relays hooked together for taurus fan?

[v84x4]

i am going to use a taurus fan for cooling my s-10 and have heard that you need a high amp relay for th high speed but cant find any thta are trated above 30 or 40 amps. so i found this diagram <a href="http://chevyhiperformance.com/howto/p34220_image_small.jpg" target="_blank" target="_new">http://chevyhiperformance.com/howto/p34220_image_small.jpg</a> where they use 2 30 amp relays wired together. could i do this witht the high speed and then i would have 3 30 amp relays in the truck. 1 for low speeda nd 2 for high speed

[FireStruck]

I got a relay from Radio shack that is working great for my Taurus fan. I used part # 275-226 It is a 30A automotive relay from RadioShack, it works great. I have been using it for about 2 months.



Steve

This relay is only $6.29





&lt;font size=1&gt;[ This message was edited by: FireStruck on 2004-11-11 15:09 ]&lt;/font&gt;

[loweredd]

I think most people just have them hooked up as on and off.



*edit* that and I cant see the picture. WAY too small.

[v84x4]

http://chevyhiperformance.com/howto/4572/ here is a link to the whole article i found the info in maybe it will have a better pic

[Scotty_S-15]

I\'ve been using the 30-amp ones that Jeg\'s and Summit sells, marketed by Perma-Cool, and they\'re only like $8.95 or so.

......... And regarding that diagram, it was kinda blurry when I blew it up, so I\'m not sure what was going on there...........



After-the-fact: OK, I found that link but it\'s just as blurry there. And I really hate it when they draw a schematic (wiring diagram) like that.... 4 wires going to a relay, and they give no indication of which wires are for the coil, and which are the contacts. That seems to be the norm with automotive schematics. Power wiring (machinery and such) generally provides you with an idea of what\'s going on.

........... But apparently the left and right terminals engergize the coil, and the top and bottom terminals are the contacts.... that is, the power terminals.

[v84x4]

that is what i figured. didn\'t think 2 relays would work connected but since i found it in a soposadly reputable car mags web site i thought i would look into it. i will just get 2 of the 30 amp relays and run one for each speed on the taurus fan. plan to run low speed from the temp sensor sold on this site and run high spped either from a/c on signal or maybe a seperate toggle switch

[Scotty_S-15]

Hey V84X4, don\'t ya hate it when were both talking at the same time? http://www.s10v8.com/images/smilies/icon_razz.gif I already changed the above message..... after reading the text, it doesn\'t look like they are paralleling the POWER congtacts on the relays, but rather paralleling the coils of the two relays, using one for each fan. That\'s just fine.

[mzoomora]

Large diagram (http://chevyhiperformance.com/howto/p34220_image_large.jpg)



Here is a link to the lrage version of the diagram. It could work like that, and the extra current would probably make the fan pull more air. The diagram gives you the numbers that normally appear on a Bosch type relay, which you can find a expand diagram for on the internet. If you were to run it that way you would need to make sure that terminal 87a was well covered, because it will get power when the fan is turned off. Not to mention that they dont show the relay being grounded. 30 gets power from the battery directly, and then you can hook 86 to ground and 85 to your trigger source, or vice versa. It will work either way.



Edit- they are using the thermostat control to switch the ground, which will work.

[Scotty_S-15]

Mzoomora, Thanks for the readable diagram. Now that I can read it, I\'ll go back to my original statement (that I edited out) ........ which was, that\'s NOT a good way to do it. Paralleling load contacts is never a good idea for two reasons:

1) One relay will always close ahead of the other, even if its a matter of a millisecond. That relay will take the \"BIG SHOT\" of the start current, tending to burn the contacts.

2) The load will never be evenly distributed between the two contacts, one will always be carrying more current than the other.

........... So yeah, if you\'ve got a 35 amp load, using (2) 30 amp relays is certainly better than one, BUT, the right way would be to use a 40 amp or larger rated relay.





Oh, and another thing, if those terminal #s are for the Bosch type relays only..... then the Permacool relays that I\'ve been buying from Jegs/Summit IS THE SAME! Yeah, that\'s the terminal #s on the Permacool relays.

Where do you get yours? regular auto parts house?

[mzoomora]

I get mine from the install department at Best Buy. They use them for alarms and stereo installs. My cousin works there, and they only cost me like $3 with the harness plug. I have had them in my truck for 2 years now, still holding.

[primed92]

I used 2 Bosch \"cheapie\" realays commonly used for remote start systems and such. They are rated at 30A continuous/ 40A max. No problems whatsoever. The numbers are the same on every make of relay i have seen in 3 years of car audio work. Scotty- I don\'t understand what you\'re saying about \"Paralleling\" load contacts. Do you mean battery power or the ground triggered input to the relay coil?

[Scotty_S-15]

On 2004-11-11 21:03, primed92 wrote:

I used 2 Bosch \"cheapie\" realays commonly used for remote start systems and such. They are rated at 30A continuous/ 40A max. No problems whatsoever. The numbers are the same on every make of relay i have seen in 3 years of car audio work. Scotty- I don\'t understand what you\'re saying about \"Paralleling\" load contacts. Do you mean battery power or the ground triggered input to the relay coil?



1st, please bear with me, my background is in AC power wiring and machinery wiring. I\'ve always said, that I think my background can actually be a drawback in understanding auto electric. While the basics remain the same, the means of accomplishing a result is soooo different. And of course, terminology is different.

............. But yes, by load contacts, I\'m referrering to the battery on one side of the contact, and the \"load\", or fan, on the other. And the coil, or trigger, needs +12V (low current) on one side, and ground on the other.

.......... What I was saying is that its perfectly OK for the same \"trigger\" source to pull in (energize) 2 or more relays. For instance, one thermostat to energize two relays, each for a sepearate cooling fan cooling. But it\'s NOT good for two 30 amp relays to be doubled up (paralleled) to provide \"battery\" power to a 40 amp \"load\".

[v84x4]

ok thanks to this thread i started i think i have learned alot about hooking up relays. the correct way of using 2 relays hooked together would be to have one source(thermostat) turning on the 2 relays for say a dual fan set-up(not a 2 speed fan but 2 seperate fans) let me know if i\'m correct. also i bought 2 relays from HAYWIRE at a local strret rod show and they have terminal 30 as power to fan (or whatever) and 87 as power in from the battery and the bosch diagrams i have found those 2 termanals are switched around. does it matter which of the 2 has power in and power out to the fan?

[Scotty_S-15]

Wow, check this price out!! $1.98 for Bosch relays! And, they even have matching plugs for $1.50! Stumbled across these while seaching for diagrams. Nice.Cheap relays (http://www.partsexpress.com/pe/pshowdetl.cfm?&amp;DID=7&amp;Partnumber=330-070)

if you click on the \"free wiring diagrams\", there is a bunch of scenarios for wiring all sorts of things. Sadly, there is no diagram of the internal workings of the relay.



OK, here is a good basic diagram showing the relay #\'s and what goes on inside the relay. Note #30 is normally called the \"common\" wire, and is the one that goes to the high current power supply. Either the 87 and 87A would go to the \"load\" or fan, pump, or whatever. I say either, because 87 gets power when relay is energized, 87A when relay is NOT engergized, this is called normally open, &amp; normally closed contacts. For most of what we do, we\'d use the #87, or normally open contact. You could also bring the power to the #87, and the load on #30 and it would work just fine, but standard practice is that the power would go to the #30.

.......... And the coil is #85 &amp; #86. Either one can go to ground, the other gets the \"trigger\" +12V to hold the relay engergized. Because the coil only uses in fraction of an amp, this wiring can be very light, and poses little strain on the switching device, such as thermostat, light duty switch, etc.



Basic Relay internals (http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm)

[MOREPOWER]

85 and 86 cannot be either ground or power. It depends on the relays. If it has a diode internally for example then u best be hooking it up right. Thier also resistors than can be used also. But u would be able to see it on the relay itself. It costs more. But don\'t forget to use a diode on ur fan. U will burn out the contacts sooner. ANd power used for coil for 85 -86 is about 200mA . Not very much is need to power them.

[MOREPOWER]

Just relays. check it out. (http://www.bpg-inc.com/bpghome.html)

[JayDee]

99 cent 30/40 relays with pigtails and diodes and email wiring digrams.Cheap 30/40 relays (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&amp;category=6763&amp;item=79372931 86&amp;rd=1)