EV Digest 5112
Topics covered in this issue include:
1) Donor, Not Gliders (Was New Kits)
by Electro Automotive <[EMAIL PROTECTED]>
2) Re: 12volt alternator or dc-dc convertor
by Lee Hart <[EMAIL PROTECTED]>
3) Re: Another NiCd run in my Sparrow
by "John G. Lussmyer" <[EMAIL PROTECTED]>
4) Re: 12volt alternator or dc-dc convertor
by Lee Hart <[EMAIL PROTECTED]>
5) Re: 10hp clark Industrial truck motor 36-48 volt dc NOS Item number:
7581988119
by Lee Hart <[EMAIL PROTECTED]>
6) Thank You, Roderick Wilde!
by John Wayland <[EMAIL PROTECTED]>
7) Re: 12volt alternator or dc-dc convertor
by "Mark Grasser" <[EMAIL PROTECTED]>
8) Re: chevy astro conversion?
by Lee Hart <[EMAIL PROTECTED]>
9) Re: 10hp clark Industrial truck motor 36-48 volt dc as a hydro drive
by Jim Husted <[EMAIL PROTECTED]>
10) Re: Zapi H2 user feedback sought
by Lee Hart <[EMAIL PROTECTED]>
11) Re: 30 min on 30min off charging
by "Roland Wiench" <[EMAIL PROTECTED]>
12) Re: Evcort break upgrade
by Nick Austin <[EMAIL PROTECTED]>
13) Re: is this a good idea?
by Lee Hart <[EMAIL PROTECTED]>
14) See this video!
by "stU" <[EMAIL PROTECTED]>
15) Re: Paralleling and Serialing Controllers
by Lee Hart <[EMAIL PROTECTED]>
16) Re: See this video!
by Jim Husted <[EMAIL PROTECTED]>
17) Re: EV music?
by Lee Hart <[EMAIL PROTECTED]>
18) Re: Zapi H2 user feedback sought
by Ralph Merwin <[EMAIL PROTECTED]>
19) Re: Paralleling and Serialing Controllers
by Lee Hart <[EMAIL PROTECTED]>
20) Re: 1231C and Lynch motor
by Lee Hart <[EMAIL PROTECTED]>
21) RE: Paralleling and Serialing Controllers
by Mike & Paula Willmon <[EMAIL PROTECTED]>
22) Re: battery or dc-dc convertor for motorcycle
by paul wiley <[EMAIL PROTECTED]>
23) Re: 12volt alternator or dc-dc convertor
by Jeff Shanab <[EMAIL PROTECTED]>
24) Re: Paralleling and Serialing Controllers
by "David Roden" <[EMAIL PROTECTED]>
25) RE: Bad floodies??
by "David Roden" <[EMAIL PROTECTED]>
26) RE: Sep Ex - Is it really as bad as I make it out to be?
by "David Roden" <[EMAIL PROTECTED]>
--- Begin Message ---The cars we choose should have enough units on the road to be able to find gliders.Unless you are getting new chassis less drive train, you are talking about DONOR cars, not GLIDERS.Shari Prange Electro Automotive POB 1113 Felton CA 95018-1113 Telephone 831-429-1989 http://www.electroauto.com [EMAIL PROTECTED] Electric Car Conversion Kits * Components * Books * Videos * Since 1979
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--- Begin Message ---Bill Dennis wrote: > If you're using a DC-DC converter, which is acting like an alternator > to charge the battery, it sounds like you just need an SLI battery, > right, since it's not usually going to get pulled down very far in DOD? Correct. If your DC/DC is only "on" while driving, then the stock SLI battery can be used. It will last about as long as it does in a normal ICE (a few years, typically). And it will be ruined if you accidentally leave something "on", or the EV sits idle long enough for it to go dead. > I've also heard of some people using a deep cycle battery instead of > an SLI. If you use a deep cycle with lots of amp hours, would that > tend to work without a DC-DC? Right again. Since you never draw high "starting" currents, you can use a deep cycle battery instead. The deep-cycle battery lasts longer (5-10 years), and isn't hurt as badly by accidentally being run dead. And, you can leave your DC/DC "on" all the time if you limit it to a safe float voltage (around 13.5v new, and reduced as the battery ages). You can also use a deep-cycle battery without any DC/DC (or alternator) at all. It has to have enough capacity to handle your 12v loads by itself. You recharge it when parked, along with the rest of your batteries. Your lights will be a little dimmer and 12v motors will run a little slower. -- Lee Hart
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--- Begin Message ---At 10:34 AM 1/21/2006, Lee Hart wrote:How about using my Battery Balancer or an equivalent setup? It monitors individual cells or groups of cells, and uses a single DC/DC to transfer as much as 30 amps between them (limited by the 30a relays I used). If there is (say) a +/-20% variation in capacity between cells, then this gives you 20% more range.Which still needs a big DC-DC to work.Also, these are 1.2V NiCd cells, and so far my tests have shown them to be very consistent in capacity. Not much variation at all.-- John G. Lussmyer mailto:[EMAIL PROTECTED] Dragons soar and Tigers prowl while I dream.... http://www.CasaDelGato.com
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--- Begin Message ---Cor van de Water wrote: > You want to get stuck on a railroad crossing (or any other > roadway crossing) because you were too cheap to install a > DC/DC converter and your 12V battery died? Yes, it could happen. Extremely unlikely, though. Batteries don't suddenly die; they gradually fade away. You'd have plenty of warning. My early EVs had no DC/DC converter or alternator, and just ran all 12v loads off the accessory battery. Given that they were 50-100 amphour batteries, and my maximum 12v load was 25 amps or less, I could drive off the accessory battery for 2-4 hours. That was a *lot* longer than my propulsion pack would last! > Look at what Toyota did with the Prius. They could have > installed an alternator - the engine normally does not > shut off for more than a few minutes. > Why then did they add a 100A 12V inverter to the motor > controller? Guess? Because their 12v system powers an electric heater, the power steering, power brakes, etc. -- Lee Hart
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--- Begin Message ---Jim Husted wrote: > > Hey Darin > > I'm sorry I thought I had replied to this. This will make a good smaller > EV drive motor. The biggest problem will be converting the shaft. I've > replaced those shafts with an ADC shaft after mod'ing it to fit. This is a > series wound motor and although it is smaller in diameter than the ADC8 it is > longer and is just shy of the 8's mass. It is wound with thicker wire to > have the lower voltage rating and draws higher current than the ADC8. If you > can get past the shaft issues it should push Jim (or others), How hard is it to find a hydraulic pump to fit these motors? One possible idea is to install the hydraulic pump on one of these motors, and use hydraulic wheel motors to drive the wheels. This is exactly how many industrial and earthmoving vehicles are set up. IF you pick the pump and motor carefully, they can be over 90% efficient. Such a setup could also be far easier to add to an existing vehicle, since the existing driveline isn't used at all (and could even be left in place to make it a hybrid). -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---Hello to All,I want to publicly thank Rod Wilde for all his dedication and hard work serving as NEDRA president all these years. His energy and drive is something that is needed in a president, and losing him in that position is a BIG loss for our sport.Rod and I were two of the the founding EVers that dreamed up the idea of NEDRA, and when I was the original president he served with me as Vice President. It's funny, because at one time he and I were staunch competitors who really didn't want to like each other :-o It all started back in '94.....man, I'm sounding like an old geezer!For nearly 5 months now, Rod has been trying to get new rules and new voltage divisions past for the good of all EV drag racers. He set up a rules committee, and I was asked to be part of that committee. Quite frankly, many of the proposed rule changes adversely affected my own EV, but I voted for them because I could see they would make electric drag racing safer, open new areas for innovation, make it possible for new world records to be set, and in general, improve the sport. Rod and all of us on the rules committee wanted to have everything done before the turn of the year so that, in particular, the competitors at the first NEDRA EVent in 2006, Battery Beach Burnout, could have a shot at setting new records in the new classes and divisions. Rod was 'very' active throughout the process, and when things got bogged down, he would inject his energy and push things back into gear. He demonstrated strong leadership through the whole ordeal.We've lost Rod as president now, but he's still an active NEDRA member, so we'll still be hearing a lot from him....thank goodness for that! Thank you, my friend Rod Wilde!See Ya.......John Wayland PS: Ken Trough has a synopses of the recent turmoil within NEDRA at: <[EMAIL PROTECTED]>
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--- Begin Message --- What bothers me about running off just a battery is that it is only 12 volts. Too dim of headlight for me. My work-in-progress will get a DC to DC that runs an output of 14 to 14.5 VDC no battery. This is the level present ICE cars run at and is the voltage the headlights and accessories were designed to run at.Mark Grasser Subject: Re: 12volt alternator or dc-dc convertorCor van de Water wrote:You want to get stuck on a railroad crossing (or any other roadway crossing) because you were too cheap to install a DC/DC converter and your 12V battery died?Yes, it could happen. Extremely unlikely, though. Batteries don't suddenly die; they gradually fade away. You'd have plenty of warning. My early EVs had no DC/DC converter or alternator, and just ran all 12v loads off the accessory battery. Given that they were 50-100 amphour batteries, and my maximum 12v load was 25 amps or less, I could drive off the accessory battery for 2-4 hours. That was a *lot* longer than my propulsion pack would last!Look at what Toyota did with the Prius. They could have installed an alternator - the engine normally does not shut off for more than a few minutes. Why then did they add a 100A 12V inverter to the motor controller? Guess?Because their 12v system powers an electric heater, the power steering, power brakes, etc. -- Lee Hart
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--- Begin Message ---lee parrish wrote: > What originally sold us on the Astro/Safari was > meeting a contractor at the lumber yard one day, who > always carried about a ton of tools in the back of his > Safari, and with his V6 got a steady 21mpg. And that > was with unmodified, stock set up. That's typical for many minivans. Here are the ones I've owned. My 1961 Corvair Greenbrier got 25 mpg. My 1971 full-size Chevy G20 van got 18 mpg (V8, manual transmission). My 1987 Dodge minivan got 27 mpg (4-cyl, automatic transmission) My 1994 Plymouth minivan got 30 mpg (4-cyl, manual). My 2000 Toyota minivan got 24 mpg (V6, automatic). My 2002 VW minivan gets 19 mpg (V6, automatic). The Astrovan is fairly heavy. I think you can do a lot better with one of the lighter minivans. For an EV conversion, you want one with a manual transmission (hard to find). -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---Hey Lee, all The pumps for these motors are as available as the motors or darn close (every motors needs a pump right? lol). There are shops that do nothing but rebuild them so it seems they should be easy to find and or repair. These pumps are able to lift 3000 to 5000 Lbs. on the units they operate for. I'd have no idea what it would take to drive a car, maybe Wayland could shed some light as to their PSI and such. Now these motors with the pumps as an OEM unit are rated at only a 5 minute duty cycle so I'm unsure as to how they would hold up to being run continuously at the load they would be running. Another concern is that these spline setups are the major reason for failures with these motors. A 24 hour a day distribution center can wipe out a new spline and pump in about a year sometimes less if they have abusive drivers or real heavy loads. I really like the idea and it seems that if one didn't do it then two would and like you said maybe make a hybrid. You stated that it would be an easier project, do they make hydro drive wheels?? or would this need to be addressed?? Either way I still feel that the shaft is the weak link with these motors. ADC has made a larger motor with a larger spline but they cancel each other out resulting in the same wear times. If the larger pump and spline were added to say this motor it would have a much longer wear out period. I'd like to hear more on what it would take to do a hydro drive conversion. Hope this helps Jim Husted Hi-Torque Electric Lee Hart <[EMAIL PROTECTED]> wrote: Jim Husted wrote: > > Hey Darin > > I'm sorry I thought I had replied to this. This will make a good smaller EV > drive motor. The biggest problem will be converting the shaft. I've replaced > those shafts with an ADC shaft after mod'ing it to fit. This is a series > wound motor and although it is smaller in diameter than the ADC8 it is longer > and is just shy of the 8's mass. It is wound with thicker wire to have the > lower voltage rating and draws higher current than the ADC8. If you can get > past the shaft issues it should push Jim (or others), How hard is it to find a hydraulic pump to fit these motors? One possible idea is to install the hydraulic pump on one of these motors, and use hydraulic wheel motors to drive the wheels. This is exactly how many industrial and earthmoving vehicles are set up. IF you pick the pump and motor carefully, they can be over 90% efficient. Such a setup could also be far easier to add to an existing vehicle, since the existing driveline isn't used at all (and could even be left in place to make it a hybrid). -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net --------------------------------- Yahoo! Photos Showcase holiday pictures in hardcover Photo Books. You design it and well bind it!
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--- Begin Message ---Mark Freidberg wrote: > The Curtis 1221 controller in my 1980 Electra Van is overheating > easily. Not surprising since there's no heatsink, no fan, and > ventilation appears limited where it is located. Why not just add a fan, heatsink, cold plate, or other cooling to it? -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---You will notice that a 120 vac receptacle has one longer plug-in slot than the other. The shorter one is the line wire (or some times call hot) and the other longer plug slot is the neutral (or white wire). Normally back at the main circuit breaker panel, then mains coming in from the service entrance will be mark L1 (for Line 1) and L2 (for Line 2). Sometimes L1 wire is a black wire and L2 is a red wire. A volt meter reading from L1 to L2 will be a voltage that may range from 220 to 250 volts, depending on how the service transformers are tap. A volt meter reading from either L1 or L2 line lugs to the Neutral Bar (which the white wires are connected up to) should read 1/2 of the voltage than the voltage between L1 and L2. If the voltage between the black and red is 240 volts, than the black or red to white should read 120 volts. Now taking a volt meter lead and inserting one into one short plug slot in one receptacle and the other lead into the next receptacle short plug slot, you may either read nothing, meaning both receptacles are on the same Line, either L1 or L2 (black or red wire). Check each receptacle if there is even power to it, by inserting the voltmeter leads in one receptacle, with one lead going to the short slot and the other lead going to the longer slot. You should than read 120 volts if the circuit breaker is on. If you get 240 volts between the two receptacles, then you must turn off two circuit breakers to turn off both receptacles If you open up the receptacle boxes, than you will notice that there may be only one neutral wire connecting to both receptacles This is a common practice in commercial wiring even for receptacles that are space on a wall surface. Each receptacle is connected up which alternated between each L1, L2 and even a third L3. In residential wiring, we normally used only two lines or L1 and L2 mark as black and red. A common neutral can share between any two L1 and L2 circuits, because the neutral is shunted out while both L1 and L2 circuits are on. So even if you have two 20 amp circuit breakers on, the maximum neutral current will be 20 amps, not 40 amps. If you used two lines coming off two receptacles that is L1 or L2 or 240 volts, than the circuit breaker handles must be tie together. If a user is using one receptacle and a replaces the other receptacle power is on and if you have to break the neutral connection, you will still have current flowing threw that neutral. If you find that there are 240 volts or L1 and L2 circuit at the box, then its is best to change the receptacle with a 120/240 V 3-pole, 4-wire, 20 amp maximum rating if the wire size is a No. 12 AWG. If the distance from the circuit breaker panel is at 20 feet, the wire will have about 1 percent voltage drop if you pull all of 20 amps. It is best not to go over 80% or 16 amps on a 20 amp receptacle. You will have a voltage drop of about 3 percent at 42 feet. If the distance is over 50 feet, than the wire size should be a No. 10 AWG for 16 amps. The reason I'm so long winded on this subject, I used to teach electricians and technicians the National Electric Codes or NEC requirements. Roland ----- Original Message ----- From: Rush<mailto:[EMAIL PROTECTED]> To: [email protected]<mailto:[email protected]> Sent: Saturday, January 21, 2006 8:01 AM Subject: Re: 30 min on 30min off charging Peter wrote - >> 2- The boxes that have a two 2-gang outlets...is there >> a way to figure out if there's both a black wire going >> to one, and red to the other (without opening the box) > > yeah, use a voltmeter Can you explain how to do this? Thanks Rush Tucson AZ www.ironandwood.org<http://www.ironandwood.org/>
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--- Begin Message ---On Sat, Jan 21, 2006 at 11:35:05AM -0000, Paul Compton wrote: > >Does anybody know if a 4 caliper brake upgrade, or a rear drum to disc > >conversion kit is available for a 1993 Evcort? > > Why would you want one? If you're after more braking torque on the rear > wheels then this is the wrong way to go, only if you're experiencing > overheating brakes at the rear does the disk conversion make sense. There's > a bolt on vented disk/caliper solution at the front, Madman has them on his > Fiesta. Cool! Do you have a link to the front upgrade kit? Today the Evcort does not have enough breaking power, so I'm trying to improve the situation. I thought that discs on the rear would help as well. Thanks!
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--- Begin Message ---Dale Curren wrote: > A friend and I have been playing with an electric car. It currently > has 4 batteries in series (48v) and a got-for-cheap curtis controller > that is rated at only 48 volts... we had the idea to put two more > batteries in the series but AFTER the controller. We would use a > manual switch to insert these two batteries in the series after > we're already full throttle using 48 volts... Will this allow our > 48 volt controller to feel no more than 48 volts of pressure, thus > keeping it happy. It could work, depending on how you wire it. The Curtis controller switches M- (the negative side of the motor) between B+ and B- (the + and - of your 48v pack). The positive side of the motor is normally tied to B+. You can add a SPDT (Single Pole, Double Throw) contactor to switch your extra batteries into the positive side of the motor. Try this: 1. Disconnect motor positive from B+. 2. Connect motor positive to the common of the SPDT contactor. 3. Connect the normally-closed contact of the contactor to controller B+. 4. Connect the normally-open contact of the contactor to the positive of your 24v "afterburner" pack. 5. Connect the negative of your 24v "afterburner" pack to the positive of your main pack. With the contactor off, your 48v pack, controller, and motor all work the same. The motor sees 0v to 48v as you move the throttle from "fully off" to "fully on". With the contactor on, the positive of the motor is now at 48v + 24v = 60v. The negative of the motor is being switched (by the controller) between 0v and 48v. Thus the motor sees 24v to 60v as you move the throttle from "fully off" to "fully on". The controller never sees over 48v, so it's ok voltage-wise. However, the controller's current limit DOES NOT WORK when the afterburner contactor is energized! Therefore, you can only energize that contactor when the motor is at a high enough rpm so it won't draw high current. Also, you can't switch the afterburner contactor on or off while the motor is at high current. If you do, it will burn its contacts from arcing due to motor inductance. The sequence of events is: a. Accellerate until the motor is above X rpm. b. Release the throttle. c. Switch afterburner contactor "on". d. Apply throttle again. To slow down, reverse the sequence. e. Release the throttle before rpm falls below X. f. Switch afterburner contactor "off". g. Apply throttle again. -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---For a Good Time Click <http://68.148.5.74/~devildevil/Hydrofoam/Hydro-foam%20Boat%20Planes.wmv> Watch the entire clip. Electric motor powered. http://www.hobbytron.com/HydroFoam.html<<attachment: winmail.dat>>
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--- Begin Message ---David Dymaxion wrote: > Well, actually, I would like to actually hook things up and see what > happens, maybe even enjoy a smoke and light show, but the EVDL is a > much cheaper way to learn. :) Good. Before you go hiking in the quicksand bog of controller design, it's good to see what paths others took, and what happened to them. "I do not learn from my mistakes. I learn from *other people's* mistakes." -- Kaiser Wilhelm Running two controllers in series or parallel is possible, but a lot harder than one. You can find lots of literature on it with regards to running switchmode power supplies in parallel or series. The scheme of splitting a motor's field into two inductors, and using each one with its own controller, and driving a single armature is probably the simplest route. But it still will require careful control of the two controllers to avoid unpleasant surprises. > What if each switch has a large capacitor across it? It seems the > capacitor would work hard to keep the voltage the same, so the switch > would not suddenly see full voltage. If you are switching fast > enough, and your capacitor time constant is slow enough, might you > then get away with two switches (i.e. controllers) in series? Yes, this is possible. This is how "snubbers" work. You also need resistors and/or diodes in series with each capacitor to limit the peak current when a switch turns on, or if the switches turn off at slightly different times. There is also a rich field of "lossless" snubbers, "soft" switches, resonant and quasi-resonant switching, and other techniques to carefully shape and control the voltage and current in a high-speed switch to maximize efficiency and reliability. Most EV controller builders haven't discovered these techniques yet, though they are widely used in other fields. -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---Those are freaking awesome. I want one bad!! My sone Matt is goon flip his lid when he sees this. They just need to make them car sized now, lmao! Just had to say WoW, and thanks for sharing. Jim Husted stU <[EMAIL PROTECTED]> wrote: For a Good Time Click Watch the entire clip. Electric motor powered. http://www.hobbytron.com/HydroFoam.html --------------------------------- Yahoo! Photos Showcase holiday pictures in hardcover Photo Books. You design it and well bind it!
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--- Begin Message ---Evan Tuer wrote: > > On 1/20/06, Shawn Rutledge <[EMAIL PROTECTED]> wrote: > > OMD - Electricity > > Kraftwerk - Electric Cafe > > Moby - Electricity (should be good but can't remember hearing it) > > Captain Beefheart - Electricity > Pan Sonic - Voima - Sähkötin. ... and maybe someone will record some of my EV filk songs ("The Man Who Never Recharged", or "Gas Hog Lincoln" for example :-) -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---Mark Freidberg writes: > > The Curtis 1221 controller in my 1980 Electra Van is overheating easily. > Not surprising since there's no heatsink, no fan, and ventilation appears > limited where it is located. As Lee suggested, try adding something to cool your controller. You'd have to do this if you got a Zapi anyway, so it's worth the effort. I have a home-made cold plate (sized for a Zapi H2) that might fit your Curtis if you're interested. > I'd like to replace it with some other controller, and provide adequate > cooling for the replacement. The Zapi is of interest because of its regen > braking potential. What have user experiences been with the Zapi? I used to have a Zapi H2 with regen in my Geo Prizm. This was with a 120v pack and a 9' ADC motor. I had to drill/tap holes in the motor to allow the brushes to be set to neutral timing. You motor may already have the appropriate holes. When I first got this setup running I had the 'braking regen' connected as well as the 'off throttle' regen. I disabled the braking regen after a couple of trips because it felt too harsh. Off throttle regen seemed to work pretty well, but the motor made an odd sound at low speeds, similar to chains dragging on the ground. One problem with the regen was that it could easily pump 50 amps into the pack, so if the pack was already fully charged (e.g. going down a hill right after charging), the batteries were getting overcharged. My Zapi quietly died one day when I accidentally bypassed the charger interlock and turned on the ignition when the charger was running, which subjected the Zapi to about 160v. I sent it to the Zapi repair shop and they said it wasn't worth repairing. Overall, I would not recommend the Zapi H2. Adding cooling to your Curtis is a good first step. Otherwise I'd recommend a Zilla. Ralph
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--- Begin Message ---Mike & Paula Willmon wrote: > Don't MOSFETS have a negative thermal resistance curve? I think you mean a positive electrical resistance coefficient. That means the hotter they get, the higher their on-state resistance. This means MOSFETs in parallel tend to self-equalize the current sharing; the hotter devices gets less current, shifting the load to others. Most other semiconductors (diodes, bipolar transistors, SCRs, IGBTs, etc.) all have negative coefficients; the hotter they get the *lower* their on-state resistance, so in parallel, the hotter ones hog the current and get still hotter. In severe cases, this leads to a chain reaction of failures! But, these effects are generally small. They help if the parallelled devices are well matched to begin with, and all tightly coupled thermally (all on the same heatsink and near each other). But you can't depend on them with randomly selected devices, or when they aren't mounted on the same heatsink, or the stress levels are already very high. -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---Tim wrote: > Instead of inserting inductance (extra cost, space, weight, > losses)... can a person just find a controller that operates at > a higher frequency or raise the frequency of the controller you > now have? What frequency would you actually need that would allow > the Lynch to operate without inserting the extra inductance? Yes, it is cheaper and lighter to leave out the inductor. But it worsens efficiency, and makes the controller's current limit work poorly (lowers reliability). Done right, the inductor *raises* efficiency. If you run high frequency AC into an inductor with a core designed for low frequencies, it creates core losses. Motors don't have good high-frequency cores. When the motor is used as an inductor, this means extra heat and loss in the motor. When you use a separate inductor chosen for low losses at the operating frequency, it increases efficiency and makes the motor run cooler. -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---yes, thats zactly what I meant. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Lee Hart Sent: Saturday, January 21, 2006 12:01 PM To: [email protected] Subject: Re: Paralleling and Serialing Controllers Mike & Paula Willmon wrote: > Don't MOSFETS have a negative thermal resistance curve? I think you mean a positive electrical resistance coefficient. That means the hotter they get, the higher their on-state resistance. This means MOSFETs in parallel tend to self-equalize the current sharing; the hotter devices gets less current, shifting the load to others. Most other semiconductors (diodes, bipolar transistors, SCRs, IGBTs, etc.) all have negative coefficients; the hotter they get the *lower* their on-state resistance, so in parallel, the hotter ones hog the current and get still hotter. In severe cases, this leads to a chain reaction of failures! But, these effects are generally small. They help if the parallelled devices are well matched to begin with, and all tightly coupled thermally (all on the same heatsink and near each other). But you can't depend on them with randomly selected devices, or when they aren't mounted on the same heatsink, or the stress levels are already very high. -- If you would not be forgotten When your body's dead and rotten Then write of great deeds worth the reading Or do the great deeds worth repeating -- Ben Franklin, Poor Richard's Almanac -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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--- Begin Message ---{snip} You can also use a deep-cycle battery without any DC/DC (or alternator) at all. It has to have enough capacity to handle your 12v loads by itself. You recharge it when parked, along with the rest of your batteries. Your lights will be a little dimmer and 12v motors will run a little slower. What do you guys think about this on an electric motorcycle? I have a 48v pack, and was thinking the weight of an 6 ah, 12vbattery is better than the extra draw of the dc convertor on an already low voltage pack. Am i off my rocker --------------------------------- Yahoo! Photos Showcase holiday pictures in hardcover Photo Books. You design it and well bind it!
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--- Begin Message ---is it just that simple? What if a step-up pully is used to spin the alternator fast and the field is in series with the brake light switch? Combined with an aux battery, this could keep it topped off in most commutes there could be a bypass switch to kick it on as needed on highway like commutes >From what I hear, Automotive Alternators are very poor efficency, except for some of the new bosch used on BMW and Mercedes.
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--- Begin Message ---On 20 Jan 2006 at 16:27, Andre' Blanchard wrote: > Something like this may work. Split the field and let each controller have > 1/2 > but share the armature. I seem to remember a lashup from 10 or 15 years ago. Can't recall who did it - he had an unusual military-sounding name, IIRC. I think he left the field intact and brought out extra armature (brush) connections - there were 4 arm terminals to use with two controllers. I don't recall now how the field was connected. Maybe someone else does. David Roden - Akron, Ohio, USA EV List Assistant Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Want to unsubscribe, stop the EV list mail while you're on vacation, or switch to digest mode? See how: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" or "etpost" addresses will not reach me. To send a private message, please use evadm at drmm period net. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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--- Begin Message ---On 17 Jan 2006 at 20:51, Mike & Paula Willmon wrote: > Sulfate due to cycling builds up less in the sealed > batteries. Once again, I don't see any physical reason for this to be the case. In fact I can see a way that the contrary might be true. Sulfate formation is a normal process of discharge. Our concern is with the large-crystalline sulfate (I hope that's the right term, as I say I'm not an electrochemist) which forms when the battery is chronically undercharged or else sits for an extended period in a discharged state. It resists participation in the charge reaction. In a flooded cell these crystals can and do shed from the electrodes and precipitate. There is usually space provided in the bottom of the cell for this very purpose. However, I don't see the mechanism by which this sulfate shedding can occur in an immobilized electrolyte cell. > So much so that many manufacturers tell you not to equalize your > AGM's or Gels or at least not do it as as often. I think they advise this rather because equalization is potentially more damaging to VRR batteries. If the current is too high the battery will vent, and the water lost can't be replaced (at least not without opening the battery and voiding the warranty). > Its true you can boil off much of the sulfate in a flooded cell as > often as you > like and still maintain your capacity, but you give up cycle life by doing > this. As I understand it, once the sulfate has formed large crystals, it can't be "boiled off." It represents active material that's no longer available to provide usable capacity. But it's true that one can equalize a flooded battery more frequently, and make the most of the capacity that it retains. Getting the best life from any lead battery involves balancing capacity loss from overcharging with capacity loss from undercharging. There's probably more art than science to this. David Roden - Akron, Ohio, USA EV List Assistant Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Want to unsubscribe, stop the EV list mail while you're on vacation, or switch to digest mode? See how: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" or "etpost" addresses will not reach me. To send a private message, please use evadm at drmm period net. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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--- Begin Message ---On 18 Jan 2006 at 12:44, Roger Stockton wrote: > You are looking at spending $125-150 for a series field (plus labour?); > have you considered just purchasing a proper sep-ex controller for your > motor instead? I agree with Roger. IMO, a series motor's only advantage for a vehicle is high initial torque. Well, that and the fact that almost any dumb controller can run it. Matching the field controller to the motor's characteristics seems a lot fussier in sep-ex applications. If you can get the controller and motor well matched, I think you'll prefer the overall driveability of a sep-ex motor. Just make sure you have enough power available move that little guy off the line. David Roden - Akron, Ohio, USA EV List Assistant Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Want to unsubscribe, stop the EV list mail while you're on vacation, or switch to digest mode? See how: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" or "etpost" addresses will not reach me. To send a private message, please use evadm at drmm period net. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
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