iani Posted March 28, 2018 Report Share Posted March 28, 2018 I fitted a Revotec fan today, wired using supplied kit with a relay, the power coming from an auxiliary fusebox with a feed directly from my Alternator. Battery voltage with ignition off is 12.7V. My Ammeter normally goes into the positive for a couple of mins after firing up, then drops to nothing unless I add some load, now however it's going into discharge straight away. Once the fan kicks in, it goes way into discharge, the alternator output is around 12.5v, this is a new alternator, fitted a couple of weeks ago and was working fine up until now. Not being an electronics guru, I'm just wondering if I could have screwed anything up with the installation? I have changed nothing else beyond adding the fan, the belt is tight and all wiring connected. Quote Link to post Share on other sites
RobH Posted March 28, 2018 Report Share Posted March 28, 2018 You must have disturbed something in the alternator connections or it has failed, because that output voltage is too low. It should be higher than the measured battery voltage. The immediate low discharge is probably the battery feeding the ignition circuit plus any other drain there might be and that shows that the alternator is not supplying any current. How did you make the new connection to the alternator and what type is it ? Quote Link to post Share on other sites
iani Posted March 28, 2018 Author Report Share Posted March 28, 2018 It's an A127, I simply transferred the two wires that were on the previous alternator to this one, then I added the auxiliary wire to the stud connection. Quote Link to post Share on other sites
RobH Posted March 28, 2018 Report Share Posted March 28, 2018 So the new feed is connected directly to the B+ stud connection on the back of the alternator - is that also the connection from the wiring loom or does that use the spade connections ? Is the dash ignition light on all the time even with the engine running ? The reason I ask is that the alternator needs the lamp current in order to start up. If the lamp connection is bad or the bulb blown you won't get any output. Quote Link to post Share on other sites
iani Posted March 28, 2018 Author Report Share Posted March 28, 2018 (edited) No, the standard feed and the warning light both go to lucar terminals via the connecting block, only the aux feed goes to the post terminal. The charging light works fine. Edited March 28, 2018 by iani Quote Link to post Share on other sites
RobH Posted March 28, 2018 Report Share Posted March 28, 2018 Well an easy first check is to remove the new connection and see if the alternator now works as it did before. Quote Link to post Share on other sites
iani Posted March 28, 2018 Author Report Share Posted March 28, 2018 I didn't add any additional connections today, I did that over a week ago without any issue. I've just swapped out the regulator/brush pack and it made no difference. I swapped back to the original alternator and all is well, not any use though as I don't have an engine fan now and need the auxiliary loom to work so the electric fan is powered. Quote Link to post Share on other sites
RobH Posted March 28, 2018 Report Share Posted March 28, 2018 I didn't add any additional connections today, I did that over a week ago without any issue. But in your first post you said you had just done it. Do you mean you connected the new fuse-box some time ago but only connected the fan to that today? Sounds as though the new alternator is u/s or your connection of the fan killed it. - so why can't you connect the auxiliary loom to the old alternator which apparently works? Was the old one a lower-rated type? Quote Link to post Share on other sites
PodOne Posted March 28, 2018 Report Share Posted March 28, 2018 As said disconnect the fan and measure the output at the alternator should be around 14v - 14.3 and across the battery which should be similar. If not the alternator is probably toast. The new fan will be greedy for current. Best of luck Quote Link to post Share on other sites
iani Posted March 28, 2018 Author Report Share Posted March 28, 2018 All sorted now, I had another A127 in the garage, for other side of the engine though, thought I'd see if I could make one good one out of the two, now fitted and outputting 14V. Now, when I stripped the unit down that had failed, I found a lot of moisture on the stator, obviously from when I'd been moving the rad I expect, I'm assuming this is what has killed that unit. Thanks for the advice, more care required next time. Quote Link to post Share on other sites
astontr6 Posted March 28, 2018 Report Share Posted March 28, 2018 All sorted now, I had another A127 in the garage, for other side of the engine though, thought I'd see if I could make one good one out of the two, now fitted and outputting 14V. Now, when I stripped the unit down that had failed, I found a lot of moisture on the stator, obviously from when I'd been moving the rad I expect, I'm assuming this is what has killed that unit. Thanks for the advice, more care required next time. Hi Iani !n my experience as all ready stated by PodOne, they need a lot of current often well over 20amps. A 15 ACR alternator on a CP car, cannot cope with the current required especially if you have the heater fan going along with the indicators etc. as this will take you past the output rating., without taking the pump or lights into account. In my view the minimum size required is an 18 ACR rated at 45amp. What is a A127? Bruce. Quote Link to post Share on other sites
DaveN Posted March 29, 2018 Report Share Posted March 29, 2018 20 amps? They may draw that as an instantaneous start up current but running I bet no more than 7-8 amps. Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 For my configuration with electrical fan, I use a Bosch alternator....55A....0 986 036 010....my old 18 ACR was done after only 2.000 km. Jochem Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 a typical modern electrical fan such as SPAL does not draw 20 Amps each time it starts up....A 120W electrical fan only kicks in when its needed an draws about 8 amps. Use a secondary tempswitch with high load resistor to run at 50%. Most of the time thats all you need. Jochem Quote Link to post Share on other sites
iani Posted March 29, 2018 Author Report Share Posted March 29, 2018 Hi Iani !n my experience as all ready stated by PodOne, they need a lot of current often well over 20amps. A 15 ACR alternator on a CP car, cannot cope with the current required especially if you have the heater fan going along with the indicators etc. as this will take you past the output rating., without taking the pump or lights into account. In my view the minimum size required is an 18 ACR rated at 45amp. What is a A127? Bruce. The A127 I have fitted is a 70 Amp unit Bruce, fitted precisely because of the limitations of the original unit. Quote Link to post Share on other sites
RogerH Posted March 29, 2018 Report Share Posted March 29, 2018 (edited) Hi Jochem, There appear to be a problem with relay #3 and temp switch T2 There is a red 12V wire going into relay 3, through its coil and passes down to temp switch T2 on the blue wire. The red wire to the relay 3 also branches off and goes to the other side of temp switch T2 With Temp switch T2 open circuit no current will flow through the relay and so will not work. With Temp switch T2 closed there will be 12V on each side of the Relay 3 coil and so will not work. The same applies to relay 2 and temp switch T1 You need the relay going to earth and the Temp switch (T1 & T2) in the 12V feed to the relays. Roger Edited March 29, 2018 by RogerH Quote Link to post Share on other sites
RobH Posted March 29, 2018 Report Share Posted March 29, 2018 (edited) That circuit is also a rather complicated way of achieving the object. You can do the same thing with only two relays. Edited March 29, 2018 by RobH Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 Hello Roger, thank you for your input....however, since I am already driving with this schematic, and everything works, I am trying to follow your reasoning of possible faulty wiring. Relay 3 is designed to have the fan run after ignition is off. So some of the heat build up under the hood is blown away. This motor runs on 50% due to Resistor R1 until T2 is reached and opens. a. T2 closes when certain temperature is reached. b. The coil in relay 3 is activated and closes the relay which in turn, turns on the motor. c. Coils of relay 2 and relay 3 are only activated when T1 und/or T2 reach their set temperature. I hope I explained it correctly. Jochem Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 RobHPosted Today, 10:12 AM That circuit is also a rather complicated way of achieving the object. You can do the same thing with only two relays. Hello Rob, yes, but I do not want any load going thru the ignition. This is the reason for my 3rd relay. jochem Quote Link to post Share on other sites
peejay4A Posted March 29, 2018 Report Share Posted March 29, 2018 T1 and T2 seem to put a short across the relay coils as I read the circuit diagram. The thermoswitches both show an earth connection and I'm not sure what that represents but if they were between the relay coils and earth then it works. That red connection going from the thermoswitches to +12 is confusing me. Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 Hello Pete, these are Revotec therm switches. Jochem Quote Link to post Share on other sites
RobH Posted March 29, 2018 Report Share Posted March 29, 2018 The internals of the thermal switches are not as you have drawn them Jochem. The contact will be between blue and black, not blue and red as per your circuit diagram. Thats why people though it was wrong. Quote Link to post Share on other sites
JochemsTR Posted March 29, 2018 Report Share Posted March 29, 2018 my bad.... Quote Link to post Share on other sites
peejay4A Posted March 29, 2018 Report Share Posted March 29, 2018 All clear now. Quote Link to post Share on other sites
Mike C Posted March 29, 2018 Report Share Posted March 29, 2018 The A127 I have fitted is a 70 Amp unit Bruce, fitted precisely because of the limitations of the original unit. My Lucas unit was reworked for 45 amps because I was concerned about putting more current through the original wiring even after I'd upgraded the ammeter as a partial concession. At the time the auto electrician said he could have given me more output if I needed it. Do you know if your wiring sizes have been increased? If the standard wiring is up to it I might go for more capacity next time the unit is rebuilt. Quote Link to post Share on other sites
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