Emax Li-ion conversion

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rgx
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Emax Li-ion conversion

Here's my new project
emax_li_ion2.jpg
I will write more about it soon, it's not ready yet but it looks promising.

Some preliminary data
14 x 50 Ah cells
50.4 V voltage
Weight of pack 22.4 kg (33 kg less than OEM)

I haven't increased power yet as described by PJD, but I should be able to pull up to 150 A if necessary. I am leaving the controller unmodified a while.

Regards,
Rolf

JDELUNA
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Re: Emax Li-ion conversion

I like :) I like :) !!! Please tell us more information when you can !!! Wow almost a 75 pound weight savings :jawdrop: !!!

Also do you lose any of your underseat storage area ?? What is the size of the cells and how much are they if we want to purchase them too ?? Thanks for any info. God Bless :)

PJD
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Re: Emax Li-ion conversion

...yes, the cost?

I suppose the krona is high relative to the dollar over here...

thekausthery
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Re: Emax Li-ion conversion

;) Awsome man, your pulling 150 Ampers?
I 'm fairly new to this and I'm real excited about Electric Bikes/ Cars/ just any mobile Electronic$. Hey, by the way I'm Brandon, I'm from Amarillo, Tx. My Old Boss was working on something of similar, proportions,; he was working on an electric car, so I find this to be spectacular You should E-mail me back if you find this to be very entertaining... Bye,

P.s. Love the sock pic...!!!!!!!!LOL...

rgx
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Re: Emax Li-ion conversion

All in all I have spent around 3500 USD (plus the scooter). That's a lot of money and I can't argue that it's worth it. The cells are about half of the total cost, and you can't get them much cheaper. The rest is for BMS, charger, transport and other stuff you need (cables, tools, etc.). It should be possible to make a BMS far cheaper than what I spent, but I decided I didn't have the patience to wait or build my own. The BMS is from Reapsystems (UK), and they can really be recommended. If you want to learn more about li-ion, visit their site www.reapsystems.co.uk

On the other hand, if durability and performance is anyway near what people report about these cells, they should last for years, and during that time give consistent range of up to 100 km (assuming 80% of nominal capacity is used). I made a test drive yesterday of 44 km, and used 19 Ah. The e-max charge meter was pegged to the top, only at the end of the ride when using turbo did it move briefly into the green area.

The reduced weight also brings a few advantages. It improves performance, together with the slightly higher voltage I estimate it to around 20% faster acceleration and hill climbing. Rolling resistance and power consumption is reduced, as well as handling and braking.

Some of the under-seat space will be lost. The installation isn't ready yet, but the plan is to raise the floor of the "bucket" around 35 mm, so it won't hold a helmet anymore. If it is really needed, a top-box can be added - which I want to avoid though.

To clarify the current draw, the controller is (still) unmodified, so it takes around 40 A max, or 72 A max for up to 90 s, when the "turbo" button is pushed. During the test drive, the cells heated to around 40 deg C, so I guess around 40 A is max continueous without forced air cooling.

The sock is there only for comparison of size. :-)

Regards,
Rolf

JDELUNA
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Re: Emax Li-ion conversion

So does it look like there is any more room to put 2 or 3 more cells to make a 60 volt pack ?? Also you are expecting 100Km range ?? Wow that would equal about 60 miles and would be great if that were true :) God Bless :)

Kmullee
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Re: Emax Li-ion conversion

Very nice RGX, are those Thundersky cells and what are you using to charge them?

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

rgx
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Re: Emax Li-ion conversion

The cells are Thundersky TS-LCP50AHA, LCP meaning the cobalt-based electrodes. The charger is a Piktronik KOP601, a version that is configured for use together with the BMS. The BMS controls the charger via a PWM signal. (Simple solution, but it works fine.)

And yes, it would be possible to fit another 10 cells under the seat.

VT-01
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Re: Emax Li-ion conversion

Hi Thekausthery,

Welcome to the V-is-for-Voltage Forums!
We have another user or two from the great state of Texas.

Welcome Aboard!!

RGX - Those sure are some purdy cells, I bet you might change your mind about them being worth it when you find that you are able to make those long trips ... ;)

Regards,
VT-01
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PJD
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Re: Emax Li-ion conversion

I could never justify the $3500 cost to the "other" member of my household.

Can you give any information on the cost of the individual components? In particular, the Piktronic programmable charger: http://www.rectifier.co.za/Catalogue/Manual.PDF seems to be an impressive product. What did it cost?

rgx
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Re: Emax Li-ion conversion

Don't get me wrong - I am all about sharing information on this forum - but since I don't represent Reapsystems I am reluctant to give you the pricing details. You better ask them for a quotation. Then again, the charger is a special version, for use together with the BMS. I guess the standard item (to use with SLAs) would be around USD 300 + VAT + freight. It's difficult to tell, pricing is not exactly transparent over the Atlantic. (Sometimes I have a feeling that for any given product you pay as much in dollars as we pay in euros, or even pounds in some cases. For instance, if I translate the price I paid for the e-max, at today's conversion rate, I paid USD 4000 - including VAT. Plus another USD 140 for an extra charger.)

And yes, the Piktronic charger looks and feels solid. I will keep you updated on its performance.
http://piktronik.tovarnaidej.com/index.php?lang=eng

founder
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Re: Emax Li-ion conversion

33 kg less will make driving in the mountains also more easy.

With 2 persons ans luggage can be soon a thermal shut down of the engine

http://car.pege.org/2007-e-max-s/thermal-engine-switch-off-05221.htm

jdh2550_1
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Re: Emax Li-ion conversion

This is great - this is exactly the sort of mod I want to do to my XM-2000 when I get it.

If you have time please tell us your real world results.

All the best.

John H,
EV Wannabe
Ann Arbor, MI

John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.

rgx
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Re: Emax Li-ion conversion

After 6 months and 2500 km it's time to summarise. I will start with describing the components.

Batteries
Cells are 14 TS-LCP50AHA, with nominal 3.6 V and 50 Ah capacity. Nominal pack voltage is 50.4 V, slightly higher than SLAs. Maximum charge voltage is (@4.25 V) 59.5 V.

Cells are 116x190x46 mm and weigh 1.6 kg, in total 22.4 kg. (OEM SLAs weigh around 56 kg, so thats about 33 kg weight reduction.)

BMS
The BMS is from Reapsystems (reapsystems.co.uk).

The BMS is delivered as an assembled printed circuit board, without casing. A lot of wiring and connection was required to get it work. I also had to fabricate a simple connection board, hosting fuses and resistors that are needed for protection and voltage division.

All settings in the BMS can be configured via RS232. The RS232 output can also be connected to a small on-board display (not installed yet).

Charger
The charger is a Piktronik KOP601 500 W 48V charger, configured for charging lithium cells, and for control by the BMS (simple PWM input). The BMS controls the complete charge process. Maximum charge current is 9 A. Charge voltage is set in the BMS.

Mechanical installation.
You see the battery configuration in the top of this thread. It is very important to prevent swelling of the cells by keeping mechanical pressure on them. I used threaded steel bands for this (similar type used for clamping water hoses and rubber tubes in cars, but in 5 m length that could be cut to measure). The 2x5 cells in the lower box are clamped using the pressure plates that were delivered with the cells (OEM TS plates). The 4 cells in the top, rear box are squeezed into the box, then pieces of wood push on the outside of the box - using the same type of threaded steel bands. This is still not 100% perfect, and two of the cells in the top box deviate slightly in voltage from the others. I suspect it might be related to the pressure, or the temperature, or that they are tilted slightly. Not sure.

Electrical installation.
I kept the e-max wiring as far as possible, and have basically only connected all of the minus cables to the new minus pole of the pack, and all the plus cables to the current shunt. The other end of the shunt is connected to pack's plus side. The special e-max arrangement with the relay box and all is still there - and seems to work fine. I use one e-max charger port for charging (broke the other during the installation). Then there is all the wiring to the BMS. 14 voltage sensing/balancing wires - with separate fuses. Power supply. 7 temperature probes (2 wires each). Current sense. Charger interface. Input from the ignition - so that BMS knows when bike is ON. And finally, a PWM output that regulates throttle down when charge level or voltage is too low, or temperature is too high (hasn't happened yet).

rgx
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Re: Emax Li-ion conversion

Performance.
The reduced weight does improve performance a lot, both acceleration and up hills. I don't recall any longer how the scooter felt with SLAs but I do remember being surprised of the difference. Also other handling such as braking and cornering improves slightly.

Voltage starts higher and stays higher than for the SLAs throughout the discharge. Voltage drops significantly only at the very end.

The performance is reduced heavily in low temperatures though. When the cells are cold, internal resistance is higher and voltage drops at high currents. The effect can be noticed below 15 deg C, and then increases gradually until at 0 deg C turbo mode can't be used. When driving, the batteries heat up slowly by themselves so the impact is worst for short distances. In fact, you only notice the effect when leaving the scooter outdoors for longer time. (Mine is parked in a heated garage.) As long as you keep driving the batteries will keep warm and give full performance.

The effects of low temperature and low charge level are combined, so it's worst with low charge and low temperature.

Range.
I was a bit too optimistic at first. I measured range to about 70-80 km when driving slow (40 km/h). I haven't done any range testing recently, for several reasons. First the low temperatures - affecting battery performance, secondly the constant raining lately - routes are always wet which affects range and thirdly the odometer wire/gear hub skips when cold so I'm not sure the distance will be correct. I will do some testing later, to be able to compare with the tests from last summer.

I have set the charge level to 4.10 V to reduce aging of the cells, which means they are not charged to 100%, but rather to perhaps 80-90%. Maximum charge level is 4.20 to 4.25 V, which would allow a few more Ah to be stored (and released at higher voltage for the first part of the discharge). 4.10 V gives more than enough range for my daily driving.

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