Ok i will ask all of you are you going to use a transmisson if so there will be a power loss just like you are saying i would be geting rid of the trany your going to use and replacing it with hydrostatic drive so power loss is about the same but with the hydrostatic drive i controll speed and load with the way you are doing it you need a controler for the motor to control speed and load
You still need electronic voltage control for the motor, you don't want just a giant on/off switch connecting the motor to the pack, and the electronic motor control also controls regenerative braking energy from the motor back into the battery pack. If you are doing a relatively low voltage system you could just use a large contactor, but it's not the ideal setup. I'd still like to see some factual information on the efficiency of a hydrostatic drive. The main advantage I see of hydrostatic is the infinitely variability, which you don't need with an electric motor. In my conversion I will be keeping the manual transmission for 2 important reasons: 1. I already have it so it's free and it's mounted in the vehicle. 2. I'm using a small moderate voltage system which needs some gearing to work properly in a vehicle this size. I could probably get by with only 2 speeds but since I have 5 that's what I'll be using. If I had a more powerful AC system that could go to 10,000 or more RPM I wouldn't need a transmission, or if I had a powerful DC system and a really light vehicle with a properly geared rear end I could also skip the trans.
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10:51 AM
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
if you dont run a trany and just go direct to the wheels will it still be as fast on acceleration or will this slow the car acceleration down to much thats why i thought they where using the trany
As I mentioned with wheel motors the main problem with no gear reduction is the high amperage draw that is required at start up. A properly sized E motor can do it but you have to beef up all your wiring just to handle the high amp draw at startup and cool the motor more aggressively, it's not efficient. Without gearing the E motor won't get to it's most efficient operating range and will continue to draw more amperage than it would if geared down. With direct drive you might only have the motor turning at 1000 RPM at 60 mph when it's efficiency range might be closer to 3000 RPM. E motors draw fewer amps at higher RPM. Unless you are building something that will consistently be running above 100 mph or so you want some gear reduction.
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11:02 AM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
I would venture to guess that some might use the transmission to compensate for not having a big enough motor, or enough voltage, for the weight of the vehicle.
Exactly. DIY EV is full of compromise unless you have deep pockets, but there are fewer and fewer compromises needed all the time as prices come down and more products become available.
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11:07 AM
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
While I was thinking about this I realized that there is another reason to keep a transmisson. If you desire to build a multi-purpose vehicle, as I do, the availability of different gearing for each purpose may be worth the penalty. Rather than having to change actual parts for a blast down the dragstrip, a trip to the grocery store, or a quick run down a winding country road, you have the ability to simply select the appropriate gear. It's an adjustment on the normal use of a transmission because it's really like a "mode" selector. Like selecting normal, sport, or competition in one of the new sport cars.
I am thinking about keeping my transmisson and eventually running one of those mini (4.5, 5.5, or 7.5") stock car style clutches, that is basically like an on/off switch. The right one can handle massive amounts of torque, but are considered unfeasible for ICE-powered street cars because it's either engaged or disengaged - no perceptible inbetween state. For an EV, that wouldn't matter because you can just select the appropriate gear while at a standstill and go. I am also thinking about eventually running a formerly impractical straight-cut, dog-engagement, racing transmission. The straight-cut gears are more efficient, and the fact that it can't be shifted smoothly, cruising around on the street, is inconsequential because I don't have to shift. The other advantage is they are much lighter.
Some of this doesn't apply to Fieros, because I don't think there is a cheap, dog-engagement, transverse tranny available - I'm building a conventional front-engine/rear-drive street rod - but the basic points still apply. I am finding so many opportunities to rethink "how" with this technology. You have to reprogram your mind to think outside the confines of normal ICE life. Even though the first steps are converting ICE designs to electric, there are a lot of possibilities in how to use current technology differently.
For instance, one possibility I thought of for a Fiero conversion with a properly sized motor, and enough "juice", is to use a 4wd S10 front differential in place of the transmission. It uses fwd style axles so, with some mixing and matching (like the guys do to swap in better transmissions), you should be able to get it in place relatively inexpensively. They should also be available in scrap yards pretty cheap. Couple the motor directly to the diff and you have eliminated the weight of the transmission but still have the ability, through the ring and pinion gears, to get it dialed in for your intended usage. Same old ICE technology, used differently...
[This message has been edited by toddshotrods (edited 01-24-2009).]
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12:14 PM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
I'll be running my transmission without a clutch since there won't be a lot of shifting and since the E motor has so little rotational mass it won't be hard to sync the gears up when I do shift.
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02:22 PM
Nohbdy Member
Posts: 587 From: Grand Rapids MI Registered: Dec 2008
the advantage i see with the hydrostatic, if i understand it right, is that the farther down you push the gas pedal the higher the gearing on ur car. the swash plate tips, changing the ratio, so he was saying that w/ correct setup u could be at maximum efficeincy at all times. shouldnt that make the energy loss from the transfer worth it? from what i know the major problem with electric motors is A) not enough gas stations have something to charge your battery B) the effective range is so much less than that of an HC car.
I think NohBdy has what i am saying if you are at a stop the motor is turnig but it like in nutral no load as you push the pedle dow then you move due to your puting load on the motor and turning the wheel motors so no need for the motor controler just an on off will work .other things that need to be factored in is how much loss is the motor controler costing and starting the motor from a dead stop
[This message has been edited by engine man (edited 01-24-2009).]
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03:55 PM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
I get your point and it would be interesting to see some of the advanced physics guys here do some quick math on it. I would still put my money on the controller-based EV, because the motor only turns when it must. Your motor is turning constantly, aways using energy. When the hydrostatic drive starts moving the vehicle it is still going to place an increased load on the electric motor (the energy has to come from somewhere) which means that in addtion to the constant drain, you still have the occasional demand for more. At least that's how I see it...
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04:16 PM
PFF
System Bot
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
I think NohBdy has what i am saying if you are at a stop the motor is turnig but it like in nutral no load as you push the pedle dow then you move due to your puting load on the motor and turning the wheel motors so no need for the motor controler just an on off will work .other things that need to be factored in is how much loss is the motor controler costing and starting the motor from a dead stop
Really bad idea. In your setup full battery pack voltage is going to the motor at all times. If you are sitting at a stoplight with no load on the motor and full voltage going to it the motor will spin out of control and blow itself to pieces. One of the benefits of an electric motor is that it never needs to waste energy when stopped. And I'm still waiting for any factual evidence that points to the efficiency of a hydrostatic drive.
[This message has been edited by JRP3 (edited 01-24-2009).]
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08:12 PM
Nohbdy Member
Posts: 587 From: Grand Rapids MI Registered: Dec 2008
one thing that i just found out by googling this, hydrostatic drives have an inherent braking system, if u shift into neutral w/ a hydrostatic u stop ur car, because it stops oil flow, stopping the drive shaft. by this fact, couldnt u set up the engine to lose voltage flow in neutral? the only time ull b in neutral is when ur no longer moving nyway, so it would solve the issue w/ the engine blowing up from lack of a load.
Yup, but again, without speed control you are slamming the motor with full pack voltage every time you start again which is no way to start a motor. You also lose regenerative braking capability which will shorten your possible range. You guys are trying hard to make this hydrostatic idea work with no proof at all that hydrostatics are somehow equal or better than a single speed gear reduction. That's where you should really start, find out the real characteristics of hydrostatics to see if trying to make them work is even worth it. I can tell you that the ideas you've presented probably won't work for the reasons I've laid out.
Give me a break the motor will spin till it explodes i have taken motors with no load or even conected to any thing they have never spun till they explode. it is amps that drian a batterie not volts volts is pressure and amperage is flow i know this from what i read so if your using low amps siting there you are draining the battries less than starting it from a dead stop that takes alot of amps .thats why they use start up capacitors to store the extra energy to get them going. why a high voltage motor is more efficiant it use's less amps and more voltage they use a smaller wire on the winding but put more windings on it http://www.linde-mh.com/en/...ic/hydrostatic_1.jsp HydrostaticExample: Hydrostatic It was all of 50 years ago that Linde Material Handling registered its patent for a hydrostatic drive. The principle is as simple as it is effective: unlike a mechanical drive, the motor drives a pump. It passes on the power via a closed oil circuit to each hydraulic motor to the drive wheels. The twin pedal controls ensure that the forklift truck moves either forwards or backwards. If the pedal is released, the vehicle stops: brakes are unnecessary. The oil pressure transfers the power evenly via the motors to both wheels. As a result, a differential gear is as superfluous as are clutch and transmission: the hydrostatic Linde drive works continuously and direction is controlled via both pedals.
Benefits for people The hydrostatic drive simplifies handling: the forklift truck reacts sensitively to every command, it can be steered with enormous precision past obstacles and thresholds and simply directed forwards and backwards with the twin pedals. The motor cannot stall. And since the vehicle stops hydrostatically, no fine dust arises during braking.
Benefits for the environment In the case of hydrostatic drives, neither transmission and differential oil, nor brake and clutch linings are required. This conserves resources. The generation of environmentally harmful fine dust is completely avoided. The degree of efficiency of the hydrostatic drive is 90%. By comparison: in a diesel engine it is only 45%.
Is it worth it? Drivers can increase their working efficiency by 20% with the interplay of Linde Load Control and the twin pedal controls. This means delivery times can be shortened and the fleet size reduced. And thanks to the hydrostatic drive, operating costs fall significantly. It saves up to 30% fuel and an oil change is only necessary every 6,000 operating hours. The degree of efficiency amounts to 90%, while the tyre wear is only half as great. The residual value is increased by up to 15%.
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11:18 PM
Jan 25th, 2009
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
Are you talking about single speed industrial motors? They are a different animal than EV traction motors. The people who actually build EV motors warn you to never put more than 12 volts to an unloaded motor because they can overspeed and tear themselves apart. Traction motors do not have capacitors inside them, they are in the speed control box. That description of hydrostatic drive makes little sense. No oil to change? They are filled with oil. Comparison to a diesel motor? What is driving the hydrostatic drive? It's just a transmission, not a motor. In any case if we take their figure of 90% efficiency we see it pales in comparison to other types of gear drives: http://www.roymech.co.uk/Us...Gear_Efficiency.html Spur 1:1 to 6:1 25 98-99% Helical 1:1 to 10:1 50 98-99% Double Helical 1:1 to 15:1 150 98-99% There are probably good reasons that no road going EV uses a hydrostatic drive setup as you describe.
I think they where talking it powerd by an electric motor the whole system was 90 percent are you trying to say a car trany will give you 99 precent of the power put in I know thats not true but there saying this will give you 90 precent of the power put in plus why dont you come up with the figure to diss prove me i posted what you asked and you still try pissing on it and i want to see the proff that the motors will explode show me the article i mean you are telling me things that i dont know if it is right or wrong
The three most basic units in electricity are voltage (V), current (I, uppercase "i") and resistance (r). Voltage is measured in volts, current is measured in amps and resistance is measured in ohms. Karl Weatherly/Getty Images More voltage in an electrical system makes more current flow.
A neat analogy to help understand these terms is a system of plumbing pipes. The voltage is equivalent to the water pressure, the current is equivalent to the flow rate, and the resistance is like the pipe size.
There is a basic equation in electrical engineering that states how the three terms relate. It says that the current is equal to the voltage divided by the resistance.
I = V/r
Let's see how this relation applies to the plumbing system. Let's say you have a tank of pressurized water connected to a hose that you are using to water the garden.
What happens if you increase the pressure in the tank? You probably can guess that this makes more water come out of the hose. The same is true of an electrical system: Increasing the voltage will make more current flow.
Let's say you increase the diameter of the hose and all of the fittings to the tank. You probably guessed that this also makes more water come out of the hose. This is like decreasing the resistance in an electrical system, which increases the current flow.
Electrical power is measured in watts. In an electrical system power (P) is equal to the voltage multiplied by the current.
P = VI The water analogy still applies. Take a hose and point it at a waterwheel like the ones that were used to turn grinding stones in watermills. You can increase the power generated by the waterwheel in two ways. If you increase the pressure of the water coming out of the hose, it hits the waterwheel with a lot more force and the wheel turns faster, generating more power. If you increase the flow rate, the waterwheel turns faster because of the weight of the extra water hitting it.
On the next page, we'll talk more about electrical efficiency.
Electrical Efficiency
Spike Mafford/Getty Images Electrical systems are more efficient when a higher voltage is used to reduce current.
In an electrical system, increasing either the current or the voltage will result in higher power. Let's say you have a system with a 6-volt light bulb hooked up to a 6-volt battery. The power output of the light bulb is 100 watts. Using the equation above, we can calculate how much current in amps would be required to get 100 watts out of this 6-volt bulb.
You know that P = 100 W, and V = 6 V. So you can rearrange the equation to solve for I and substitute in the numbers.
I = P/V = 100 W / 6 V = 16.66 amps What would happen if you use a 12-volt battery and a 12-volt light bulb to get 100 watts of power?
100 W / 12 V = 8.33 amps So this system produces the same power, but with half the current. There is an advantage that comes from using less current to make the same amount of power. The resistance in electrical wires consumes power, and the power consumed increases as the current going through the wires increases. You can see how this happens by doing a little rearranging of the two equations. What you need is an equation for power in terms of resistance and current. Let's rearrange the first equation:
I = V / R can be restated as V = I R Now you can substitute the equation for V into the other equation:
P = V I substituting for V we get P = IR I, or P = I2R What this equation tells you is that the power consumed by the wires increases if the resistance of the wires increases (for instance, if the wires get smaller or are made of a less conductive material). But it increases dramatically if the current going through the wires increases. So using a higher voltage to reduce the current can make electrical systems more efficient. The efficiency of electric motors also improves at higher voltages.
This improvement in efficiency is what is driving the automobile industry to adopt a higher voltage standard. Carmakers are moving toward a 42-volt electrical system from the current 12-volt electrical systems. The electrical demand on cars has been steadily increasing since the first cars were made. The first cars didn't even have electrical headlights; they used oil lanterns. Today cars have thousands of electrical circuits, and future cars will demand even more power. The change to 42 volts will help cars meet the greater electrical demand placed on them without having to increase the size of wires and generators to handle the greater current.
[This message has been edited by engine man (edited 01-25-2009).]
JimL: At last springs Formula Hybrid event, in New Hampshire, the University team from Taiwan gave a presentation for their hydro-static drive race car (it was not presented for judging, as it was not complete). After the presentation we had some private discussions about the difficulties they were encountering.
Items: - Extreme heating at high flow rates/high loads.....some difficulty keeping the fluids inside the joints, due to viscosity thinning at near boiling points. They all said, "Many, many leaks!!"
- Good low speed power transfer, poor high speed transfer as the hyrdraulic motors were resisting "high RPM".
- I was concerned that the car cannot be backed up without flow direction control. Pushing forward requires multiple, manual by-pass valving (we discussed concern for clearing the course in event of malfunction). They acknowledge this problem was discovered during initial testing (especially complete lockup of their hydraulic motors when trying to push backwards).
- Accumulator design may need some creativity to handle wide flow range (they were trying to operate without an accumulator system).
I only know a little about this stuff, from "long ago" trying to keep a John Deere back-hoe working through a summer, but I'm thinking "dead end" and probably PITA in staging lanes!
Of course...unlimited power, a zillion gears in the wheel hub, could be an interesting challenge!
There sure is some neat stuff to daydream about on this board!! :-)
Regards, JimL Rex Schimmer: I just had to comment on this subject. I am an application engineer for a company that makes the finest hydrostat drive systems in the world. We build pumps and motors that are rated at over 800 hp. The best hydrostatic drives use a pump that has a variable displacement and also is able to pump in both directions, this is called going over center. Using this type of pump you no longer need valves, the pump has two fluid ports and the motor has two fluid ports so you connect the pump to the motor and then the motor back to the pump. The oil flows from the pump to the motor and then back to the pump, this is called "closed loop" drive. There are a number of additional things that are required to make it work but this is the basis of it. Now if you vary the pump displacement the motor speed varies and if you reverse the direction of the pump flow, go "over center" the motor will reverse direction. The speed that the motor turns is a function of the ratio of the pump displacement (usually measured in cubic inches/revolution) to the motor displacement. If you have a pump that displaces 10 cu. in./rev and it drives a motor that is 5 cu. in./rev then when the pump is at full displacement the motor is turning at twice the pump speed. If you want more speed then you can have both a variable displacement pump and a variable displacement motor, which theoretically gives you an infinite speed range. (Not in real life thought!)
Our pumps are approx 91-93% overall efficiency and the motors are about the same so when you put them in a drive system you get an overall efficiency of around 83-85% plus you do loose some in the plumbing. So I would not think that they would be what you would pick for a Bonneville car. Besides our pump that transmitts 800 horse power weights around 700 lbs. The student that were building the "hydrostatic" drive car needed to do a little more research especially regarding heat, which means the system is not efficient and also up to date plumbing, the O ring face seal fittings that are used today are completely leak free. Like wise we sell hydraulic motors that will turn 10,000 rpm, not much torque but good horse power or we have motors that will only turn 10 rpm but make 1,000,000 lb-ft of torque.
Rex
jl222: Quote from: Rex Schimmer on October 21, 2008, 12:44:21 AM
I just had to comment on this subject. I am an application engineer for a company that makes the finest hydrostat drive systems in the world. We build pumps and motors that are rated at over 800 hp. The best hydrostatic drives use a pump that has a variable displacement and also is able to pump in both directions, this is called going over center. Using this type of pump you no longer need valves, the pump has two fluid ports and the motor has two fluid ports so you connect the pump to the motor and then the motor back to the pump. The oil flows from the pump to the motor and then back to the pump, this is called "closed loop" drive. There are a number of additional things that are required to make it work but this is the basis of it. Now if you vary the pump displacement the motor speed varies and if you reverse the direction of the pump flow, go "over center" the motor will reverse direction. The speed that the motor turns is a function of the ratio of the pump displacement (usually measured in cubic inches/revolution) to the motor displacement. If you have a pump that displaces 10 cu. in./rev and it drives a motor that is 5 cu. in./rev then when the pump is at full displacement the motor is turning at twice the pump speed. If you want more speed then you can have both a variable displacement pump and a variable displacement motor, which theoretically gives you an infinite speed range. (Not in real life thought!)
Our pumps are approx 91-93% overall efficiency and the motors are about the same so when you put them in a drive system you get an overall efficiency of around 83-85% plus you do loose some in the plumbing. So I would not think that they would be what you would pick for a Bonneville car. Besides our pump that transmitts 800 horse power weights around 700 lbs. The student that were building the "hydrostatic" drive car needed to do a little more research especially regarding heat, which means the system is not efficient and also up to date plumbing, the O ring face seal fittings that are used today are completely leak free. Like wise we sell hydraulic motors that will turn 10,000 rpm, not much torque but good horse power or we have motors that will only turn 10 rpm but make 1,000,000 lb-ft of torque.
Rex [/quote Hi Rex
How about one of your pumps to drive a centrifugal supercharger or any blower?
JL222
floydjer: Let`s stir this pot a little. How about using some form of variable speed hydraulic transmission feeding into a ring/pinion rear? Some means of varying the input to the final drive w/out getting on/off the throttle. Jerry
Rex Schimmer: Jl222, No problem driving a blower, plus you could put a pressure transduce in the output and we could uses that at the feed back for a closed loop blower control system, i.e. you would set the boost you want and the control system would spin the blower at what ever speed required to make the set pressue and it would do this at any engine rpm that provided enough power to run the blower at the set speed. You could also program the pressure to increase or decrease depending upon what ever parameter you needed. It only requires $$$$$$$!
floydjer, We have done exactly that on some large diesel trucks, a variable pump on the engine and a variable motor on the diff. They ran the engine at a set rpm, around 1000 in this case, and the speed was varied by the hydrostatic drive and the horsepower was controlled by the turbo boost. These got over 10 mpg wiht a 40,000 lb load. Again the problem is that we are talking some big chunks of iron and very expensive plus you need to have some sort of control system, electronic or manual.
Just a note of history, the very first Indy turbine car that PJ almost won Indy in was 4wd and use hydrostatic drive.
Rex
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12:49 AM
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
Our pumps are approx 91-93% overall efficiency and the motors are about the same so when you put them in a drive system you get an overall efficiency of around 83-85% plus you do loose some in the plumbing. So I would not think that they would be what you would pick for a Bonneville car. Besides our pump that transmitts 800 horse power weights around 700 lbs.
Thank you. Your post just proved my point. The chart I posted clearly shows the higher efficiency of gear drives, I've already said that a full transmission is not necessary, just a simple single gear reduction. As for over revving a motor:
quote
Never free spin (no-load) a series wound DC motor with anything other than 12 volts as they will over-rev and blow out the comm bars which destroys the motor and any nearby flesh
http://hitorqueelectric.com/motor-repair-101/ Now it's true that AC induction motors may not follow the same rule, I'm not sure, but variable speed AC traction motors are not the same thing as AC industrial motors. Industrial motors are heavily built to run for hours, even days at a time, and designed to run at a certain speed from line voltage, which is fairly constant. A traction motor is designed to run faster as more voltage is applied to it through a controller. A battery pack is a constantly changing power source. A 12 volt battery is 12.75 volts or more fully charged, closer to 13 fresh off the charger. So a 288 volt nominal battery pack is actually closer to 306 volts fully charged and 316 volts fresh off the charger. Without a controller in line to regulate that you might damage the motor but you will definitely have trouble switching that on and off because higher voltage will jump across contacts and can cause them to weld shut. I don't know if any of this will matter since you are obviously so enamored of this idea that it seems nothing will deter you. In my opinion it's impractical and unnecessary and I've clearly stated why I think so. I'll refrain from further comment on that subject.
limitng factor that i would think on the RPM is brush there going to float and loss contact and it you put high spring presure on them you will have high drag killing efficientcy and if your voltage starts to arc it will slow it down and amps are what makes things weld to gether not volts i cant take a car ignition coil and go out and do any welding with it but they put out 10000 plus volts but only less than 1 amp and all your welder a rated in amps not volts . now can a motor blow up sure put to much load on it it will draw more amps than the windings can handle and sparks will fly. I am talknig transmision and you are tallking single gear reduction and i would say that if you do a single gear reduction then it would be more effiiciant but if where talking 5 speed trany VS a variabl speed hydrostatic drive then hydrostatic drive wins . OK lets say it would over speed with out control there must be a way that you can put a rpm govner on the motor that keeps it in its peak efficiency rpm Oh i looked and read it never free spin a 12 volt motor with more than 12 volt well if you have a motor designd for 12 volt and you hook it to 120 you would have to be a moron you only hook a motor to the voltage it is designed for you wont have a problem
[This message has been edited by engine man (edited 01-25-2009).]
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09:40 AM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
Originally posted by engine man: ...I am talknig transmision and you are tallking single gear reduction and i would say that if you do a single gear reduction then it would be more effiiciant but if where talking 5 speed trany VS a variabl speed hydrostatic drive then hydrostatic drive wins...
I am not trying to knock your idea, I just don't understand what you are trying to accomplish. Transmissions are not necessary in a well-designed EV, so there's no need for a better option to replace it. The people who keep the transmission in their DIY EVs do so because it's cheaper and more convenient than coming up with a new single gear reduction drive.
The transmission in a typical vehicle is there to compensate for the fact that the ICE doesn't have enough torque off idle to get the vehicle moving from a standstill, and keep it moving through varying circumstances, with only one gear. The electric motor you are considering using to power your hydrostatic drive actually has full torque where it's needed most, and with one gear reduction a properly sized and implemented electric motor can actually get the vehicle moving and keep it moving. Your idea may work fine, but it's completely unnecessary.
Now if you want to build an alternative fuel vehicle it makes more sense. With a diesel your hydrostatic drive makes sense because it will keep the ICE operating near peak efficiency while the vehicle manages to start moving and adapt to changing circumstances. In that scenario, your drive is providing greater efficiency. You can also concentrate on the benefits of being able to run a variety of fuels, and maybe injecting hydrogen like the guys with the Hummers.
My point is the hydrostatic drive seems to be the centerpiece of your thinking, so build on that foundation with things that complement it, or things it complements. IMO diesel and hydrostatic seem like a match made in heaven.
[This message has been edited by toddshotrods (edited 01-25-2009).]
Ok my thought was you would keep the motor in it peak efficiency but if it is there from 0 to 9000 rpm no need to but I was told that it takes a lot of amps to just start a motor and amps drain you batteries not volts amp= current plus if you got rid of the controller that would save power due to I am sure ther not 100 precent efficient you would just control the speed of the car with the veriable speed hydrostatic drive . now there is no need for the 5 spd trany that has losses my thinking when you combine all the loss from the controller to the 5 speed and the total loss in eficiency is much higher than that of the hydrostatic drive
can you tell me what the efficiency is of a motor controler if it is 80 precent or less then the hydrostatic with out a controler would be more efficient
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10:48 AM
toddshotrods Member
Posts: 1177 From: Columbus, OH, USA Registered: Aug 2004
It would be interesting to see real-world comparisons of a traditional controller-based EV and your concept. In a sense you are putting a carburetor on an EFI engine. I personally would still go with the controller because I love the possibilities computer control offers. I really want a bigger, badder, controller than anything I have seen. I want one "super computer" that can integrate, monitor, and control every aspect of the vehicle's performance.
One other thing to consider is the hydrostatic drives seem to be fairly heavy. You're going to have that drive, plus the electric motor, plus the battery pack. By comparison, the transmission you are replacing is relatively light. You'll need a way to shave some pounds, or you'll lose the theorectial gains in efficiency just pushing the extra poundage around.
yes it is heavy they are built for tractors and who cares in that world but if they would go from cast iron to aluminum that would lighten it a lot and i think this could be computer controled with sensors on motor load vs speed to keep every thing working as efficeint as it can be
[This message has been edited by engine man (edited 01-25-2009).]
OK i did some more research and i think this is where we both are looking at things from a different point you are looking at controlling the volts to controll the speed of the motor where i need a motor with one constant speed and i would be controling the amp draw by the load placed on the motor
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12:59 PM
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
limitng factor that i would think on the RPM is brush there going to float and loss contact
Also the commutator can fly apart, (explode), if the RPM's get too high. I've seen the pictures, it's not pretty.
quote
Oh i looked and read it never free spin a 12 volt motor with more than 12 volt well if you have a motor designd for 12 volt and you hook it to 120 you would have to be a moron you only hook a motor to the voltage it is designed for you wont have a problem
Look again. He's talking about motors rated to run from 36 to 120 volts and saying not to test them unloaded with more than 12 volts because they can over rev and fly apart.
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01:10 PM
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
can you tell me what the efficiency is of a motor controler if it is 80 precent or less then the hydrostatic with out a controler would be more efficient
i have been looking at electric fork lifts and they seem to be using hydrostatic drives not sure why they would do it or what there system is but they need to get the most out of a charge i will keep looking and investagating all posible ways
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01:31 PM
Nohbdy Member
Posts: 587 From: Grand Rapids MI Registered: Dec 2008
the 700lb peice put out 800 horsepower right? u could use something other than steel to make the peices, and how many people on here seriously plan to put 800 hp in their fiero? im seeing this as being 1.143 hp per lb, which would be raised if u didnt need to hold in 800hp worth of pressure in the pipes. can ny1 get the weight to horsepower ratio for what ur suggesting?
OK another ? if i have a 30 HP motor that is 22380 watts if i use a 480 volt system then my total amps should be 46.625 now how many amp hours do i need is it 46.625 or something more if it is 46.25 then 93 amp hours would get me 2 hours at full load
HP X 746 = watts total watts / by volts = amps
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02:47 PM
PFF
System Bot
dratts Member
Posts: 8373 From: Coeur d' alene Idaho USA Registered: Apr 2001
I don't know if anyone has mentioned it, but tesla has gone from the original 2 speed to a complete new drive train with a liquid cooled motor and a one speed transmission. I'll bet they have researched it more than we have.
can some one tell me how this electromagnet can be so powerfull with such little power why not wind a motor in this same way but may be it is not possible but it has a 500 pound lifting force from 2 d cell battries
the more turns an electromagnet has the stronger the magnetic field generated i beleive. with 4 28guage wires wrapped 175 times ur at 700 turns, so it wouldnt take all to much power to make a strong magnet. it ends up being less than a pound per turn with that.
there was one guy touting that amps are not the way he claimd a whole lot of winding like a mile of wire and higher voltage and milly amps his name was josph newman and made the newmen motor
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10:48 PM
Jan 26th, 2009
JRP3 Member
Posts: 318 From: Central NY State Registered: Jan 2009
i have been looking at electric fork lifts and they seem to be using hydrostatic drives not sure why they would do it or what there system is but they need to get the most out of a charge i will keep looking and investagating all posible ways
They probably use hydrostatic because it's an easy way to make a vehicle maneuverable, and for the torque multiplication which allows them to use a smaller lower voltage setup, not for efficiency. Electric forklifts move at low speeds and are never far from a charger so range and efficiency aren't that important. I think some lifts do use more than one electric motor, one for each wheel, so that they can reverse one side to spin around in tight spaces.
