SLPinfo.org wrote:
The range would be quite different because 6 volt batts have greater
Amp-Hour (AH) capacity than 12 volt. Typical 6v golf cart batts hold
200-220 AH while most 12v batts only hold 100-120 AH.
That's correct. This is why you need to compare packs by WEIGHT and not
by voltage or number of batteries.
Using the 144V system in your example, here's the difference:
(6 volt) 144 volts X 210 AH X 0.8 (max discharge) X 0.57 (correction for
Peukert effect) = 13,789 useable watt hours
(12 volt) 144 volts X 110 AH X 0.8 (max discharge) X 0.57 (correction for
Peukert effect) = 7223 useable watt hours
If we assume you'd use 350 Watt Hrs per mile (varies depending on the
vehicle) you'd get about 39 miles range with the 6 volt batts and only 21
miles range with the 12 volt batts.
These are reasonably good numbers. The actual Peukert effect will vary
between batteries, and with how fast you are drawing the batteries down
(driving at 30 mph or 60 mph).
Another crucial factor is that 12 Volt batts (no matter what the salesmen
tell you) just are not up to the task of an EV. They will die on you
quickly. I tried two different sets and both only lasted about 9 months.
Yeah; a couple years is about the best most 12v will do, *if* you can
keep the current down. Most 12v batteries are rated at a 25 amp load,
while most 6v are rated at a 75 amp load. The 75 amp load is a lot more
realistic for an EV. In fact, many hobby EVs run even higher currents,
because they don't really have enough batteries for the speeds and
accelerations they are trying to achieve.
btw - you could also consider 8 volt golf cart batteries (that's what I
did) which would hold 150-180 AH. They are sort of a compromise between
the two and would get you range somewhere in the middle. They wouldn't
last quite as long as the 6 volts, but mean less weight to carry around.
Yes, that's why I'm using them in my LeCar.
--
Humanity is acquiring all the right technology for all the wrong
reasons. -- R. Buckminster Fuller
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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