Vectrix Lithium Conversion Kit

I've been considering sending my scooter over to you for a conversion.

If you PM me your suburb and city, I can quote shipping each way via a friends transport company, depot to depot.

I happen to have enough cells and other bits to convert a Vectrix on hand, incidentally.

Obviously I gain range, but what do I lose in this conversion? Do I still have the 'fuel' gauge? Can I still pull the left lever for voltage and battery temp? Can I still get delayed charging? <--Do I still even need that? Is the charging process still fully automatic with systems taking care of the condition of the battery etc? Is there anything that stops working at all?

The fuel guage works as originally intended.
The estimated range becomes rather accurate as the energy per bar is much the same for the first and last bars (because we're not using the full capacity of the Lithium batteries).
You still get both temperature and voltage when pulling the left lever with kill switch on.
Theres less variation in voltage across the pack aswell, due to radically decreased self discharge.

The only piece of the process that is not automatic is you will need to press a reset button to start every charge.
aside from that, you set it going and just walk away, much as you would now.
The BMS prevents the charger from overcharging the battery.

I think you mentioned before that there are 3 different battery options,some of which just fit and others which needs modifications. Can you elaborate on that please?

The original Thundersky 40Ah cells were a match in heaven for the Vectrix.
luckily, the Thundersky pioneered the large format lithium industry, so every other manufacturer makes a cell in the same physical dimensions.

thus the kit is exactly the same for all cells fitting within 190mm x 116mm x 47mm.
Those cells are:
CALB 40AH
Thundersky 40AH
CHL 50AH

I'm assuming that, like now, everything is onboard and whereever I go, I can plug in if needed.

correct

I'm getting 35km now. I really want 50km. I'd LOVE 70-80km so I just never have to think about range again! Are these batteries happy with constant top ups or is there still merit in managing them with running down to redlight etc?

Don't go to red light, theres no need.
just charge whenever the oppurtunity presents itself.
If you have a very reliable range requirement that almost never deviates, you can aim for arriving home each night with a flat battery (few remaining bars) to take advantage of off-peak electricity (its a rare day indeed I charge during the day).

range happens to be reliabley 50km on 40Ah cells (actually just using all bars, which means using just 32Ah).

If using 50Ah cells, you can go past 0 bars more safely (though still flying blind).
I'm working on jigging the original fuel guage to read a capacity greater than 32Ah.

The bike from the outside looks completely stock.

Pictures to follow soon.

Matt

We have container shipped to Australia 3 weeks later,if you order from us,the sea freight would be free of charge.

Thankyou for your kind offer, I will be in contact

Matt

If you use CHL battery,I believe the top speed would be at least 5-10km/h quicker than Thundersky or CLAB because of impedance difference.

The Vectrix top speed is actually limited artificially in software to 115kmh, regardless of battery voltage.
The higher battery voltage at load will mean slightly increased range though.

The major advantage I was looking at is the 25% greater Ah capacity :)

to properly fill the battery box, 42 cells must be used, otherwise a spacer is required.
fortunately the controller will run with battery voltage up to 160V

Matt

most chinese scooter use hub motor directly drive,and top speed is effected by top voltage,so that effected by group impedance too.

true,
advanced motor controllers use what is called field weakening to get around voltage top speed problem.

They apply voltage slightly out of phase with motor rotation, to induce a current in the field permanent magents.
The induced current creates its own field, with is opposite to that of permanent magent.
The reduced field strength results in lower motor voltage, allowing increased top speed.

Vectrix vx1 starts this at 70kmh when battery voltage is 120v (top speed 115kmh)
Vmoto/Emax 110s starts at 45kmh when battery voltage is 48v (top speed 70kmh)

The controllers that can do this are expensive, meaning it is still economic to simply use lower voltage motor and more powerful controller.

Matt

My Vectrix is approaching 3 years and is past 11,000 km. My battery pack is causing problems with reduced range. I pretty much only use it for my commute (<20km round trip). For the past couple of months I've been coping by charging every night. (I have the old system - my Vectrix doesn't have it's own timer but I connect it to a timer and charge for a few hours in the night.) The last couple of days I'm now getting the red battery light after about 6 or 7 km. When the light comes on almost all the bars on the battery gauge are still showing and the bike still seems to run OK. I'm worried the red light means I my Vecrtix may not keep running for much longer?

I know very little about batteries but after reading posts on this forum, I guess I must have a bad cell or cells.

The idea of conversion to a newer battery system is appealing. The costs you mention in your posts are not out of the question for me. I am very interested. I will keep an eye on the discussion.

its not so much the distance or age that causes problems, rather how often the cells are pushed to their limits (my own nimh pack was 13'450km before conversion with no issues, but had new firmware from the beginning).

out of curiosity, why were you not charging everyday?

With the old software, the red battery light merely means the battery voltage is under 115v (IIRC, it could also have been when voltage was 108v meaning the controller is in low voltage limit, I forget).

does the red battery light stay on?
if it only comes on during acceleration, than the situation is not quite as dire as you may believe.

A bad cell or two will mean very short range, and poor acceleration.

if you are still able to make the 20km round trip, the batteries end of service life may be a bit further off yet.

I think 42cell of 50AH lithium battery will be enough to give double range than original vectrix with NiMH battery. Because it is much lighter on weight,which might reduce too much range lost.

yes and no,

Regretably I did not encounter reduced energy use per km measured at the battery in conversions just finnished,
The amount of energy used to overcome rolling resistance is small in comparison to the amount of energy used to overcome wind resistance.

Thus decreased weight has little effect upon energy used per km, at least when travelling above 60kmh.

The 40Ah cells being able to supply 32Ah (full bars) while the nimh only being able to supply 15-20Ah reliably does mean almost double the range.

I prefer to represent the range after conversion as:
70km @ 60kmh
50km @ 100kmh

readers can compare to their own bike

How does the life of the Li battery compare to what we have now? I haven't mistreated mine (on purpose, at least) yet it's down on range by about 20%.

Also, if my current battery WAS once 40ah, forgetting about the fact that it probably isn't now, why would a 40ah Li be better (apart from actually being 40ah)?

Is 40ah and 50ah the only option?

The original Vectrix battery is 30Ah,
the only time you are ever able to get that (IE go to 0 bars without red battery light) is with a pack composed entirely of good cells, immediately after a full charge and equalisation.

In practice, I found max usable capacity to be 20Ah (remembering my battery had worst cell 29Ah).
forcing equalisations everyday in case I needed the extra range I found impractical, and caused significant heating.

at present 40Ah and 50Ah are the only options.

I am working on a 70Ah solution, however, it is far more complicated.
The likely cost for that additional 20Ah is either an additional ~US$3500, or an additional US$1500 and a bike that is no longer water tight.
Due to the development involved, and my own limited resources, I may not complete the 70Ah kit, time will tell.

Matt

Hi Guys,

Thanks for the messages of support

Great job on the conversion. When my original batteries are dead - for the moment they are not too bad - I will be ordering one of your kits.

This seems to be the case with most owners,

It is hard to justify replacing a battery that still does the job, and rightly so.

At least it means demand will be steady, rather than huge peak than nothing.

update:
The kit now includes Ideal Noalox anti-oxidant paste (actually it always did, I just forgot to add it in the initial post).

Matt

Anyway my point is that they mentioned to me a new charger was over 1200 Euros. If my charger dies (again) I will do the full battery and charger upgrade from Matt. It makes no sense to sink all that money into a battery technology that will give more problems later on.

Hi Jonathon,

The kit doesn't come with a new charger, instead it makes use of the existing one.
This is necessary to make sure the original fuel guage and range estimate still work.
actually the range estimation becomes accurate, so an improvement there.

The original chargers were expensive, however, they are no longer used for replacements (except second hand I suppose).

The new chargers are manufactured by Runke, and cost ~360E

as far as I know its a straight swap, but I have yet to need to order one.

Hopefully there are many bikes out there that can be brought back into service economically.

Matt

Where do I send the check?

I plan to put the kits on ebay, at least initially, as they have a good checkout system, allowing people to use their credit cards (recoverable funds).

heres some pictures from the conversions:

The bits made of wood on the prototype will be made of polycarbonate in the actual kit.
The polycarbonate battery rest between the top and bottom layers is visible in both pictures.

This one shows the only piece of cutting you would need to do using the kit.
The original fan cover needs a piece on each side cut out so the top layer of cells will fit.
A combination of angle grinder and jig saw were used for the prototype.

This is the only part of the bike that will look not stock from the outside.
Its the reset switch for the BMS, and hides in an unused spot underneath the seat.

The full storage area is retained.

Matt

What about parking in the sun? Will the differential temperature between cells cause imbalance?

How much imbalance will a temperature difference of 15degC (45degC vs 30degC) for 16hrs/day cause

The short answer is none - LiFePO4 cells do not experience any self discharge.

There are secondary reactions that will cause self discharge, however, they also cause capacity loss.
They aren't really part of the normal operating conditions of the bike.
There are two conditions that the BMS won't prevent:

if a cell reaches 74 deg C, the LiPFH6 in the electrolyte starts to boil causing capacity loss.
I have never seen any battery on my bike reach this temperature, even out in the sun.

if a cell gets over discharged, micro-shorts will start to form internally.
given that 0 bars occurs when there is 8Ah remaining, the only way this could really happen is if:
1) the bike is rode until it basically stops, *and* there are cells that are low on capacity.
2) if the bike is left sitting for a long period of time, such that the self discharge causes complete depletion
3) or a combination of the two

The lack of self discharge is something that took a long time to get my head around, as the (revised) datasheet says <1%/month.
The original datasheet did not list self discharge, I used to think it was because they had not measured it.

It turns out they had measured it, and the total self discharge in the lifetime of the battery was less than the total capacity loss (incredibly hard to measure without the measurement equipment affecting the results)

indeed the original datasheet resulted in the sales staff spending so much time on the question "how much self discharge"? that the engineering staff eventually made up a number to put in a revision of the datasheet.

It was pretty much a case if they put in a number that was too much of an improvement, it would sound too good to be true.

I sure didn't believe it, until I saw it.

I have had cells sit on my shelf for months with no measurable self discharge, thats after they had been used and abused.
Indeed the spare cells from my first batch (2007 production date) measured no self discharge in over 2 years, those cells had never been used.

The self discharge is always due to the external circuitry.
In the case of the kit, the main sources are:
pack level:
Vectrix controller/charger (7-8mA)
BMS master (1-2 mA)

at the cell level:
BMS modules (5-10 mA) (falls to 0 when cell voltage goes below 2V)

As the BMS modules don't draw precisely the same current from each cell (partly because they are LEDs, partly manf tolerances), balancing resistors are necessary.

The BMS is there in the first place to prevent the charger from overcharging the whole pack when it locks up occasionally.
This doesn't happen all that often, I saw it happen on my Vectrix while I was still running my nimh pack 3 times in 14 months.

Basically it stays in the CP stage forever, and both reported temperature and voltage cease to reflect reality.

A nimh battery just quietly converts the overcharge into heat.
I don't know what would happen if it continues for hours on end.
I caught mine all 3 times while I was at work, so the most it could have gone on for is 2 hours, when it is night time and there was significant cold air to dissipate the heat.

After the first time I started using a timer at home to terminate charge just in case.
At work my shift was only 5 hours long, and I would only let it charge for the last 2.5 hours of my day, so it was never really much of an issue.

back to the lithium:
if you ran the charger without a way of making sure the it would shutdown when the battery is full than at best a locked up charger condition would result in a decreased capacity battery. At worst, a Lithium fire.

As an aside, when the LiFePO4 battery reaches full charge when everything is running normally, the pack voltage reaches the chargers voltage limit, determined from the battery temperature and nimh charge profile. (CP xxx, CC xxx, EC xxx).

As it happens, all the voltages the original setup charges to fit within the final voltage charge termination window of a LiFePO4 battery (3.45v - 4.1v).
The CP stage has a bit to high a current to simply stop charging at (battery not yet full) when this voltage is reached, but fortunately, the original setup just moves on to the CC stage.
3A or even 1A is fine as a charge termination current (IE 1A or 3A @ 3.45v and above).

or, if a single cell exceeds 4v because the battery is not quite yet top balanced, than the BMS disconnects the charger from the powerpoint.

I suppose I should talk a bit as to why I am using a per cell BMS merely to do the job of charge termination:

Now there is another way to achieve redundant charge termination, than using a BMS.
I'm not referring to a timer (this should be used anyway for good measure, and for TOU metering)
a half pack voltage comparison does the same, in theory, fairly reliably, however, I can't find a product thats already for sale, nor have the time to develop one myself.

unfortunately eliminating the original Vectrix charger in place of say an elcon, is impractical as it does too many other things like drive the original fuel guage, and all the warning lights.

Basically, at this point in time, using a per-cell BMS is the most reliable way to ensure a battery never gets overcharged.

The other important thing to do is ensure you don't charge a battery that has a failed cell.
in the case of the kit, the BMS won't let you, it pretty much forces you to either replace the failed cell or bypass it.

Now that MAVIZEN is going to be selling the 20 AH Flat, Prismatic cells by A123, It would sure be GREAT to have a VECTRIX powered by a 3P X 44S pack of 132 cells, giving 60AH capacity! It seems that changing a resistor on the circuit board of the VECTRIX (In the power cable Hall Effect current sense circuit) could fool the microprocessor into thinking fewer amperes have been exchanged, allowing usage of the increased capacity, if re-programming cannot be done. (of course provision to prevent excess amperage to the motor will still be needed, as the FET module has a 300 amp limit-Perhaps paralleled FET modules should be tried!-A HOT-ROD VECTRIX! Tremendous Accelleration, with double amperage! Motor temperature would need monitoring/controlling.

The Trev team from University of South Australia actaully use a Vectrix motor to power their 3 wheeled car.
The peak power output has never really been a problem, but they did destroy a motor when they ran it at above 20kw continuously.

its the controller you have to be worried about.
I can already get mine to go into thermal cut-back:
If I am doing 100kmh, and I regen all the way to a stop, and a minute later accelerate as hard as possible, when I hit 80kmh when my power band starts, I get a stop-start-stop-start like acceleration.

because I have removed my original charger, I don't get any warning lights.

I'll save my pennies and look for your posts on Ebay.

No worries Paul,
I will give a heads up when the first kits are ready.

Matt