Some time ago, I talk to a battery engineer at the Trojan Battery Co. about
testing batteries for the ampere hour rating. I said I have one of those load
testers that can test from 1 to 600 amps.
I said if I adjust that to be 75 ampere and ran it for 130 minutes which is the
Reserve Minutes for the 6 volt I have. He said you do not have to do it that
way or even at the 20 hour rating.
The formula he gave me is:
Reserved Minutes at 75 amps / 60 minutes = Hours
Hours x 75 amps = Ampere Hour
Adjust the load meter to 75 amps and only run it for a set of amount of time,
maybe only a minute to 5 minutes. This is a percentage of the total reserved
minutes rating at 75 amps
Test all the batteries at the exact amount of ampere and time. If the volt
drops is in with 0.1 volt of each other and the load ampere is in with 5% then
the batteries are consider match.
The best test if you can, is to drive the EV at a 75 battery ampere for a
certain amount of time and do the calculation at different times after each
battery charge.
The Trojan Co. recommend the user to purchase to a 75 load tester that reads
out in ampere, voltage and state of charge which all you need to test the
batteries.
He also said, it is best to do this test after having several charging cycles
on it, because the new battery pasted plates are closed tighter with
overlapping pasted. Charges and discharges will continue to open deeper
passages into the paste thus more surface area. The new plates capacity will be
less a one charge than 100 battery charge cycles. It actual took me over 740
cycles on June 18 2011 before the batteries peak out.
>From Sept 4 2009 to June 18 2011, the ah per mile started out at 4.1 ah and
>decrease to 3.3 ah/mile. Today it is increasing to 3.4 ah/mile. I can plot a
>time/ah curve which will predict when the batteries will have to be replace.
I have kept a battery log which records:
Date - Cycles - AH - SOC - Voltage - Miles - Charge Voltage - Charge Amp -
Charge Time - Ambient Temperature - Battery Temperature - Other
These records go back to April 4 1976 which included a map of travel -
something like GPS.
Roland
----- Original Message -----
From: Lee Hart<mailto:[email protected]>
To: Electric Vehicle Discussion List<mailto:[email protected]>
Sent: Thursday, October 10, 2013 10:00 AM
Subject: Re: [EVDL] Range
Roland Wiench wrote:
> You did not state what the ampere hour rating of these batteries are. I
was searching the web and came across the Interstate Battery specifications for
the 6-volt battery. The local independent auto Parts Store which I have been
going to since the 50's started to handle the Interstate Battery line which is
only 5 blocks from me and delivers items to my house.
>
> So I went to the Parts Store (which is actual name of the store) and I
notice the Interstate Battery battery truck was there. I walk in and I want to
see the data and specifications of these batteries.
>
> The Interstate battery person said, I have it right here in this book that
was laying on the counter. I said, I like to see the data on the 250 ah 6-volt
battery. He said they do not make this battery over 220 ah, but we furnish the
250 ah one which we get from the U.S. Battery Co.
>
> I said I will take it without any hesitation. I said I need for them to be
all the same manufacture date, auto post with deep imbedded stud (use this stud
connection for a BMS and also to put a greater internal pressure of the auto
post against the internal surfaces of a battery clamp.
>
> I also wanted to have these battery balance (battery balance means the
ampere hour and voltage and the deep cycle cranking ampere at 75 ampere for a
certain amount of time within a 0.1 V, 5% A and AH of each other. The
Interstate guy said this will about double the cost of the battery as a option
cost. You can do this testing yourself with the equipment we furnish the Parts
Store battery shop. We normally ship 240 of these batteries were you can test
out the best 30 batteries you need.
>
> Interstate deliver the batteries right to my house. The batteries were in
a U.S. Battery package. I pick out 30 batteries that where match with a
voltage of 6.44 volts and the cranking ampere was at 1000 amp plus or minus 5
ampere. Had to go two pallets of batteries to get this tolerance.
>
> Knowing that the actual drive test and recharge may change this results,
One battery of 30 batteries was out of tolerance, so they change this battery
for me.
>
> These batteries where install on September 4 2009 and had put on 2729
cycles on them driving only 4165 miles. In this roller coaster roads, the
actual motor on time is about 3000 miles and the motor off time is the
remainder.
>
> Today the AH per mile and charging time over the same exact route and
temperature is still 3.3 ah per mile and 7.5 minutes of charging at 20 amperes
at 250 volts.
>
> The cost of the batteries ran $125.00 for the 250 AH.
Excellent, Roland. You really went the extra mile to get good batteries.
$125 each is also a great price.
Did you happen to do an amphour test to see what the actual capacity
was? Were they really 250ah at the 20-hour rate? How many minutes at 75
amps?
The ones I bought from Sam's Club were 8v 175 amphour. I waited until
they got a fresh shipment in, and got a set of 15 of all the same date
code. I didn't test the 20-hour rate, but did test the 75-amp capacity.
One of the 15 was about 10% lower than the rest; I exchanged it for
another one from the same batch. They are 3 years old now and still
doing well. I'll have to run another capacity test though and see where
they are at today.
--
There are few industries with more BS than the battery industry.
Elon Musk
--
Lee A. Hart,
http://www.sunrise-ev.com/LeesEVs.htm<http://www.sunrise-ev.com/LeesEVs.htm>
_______________________________________________
UNSUBSCRIBE:
http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub>
http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org>
For EV drag racing discussion, please use NEDRA
(http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>)
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131010/392d1733/attachment.htm>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
For EV drag racing discussion, please use NEDRA
(http://groups.yahoo.com/group/NEDRA)
