Battery Selection

DSCF4706_RevA.jpgBattery life is often measured by cycle life, the number of full charge/discharge cycles before the battery reaches 80% of its original capacity. Keeping the discharge current relative to the battery’s ampĂ—hour capacity low and the discharge shallow improves battery longevity. Typical 12 V sealed lead acid (SLA) cells, like the ones found a Go-Ped, can be cycled 300 times. Here are a couple of tips about buying replacement batteries. Manufactures that do not advertise cycle life are probably not worth buying from, as they may use lower quality materials. Also, be wary of vendors that claim their cheaper batteries are “replacements for” and “perform similar to,” yet have no datasheets to back up these claims. As it turns out, Best Batteries (B&B) provides lots of data about their batteries, and come stock with Go-Ped Scooters. The ESR 750 contains B&B HR-9 batteries intended for high-discharge rates. The replacement battery should have the same width and length but a taller height and also be designed for high-discharge rates and high cycle life. Below is a summary for three different batteries meeting this size and discharge rate profile. All the data was taken from datasheets on the B&B website. I decided to get the EVP12-12 which I purchased locally from Brandt Services Inc. in St. Louis, Missouri, which had excellent customer service, reasonable prices, and dirt cheap shipping. The discharge rate was calculated from the Go-Ped’s specified distance, max speed, and from the stock battery’s discharge characteristics.
Model LĂ—WĂ—H (in.) Discharge Rate (A) Time (min) Discharge Rate (A) Cycle Life (cyles)
HR9-12 5.94Ă—2.56Ă—3.70 18 15 9 NA
EVP12-12 5.94Ă—3.70Ă—3.86 18 25 12 300
EB12-12 5.94Ă—3.70Ă—3.86 18 35 5 300

Scooter Cavity Extension

The Go-Ped scooter base needs modification if it is going to accommodate the larger batteries.  Much inspiration came from user Goped19 on GopedNation and battery discussions on V is for Voltage Forums.  The height was increased by stacking additional wood boards that mimicked the original base. I purchased one 24×24×0.75 inch thick piece of plyboard and drew two outlines using the original base as a template. Drill a large hole into each board and the cut the outline with a jigsaw, as shown Fig. 1.

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Fig. 1 Cutting the outline

The boards were stacked, carefully aligned, then locked into position with aluminum tension wire. The board’s height makes straight drilling difficult. Use a drill press to make mounting holes. When the holes are done, the boards can be clamped together with a screw, nut, and washer. This is handy for keeping boards together when sanding the edges with a belt sander a wood file, as shown in Fig. 2.

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Fig. 2 Cleaning up the woodwork

Finally, I connected batteries as outlined in a previous post and screwed down the board with 3.5 in. long, 0.25 in. dia., 20 count thread screw. The first trip to work was 3.8 miles with a 170 lb payload in econo-mode. I arrived with 60% remaining capacity according to the state-of-charge versus terminal voltage chart found in technical manual on the B&B’s website.

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One Response to “Go-Ped Range Modification”  

  1. 1 James Dixson

    Grant-
    Awesome post… I just ordered an ESR 750 from craigslist sans batteries. It’s awesome that you got them from a place in St. Louis.

    You’ve got my email address with this post so keep in touch.

    -James

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