jealousy

its easy to do it charges runs and charges all fine

That's great to here! I wish I were in Perth I'd definitely drop by your show and tell on how you did it.

Next up I'd love to see some side-by-side comparisons with a standard NiMH Vectrix. Yours should accelerate faster and handle better, right? How much lighter is it?

Congrats on this great project.

John;
The graph you refer to is not stating NOMINAL VOLTAGE, but the exact voltage as measured. I am trying to establish a common ground for discussion.

John wrote:
"I suspect the "manufacturer" quoting 60V nominal for your 20 cells is not the battery manufacturer".

Thunder Sky are the manufacturers of my battery and they list it as "DC 60V". The charger they supply is labeled "TSL-60"

Page 5 of the XM-3500Li Manual second line "Battery DC 60V, 40AH with LFP lithium batteries" What could be clearer?

All of the e-bike and scooter manufacturers list their packs as 12, 24, 36, 48, 60, 72 etc, whether they are LSA or LFP.
i.e. Nominal 48V LSA is actually 52.8V when the load is first applied and Nominal LFP 48V is actually 51.2V under first load.

A 12V LSA is constructed of 6 X 2.2V cells for 13.2V. The 2.2 is NOT THE NOMINAL VOLTAGE. It is the actual at rest voltage. 2V is the nominal per cell voltage. 6 x 2 = 12 which is the nominal battery voltage. In automotive use, it is not 12V under load but normally 13.8 to 14.2 as controlled by the alternator. It will go as high as 14.8V immediately after starting the vehicle. A 12V float charger puts out 13.75V until the battery will take no more current and then allows the battery to float down to 13.25V before kicking in again at 13.75V.

http://en.wikipedia.org/wiki/Nominal

The adjective nominal (ultimately from Latin nōmen, "name") generally relates to the concept of names, and often to the difference between what something is in name (ideally or theoretically) and what it is in reality. Thus it may refer to:

* Real versus nominal value in engineering - a value that is used as the name for an actual value which is close but not exactly the same.

All this from a dyslexic, high school dropout, who did manage to learn how to read (and type)!

Sorry, my assumption was wrong. You were referring to Thundersky documentation - I thought you might be referring to the bike manufacturer documentation. Shame on me for assuming stuff.

However, I still contend that, for engineering purposes, the most widely used nominal voltage for LiFePO4 is 3.2V. However, just to confuse things Wikipedia lists it as 3.3V per cell! (see http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery - see the table in the top right corner). When I googled "LiFePo4 nominal voltage" wikipedia was first and here are the next two: http://www.powerstream.com/LLLF.htm & http://evpst.com/Product.asp?Bid=17 Thise next two both list 3.2V as the nominal voltage.

I do agree with you that most ebike and escooter vendors use 3V nominal cell voltage when quoting pack size. However, I've seen at least one (if not more) attempt to use a maximum voltage (4.x V) when calculating the pack capacity - that's just plain wrong and the only purpose is to overstate the kWh pack capacity.

The trouble with "nominal" is exactly to do with it's definition: "a value that is used as the name for an actual value which is close but not exactly the same". Thus there is no "standard" for nominal value - only "commonly accepted practice". 3V per cell is a convenient value because it dovetails with lead acid and gives nice "friendly numbers" (no pesky decimal places) - thus marketing "commonly accepted practice" is to use 3V per cell. 3.2V is convenient because it more closely represents the voltage the cell will put out for the majority of it's discharge cycle and engineers care more about having a value that is closer to reality and hence better for their purposes.

So, we're both right...

;-)

A 12V LSA is constructed of 6 X 2.2V cells for 13.2V. The 2.2 is NOT THE NOMINAL VOLTAGE. It is the actual at rest voltage. 2V is the nominal per cell voltage. 6 x 2 = 12 which is the nominal battery voltage.

The 2.2V / 13.2V is the resting voltage for a fully charged cell / battery.

However taking a C/20 load (most lead acid batteries capacities are quoted at this rate) then the numbers will look something like this:

100% charged / 0% discharged = 12.6V
50% charged / 50% discharged = 12.25V
0% charged / 100% discharged = 11.5V

Further if you look at the curve it's not linear - but drops off faster towards the end of charge. Also taking into account other higher discharge rates folks end up choosing 12V as the nominal value.

I got this data by googling "lead acid discharge curve".

Note how the discharge curve is much flatter with LiFePO4 than with lead acid - this is one of it's major advantages (and an advantage it shares with NiMH).

In automotive use, it is not 12V under load but normally 13.8 to 14.2 as controlled by the alternator. It will go as high as 14.8V immediately after starting the vehicle. A 12V float charger puts out 13.75V until the battery will take no more current and then allows the battery to float down to 13.25V before kicking in again at 13.75V.

Agreed, in automotive use you don't run you accessories from the battery - you run them from the alternator. The alternator is responsible for putting out enough power to run the accessories AND charge the battery. Charging different chemistries is a different topic than "nominal" values.

In addition to the Thunder Sky documentation I also clearly referred to the bike manufacturer's documentation on Page 5 which says "DC 60V"
You seem to have a huge problem with making a mistake? You have an XM-3500. Look at your manual.

In addition to the Thunder Sky documentation I also clearly referred to the bike manufacturer's documentation on Page 5 which says "DC 60V"
You seem to have a huge problem with making a mistake? You have an XM-3500. Look at your manual.

Wow. Sorry if you think I have a huge problem with making a mistake. I don't think I do - but you may be right. However, did you read the opening paragraph to my last but one post. The one where I explicitly apologize for making that mistake? As far as the reference to XM-3500Li documentation then I'm sorry but I don't place very much faith in that documentation. Sorry, but I've had several XM bikes and the documentation can best be described as "spotty". It might be getting better.

I thought you were interested in learning why many people use 3.2V as the nominal voltage for LiFePO4. That's what I was attempting to explain. If my explanations somehow offended then I apologize.

I'm not looking to pick a fight - if you'd like to respond to why you believe that the numerous references to nominal cell voltage of 3.2V are wrong then I'm happy to continue to discuss.

Sorry to antiscab and hebbahellfire - I didn't mean to hijack your thread. It happens some times.

Back to the LiFePO4 powered Vectrix - a great and very exciting achievement !!!

This is the problem as I see it;
I referred to the 40 LFP cells in the Vectrix as NOMINAL 120V
You corrected me that 40 cells are NOMINAL 128V
You are therefore ignoring the meaning of the word NOMINAL and the industry standard description.
I pointed out that my battery manufacturer AND MY SCOOT MANUAL list 20 Cells as 60V
You say you thought I was referring to the battery manual not the scoot manual. It helps to read what one wrote when responding.
Several times you get off track, bring up and refer to cell voltage as 3.2V. Cell voltage is not under discussion. NOMINAL PACK VOLTAGE IS.
The industry standard description is 60V NOMINAL.
You not liking your manual has no bearing on anything. If you want to refer to a cell as nominal 3.2V I have no problem with that and never have had. If you insist on trying to establish that the industry standard nominal voltage for a 20 cell pack is therefore 128V, that does not fly. There is simply no support for this idea, including the many references to 3.2V as a nominal cell voltage. Nominal voltage for automotive, marine, aircraft, trucks and even scooters follow the convention of 12,24,36 etc. And yes my Hawker aircraft had 18V batteries.
If we refer to the LFP pack in the Vectrix as Nominal 120V everyone in the scooter world will immediately know it has 40 cells. Perhaps, I am wrong with this statement? Perhaps one person will not be able to figure it out because they are confused between nominal cell voltage and nominal pack voltage. I will leave this decision to the community at large. When it adopts a new nominal pack voltage description, I will quickly follow the convention so I too, may be clearly understood.

original reply deleted by author...

WOW.
Am i seeing things.??????

how nice a vectrix with lithion-ion.??
cells ?? what when where how much how easy how log to do and whats the bms look like and etc etc

nice run down ..

tell us more .
kev

Kevin;
Here is one source I have found for the cells and BMS;
http://elitepowersolutions.com/products/index.php?cPath=16&osCsid=367e1caf22a0f49ef1ff64956a4d9678

Thunder Sky are available from many different sources and I was happy to find them available locally from a GP Battery Dealer. GP are not some no name, no address, no phone number, FOB Hong Kong website, but real people who give you a fair price and you can walk in and talk to. With so much grief dealing with freight damaged parts and customer service problems, I like doing business the OLD way.

this is th bms used by hibba

http://evworks.com.au/tech/EVPowerBMS/

simple and effective, seems very popular with EV convertors using thudersky cells in Australia

Reid, if as you say yourself the word nominal means approximate, then a pack can be described anyway you want. It's a convenience to describe it in multiples of three, it's more accurate to describe it in terms of multiples of nominal cell voltage. Both are nominal values though, so fit your description as an approximation. I wasn't aware of an industry standard and I describe my 26 cell pack as nominally 84 volts, even though 84 = 28 x 3, and is not an exact multiple of 3.2V.

An interesting Thundersky manual I have not seen before

http://www.thunder-sky.com/pdf/2007030222.pdf

i will do the side by side run and tell you how well it goes its 26kg lighter
should make the 0 to 80 quicker than standard specs

That would be cool Hibba, thanks.

Also interested in the range. A useful test for me would be constant 80km/h from full battery (3,6V per cell) until either the BMS flags a cell down to 2.5 or the Red Battery light, what ever comes first.

DaveAK;
You can describe your pack of 26 cells anyway you want. I think the question you should ask yourself is what someone reading your description understands from your 84V tag. Do they immediately say "oh, he has 26 cells" or do they say "what the hell does this mean?" Do people understand what you have done better because you say 84V or would they have a better understanding of 78V? The choice is yours.
The concept of nominal is not to accurately describe VOLTAGE. It is to follow the convention of approximate value. This has nothing to do with me, or my choice. Someone in their wisdom, long ago, decided to call 3 X 2.2V cells LSA 6V and for the most part the convention has been followed with 12,24,36 etc. The vast majority of EV's and battery manufacturer's have standardized their descriptions of the battery pack, controller and motor, to go along with this convention. I don't see automotive manufacturer's advertising their electrical systems as 13V, 14V or 14.8V, all of which are valid, and I don't think listing EV voltages as goofy numbers to puff up a product, makes any more sense.
How do you compare two scoots when the first says 60V and the next 64V for the identical battery pack, charger and controller. What purpose does this serve, other than to confuse the customer. When you begin by advertising something with less than 5% of the content, as Made in America, I find it dishonest. When you start from this point, it only follows that you should distrust all the other data in the description. When you import a container of parts from China and assemble them in Mexico, does this make it a Mexican scooter? We saw this discussion so many times with Harley Davidson vs Honda Goldwing. The last time I checked Harley was 49% and Honda 51% made in USA. I don't go along with this made in the USA BS and am not amused when after waiting 6 weeks for a set of piston rings, they come in a Honda box labeled "made in China," The same goes for the parts of a "Designed, Engineered and Manufactured in America" EV. The Vectrix fiasco didn't teach us anything. We are all sitting in line with our checkbook, waiting for the next one.

p.s. I'm very happy to have a Chinese made 60V scooter. It goes well, goes far enough on a charge, and I know where to get parts for it.

this wednesday i should have it finished will do that test for you 80km speed
bms goes off at full charge @3.66 volts
i still need to add 2 more cells waiting on them to come from china
does any one know can i change the settings off the standard charger it just ramps it to 154 volts and cuts out theres no slow charge at the monment with standard charger?

Hi Hibba,

I think changing the charger parameters are going to be so difficult as to not be worth it.

Have a chat with Xvectrix on this forum, very knowledgable and helpful fella.

Have you got the 240V supply to the charger interlocked through the EVworks BMS?

Do you have any indicatiion on your dash to show that the BMS has tripped low voltage? I think the stock controller red battery lights when the pack can't deliver 7.5kW (70A @ 108V, but please becareful of these figures, just remembered hear-say...) that would be at about 2.7V per cell with 40 cells, 2.57 for 42. That is with the "old" software though.

The 155V supplied by the factory charger looks to be just about perfect for 42 Cells (3.69V) Enough for balancing but not enough to hit the 4.1V cutoff if the pack has anything like a reasonable balance to start with. 42 cells does seem to be a really good match for the factory charger and controller settings.

"it just ramps it to 154 volts and cuts out theres no slow charge at the monment with standard charger?"

Doesn't it do the "EC" part at 3A?

Is it your BMS that cuts out at 154V or the stock system?

It might be that the stock system is expecting an empty battery and wants to continue charging until the hourglass shows 16/17th full. Then it would reduce the charge current.

You may need to match the battery SOC with the SOC which the stock system expects.

What does the display show when it's at 154V?

the BMS will trip if a cell hits 4.1V.

that might be happening at 154V if the pack is very unbalanced

But I think your scenario is more likely mik.

It will be interesting to see if a complete dischage of this lithium pack triggers the red battery light and "fuel gauge" reset.

its ramming 10 amps in until the pack reaches 154 volts and the stock system kicks in and stops charging
there is no 3 amp charge, all the way its 10 to 11 amps and stops whitch is ok it charges the lith ion pack
pretty quick about 2 hrs charge from empty it reaches 140 volts and then in 5 mins its to 154 volts and shuts down .
i havent had the ev works BMS kick in yet as the stock system has been doing all the work.
and iam talking only about 40 cells in all this things may change with 42 or 44 cells
i wont do full distance testing untill i get the other two.
but i will take some photos for you all on tuesday .
its almost there .iam just thinking what number plate to put on it .( lith ion ) may be, or RUNSONSUN
i have a 4.3 kw solar system grid conect
hibba out

no i think its 102 volts that happens i did my own testimg with a voltage gauge hooked up 102 volts bulslue coms up with battery light
but your right 42 cells is the magic number live and learn

how about SOL ONE (your not too young for the Paul Cronin ref are you :) http://www.classicaustraliantv.com/mpsolooneeps.htm )

2hrs at 10->11 A is only 20Ah into the cells.

That sounds to me like what Mik was saying, that the charger thinks that the pack is at a much lower state of charge than it actually is and is trying to put in more than the battery can take. Are you certain the pack was empty?

Not surprised the EVworks BMS hasn't tripped yet. The numbers, even on a 44 cell string, look like the factory systems cutting charge and discharge before you hit the safe limits for these cells.

Thanks for your help, very encouraging to see what you've done.

I will try to catch up with EVworks this week about supplying the components to do this with the Sky Energy cells, don't tell the mrs :)

102 for BusVLT, nice to know.

That is actually a bit worrying, 2.43V per cell on a balanced 42 cell pack. The TS cells are spec'd to a minimum of 2.5V. the SE cells 2.0V. Maybe they will handle it better.

The BMS should alarm with the BusVLT

I always thought TS cells had a minimum discharge of 2.5V until I received a personal email from TS China saying "2.2V will not hurt anything."

Then I read the TS manual which states as follows;

"The discharge voltage of LFP battery can be 2.0V~2.5V, which is not harmful to LFP battery."

In discussion with the local supplier of TS, GP Batteries, they said with a good BMS you are safe at 2.0V per cell but, to be safe without BMS, stick to 2.2V X number of cells, if you are only checking total pack voltage.

The TS PDF manual is on this website under Handbooks.

I've just upgraded my bike (SakuraS50/Erato04/EfunA) from SLA to LiFePO4 and the flatness of the discharge curve is very noticeable. Now you get exactly the same performance at the end of the trip as at the start, whereas on SLA the top speed and 'nip' both slowly decline during a run. This does also mean that the simple voltage-meter 'fuel guage' doesn;t do anything much until the batts are nearly empty.

On the nominal voltage thing I'm with jdh. In practice there are two different LFP 'nominal' nomenclatures in use. One for marketing/sales, and one for engineering. As Reid observes, bikes tend to be sold as '48V' '60V' '72V' etc, whether SLA or LFP, but anyone talking about LiFePO4 packs in an engineering context, e.g. on endless sphere, uses the cellsX3.2V nomenclature. These are both valid nominal voltages. So my now LFP-powered bike is still a '48V' bike, not least because of its heritage, but the 16S3P pack is 51.2V nominal. Reid250 doesn't seem to like this, but it's still true. It may be that over time the 'marketing/sales' usage will win out as it's undeniably convenient, and even engineers will give up on their current usage. We shall see, but trying to tell people that people using the cellsx3.2 nominal values don't know what 'nominal' means and are 'wrong' is just silly.

Oh, and Hibba, would it be too much to ask for a little punctuation in your posts? They are awfully hard to read. Nice job on the conversion - I'm slightly surprised it's taken so long for someone to do this, given how much moaning there has been about the stock battery.

iam just a simple man and not very smart but i can lift heavy things.

Please read what I wrote;

"I think the question you should ask yourself is what someone reading your description understands from your 84V tag. Do they immediately say "oh, he has 26 cells" or do they say "what the hell does this mean?" Do people understand what you have done better because you say 84V or would they have a better understanding of 78V? The choice is yours."

"I have no problem with 3.2V cell voltage."

If one seller describes his scoot as 60V and the next seller with the identical battery states 64V or 68V is the purpose to make a fair comparison or to mislead? Who does it serve? This is a new industry, with 95% of the eventual customers still to come along. The point is not to create confusion for these customers. I don't care what nominal 60V refers to. I do care that everyone, both old and new to EV's knows that it means 20 cells, not maybe 18 or 19. If understanding a product becomes a science, a lot of customers will walk away. I think it is in the industries best interest to stick to the nominal voltages adopted by the major manufactures and not try and puff up their products by using number of cells X 3.2V.

THE CHOICE IS YOURS!

But people already make '60V' mopeds with both 20 and 19-cell packs. '60V' in a moped/e-bike designation means 'equivalent to lead-acid 60V' or 'somewhere near 60V'. You can do that reasonably with either 19 or 20 cells. Those packs have nominal voltages of 60.8V and 64V respectively. There is nothing magical about the '60V' designation that requires the bike to have 20 cells. Ultimately consumers probably don't care that much - they'll both work, the 19-cell will be a tad cheaper and a tad slower.

So using the prices from http://www.evcomponents.com/ProductDetails.asp?ProductCode=TS%2DLFP40AHA for batteries and the site you listed for balancers, The total cost in US is a little under $3000.00, If you can get your Vectrix up to 60 miles of useful range (I get 25 miles of useful range out of the stock pack.) I will definitely upgrade mine! I hope you plan on making a web site with a step by step once you have all the kinks worked out! Thanks so much for the fantastic pictures and updates.