Two months into the internship I could not get to work any more. I opened the scoot scooter top to find 4 sealed-lead-acid (SLA) batteries with a pack configuration shown in Fig. 1.
Fig. 1. Stock Go-ped battery pack configuration.
From previous work I did with laptop batteries, I learned that manufacturers typically tie together parallel cells such that they form a pack similar to the one shown in Fig. 2, Step 4, which has two advantages. First, it halves the number of sensors that measure voltage. Measuring two voltages, one across B1A and another across B2A is essential for determining when to end charge and discharge, major factors that affect battery life. Unfortunately, the scooter model only measured the stack voltage, the total voltage across B1A and B2A. The second advantage is that it provides a balancing effect. If a cell becomes weaker, the adjacent cell gives it charge. Having cells reach end-of-charge and discharge in unison is the most beneficial situation. After two months my batteries were significantly damaged. I parallel tied my batteries, which allowed them to die more gracefully and it also gave me about 20% more range, both which helped me get to work and back until the end of the summer.
Fig. 2. Steps to extend Go-Ped pack configuration
IMPORTANT: Do not reconfigure the battery pack if you do not know what you are doing, and expect to void your warranty too. However if you want to take preventive measures follow these steps.
STEPS TO MODDING GO-PED BATTERY PACK
- Find a well ventilated area to work in.
- Disconnect the scooter from the charger and open the board with a torx screw driver.
- Remove the four quick-connects at the top and bottom of the batteries.
- Remove the two metal tabs that connect B1A to B2A and the one that connect B1B to B2B.
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Create a wire harness that replaces the function of the metal tabs and will tie together the cells.
- You will need two short pieces of stranded 12 AWG wire and four yellow T2 female quick connect terminals and one long 18 or 22 AWG.
- Strip the wires and crimp both an the 18 AWG and the 22 AWG terminal into the same terminal.
- Crimp the other terminals so that the harness forms an H shape.
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IMPORTANT: you must balance parallel batteries before you connect them together. Otherwise you will cause a spark and damage your batteries.
- Connect small resistors, about 100 Ω, between parallel batteries, and let them balance for a few hours.
- Once balanced you can proceed to reconnect your pack.
The final connected harness should look something like the one in Fig. 3.
Fig. 3. Completed wire harness
Once you have made these modifications to you scooter there are some other life extension options to consider. Re-configuring the pack was a simple form of cell balancing, where charge moves between adjacent cells. There are commercial active cell-balancing products such as BattEQ and Power Cheq that moves charge from different levels of a stack. Check your scooter dimensions for free space. Another option is higher quality, larger capacity batteries. Ultimately I choose the last option, which I will discuss in another article and describe other scooter modifications.
UPDATE:
My wife and I have been able to get a couple rides into work this summer. We have been very happy with the new pack. I am able to ride 5 miles to work all on turbo mode . I measured the pack once, which indicated that this distance depletes the pack by 50%. I live in Illinois, which is as flat as you can get. I recently added some packaging foam around the batteries as the bigger batteries were causing a lot of road vibration. This easy mod made our rides a lot more comfortable.
My chain was starting to get stretched out from use. I tried to use my bike chain tool to remove some links, but Go-Peds chains are much smaller. I the bought the chain tensioner add-on for the scooter which works like a charm. Looking back, I should have built my own. $40 for a piece for plastic is a bit pricey.
Hi
Nice work on the battery reconfiguration. I don’t have a GoPed, but am thinking of getting one. I live in NYC and getting around on one of these could be a blast and save a lot of time. Plus, they are building new bike trails all over the place. Ever since I got an electric scooter for my boy for Christmas, I want one too. I got him a cheaper 500W IZip which is fine for him now. I just want a super powerful one if I get one.
Anyway, I was thinking, if your batter reconfiguation offers better performance, why doesn’t the company wire them like that in the first place? And, do you think this will work on the bigger model, the ‘EX’ model which they came out with? I know an electrical guy who could figure this out, I just have to decide when and where to get one. Thanks
Max
Make sure you read your state’s policy on E-Scooters. They are actually illegal in New York. California treats them as bicycles, which is convenient with all their bike lanes.
The reason they do not wire batteries this way is because it adds slightly more labor cost. Initially, when all the batteries are fresh and about the same, you see no added performance. All manufactures spec their scooters when the batteries are fresh. The benefit is not clear until you ride the scooter for a while (after which point you already bought the and the manufacturer does not care).
Thank you for this interesting experiment with your Goped batteries. I am eagar to read about the other modifications you have made as I too own a Goped (the new Hoverboard, it’s a blast but the range could be better even though it is the best of the bunch).
-Mike Daniels
Los Angeles, CA.
Found your tips fascinating, including your oversized SLA battery mod. I just bought a hoverboard, but need to lighten it significantly for train commuting. The new goped Li battery models are just too pricey! I have been researching NiMH batteries. Given your experience with the laptop batteries, I thought you might have some insight for me. Check out the “scooter batteries” at batteryspace.com & all-battery.com and let me know what you think. Hope to hear from ya.
Great suggestions - your idea inspired me to get out and purchase some tools and materials to modify my battery setup - searched the gopednation forum for your posts there, and some folks were looking for some more detailed photos -
I have two questions -
Could you draw a simple diagram / take photo of balancing batteries with resistors?
Could you take a photo of your battery setup with the wiring spread out a little more? The yellow leads look like they are spliced into the control box…would be very helpful!
I have almost no electronics experience, and would hate to mess up my batteries…looking forward to your reply!
I uploaded a new step-by-step diagram that shows how to add that balancing wire and posted a status update on my pack. I hope what I did is clearer now. If not, please tell me. Thanks for your interest.
Hi again Grant. I am picking up my new goped tomorrow and will use your new updated diagram and step by step clarifications to install the balancing wire on the new batteries. I went to the cell balancing device websites you had for us, but could not see imediate pricing available…oh well. I’m guessing your appraoch will help quite a bit for now until I have the patience to further attempt contacting these companies and getting quotes. Appreciate your sharing your knowlege with us.
The BattEQ is available for purchase from Staab Battery. Their website no long lists their price, but they were around $120.
The company that makes the BattEQ is located in town and was founded by my thesis adviser. If I can get about ten people interested I can try to negotiate a better price with the company directly.
I had previously requested to get a freebie or discount for just myself, but did not get any bites
Maybe if I get some more enthusiasts they will change their tune.
Karl Reply:
August 26th, 2008 at 4:28 pm
Hi Grant,
What would think of hooking two of these battery packs (see below) with one of these balancing devices?
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=995
Hi Grant,
What do you think of the specs on this battery at http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=1243
Grant Pitel Reply:
August 27th, 2008 at 11:52 am
Karl,
I recommended staying away from batteries that do not list a manufacture or provide detailed data sheets. My brother and I made such a blunder and purchased a whole lot of NiMH batteries, none which worked for very long. While you may pay 20% more for brand name, its very possible it will more than pay for itself in battery life. An associate of mine performed life cycle tests on Li-ion batteries from two different manufactures. One achieved 200 more cycles than the other, which for Li-ion, is significant.
I would email batteryspace to find who manufactures those cells, I am actually curious myself, please post who if they response.
Looking back at my battery article, a continuous discharge of 18 A (which I think is roughly turbo mode) will deplete a a 12 Ahr pack in 25 minutes, so roughly 2C. If you used two pack, each cell would see 1C, which is within the spec on the website (provided that pack uses the same cell given in that second link). HOWEVER, this is continuous discharge. The peak current draw (a.k.a pulse current and cold cranking amps) is in fact much higher on a scooter. They occur when you go up hills and accelerate. Lead-acid are wonderful in this category.
As the pack was designed for electric bikes, I suspect that it would work. Go-Ped does bring the voltage above 24 V to extend lead-acid battery life. I would check Ni-Mh datasheets to make sure this chemistry can handle the over voltage. I have posted some data I have taken from my scooter that you may fine helpful. I think 27.3 V was the highest I have encountered.
GO-PED BATERY INDICATOR
3 = Red+Yellow+Green
2 = Red+ Yellow
1 = Red Blinking
Supply (V) / Indicator
27.3 / 3
23.1 / 3
23 / 2
22.9 / 2
22.77 / 2
22.5 / 2
22 / 2
21 / 2
20.9 / 1
20.5 / 1
20 / 1