maanantai 11. kesäkuuta 2012

Mulling over

I'm mulling over the options one of which is the motor. I've pretty much settled on the ME1003 actually. Usually when there are two options and you know which one is the better, but you end up choosing the other one just because it's cheaper you also end up thinking you should have gone with the better option. You also know you'll be stuck with what you got because you can't afford to buy a whole new set anyway. In this case better motor comes with a more capable controller and probably a sturdier contactor as well. Controllers are also a significant portion of the cost. Less so with the brush type motors, more with brushless, but a portion none the less.

In an ideal world I wouldn't actually be making my pick between these two motors at all. If money was of no concern I'd definitelty go with the MHM602 from Enertrac. It's a beautiful, brushless hub motor meant for motorcycle conversion and it can deliver around 10 kW continuous and 30 kW peak. Being brushless and beautiful does come with a price tag to match, as usual. As if it was not enough that the motor itself is twice as expensive as the brush type motors it also requires a more expensive controller. All this adds up to a price tag of around $2600 for the kit with shipping as opposed to the $1000-1500 of the brushed, chain driven counterparts. Of course you'd win back some not having to by sprockets and chain, but nowhere near a grand. You would however have more space for batteries and no chain at all, which is why the hub motor would be so beautiful. What I have is an hate-hate relationship with chains. I don't like them and they don't... Well, they don't really have emotions, but I'm quite sure if they did they'd hate me back.

A friend of mine asked me to write about the weight issue. I don't have anything to properly weigh the bike as it is, but thanks to the wonderful world of Google (previously known as the Internet) I found out you should be able to use an ordinary bathroom scale to do the weighing by adding up the results from the front and rear wheel. Whatever education I've had might also have attempted ingraining this knowledge into my brain, but Google is a lot better at indexing stuff than my little grey cells. So off I went with an Ikea Bolmen bathroom scale and measured the bike. The Bolmen is a horribly inaccurate little scale, but it looks sturdy, is very cheap at less than five euros and goes up to 120 kg. The registration of the bike indicates that the curb weight should be 210 kg, so you can imagine my amazement when the front wheel read 100 kg and the rear wheel 110 kg. Exactly as the gods intended. I now had a semi-reliable method of weighing the bike and an idea of the weight distribution with no driver in the saddle.

Based on what I've been able to gather the weight of the 500 cc internal combustion engine currently propelling the motorcycle could be around 50 kg. The ME1003 motor and associated electrical parts should be around 20 kg. The battery I'm planning to use in Phases One and Two will weigh 20 kg as well. What I call Phase One is replacing the ICE with the electric motor and AGM batteries. Phase Two will come after the inspection of the bike and entail swapping the AGM batteries to LiFePO4. The AGM and lithium packs will be similar in size, weight and voltage, with the lithium version eventually packing a lot more punch than the ancient battery chemistry. In any case the electrical parts should weight less than the smelly dinosaur powered noise generator. With AGM the range will be abysmal and performance severely limited. Phase Two lithium pack should improve both performance and range, but I'm still not hoping more than 30 km on a charge. Enough for a bit of cruising around town, but not much more. Phase Three and all phases after that should gradually improve the range in approximately 20-30 km increments via new battery pack connected in parallel.

Funny how things add up and end up being in such harmony. Partially by design, but also by mere coincidence each phase ends up costing about 1000€. In Phase One this will be the cost of the motor kit, in Phase Two the 20 Ah 72 V 20 kg LiFePO4 pack, Phase Three the second 20 Ah 72 V 20 kg pack and so on for all the future phases until the bike gets too heavy or a new battery chemistry becomes viable. Each Phase will also weigh around 20 kg. Granted, Phase One will actually by 40 kg, but half of it is the AGM pack that will be replaced in Phase Two with as much lithium based storage. I also cut another corner in Phase One pricing - the import taxes will probably raise the total price and I still have the charger issue unsolved, but I believe you can still see the 1000€ per 20 kg per Phase harmony here. At least I can and I find it highly satisfying.

Oh. One more thing. Another big issue to mull over is the bike itself. It may also end up being a completely different bike that gets converted if a suitable rolling chassis ends up rolling my way. I may have to limit myself to Kawasakis though. It wouldn't be a kWsaki anymore if it was a Suzuki...

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