Chinese E-scooter. Battery and Controller upgrade

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nanoT
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Chinese E-scooter. Battery and Controller upgrade

Post by nanoT » Oct 14, 2017 7:30 am

Hello folks!
Have been hanging here a while, making my reading and looking at some amazing builds.
I bought an e-scooter for 8 months ago and I love this thing more than any other vehicle I owned. Put 2000 km on Odo already and planning to upgrade it to get a better range.

Here is what Ive got:
Chinese JIANGSU XINRI e-scooter, weight 90 kg.
Rider 90 kg, terrain with small slopes
Motor BOSCH 1000W (marked EJ580R60*eM and RBMBLEJ172210004)
TIAN NENG 6DZM20 Lead-Acid batteres 12V20Ah (6 pieces) connected to give 72V20Ah
10 inch wheels with disk brakes
Controller SINE MOTOR for PMSM. Rated 72V, max current 35 A. Protection 63V
DC-DC converter INPUT 48-80V. OUTPUT 12V-10A
- more details are on attached pics

I travel 30-40 km/h with median range of 25 km. I am quite happy with the speed but would like to increase the range to 40-50 km and make the battery pack removable - to charge in the office.
Now onto questions:
My idea is to upgrade the battery to a Lithium pack of 60V 30 Ah with Andersson contacts. Would it be sufficent? The motor is getting 72V now, not sure if the 60V will do. The problem is a huge price gap between 60V and 72V Li packs otherwise I woud get 72V.
Which Kelly controller would be suitable for this? There are plenty on Kelly website and I have no idea which one to chose. Is regen necessary? As I understod it gives 5-10% gain of range. KEB72301x?
I guess I can use the old DC-DC converter.

All help is much appreciated. I will post more as I will upgrade the scooter.
Regards,
Otto
Attachments
1.JPG
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the charger
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model plate
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batteries
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label under the seat
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hub motor
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7.jpg
controller
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8.jpg
dc-dc
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amberwolf
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Re: Chinese E-scooter. Battery and Controller upgrade

Post by amberwolf » Oct 14, 2017 2:04 pm

nanoT wrote:TIAN NENG 6DZM20 Lead-Acid batteres 12V20Ah (6 pieces) connected to give 72V20Ah
Controller SINE MOTOR for PMSM. Rated 72V, max current 35 A. Protection 63V

I travel 30-40 km/h with median range of 25 km. I am quite happy with the speed but would like to increase the range to 40-50 km and make the battery pack removable - to charge in the office.

My idea is to upgrade the battery to a Lithium pack of 60V 30 Ah with Andersson contacts. Would it be sufficent? The motor is getting 72V now, not sure if the 60V will do.
If you're happy with the speed now, keep in mind it won't be as high after you're done. Speed will be slower by the same ratio as the battery voltage is lower.

The slower speed by itself will give you more range, because it takes less power to go slower. (assuming you're going faster now than it will be capable of after the change).


You'd have to change the controller (don't know which kelly is good) because your battery pack's nominal voltage will be lower than the LVC (protection voltage) of the existing controller, meaning you'd only get to use a very small portion of the new pack before the controller shut down.


As to whether any particular pack will work, you first have to test on your actual ride how much current your system draws from the pack now. Then make sure the continous rating of the new pack is at least as good as that (better, if possible, for longevity).

If the new controller you're getting will make the system draw more current, then your pack also has to handle the new higher load, too. Until you change the controller and test the actual current draw, you won't know what that load is, though you can make some basic guess from the controller specifications. (I've had various controllers that are rated at a particular current, but either can't deliver anything near that current, or they supply much more than that rating even though they aren't supposed to).


To know if you will get the range you want, you need to know how many Wh (not just Ah) your system is actually using on the trips you take. You'll need a wattmeter to measure that.

You can divide that by how many miles (or km) the trips are, to find out the efficiency of the system. Then use that Wh/mile (Wh/km) to multiple times the new range you want, to find out the minimum Wh you have to have for that.

Then when you know the Wh, you can get a battery pack that is rated for at least as many Wh as you want for the new range.


The Cycle Analyst v2 (or v3 but you don't need it) http://ebikes.ca does all the readings above, including the wh/mile (wh/km) if you attach a speed sensor.

There's dozens of hobby RC wattmeters that do the other stuff, but they don't track the last one. (no speed sensor).

Chah
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Re: Chinese E-scooter. Battery and Controller upgrade

Post by Chah » Nov 09, 2017 2:17 am

I live in China, and I undertook a similar mini-project that you're trying now and came up with a nice solution. My original E-bike battery is 60V 20Ah SLA. I also wanted more range, more speed, more acceleration, and a removable battery to charge in office or in the apartment. For me, these criteria were met by buying a 60V 20Ah Li-ion and hooking it up in parallel with my existing 60V SLA battery. I wasn't sure at the start whether putting batteries of different chemistries in parallel would have any issue, but so far, I haven't had any. I charge each battery with its own dedicated charger. The 2 batteries will help each other reduce the current draw from each and the depth of discharge (assuming you recharge at the same frequency as before connecting the second battery) and should thereby increase battery longevity.

As was mentioned, going from 72V down to 60V is going to result in a drop in speed and drop in power (ie: poorer acceleration) and is probably not what you would like. I'm actually looking at trying to go from 60V up to 72V and I'm wondering if I can just change the battery without burning anything out. In your case, I understand your concern about the price of the 72V battery. You might consider these options:
1) Make your own battery from 18650 cells. There are some excellent tutorials online and on you-tube, I would recommend the ebikeschool channel. You get full control over the kind of battery you want and you can choose the cells and therefore control the final price. In the end, this should end up being cheaper than buying a ready-made 72V 20Ah battery.
2) Buy a 60V battery and a 12V battery and connect them in series. Connecting in batteries in series is a little more tricky (risky) than connecting in parallel because if the batteries don't have the same capacity, one battery is going to cut-out before the other and continuing to discharge such a battery is dangerous. So don't let the batteries go all the way down if you do this. Also I would recommend charging each battery with its own dedicated charger. Here is a cable that allows you to connect 2 batteries in series: https://item.jd.com/13936790374.html.

In my case, I didn't remove the SLA batteries from the bike, I left them where they were and bought a 60V20Ah Li-Ion which just fits under my seat. Using one of the above mentioned cables, I cut off the 2 female connectors and connected them in parallel (because I'm wanted to connect batteries in parallel rather than in series). I then plug one end of my home-made cable into the Li-Ion battery and the other end into the charger port on my bike. So it is like I'm charging my SLA battery on-the-go, using the Li-Ion battery to do it. I found my bike allows you to run while "charging". BTW anybody who undertakes something similar, be very careful to reconnect your cable plus-to-plus and minus-to-minus, and not plus-to-minus/minus-to-plus. Otherwise you'll short-circuit both your batteries when you plug it in which will be REALLY bad. Check it with a multimeter.

The Li-Ion battery has a fully charged voltage of 71.4, while the SLA is fully charged at about 68.5V. When they are connected in parallel, the voltage is higher and remains higher for longer giving me more acceleration and higher top-speed and better range.

Let us know how your modding goes. I'd like to know if you're successful and how it goes. Your bike looks similar to mine. I can't seem to find a lot of info in English on my bike...

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