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Alvin

Toyota Advanced Member
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About Alvin

  • Birthday 12/20/1955

Previous Fields

  • My Toyota Motorhome
    1989 Odyssey
  • Location
    Salt Lake City, Utah

Contact Methods

  • Website URL
    http://www.alvinkimball.com
  • Skype
    801-438-6915

Profile Information

  • Gender
    Male
  • Interests
    Electrical Engineering, Astronomy

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  1. Solenoid if I remember right. Haven’t touched that ever.
  2. My guess would be that the fan requires 5A at 12VDC max then the solar panel needs a minimum of about 80 to 100 watts to run it at high speed. Perhaps 20 watts at low speeds. This is assuming about 21 volts output in full illumination and a voltage regulator to get this down to the voltage needed by the fan. The losses are mostly in the regulation. As daytime slips away Vout will drop.
  3. You want things to work as well as they can work? Or just kinda work lol. if I wanted to drive my Odyssey to Alaska, I would be very grateful to have things working quite well. I would probably even go to great lengths to point my solar array perpendicular to the sun. No harm knowing the rocket science details.
  4. You and I are in agreement. My comment was actually directed to Linda, and she not wrong; she makes a good point. But she doesn’t consider the case of getting the most efficiency out of a small under-sized RV solar array: The traditional method of running solar power through a charge regulator into a battery and then out of said battery and finally to the fan motor Involves several power losses. 1) charge convertor losses 2) battery charging loses (all batteries have internal effective resistance) 3) battery source resistance, and 4) device motor losses… ignoring wiring copper loses. To get the most out of available solar panels, it would be desirable to direct connect the solar panel to the fan… if possible. From a losses standpoint the best solution would be a dc-dc regulator but those are $50 and up, so I recommended an LDO (low drop-out) voltage regulator for the solar panel direct connection. Most of the dc-dc power supplies I design are 85% to 93% efficient where efficiency of the LDO will be somewhat worse. But nothing beats the price of an LDO.
  5. I design power supplies for USA defense. The question was not whether the solar panels were connected in typical fashion. The question was about how to keep the voltage presented to the fan from going as hot as 13.6V…. Which easily happens with solar panels directly connected to a device. Yes most people use regulated battery voltage to run the 12VDC RV appliances… and those batteries are charged from any number of sources… vehicle engine, generator, shore power, … you could use hamsters in cages if you want. And if you want to charge your house batteries with solar, then you would use a solar charge convertor as you said. But if somebody wants to forgo the charger and connect the panels up directly, that’s doable too with a voltage regulator.
  6. I would need to know the current requirements of your fan, but it Looks like some Maxxair 12VDC ceiling fans require about 12V and 5A. You could go with a large linear voltage regulatir such as Analog devices LT1084CT-12#PBF. DIGIKEY has them for $11.22. You’ll also need a couple of low cost caps (see the datasheet).
  7. I need to know the current requirements of your fan, but it Looks like some Maxxair 12VDC ceiling fans require about 12V and 5A. You could go with a large linear voltage regulatir such as Analog devices LT1084CT-12#PBF. DIGIKEY has them for $11.22. You’ll also need a couple of low cost caps (see the datasheet).
  8. Thank you and what a great set of instructions to get me started. As luck would have it, I inherited my Father’s set of gauges for recharging ac... i don’t know how to use them but will do the research.
  9. Had great ac in our 1989 Odyssey until just this year. I’m going to be looking for the obvious before I take it to someone to do an expensive leak check and recharge...because it went down after the long cold winter and seems kinda sudden. I’m ‘about’ to look at the ac compressor belt and electrical connections. We did call an ac shop who said they don’t work on 89 toyota trucks because they’re too old. They also said it would need a conversion.
  10. Battery charging is all about the internal resistance of a given battery. When the batteries are new, they have lower resistance...charge faster. This will change over time. Not sure you have a problem.
  11. I still think I’m right...thought I’d add two more schematics I have on hand to add to the confusion. I think the part is an Isolator and not a solenoid. I have one in my 89 Odyssey.
  12. I marked up your drawing. Get rid of the two wires with red zigzags over them. Connect, using one heavy peice of alternator grade audomotive wire, the connection shown in my drawing in blue. You don’t want any splices... it should be one heavy wire between alternator and isolator. If you splice thats a future breakdown due to corrosion.
  13. Linda, that is exactly right. A diode is a semiconductor which only allows positive current flow in one direction. An isolator is a device with two back to back diodes built in, and the alternator is the source of this ‘positive’ current, supplying current when the engine runs. The alternator connects to the isolator junction of both diodes and supplies charging current through each diode, one to the house battery charging system and the other to the vehicle battery. When the alternator is not supplying current (when the vehicle engine is not running) then the house battery can’t short to the vehicle battery and visa-vera due to their respective one-way diodes in the isolator. It means you can turn off the engine safely with each system, vehicle and house, remaining separate.
  14. The schematic Derick up North provided is correct. The idea is the alternator charges both the house and engine batteries when the vehicle engine is running...or when the alternator is turning. The back to back diodes in the “isolator” keep the two systems, engine and house battery, separate except for alternator charging.
  15. So...that;s not a soleniod is it? Looks like the house/cab isolator. A back-to-back automotive diode.
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