85 Supra -Condensor motor replacement? - Page 2

Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21
  1. #11
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    877
    Well, I measured the static resistance of the stock motor and it is 1.4 ohms. When the circuit is first activated, the voltage divider effect of a 0.13 ohm resistor in series with the 1.4 ohms motor will draw 8.2 Amps. This results in about 1.1V drop over the 0.13 ohm resistor which generates 8.7W of heat from the resistor. Normally you would want to double the wattage rating of the resistor so there is a safety margin to prevent the resistor burning up.

    However, once the motor starts running, the inductive load of the motor generates a back-EMF which effectively reduces the current load of the motor. How much?
    Well, I fired up the car and turned the air conditioning on so the condenser fan was running and after 5 minutes one could feel heat being generated in the 0.13 ohm resistor, but I could easily keep my finger on it without burning myself. It was merely warm to the touch.

    I wasn't going to take the harness apart to measure the voltage drop over the resistor to get an indication of the circuit current, but based on the temperature, I would be surprised if the resistor was dissipating more than 2W of heat. A 5W rated resistor should be very safe.

    My biggest concern would be weather proofing the resistor and connector so that water doesn't short the resistor. I suspect that Heat Shrink Tubing would do an adequate job, but water can be difficult to seal out.

    Dale
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  2. Remove Advertisements
    CelicaSupra.com
    Advertisements

  3. #12
    CelicaSupra.com Member ddd228's Avatar
    Join Date
    May 2005
    Location
    N. Seattle.
    Posts
    5,232
    I have (3) 1 ohm ceramic ones in stock. They are used for a simple brake light circuit for dirt bikes.

    https://www.ebay.com/itm/5Pcs-Power-...QAAOSwCAlbj58n


    OOPS. The white one is only 1/10th of an ohm.
    Last edited by ddd228; 08-18-2019 at 11:28 AM. Reason: FIXED IT.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  4. #13
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    877
    Yeah, they look suspiciously similar to the Toyota resistor in shape and texture. The only things different are the axial leads. These have the leads exposed. On the Toyota, they are covered and attach to a shielded wire where they attach to the connectors.

    I don't know what effect a change from 0.13 ohm to 1 ohm would do to the fan speed. This may be significant. I was hunting for these in the sub-one ohm range and they seem to be somewhat harder to find than they used to be!
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  5. Remove Advertisements
    CelicaSupra.com
    Advertisements

  6. #14
    CelicaSupra.com Member ddd228's Avatar
    Join Date
    May 2005
    Location
    N. Seattle.
    Posts
    5,232
    Quote Originally Posted by supraz View Post
    Yeah, they look suspiciously similar to the Toyota resistor in shape and texture. The only things different are the axial leads. These have the leads exposed. On the Toyota, they are covered and attach to a shielded wire where they attach to the connectors.

    I don't know what effect a change from 0.13 ohm to 1 ohm would do to the fan speed. This may be significant. I was hunting for these in the sub-one ohm range and they seem to be somewhat harder to find than they used to be!
    Did you see this one?
    https://www.ebay.com/itm/Dale-1-Ohm-....c100005.m1851

    Or this one?
    https://www.ebay.com/itm/100W-0-01-2....c100752.m1982
    Last edited by ddd228; 08-18-2019 at 12:34 PM. Reason: RESISTORS.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  7. #15
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    877
    No I hadn't. They might mount better than the ceramic rectangular ones too.
    I like the rectangular ceramic ones because they look closer to the stock shape, but I would imagine that any of these would work nicely.

    You know things have changed SO much from when I was involved with electronics. All the manufacturers have merged/been bought/chapter 11'd that I don't know this market at all. I thought that the rectangular ceramic resistors would be easy to find, but they are quite rare! The vendor that makes something the closest, is from Finland, and try to find a distributor here. Sigh.
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  8. #16
    CelicaSupra.com Member ddd228's Avatar
    Join Date
    May 2005
    Location
    N. Seattle.
    Posts
    5,232
    I use those"Dale" resistors in my solar panel set up for a DUMP LOAD when they try to overcharge.
    Mounted on an aluminum board,they dissipate heat well.

    The other issue is that they have bare wires sticking out.
    I soldered them with solid copper wires to my dump load. I didn't heat shrink them at all.
    14 G, insulated wires could be used,easily.Then,heat shrink.Add connectors.
    https://i.imgur.com/bwTeFWE.jpg
    I make a LOT more power than I can use sometimes ,and it has to go somewhere.Into those resistors and a fan and a Halogen head light bulb! Out put is 700 watts PEAK.I usually use only 250 watts.

    If you use 2 resistors in parallel,the wattage goes up,but resistance goes down. I went through that math BS a few times to get the correct resistance in parallel.

    Use the Dale resistors=WAY better.
    Dave in Seattle. I keep LATE hours.Hidden Content
    '84 type "L" ,Auto ,daily driver. Dk blue.

  9. #17
    Member Beernuts's Avatar
    Join Date
    Feb 2008
    Location
    Tonsberg, Norway
    Posts
    36
    Also .15 ohms at Aliexpress, they might have some nearer as well.
    As of the delivery, don't wait by the mailbox..
    https://www.aliexpress.com/item/3295...0-888d6dad7c21
    I would also try to find a ceramic type just to keep it stock, but from the ones I saw browsing, none had the spacers (bumps) to ensure that it wouldn't move in the holder.
    Last edited by Beernuts; 08-22-2019 at 03:08 AM.
    '83 Celica Supra 2.8i Euro spec
    '67 Toyota Crown 2000 Special
    A lot of Audis..

  10. #18
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    877
    Quote Originally Posted by Beernuts View Post
    I would also try to find a ceramic type just to keep it stock, but from the ones I saw browsing, none had the spacers (bumps) to ensure that it wouldn't move in the holder.
    That's a very good observation.

    I looked at the original in my car and it almost looks like Toyota added a separate ceramic piece to a standard ceramic resistor.

    AC Condenser FAn Resister.jpg

    Could the ceramic part with the bumps be removed from the broken resistor and glued onto a new ceramic resistor?
    I don't know what glue one would use, but there must be a ceramic glue that would work.

    I have been thinking about how Toyota weather proofed the bare wires, and it appears to be Glyptal painted onto the wires.

    https://www.electro-wind.com/glyptal...can-361-g.html
    It's extremely expensive, but from the description it is used as an electrical insulator and a weather sealer. It is also described as an adhesive so I wonder if this could be used to adhere ceramic to ceramic.

    https://www.usbr.gov/power/data/fist..._3/vol3-18.pdf
    This article indicates that electrical transmission companies use "epoxy" materials to reattach broken porcelain although they paint porcelain with Glyptal to improve resistance to minor defects.
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  11. #19
    CelicaSupra.com Member
    Join Date
    Aug 2011
    Location
    Arlington, WA
    Posts
    1,426
    The value of the resistor is chosen as the best compromise between limiting the startup current surge which can be 3 or 4 times what the running current is and its effect on the speed of the motor. Adding the resistor means that a smaller gauge wire can safely be used than without it. There's more than one reason that that's a good choice like cost, weight, space available, ease of installation.... I seriously doubt that an exact match is critical. Toyota likely sourced whatever was available closest to the theoretical ideal value vs having custom ones made.

  12. #20
    Member Beernuts's Avatar
    Join Date
    Feb 2008
    Location
    Tonsberg, Norway
    Posts
    36
    Quote Originally Posted by supraz View Post
    That's a very good observation.

    I looked at the original in my car and it almost looks like Toyota added a separate ceramic piece to a standard ceramic resistor.

    AC Condenser FAn Resister.jpg

    Could the ceramic part with the bumps be removed from the broken resistor and glued onto a new ceramic resistor?
    I don't know what glue one would use, but there must be a ceramic glue that would work.
    No, I have seen (and used) resistors with similar spacers/bumps, just not in this resistance range. The bumps are molded.
    If you use a standard ceramic resistor without bumps, it's probably no problem to just solder the wires and use some heath shrink tube.
    I'd just use some heat shrink where the holder is as well to stop it from moving.
    '83 Celica Supra 2.8i Euro spec
    '67 Toyota Crown 2000 Special
    A lot of Audis..

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts