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Success! Building my own secondary TC battery - and it works!  

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socobelfast
Posts: 42
(@socobelfast)
Eminent Member
Joined: 2 years ago

As those who browse this forum will know, I have been working on a project to build my own battery for my Super Soco TC.

I use my bike to make a living delivering fast food. The problem has been range: I get paid a fee for every delivery, and when my battery reaches 15-20%, I have to return home to charge my battery.

Even with conservative management of the battery (using eco mode 1 far more than I'd like, and never using sport mode 3), this means I have to return home after 2hrs and 30mins. Not using sport mode 3 literally costs me money. If I can go 40mph on the main roads, as opposed to 25-30mph (apologies to those who use km/h!), it means I can get food to the customer faster and take another order from another customer that much quicker. The problem, I quickly discovered, was that using sport mode 3 drained my battery far too quickly to justify using it. Sticking to normal mode 2 might mean I made less money per hour, but it meant the battery lasted longer, and that was key, because charging the battery took a lot longer than draining it.

Getting a 10A fast charger from Outdoordreams really helped. That meant I could do the lunchtime shift, come home at about 3pm, and have a fully charged battery ready for 6 or 7pm. On a good day, I could drain the battery in the evening by 9.30pm, and then squeeze another delivery or two in after another partial recharge until 11pm, when the delivery service I work for stops operating.

Why not buy a second battery? Well, they're overpriced and they're not that good. They use 18650 cells with a fairly low capacity. The construction is good, but compared to what is available on the market, the cells are not exactly top of the range.

The reason I'm doing fast food delivery is because I'm studying for a degree in economics and applied mathematics. The Super Soco is great, because I pay no tax, maintenance is minimal, reliability is excellent and I pay only around £10 per month in extra electricity costs to run it. It wasn't too difficult for me to work out that with the latest 5Ah 21700 cells, I could build a battery that had the same capacity that took up half the volume. In theory, that meant I could triple the bike's range.

For those who are interested, I built a 17 series/6 parallel battery of cells, using Samsung 50Es with approx 5Ah of capacity per cell. This matches the original battery in terms of voltage and capacity, although it uses far fewer cells in parallel. The advantage is that my battery takes up about half of the volume of the space left for the secondary battery. When I ordered my cells, I got them from NKON in the Netherlands, and I ordered 200, thinking that I would probably need a few spares in case I messed up at all. Like an idiot, I hadn't done my research. I assumed the battery was 16s, based on the 60V rating. Thanks to various members of this forum, I realised this was not true! So I need to order 4 more cells in order to make another battery, to max out at 90Ah.

For now, although I may build another one, I am just using my own battery in parallel with the original. I unscrewed the lid from my own battery and connected a parallel xt-60 connector cable inbetween the power socket and the original battery, allowing my to connect my new battery in parallel. This way, I saved having to buy the official battery paralleler or connect up a second power supply. Credit to @flyingelectric for this suggestion. I drilled a hole in the lid to allow the parallel cable to be accessed, and then screwed it back on.

Needless to say, this invalidates the warranty on my battery. But if anything ever went wrong, I'm pretty confident I could rebuild a better-than-original battery by salvaging the original BMS and using superior cells. So I took a calculated decision and went ahead.

Turns out the display still showed the same range. The good news is that when I connected the two batteries, nothing bad happened!

When I took the bike out for a test ride, I used sport mode 3 exclusively. I spent about fifteen minutes riding, which took about 8% of the battery. When I got home, I tested both batteries using a multimeter. Both batteries had reduced voltage by precisely the same amount. Good news: the method of connection had worked, and although the displayed range had not increased, in practical terms, it had in fact doubled!

I had a feeling this would be the case, since I knew from experience that the kind of test ride I had done would not normally have left me with over 90% battery (I had left the bike on and departed with 98%).

I have now drunk half a bottle of red wine to celebrate, so I will further update the forum with performance notes etc on future dates. Hopefully, I will now be able to ride faster, get more deliveries done, stay working for longer and ultimately earn more money.

I have posted one or two pictures of the work I did. Any questions are welcome, happy to help anyone else considering this option.

20200114 031227[1]
20200114 160953[1]

 

 

27 Replies
Jim
Posts: 23
 Jim
(@jim)
Eminent Member
Joined: 7 months ago

Great job!

Let us know how it works out next couple of days.

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flyingelectric
Posts: 98
(@flyingelectric)
Trusted Member
Joined: 1 year ago

Epic and nice story @socobelfast

What I have heard there may be a small issue when the new battery equalize with the soco battery but depending on where you do parallel the battery connectors maybe this will never occur or be an issue for you as you paralleled the batteries in the best place.

If it equalize it will show the "regenerate" icon and cut throttle for 2-3 seconds. Have you ever have that happen to you or do you even care about it? 

Do you have any pictures of your battery?

Cheers

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1 Reply
socobelfast
(@socobelfast)
Joined: 2 years ago

Eminent Member
Posts: 42

@flyingelectric

I did post two pictures, I think they don't come up on a mobile browser but they are showing up on my laptop.

The regen issue was happening to me anyway, even with just the original battery, and it is very annoying, but short of reprogramming the controller (not within my capabilities!), I don't see how to resolve that problem.

As far as equalizing the batteries, I think it helps that I have a very similar capacity battery in parallel. When I tested the voltages, they were within 0.1V of each other, and I didn't notice the regen issue much at all on my test ride.

I'll keep an eye on this happening and keep the forum posted.

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flyingelectric
Posts: 98
(@flyingelectric)
Trusted Member
Joined: 1 year ago

Yes I saw them in my mobile browser only. Nice build. Good build pattern. What outside box or protection did you put on your battery?

I don't think you'll get any issue with equalizing or regeneration then. If the battery capacities where more different then this equalizing would happen more often.

Software and drivers can be updated by a reseller if they have the ability and the tools. I wouldn't do it as they may update other things as well like turning of mode 3 overdrive you know. I'm not sure what they update, in the France forum someone said they lost 2a in maximum power but really I wouldn't like to mess when something is working good enough

youtube video software update:
https://www.youtube.com/watch?v=pq8heYRwzU4

 

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1 Reply
socobelfast
(@socobelfast)
Joined: 2 years ago

Eminent Member
Posts: 42

@flyingelectric

I covered the whole thing in neoprene foam and wrapped that in gorilla tape, then covered the whole thing in heat shrink. I then have thick neoprene foam lining the cavity at the bottom, and for now I'm stuffing a jumper in the remaining space to keep the new battery from moving. Once I build the second new battery, they will keep each other in place.

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socomods
Posts: 90
(@socomods)
Trusted Member
Joined: 7 months ago

awsome ✌️

i am contemplating replacing the cells in my original battery, and considering whether or not these cells may be the way to go

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1 Reply
socobelfast
(@socobelfast)
Joined: 2 years ago

Eminent Member
Posts: 42

@socomods

The cells I used are 21700, which are larger in diameter. The original battery uses 18650 cells, so if you plan on using the same cells as me, you're not going to be able to fit them within the framework that holds the original cells in place.

If you are prepared to discard that framework, use offset packing, and rewire the original BMS, I think you could probably fit a version of my battery within the original case.

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