Hi All,
I am about to start my Vectrix lithium upgrade and had a quick look under the battery cover today to take some measurements.
I decided on Sinopoly purely on cost and, yes, they are a tad wide when 2 cells are side by side - 232 to 233mm. So first job, sand down one (narrow) side of each cell alternately with a big belt sander, being careful not to heat the case too much. This took about an hour. I'll be strapping the cells together in 3 banks using plastic strapping and stainless steel end plates.
As it happens, I could have saved myself the trouble of sanding 12 of the cells as I now plan to do a different layout to Matt (antiscab)'s one saving me the hassle of cutting the battery cover and thereby reducing its weather-tightness. Bottom layer is much the same, 1 bank of 14 cells and another of 16 standing upright, in pairs of 2 cells, (narrow) side by side. Then a 20mm space for BMMS boards and battery connectors. I'm going to use a 'C' section of 2mm stainless steel secured above the top edges of the bottom row of cells using nutserts (rivnuts) fixed into the V's aluminium square tube frame verticals. These will stop the cells moving around and make a secure gap between the cell layers. A piece of 6 or 8mm perspex will sit atop the 'C' sections and the top bank of 12 cells, on their narrow sides, will sit on top of that and be secured to the perspex/frame in a manner yet to be decided - perhaps using a piece of angle at front and rear fixed to the perplex to prevent to and fro movement and a ratchet strap to hold them down.
This system will allow me to get all 42 cells well within the existing NiMh pack volume. The fans can then stay in place for a (hopefully!) future addition of a ChaDeMo charging capability… don't know if that'll ever happen or, indeed, work anyway. I intend fitting my BMMS control unit in the rear storage area - it is only 6" x 4" x 1.5" - and an even smaller Compulab Fit PC-2 opposite the BMMS box to allow me to access the V remotely, log the BMMS readings, provide a GPS tracking facility and power the TFT BMMS monitor I plan to mount to the windscreen. I thought about putting them in the glove box but it's a bit prone to water ingress.
I'll do a blog on my website in due course.
If anyone has any observations, I'm all ears. I'll be starting in a week or so.
Martin,
I enjoyed your description of mod to fit Lithium cells in NiMh space.
Also interesting is your GPS Tracking module. A friend in Asia is using one, made in China, and sold by the company she works for. I would like to obtain one also, for use in the US.
What GPS will you use? Does it include Map Tracking?
I saw your battery sketch on your web site. What drawing system are you using?
Thanks,
Jack_son
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EWheels EW475 eBike LiFePO4 36 V 10 AH Bat
Hi Jack_son,
I'm not sure if I'll re-use the one I had on my now-defunct van or get a newer one. But it was/will be a USB 'dongle' type. As for map tracking, that would be down to whatever software you choose to install. I'll be relying on my iPhone for navigation bluetoothed to my helmet. The GPS attached to the 'bike-puter' would only be used to log my position and send GPS data when the system was asked for a status update by SMS. There is no reason you could not use a free, web-based tracking service. I used to use LocateA but I see it costs money to use, these days (edit - no, there is still the free side to it, including a 'server' app for java enabled mobile phones, windows mobile and windows XP - http://locatea.co.uk.
I can't remember what drawing app I used for that but I pretty much just rely on SketchUp nowadays - or the graphics side of Word or even OpenOffice will do for something simple.
MW
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
There are issues about using lithium cells that are not in the upright position. The last thing you want to do is get a 150 volt battery out of balance because you installed some of the cells on there sides so for that reason I would try to keep all the cells upright.
My guess is to not try to support the heavy weight of batteries the way that is shown in your drawing. Allot of travel on bumpy roads would stress the aluminium square tube frame area in a way it wasn't designed for which is not good. Also driling big holes in that square material would probably weaken it. It would be better to mount the second layer of batteries on top of the first layer of batteries with a piece of Lexan in between so the wieght of the 2nd layer of batteries is supported by the first layer. Another thing is you need to use a plastic type solvent that kind of welds plastic together to weld plastic strips on the bottom of that piece of Lexan so the wieght of the 2nd layer isn't on the battery terminals but the top of the 1rst layer of batteries.
I'm also upgrading my Vectrix VX-1 with 40 Ah lithium (yellow) batteries and I'm thinking of strapping the the cells together also but I will use metal strapping instead of plastic. I'm not so concerned about the internal preasure buildup possibility as much as the movement of the batteries relative to one another and over time causing the interconnects to come loose.
Since I can't understand how your plan to strap the cells together would work I'll just describe my plan.
The biggest problem doing this is the two bottom rows, there is only enough space for two preasure plates per row of 15 cells wich I think is doable but it would be complicated.
My plan is to make a jig that would help me to make 12 identical metal straps then using 4 pipe clamps to clamp the batteries together enough to attach the straps. If the straps are not exactly equal in length it would cause the row of batteries to bow and consequently would'nt fit in the battery compartment.
To install and remove the 1rst layer of battery rows I would do it one row a time using a rectagular piece of plywood as long as the 15 cell battery row with two hand holds cut into the top and holes drilled into the bottom that would correspond to the locations of the battery interconnects. Then using a nylon string, string them together like putting shoe laces on shoes but between the holes in the plywood and the interconnects. The reason for doing this is it distributes the weight of the battery row equally over each interconnect.
Hi Anderson,
With the cells on their narrow sides, the cell plate edges are all still sitting in the electrolyte so this arrangement should be - and there is some historical evidence to confirm this - fine.
There is, as you suggest (and poorly shown in my sketch), a 6mm thick acrylic sheet sitting on top of the stainless steel 'C' sections and it is bolted to them. This fact and the fact that the 'C' sections are bolted to the aluminium frame should make the resulting structure stronger overall than the original. Also the weight of the new pack is some 10kg less than the original NiMH pack.
Strapping will be done like this (these are 160Ah cells)...
…which holds the cells very rigidly in one lump and minimises problems of connecting the cell's terminals together with semi-rigid copper straps - again as you point out. The end plates are also only 2mm thick so there is plenty of room lengthwise for the 2 sub-packs of cells. To aid extraction and insertion, I will try to remember to sandwich a plastic strap at each end forming an eye to connect my engine hoist to.
Thanks for your input. MW
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
A quick edit to my first post… my cell arrangement is:- the bottom layer consists of 2 rows of 15 cells, upright with narrow sides touching and outer narrow sides sanded down to fit into the width of the battery tray. The second layer is as per the sketch, so cells lying on their narrow sides, but 12 in number and no need to sand them down. The terminals are on the off side as it makes it easier to install the flexible interconnects. MW
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
Any news?
Hi CO2,
Yes… I have completed the upgrade but I am still testing…
I does appear that I still do not have quite enough range to do my now 44 mile return trip with sufficient reserve for battling strong headwinds etc unless I do an impracticably slow speed on the dual-carriageway sections of my journey. So I am trying to reverse the withdrawal of permission to charge at work, or find somewhere else to charge near enough to work that I can walk between the two all-clobbered-up with m/cycle gear.
Beside that, the main problem I have had with the upgrade is still the issue with the Runke charger having the 32Ah charge limit on it. If I had not replaced my ESD charger (that blew up) I could use one of the alternative charger firmwares to solve this issue. I have rigged up an on-board Windows PC that, in combination with the Elithion BMS allows me to access the Scooterdig software to reset the Ah remotely (via Wifi) and continue charging beyond 32Ah but this is a real PITA to have to do very time I charge the bike. If I could charge at work this would not be anywhere near such a problem.
Some images...
I decided to make my own interconnects as they cost at least £2 and having bought a bulk load of copper strip, I can make them for <£0.20 each - 100A continuous capacity.
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Installing the bottom layer of cells.
Top layer installed.
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
Awesome!!!
Great job!!.
Please keep us updated.
An update…
Done about 400 miles now on the new pack. Unfortunately, it is still not enough to get me to work and back without having to have a good 30 minute top up and as I can't do this at work still I am not using it as much as I was. At least I have my iOn (i-Miev) to use instead!
I am still trying to figure out a way round the irritating 'full charge in two goes' business but hoping someone will come out with a hacked firmware compatible with the Runke charger that gets around the 30Ah charging limit. Alternatively, I suppose I could put in a different charger but then I'd lose some of my instrumentation… I suppose I could put a big charger in… perhaps one the the EMW ones would fit? Having a 20 minute recharge would go a long way to offset the downside of having to change the charger.
All in, tho, I wish I had waited another few weeks so I could have got my hands on the LEAF cells that are now apparently fairly freely available and cheaper than the LiFePO4 cells I ended up with - and 65 Vs 40 Ah - more than enough for my 2-way commute! MW
Regards, Martin Winlow
Isle of Colonsay, Scotland
evalbum.com/2092
What do the Leaf cells go for where you are (in the UK, I assume)? They seem to go for $110 USD 'round here in the US and I've found only one supplier online, so not that readily available.
About your charger, you may want to check the pricing of an ESD charger with Piotr from the Poland Vectrix, who bought the spare parts stock from the US liquidation auction. Don't know what one of these would go for now ...
double post sorry!
I'd agree with Kocho - My Li conversion, with ESD charger but similar cells, will do the sort of distance you're talking about. Worth a try anyway, an ESD charger has to be cheaper than 18 or 19 Leaf cells!