Showing posts with label Electric. Show all posts
Showing posts with label Electric. Show all posts

Friday, November 18, 2011

Electric Vehicle Conversion: Automatic or Manual Gear Box?

!: Electric Vehicle Conversion: Automatic or Manual Gear Box?

Someone raised this issue the other day and I know it's been talked about a lot, with most opting for a manual gearbox, but it got me wondering if there is a benefit to having an auto box.

For my Starion, frankly greed got the better of me in choosing a larger motor - Kostov 11 inch - and running it with the only available speed controller at the time, the Curtis 1231C. It's not an ideal match; a larger motor coupled with a smaller controller could yield all sorts of induction field issues. I had always intended to upgrade to a Zilla controller and get a few more batteries on board but Zilla seem to have endless problems and may indeed die out like the dinosaurs.

So what's all this got to do with gearboxes?

Manual gearboxes are more efficient for an EV, particularly if you have refined gear-handling driving experience. End of story. Or is it? Perhaps keeping the clutch disc in a car with a larger motor would have allowed for quicker gear changes under varying circumstances (I am no racing expert who can shift quickly with no clutch). Most EV conversions do away with the disc and pedal and hence become 'semi-automatic' (and save a bit of weight in the process). However, it takes a couple of seconds longer to synchro-engage the gears. You have to 'feel' them meshing together and try not to force it. Smaller vehicles may only use two gears and reverse. Heavier vehicles need to shift more if the pack and controller are modest.

Under demanding situations (e.g., driving up a steep hill with an idiot on your six) a quick gear change is not an option, thus forcing the poor EV to struggle under the wrong gear, sucking more amps. Two or more seconds trying to engage the gear would be enough to have that idiot hit your tail. In heavier cars, poor gear changes could result in using more 'fuel', reducing range and harming the pack if the controller is not up to spec. It takes good practice to shift quickly but not every road circumstance will be friendly enough to allow it.

Reduced Range on Auto?

Most EVers say an auto box will reduce the range since it takes continuing energy to run the hydraulics for auto gear selection. In an EV, for a manual stopped at the lights, nothing happens. The motor is not turning; no energy is used. For an auto you have to up the rpm permanently for smooth stop and go. This is where you lose effective range. Swapping a gearbox would mean you'd also need the wiring loom and computer for the overdrive. Setting the torque conversion revs would be tricky.

But in a simple three speed auto electric vehicle, perhaps the accelerator can be adjusted to a persistent voltage above zero and a revs check done. Haven't seriously looked into this, but if enough revs so the synchros engage correctly from a stop position is all one needs, perhaps 300 revs or so could work. Some EV'ers with autos say they don't need to do this, but that depends on the weight being hauled and type of auto gearbox it is, from a CVT to basic no frills hydromatic (ah, the old days).

With auto transmission it's true; more energy is used. But for a larger car with a modest controller, perhaps an auto transmission is a better option. Correct gear selection every time does preserve the battery pack from excessive current demand (and your bus-bar battery interconnects stay cool) and the controller and pack are happy for it. The loss in range may actually be LESS than using a clunky manual gearbox, depending on the vehicle, gearbox (some autos do shift slower than others) and driving conditions.

Five speed gearboxes are probably not suitable for modest EV spec'd larger vehicles. Many have converted vehicles with auto transmissions and as mentioned above the expected flat spot (where there are no revs from going from zero) seems not to be an issue for most. It just takes a second or so from foot down to go from stop. Upping the revs a little for permanent motor turning at stops is the only way to do it for larger motors (and I believe the new Soliton 1 controller has a facility for fine-tuning with an auto transmission).

Abuse is no Excuse

Since the previous owner of my coupe clearly abused the vehicle (boys will be boys), third gear is a little noisy. I could swap to an identical four speed box. Something to ponder, perhaps. So in summary, when considering a conversion look at all your power options. This is of course dictated by cost, but a modest conversion may indeed benefit from an auto transmission - and it's easier to shift manually if you want.

No gearbox at all

The rate battery technology is improving, commercial electric vehicles will do away with gearboxes altogether. For my vehicle, I could increase the volts (the motor would handle it) and thin 4th gear every time. I'd have to replace the bus-bars of course, and the charger which has a pack voltage limit, so the extra cost could be considerable.

In a perfect world no gearbox at all, wheel-mounted AC induction regen motors, pack inverter and plenty of amps/range would be just the thing, but I'd need more green to go that green:-) so for most home builders on tight budgets, keeping the gearbox will get around numerous cost issues.

As battery and component technology improves and gets cheaper my next conversion may indeed gearbox at all.


Electric Vehicle Conversion: Automatic or Manual Gear Box?

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Wednesday, November 2, 2011

Energy Efficient Ranges and Cooktops - Which to Buy - Induction, Gas, Or Electric?

!: Energy Efficient Ranges and Cooktops - Which to Buy - Induction, Gas, Or Electric?

When you turn on an electric or gas burner, a good deal of the heat does not go to the pan, but into the air. If you open the oven door, the heat rushes out of the oven and into the air and the oven has to reheat. When you turn off an electric burner, even though the the power is off, heat is still given off and is considered to be wasted. So by strict definition of "energy efficiency" one of the most used appliances in your home just doesn't measure up.

Even though cooktops and ranges do not earn the Energy Star rating under today's standards, there are some products that are more efficient than others.

I am in the market for a new kitchen stove and began the research to find the most energy efficient product that fit into my budget. With the tax credits available for Energy Star appliances, I asked if there were any Energy Star rated stoves (ranges if you will). The answer is, no. Why? Very simply, because energy efficiency is measured on how much energy it takes to perform a particular function compared to how much energy is lost or wasted by that same process.

Solar Powered

There are some small solar powered stoves and hybrid solar (solar with electric backup) for those days when the sun doesn't shine on the market today. Most of the specifications indicate a minimal temperature range and have very limited capacity. The largest capacity I found measured 21.25 inches square by 7.78 inches deep. If you are looking to experiment with solar cooking, there are any number of plans on the internet to build your own solar stove using materials found around your home. However, the solar solution may not be the most practical for a busy family. For now, being somewhat of a pragmatist, I've focused my search and the following article on the more practical options for today's busy family.

Induction/Electromagnetic

The new induction cooktops and ranges are the most efficient on the market tody. Induction cooking surface, when turned on and a metal pan is on the cooking element, produce an electrical current in the cooktop which creates a magnetic field that causes the pan to heat and cook your food. It's like magic. Even if the burner is turned on, when the pan is not touching the surface, you could lay your hand on the element. It's instant on and off. I've actually done this and was quite amazed. There is no heat loss when you remove the pan, which makes the induction cooktop more efficient than other cooking surfaces. The pans must have flat bottoms and be made of metal or the electromagnetic heating process won't work.

Most major appliance manufacturers offer an induction cooktop (no oven). If you are trying to replace an all-in-one cooktop and oven, there are several manufactures: Samsung, Kenmore, Viking, GE, and Diva. The oven component is typically electric with a convection option. Like most new technologies, the induction cooking appliances are still expensive. However, over the past year, prices have dropped.

Natural Gas or Propane vs Electric

If an expensive cooktop or range is not in your plan, there are other options. Based on current natural gas prices, natural gas, is still slightly cheaper to operate than an electric cooktop.. So, if you're investigating appliances based on cost of operation, you'll want to investigate average prices of electricity vs natural gas in your area. (Be aware that the proposed energy legislation will affect the cost of any fossil based fuel and prices will go up for both natural gas and electricity. How much they will rise is not yet known.) Overall, the savings of gas over electric has historically been minimal and amounts to less than a year in savings. If you are a cook that prefers gas, there are many options from which to choose. Many of the most popular brands are carried by Lowes, Home Depot and Sears.

Energy Efficient Ranges and Cooktops - Which to Buy - Induction, Gas, or Electric

The most energy efficient cooking solution would be an induction cook top with an electric/convection oven, followed by a gas cooktop with an electric/convection oven. Convection ovens are a little more expensive than an electric or gas only oven, but they require less cooking time, so you are using less energy and reducing your time in the kitchen. For the busy family, less time is a real plus. All in one gas or electric units are the cheapest solution, but not the most energy efficient. The differences in operating costs depend greatly on the utility prices in your area. However, the cost difference, based on the national average of gas vs electricity, is only a few cents, with natural gas being the cheaper.

Price Comparison

So, if you're in the market for a new range or cooktop and your primary objective is saving energy, go for an induction cooktop with an electric/convection oven. For that system, budget between 00 for a fully featured system and 00 for a whiz bang designer, professional grade system.

If natural gas or propane is available in your area, the next best combo would be a gas cook top and an electric/convection oven. Prices vary considerably, ranging from under 00 for a basic model to the mid-range of 00 -00 for a full featured stainless steel unit. If you have even a higher budget, there are some magnificent options for the person who really enjoys cooking ranging in price between 00 and ,000.

If the electric option is all you have, don't despair. Remember that the differences in energy consumption and energy cost between the gas or electric options are not that significant. By going the extra step and purchasing an electric cook top with an electric/convection oven, you will be reducing oven cooking time and, thus, energy consumption. Any reduction in energy consumption is a positive and will produce some cost savings. Prices for these units vary from 00 to 00 for fully featured stainless steel units. These are available from most appliance manufacturers. If your budget is less than 00, check out prices on the internet. There are good deals to be found on this type of stove. If I'm still talking above your budget, "all electric" or "all gas" ranges vary in price from 8 to 00. Keep in mind that the very low end products will not typically be self-cleaning, nor will they have the insulation to keep the heat inside the oven when cooking, nor will the temperature control of the oven be very precise.

While cooking units are not energy efficient according to the standards set by Energy Star. Since there are not significant differences in energy cost among the options, it boils down to budget, cooking style, and availability of natural gas/propane. I've given you some things to think about when purchasing that new stove and, hopefully, you found them useful.


Energy Efficient Ranges and Cooktops - Which to Buy - Induction, Gas, Or Electric?

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