assume that the efficiency of the charger is relatively the same
>throughout the year, but battery round trip efficiency does change with
>temperature, cycle life, and age. It appears your batteries are now using
>twice the energy from the wall to give you the same mileage. Because the
>chemistry of the battery is changing for reasons previously listed, one
>would need a charging system that would adapt as well. Using the simple
>"charge to X volts" doesn't really work (from an efficiency point of view)
>after the battery has been sufficiently used. I bet some amount of
>overcharge could be eliminated by a charging algorithm that stopped charging
>due to different criteria than just voltage and range would still not be
>diminished.
>
>Don't get me wrong, I think the PFC charger is an amazing piece of
>equipment, very versatile and powerful. It's just hard to have a the
>knowledge of how best to charge a battery as it ages/cycles/temperature as
>even the manufacturers are still learning. As you can imagine, not much
>research was performed to determine optimal end of life charging criteria
>for golf cart batteries. Now that EVs are being developed by OEMs, that
>work is being done and hopefully those lessons, algorithms, and equipment
>will trickle down for the hobbyist.
>
>Brian, what batteries are you going to replace them with? Same ones or
>something different?
>How many cycles are on them?
>What is the average depth of discharge?
>Perhaps you could discharge one at 25A and compare it to published data to
>see where it falls on the graph.
>Marc Kohler
>
>-----Original Message-----
>From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
>Behalf Of Brian Lasseter
>Sent: Thursday, August 13, 2009 10:00 AM
>To: AustinEV News Announcements and General Discussion
>Subject: [ausev] Open Garage this Sat... 9am - 1pm
>
>I have used and abused my batteries every day for the past 15
>months... and it is time for some new batteries.
>
>So, I will be holding an open garage this Sat for anyone who wants to
>help me remove batteries, anyone who wants to inspect my car closely,
>or even anyone who wants to just sit in a chair and laugh as I lift
>70lb batteries. :-) All comers welcome.
>
>@ Lasso's House : (512) 736-1677
>Saturday, August 15th : 9am - 1pm
>11402 B Ptarmigan Cove
>Austin, TX 78758
>
>
>--
>
>
>If you are wondering WHY I am replacing the pack, I seem to have been
>slowly melting a battery post over the last few weeks, and it finally
>started dripping lead last weekend. Really though, the whole pack is
>becoming unworkable. The range is still a good 30 miles, but the heat
>generated keeps my pack at a fairly constant 140°F - 150°F which is
>making it difficult for even the water miser caps to retain water.
>I've also noticed that the heat is really killing my electrical
>efficiency, and preventing me from getting anywhere near the correct
>charging voltage. At 140°F charging temperature, then 174vdc would be
>the manufacturer's recommended charging voltage... but that was rarely
>reached.
>
>For anyone interested in numbers... here are my efficiency numbers for
>the last few months of driving, and the total over the life of the
>battery pack. Efficiency has units of miles/kwh. I'm not sure if
>anyone else has any insight as to whether 6206 miles or 3882kwh is a
>good run for a lead battery pack?
>
>
> kwh end miles end kwh miles
>efficiency
>
> Jan 15456 149605
> Feb 15669 150152 213 547 2.568075117
> Mar 15869 150592 200 440 2.2
> Apr 16045 150916 176 324 1.840909091
> May 16242 151249 197 333 1.69035533
> June 16579 151523 337 274 0.81305638
> July 17080 152096 501 573 1.143712575
>
>
>
> 13270 145953
> Total 17152 152159 3882 6206 1.598660484
>
>--
>TTFN,
>Brian "Lasso" Lasseter
>
> · (512)736-1677 · AIM:digininja · ICQ:2238123 · MSN:azoreg ·
>"No Sane man will dance." -Cicero (106-43 B.C.)
>
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