Hello Steve,
One cycle of a battery may be a discharge of 100% to 20% SOC or could be 80% to
40% SOC. I count each cycle as each discharge and charge to any level of SOC.
My actual cycles for the last four years for U.S. Battery 6 volt 251 AH is 2683
cycles for 1460 days. The cycle range is from 100% to 90% SOC. The Interstate
Co. actual furnish these U.S. batteries only in this ampere hour rating. The
dealer is only 5 blocks from me who I am going to for 53 years.
I first bought Trojans 6 volts 220 AH 20 years ago using the standard auto post
which barely ran 10 years. The next set of Trojans 6 volts 250 AH using the
low profile post with the top stud. These post did not work. Could not torque
to the recommended inch lbs. as specific, because the studs started to pull
out.
I had to re-cast the standard auto post for a standard heavy duty battery
clamp. Got 8.5 years out of these batteries. I did not notice that some
batteries had different manufacture dates. Make sure the manufacture dates are
all the same.
I now have the U.S. Batteries furnish by Interstate. The ampere hour rate per
mile is actual the same as it was when I install them on Sept 4 2009. I
average 1.5 cycles per day driving 2.2 miles in the morning charging at a rate
of 20 amps for 7.5 minutes and 6.6 miles in the afternoon charging for about 25
minutes.
The 250 ampere hour battery may be a lot, but this is at a 20 hour rate or
trying to drive the EV at 12.5 amps for 20 hours.
In my case, my battery amperes during my runs is 75 amps with a 200 motor amps.
At 75 battery amperes, look at the battery specifications for the Reserved
Minutes.
My Reserved Minutes for my 250 ah battery is 150 minutes.
Converting the battery Reserved Minutes to the actual usable ampere hours:
150 minutes / 60 = 2.5 hours
75 amps x 2.5 hours = 187.5 Ampere Hours
Input the battery Reserved Minutes you want and see how many hours this battery
will run the EV to 0% DOD. Divide the hours by 2 to see how many hours to 50%
DOD.
Roland
----- Original Message -----
From: Steve Powers<mailto:[email protected]>
To: [email protected]<mailto:[email protected]>
Sent: Monday, August 12, 2013 6:57 PM
Subject: [EVDL] Cycle life T-875, Interstate Workaholic 8V or T1275 (12V)
I have 2 EV's right now and usually I tried to avoid cars with 12V
batteries for this very reason. Both cars were purpose built for short
range. One has only 10 batteries - Group 31 Interstate batteries, 120V
system on only 10 batteries. The honest range on that car is probably
15-18 miles. It has a 9" motor and 550 Amp controller with regen. The
other car has Trojan "T1275 plus" in it. Same motor, 144V 500 Amp Curtis
controller, no regen. There are a total of 12 of those batteries in it.
Believe it or not, the Trojans have about 15,000 miles on them, over 4.5
years of use (not by me). I have no idea how many miles are on the
Interstate batteries, but probably < 2000. The Trojans are shot. They are
so bad I wouldn't even take it on the street the way it is. I drive the
other car, but it has a lot less miles on it.
Some research shows that those Interstate batteries only have a cycle life
of about 85-100 cycles. Seriously, that it what I read on-line. No wonder
they are near dead.
The Trojans supposedly have much better cycle life, maybe 400, 500, 600
cycles, so I have read. Buy, I am looking for real world experience on
either of these batteries. I'd like to replace the pack in the 144V car,
but not too sure I want to drop $2700 on 12 Trojans. The dealer is
offering Crown batteries, same foot print and rating - slightly cheaper. I
not so sure about the quality of them.
I drive the car about 16 miles a day, speed 40 MPH, some slight hills up
and down. The 120V car has regen. The 144V car does not.
I'm looking for a battery recommendation - Not Lithium. I don't see these
cars as worth the $7k it would cost for the Li pack, BMS, and new charger.
Steve
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