22A fan motor turn on question
22A fan motor turn on question
(OP)
I have a 2-fan radiator cooler. At idle it draws 22A, or 11A each fan. Each fan is on its own relay. But the relays are turned on-off simultaneously. Should I turn the fans staggered to reduce transient? I have no idea how much is excessive motor current. Thank you.





RE: 22A fan motor turn on question
If it is an old-school hard-wired relay circuit with the main power coming through a fusebox and the wiring is adequately sized for the current and the battery is good and the various connections in the system are good (adequately sized and not corroded) and the battery is big enough and in good shape and it's not blowing the fuse ... good enough.
If you have undersized wiring and bad connectors (as evidenced by significant voltage drop between the battery and the fan motor) you're going to have a problem and possibly a fire.
Follow the traditional troubleshooting chart. "Does it work" - "Yes" - "Leave it alone" - "Done".
RE: 22A fan motor turn on question
If it isn't easy then what problem are you trying to cure? 60A for a second or so won't hurt your battery .
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Thank you G.L. Will do.
RE: 22A fan motor turn on question
Keith Cress
kcress - http://www.flaminsystems.com
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Still, if you are using an Arduino then why not do PWM fan control? It eliminates all inrush surging. It eliminate the mechanical relay as a possible source of failure. It provides near constant temperature control vs having the temperature swing as the fan goes on and off. It makes the system quieter since full fan speed is rarely required. Lots of wins with PWM.
RE: 22A fan motor turn on question
The Arduino controller + relay is safe from power spikes (I hope). A buck converter sits between Arduino and battery. A 5V relay sits between Arduino and the 12V car relay.
If you have other thoughts, please let me know.
RE: 22A fan motor turn on question
Of course if you want to have a bet each way use a relay to switch one to full power, and control the other one using PWM/FET . That could get very bizarre, you'd need to latch the relay on otherwise it'll cycle rapidly in some conditions.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
I read somewhere those drivers without power spike protection are bound to fail. Being non-EE I got scared. Because of your recommendation, I will try PWM. One question though. The description says heat sink for greater than 5A. How do I attach a heat sink? Looks impossible. Do they come with HS premounted? I couldn't find one
RE: 22A fan motor turn on question
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: 22A fan motor turn on question
Dan - Owner
http://www.Hi-TecDesigns.com
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
I've seen similar modules with TO220 devices so you could attach a heatsink to the tab. Find a similar device with a higher current rating if the device the board comes with isn't rated for enough current.
You can parallel FET's, but you have to be careful to keep the lead lengths and lead inductance the same going to each FET. I suppose if you parallel those boards then split the large gauge power and ground wires to a smaller gauge and use same length of wire from the split to each board. Try to keep the wires routed similarly too.
The most likely failure of that FET board is a shorted FET so I don't see you gaining much for reliability by paralleling them.
RE: 22A fan motor turn on question
RE: 22A fan motor turn on question
Use a two step thermostat to start one fan and, when needed, the second fan.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: 22A fan motor turn on question
Dan - Owner
http://www.Hi-TecDesigns.com
RE: 22A fan motor turn on question
I have a related question. I have not seen a flyback diode on any radiator fan motor. Is there a good reason?