New charger among other things

Got my big new charger yesterday. It really is big. However it does fit into my tank bag which makes it small enough to take on the road for a quick top up in about two hours from empty to fully charged. I also installed a LED light strip to function as a daytime running lamp as now permitted in the EU. This way I don't have to turn on the head or tail lights in daytime and thus save my 12 volt system from extra load. The LEDs are always on and take so little power I wasn't able to measure it with my ammeter.

But first here are couple of videos of my friend taking a ride with the kWsaki electric motorcycle. First taking off and coming back and then the actual footage from riding around Finnish countryside.

The first short video was shot with my Sony Xperia Pro phone and the latter with a GoPro on top of the tank. Here are also a couple of shots of the charger, DRL installation and an emergency cut off switch I also added which you can use to disengage the main contactor if there's trouble.

25th element

No, it's not a Luc Besson movie. I wouldn't mind if it was, they're great, but it's a cell. I now have 24 cells and a 87.6 volt charger. That makes 3.65 volts per cell as the charging voltage. CALB recommends 3.6, but with bottom balancing you want to leave a bit more headroom to protect the cells. With 25 I'd get to 3.5 which is ideal. Hence the 25th element. If I can't find one used I'll have to order. The postage will be one fourth of the whole price, but it cannot be helped.

At 3.5 I will sacrifice some SOC (State of Charge) in order to make the cells last longer and also make them stay better balanced. Right now three of my 24 cells can get up to 4 volts while charging which is way too much. They drop back into line quickly after the charge ends, but it still makes me uncomfortable. The extra cell needs to find a place somewhere, but I'm sure I'll figure it out. I should also see a couple of kilometers more range, which never hurts.

Something I realized about charging. It's just a voltage per cell. It's not a target. It's just means to an end. Sure, it won't be exceeded, but it's really the current that counts. How you should charge these LiFePO4 cells is with constant voltage and a constant current until at the end when the current should gradually drop until the pack is deemed full enough. It's quite possibly the only "BMS" you need. At least for the charging phase. Of course you should make sure you don't charge when it's too cold, or too hot for that matter, and make sure your charger is reliable enough not to exceed the set voltage and also ends the charge when due.

As for protecting the battery when discharging it's really where the magic of bottom balancing happens. If you've carefully drained your cells to the same limit below three volts before using them they should all also return to that same voltage on each and every full discharge. For a bit of additional protection I've set my controller, the AXE7245, to a low voltage limit of 60 volts. That's 2.5 volts per cell. It should be quite improssible to kill any cells this way. At least if a cell dies despite these precautions it really was a bad cell and should be put away anyway. No amount of active BMS could have saved it.

That's all there is to it really. Some human-based BMS logic is needed not to do anything stupid and keeping an eye on the cells for any physical defects, but we're just fine this way. If I was building a car with a larger battery pack, and I'm not saying I wouldn't be, someday, and especially if it was for someone else, I might consider some electronics to keep an eye on the minimum and maximum voltages. Perhaps battery pack temperature as well. Just to be safe and catch a few situations that might occur when you have more voltage and the cells are hidden out of sight. On a motorcycle, there's just no need.

Do want

I took a test drive with Pori Energia's Citroen Z-Cero (same as Peugeot iOn or Mitsubishi i-MiEV) electric car. So it's small, only for four persons, is kind of cheap looking, both inside an outside, and costs over 30.000€, but it's really fun to ride! The continuous, silent torque of the electric motor is just so much fun. We started with 111 km left on the range indicator and the estimate started dropping quite quickly once I hit the highway nearby. When we got off it the meter actually started going upwards as the electricity consumption was re-estimated. In total we drove around for about 50 km and there was over half of the pack capacity left. To be honest I didn't even register what the reading was when were done so there definitely was no range anxiety there.

Obvious reaction is that I'd really like to have one. Problem is it's quite expensive for a small car that could otherwise be had for closer to 10.000 € (Citroen C1 or a Peugeot 107). On the other had if you compare it to a Toyota Yaris, which would be my number one choice for a small car, you'd only end up paying something like 10.000 € more. With electric driving costing about 2 cents on a km and gasoline up to 10 cents per km, you'd only have to drive about 125.000 km to break even. Now that's not too hard to imagine at all. With zero emissions no less! And I have to say the C-Zero felt as nice to drive as a Yaris. Even better actually, because of no shifting and dead silent acceleration. Wind noise was quite loud above 100 km/h, but so it would be in a Yaris as well.

Immediately after that I started thinking about making one myself. You could probably get a running VW Beetle for a couple of thousand euros and a similar electric drivetrain including batteries would be about 15 to 16 thousand. Almost half the price of a C-Zero or an iOn. Of course it wouldn't be a new car, but at least you'd now exactly how it works and how to fix it since you built it yourself. The same couldn't be said of these new electric vehicles. You'd still need to take them to the local dealer for maintenance - no matter how scared the dealers are of electrons destroying that lucrative business.

All in all the car exceeded my expectations in every respect. The Nissan Leaf is usually considered to be a much better car so I wonder how good can it be if the cheap-ish C-Zero was this nice.

Spring break

New Hagon springs being installed. The forks are almost fully compressed here and that's why the springs are protruding so much. Once the forks are pulled to full length the springs disappear almost completely. I took a quick test ride and the front end seems really good now. They don't bottom and handling is much improved. I also released extra air pressure from the rear shock to make it softer which also contributed to the suspension and stopped the chain from making a noise while hitting the center stand.

As a bonus a picture of charging my Macbook Air from the battery pack which also works like a charm. Now I know where I'll head if the electricity goes out and my beloved laptop is running out of juice.

Springs and problems

It's a day of good news and bad news. The bad news is that the motor I got does not appear to be in perfect condition. The commutator seems to be out of round as you can see the brushes moving in the following video. Not really quite sure how this has come to be. I haven't had a reply from the seller yet. The motor also gets very hot.

Update: I have gotten into touch both with the seller and Motenergy. They don't see a problem in the video so I suppose everything is in order after all. Motor heating might also be within limits. Maybe.

The good news is that my new progressive front springs from Hagon arrived early! I wasn't really expecting them in weeks since they are made to order for this somewhat rare bike. I knew there was a package coming, but I assumed it would be the LED lights for the bike I ordered from dealextreme.com.

Good looking springs with proper installation instructions included. Hopefully they will also solve my problems with the front fork and it will finally become as nice to ride as it should be.

Faster charger

A new, faster charger is now on it's way from evassemble.com. It's a 2 kW model which outputs 20 amps at 87.6 volts. This should allow me to charge my 40 A battery pack in two hours which is very nice indeed. Makes longer trips with planned charging stops possible and also daytime trips to nearby locations such as the family cabin in Luvia. I will still keep my 6 A charger for overnight charging to charge the batteries slower and possibly to a more full charge when time is not of essence. I'm also planning to make a test drive to figure out the 0-100km/h and quarter mile results at 300 amps using GPS and possibly on the same charge get a feel on how far I can go if I don't drive at best speed all the time. Minus the acceleration of course. Or two. Perhaps the hypermiling test will actually need a fresh charge.

Another idea I've been thinking of is should I drain the pack completely, ideally to 2.75 volts per cell, reset the Cycle Analyst and then charge. This would reverse the amp hour counting from the current counting from zero upwards to counting from -40A towards zero. The positive side of this would be that I'd know exactly how much juice I've put into the battery and would immediately notice not only the difference of charging at 6 A and 20 A, but also if the pack loses it's capacity over time. On a negative side I'd lose the cycle counting capability of the Cycle Analyst and also the per trip statistics in favor of total average over time. In this case the cons probably outweight the pros and I won't end up doing so.

Free charging shot

Posted this on facebook a couple of days ago already, but here it is for the rest of you to gawk at as well. Went to check out the free charging station at the Pori Energia office in, you guessed it, Pori, Finland. All you need to do is send a text message and the station will lift up allowing you to plug in. Press a button on the pole and it will come down preventing your plug from being stolen. Not bad. Four normal 230 V AC plugs inside.

Kind of got me anxious to get a faster charger. At the 6 A pace you need to pretty much stay the night or a whole day to fill up an empty 40 Ah tank, but at 12 A or 16 A you'd only have to wait a couple of hours. Couple of hours are much easier to kill than a working day. 12 A is the recommended charging speed for the 40 Ah CALBs, but I suppose I could get away with 16 A. At least if I'd get that sort of missing 25th cell that would give me the optimal 3.5 V per cell at 87.6 V total. Right now I get 3.65 V per cell and some of the cells end up hitting 4 V when charging.

Street legal

So I had the bike inspected yesterday. The inspector was mainly interested in the motor and battery mounts and the weight of the bike which we measured on site. The scale tipped at a light 170 kg. 60 kg less than previous curb weight. Not a bad weight loss plan I'd say. The brakes or suspension were not inspected at all which is reasonable since they were stock and weight hadn't increased either.

Parts of the registration form for the Finnish readers. The papers cost 100€.

I also took the bike for a ride. A tankful so to speak. Spent almost everything on a 40 km trip. This did include quite a bit of top speed testing which resulted in 110 km/h. Slightly less than the 130 km/h I had calculated, but it did reach it very nicely so if more was required I think I could get it by changing sprockets. Driving at top speed isn't what the bike is for so I think I'll stick with the quite nice acceleration it now has instead. Driving slower should improve range as well. I'll let you know how many kilometres I get once I drive a tankful that way.

A friend of mine giving the bike a short test ride and the EV impression.

Don't get confused by the ICE bike starting nearby.

Charging the bike in the evening took less than 7 hours. The cells we're within 1% of 3.0 when near empty. Shortly after the charge most cells were around 3.3 volts with a couple nearer to 4 V. This is to be expected and quite normal when using bottom balancing. As you may or may not remember all cells were drained to about 2.75 volts before use which means they are equalized when empty. All cells are not created equal however and when charged the weakest ones will reach the highest voltages while the best cells don't go above 3.4. The charger then simply cuts off the current when 87.6 V total is reached. Even the weakest cells will then come down in voltage reducing the total by a couple of volts.

In other words no fire hazard also known as a BMS is needed. You just have to keep your eye on the amp hour counter and not kill the cells by draining them dead. Just like you wouldn't want to drive your gas tank to empty in the middle of nowhere. As an additional precaution the controller is set not to work below a certain voltage which will also prevent you from killing the cells. 

A slight over voltage when charging at slow speed is not that dangerous. Not at least compared to discharging them below rated voltage at 400 amps. This is why bottom balancing works and BMS does not. If you're using a top balancing BMS you charge all cells to same voltage, but when the pack is near empty you can have most cells above 3 volts while the weakest go way below that near to 2 volts which will cause them to die and you won't notice anything until it's too late. Especially because of how fast things happen at 400 amps.

Here we go

Having the bike inspected right now. Or actually waiting for the paperwork to finish. Looks like we have a winner!

Annoyances

It's hard not to be annoyed when the project is delayed due to matters not quite related to the electrification itself. The ESCS front forks have turned out to be quite a show stopper. I've now ordered new progressive springs directly from Hagon which will hopefully make the front shocks behave properly instead of bottoming and thus stop the front wheel from hitting the battery box. I might also try to raise the box a little bit to make some more room for the tire, but there isn't much space left. I may need to switch the connecting battery plates to reverse order as well. That might give me a centimeter more to play with.

The almost finished gallery

Some shots of the bike as it now stands. On the list of things to do are still front chain guard, improving battery box support in front and the extremely soft suspension. After that I think I'm ready for the inspection.

ESCS fun

Put the bike together and found out that the front dives so low that it hits the battery box. The front mud guard took some damage. However, I think the main culprit is the defunct ESCS anti dive, which makes for a really soft front suspension. Will have to look into stiffening it with spacers or something else. Progressive springs would be the proper solution I guess, but not for free as usual. Also resolved controller mounting issue by finally butchering the tank from the inside to make space for it there. Everything that can be covered is now nicely out of sight and away from little fingers as well. Took some pictures and will post them later. Thanks for reading.