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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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04-06-2015, 08:48 AM | #11 |
Not Yet Wild
Join Date: Mar 2015
Location: anderson sc
Posts: 8
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Re: option to increase speed
I am in the same boat bulls74. scottyb has the solutions.
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04-06-2015, 09:20 AM | #12 |
Happy Carting
Join Date: Dec 2007
Location: Southern California
Posts: 73,358
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Re: option to increase speed
Just a thought on how you increase voltage can change the results. Originally the cart was designed with say 2.5hp to move 500 pounds on 18" tires.
As with all electric vehicles the power to weight ratio is critical. There are many performance determining factors but lets just look at battery configuration. Average 6v battery weights based upon Trojan T105 and T890 specs T105 6v = 63 # (pounds) Xs 6 = 378# this is standard load 6/6v batteries Adding 2 more 6v batteries increases load by 126# or 25%. This equivalent to having a light passenger that never gets out of the cart. A T890 8v battery weighs 69# Xs 6 = 414# or less than 10% weight increase. Converting to 6/8v batteries saves almost 100# of dead weight ... or the equivalent of the rear seat you are planning upon adding...now what about the effects of increased tire size? Is bigger always better? |
04-06-2015, 01:12 PM | #13 |
Gone Wild
Join Date: Nov 2014
Location: St.Petersburg, Fl
Posts: 243
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Re: option to increase speed
gotta give the the bundle packages at CU hard look now. would like to upgrade then enjoy!
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04-06-2015, 01:23 PM | #14 |
Gone Wild
Join Date: Nov 2014
Location: St.Petersburg, Fl
Posts: 243
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Re: option to increase speed
also, thanks scotttyb for the additional info. now i'm going out on a limb even trying to answer this so take it easy on me, but here goes. if power vs. weight is a key component of the equation i understand how increasing the voltage would help with the additional weight batteries or other accessories.
as far as the larger tires being better, i'm unsure. from what i've read on the forum and feedback from other guys increasing tire size increases speed but lowers torgue. so i've already lost torque by going with larger tires. to gain some back and then some higher amp controller. |
04-06-2015, 03:05 PM | #15 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: option to increase speed
Your 22" tires are costing you about 18% of the torque your stock motor is capable of producing at 36V when fed with a stock (275A) controller.
Theoretically, the 22" tires should also increase the stock speed (14MPH) by 22% to 17MPH, but you are only getting 15MPH, which is a 7% gain, so you are losing about 2/3's of the mathematical gain. That could be due to weak batteries or excessive resistance in the high current cables, and/or solenoid contacts, and/or f/r switch contacts. Could also be a motor issue. Could also be that the 22" tires are amp hogs, some are, some aren't and some are in between. Probably all of the above to some degree. A series wound electric motor produces its maximum torque at zero RPM (stall torque) and decreases in torque as the RPM increases. RPM increases until the mechanical drag equals the torque being generated by the motor at whatever voltage is being applied to it at the time. Increasing the size (amps) of the controller will increase low end torque, but no matter how amps the controller is capable of passing to the stock motor, the max top speed of your cart will be about 17 MPH at 36V with stock gears (12.44:1) and 22" tires. Changing the final drive ratio (Tire height ratio times differential gear ratio) so the motor spins fewer times per each tire revolution, increases mechanical drag on motor, so the motor will not reach the same RPM as it had with shorter tires or numerically higher gears, but the cart may have a higher top speed, and usually does. Whatever happens to top speed, the cart will have less acceleration with taller tires and will slow down a greater percentage of the top speed while going uphill. The rolling resistance of the cart is directly proportional to the weight of the cart. Acceleration rate and how much the cart slows on inclines are also negatively influenced by weight. Increasing the pack voltage increases both torque and cart speed. Going from 36V to 42V is about a 16.7% increase in both while going from 36V to 48V is about a 33.3% increase. In general terms, series motors are wound for low end torque, or high end torque (aka hi-speed) or something in between. Stock cart motors are in the something in between category. However, there are aftermarket motors that produce as much or more low end torque than a stock motor, yet will spin at a higher RPM than a stock motor with the same voltage and mechanical drag applied. It is something like replace the stock V-6 in a car with a V-8, but easier to do. Upgrading a cart is a juggling act with every change contingent on something else. The trick is to figure out what the end goal is and build towards that goal. |
04-06-2015, 06:32 PM | #16 |
Gone Wild
Join Date: Nov 2014
Location: St.Petersburg, Fl
Posts: 243
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Re: option to increase speed
JohnnieB, it is definitely a juggling act. i like the idea of upgrading pack using 6 8vs (mentioned above) but itll be a slow march toward that. once its time to replace existing pack ill get 6 8vs. for now looks like two additional 6vs and 36 to 48v conversion kit.
speed wise this should get me where i want to be for now along with getting the gaining some torque back due to the 22' tires. now the hard part, convincing the wife!!! |
04-08-2015, 02:57 PM | #17 |
Gone Mad
Join Date: Oct 2009
Location: Buford, GA
Posts: 8,988
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Re: option to increase speed
I went with 8 - 6volts, due to trip times. I usually drive short trips, but sometimes drive nearly all day with four of us. Sure the extra battery weight costs some, but the total amp hours and volts make it work for my use.
YMMV |
04-08-2015, 07:21 PM | #18 |
Gone Wild
Join Date: Nov 2014
Location: St.Petersburg, Fl
Posts: 243
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Re: option to increase speed
yurtle, how'd you get all 8 to fit under seat? thought one would have to go under rear seat in back?
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04-09-2015, 07:35 AM | #19 |
Gone Wild
Join Date: Sep 2012
Location: Savannah, GA
Posts: 2,760
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Re: option to increase speed
Eight is easiest under the seat on a pds cart. A series cart requires removing the f&r then installing a reversing contactor somewhere in it's place elsewhere on the cart.
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04-09-2015, 07:56 AM | #20 |
Gone Mad
Join Date: Oct 2009
Location: Buford, GA
Posts: 8,988
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Re: option to increase speed
Moved my controller over the motor, and shortened the rod on my FNR to move it forward. Got the idea from ScottyB, the man.
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