Installation cooling fan above alternator

[Roberto Conigliaro]

Hi all, I finally installed the hybrid system LifeP04 + Lead Acid and all seem to work well apart from the fact that the alternator gets above 95 C with the engine running for 15 minutes or so. 

However, today I tried to cool the alternator down with a 240v domestic fan (pic 1) just above it and it really does the trick - temperature didn't go above 80 C with the engine running for 30 minutes.

I'd like to install a 12v car radiator fan (pic 2), so that when the engine is on, the fan switches on with it - can anybody please recommend on the wiring to that? do I need a relay?

Thanks in advance! 

 

Roberto

[Tracy D'arth]

Where and how are you measuring the temperature?

Its not the outside temperature that is important but the winding temperature deep in the windings.

[Clanky]

 

Would something like this work? Item number 185760451624 on ebay

 

Edited March 21 by Clanky
Forgot to add photo

[Alan de Enfield]

5 minutes ago, Clanky said:

 

Would something like this work?

 

It shouldn't make it any worse so give it a try.

 

What it will do is consume ~7 amps requiring the alternator to work harder / longer so it may actually be counter productive.

[Roberto Conigliaro]

8 minutes ago, Tracy D'arth said:

Where and how are you measuring the temperature?

Its not the outside temperature that is important but the winding temperature deep in the windings.

Measuring it with a infrared thermometer, all around the the alternator surface, hottest point didn't get above 80 C. How do you measure it?

14 minutes ago, Clanky said:

 

Would something like this work? Item number 185760451624 on ebay

 

That should work! but it does rely on its probe, just worried it might fail and the fan wouldn't turn on. Any other suggestions on how to switch it on together with the engine? With a relay I suppose?

[Wanderer Vagabond]

I have in the past looked at fitting some sort of fan to try to cool my alternators since I seem to go through them with some regularity due to the hostile environment of a narrow boat engine space in which they operate. Could never figure out where I'd get a source of cooler air from though. I'm very reluctant to put any holes in the side of the boat and any holes above the engine will just let rain in. Simply installing a fan will just circulate the already hot air around the engine, without much cooling effect once the engine cover is fitted. Am I missing something? or am I just a pessimist?

[Clanky]

How long is the cable from the alt to the lead? Extend it more to create more resistance or wait till the solar fills the lifepo4 up and the BMS turns them off before running the engine😂

[Roberto Conigliaro]

12 minutes ago, Wanderer Vagabond said:

I have in the past looked at fitting some sort of fan to try to cool my alternators since I seem to go through them with some regularity due to the hostile environment of a narrow boat engine space in which they operate. Could never figure out where I'd get a source of cooler air from though. I'm very reluctant to put any holes in the side of the boat and any holes above the engine will just let rain in. Simply installing a fan will just circulate the already hot air around the engine, without much cooling effect once the engine cover is fitted. Am I missing something? or am I just a pessimist?

 

You have a good point! I am gonna install an inline blower instead which is 2.5 amps, and take the fresh air near the air vent I have got not far from the batteries. Do you have any advice on how to wire it?

[PaulJ]

I use these (although not ths specific one but this example has a good range of temperatures) to control pumps/heating blowers - I do use a relay though as not sure how sturdy the contacts in them actually are.

https://www.ebay.co.uk/itm/401616239309

[Roberto Conigliaro]

2 minutes ago, PaulJ said:

I use these (although not ths specific one but this example has a good range of temperatures) to control pumps/heating blowers - I do use a relay though as not sure how sturdy the contacts in them actually are.

https://www.ebay.co.uk/itm/401616239309

Interesting! although yes a relay should be more reliable - do I connect the really to the D+ of the alternator?

[PeterF]

If you want to run it off the ignition switch then you need a 12V relay, connect a lead from your ignition switch to the positive coil on the relay, negative coil goes to battery negative. Then connect from the battery positive to one side of the relay switch, the other side of the relay goes to positive on the fan then from the fan negative to battery negative. The fan could be wired to either engine battery or domestic battery, the relay keeps the fan circuit isolated from the engine electrics. Do not forget fuses.

[Roberto Conigliaro]

6 minutes ago, PeterF said:

If you want to run it off the ignition switch then you need a 12V relay, connect a lead from your ignition switch to the positive coil on the relay, negative coil goes to battery negative. Then connect from the battery positive to one side of the relay switch, the other side of the relay goes to positive on the fan then from the fan negative to battery negative. The fan could be wired to either engine battery or domestic battery, the relay keeps the fan circuit isolated from the engine electrics. Do not forget fuses.

Brilliant, thanks so much! 

58 minutes ago, Clanky said:

How long is the cable from the alt to the lead? Extend it more to create more resistance or wait till the solar fills the lifepo4 up and the BMS turns them off before running the engine😂

I spent lots of hours and money trying different cable size and length configuration - nothing worked with my alternator. I wish I never knew about the 'long cable' method.. 

[Clanky]

1 hour ago, Roberto Conigliaro said:

 

That should work! but it does rely on its probe, just worried it might fail and the fan wouldn't turn on. Any other suggestions on how to switch it on together with the engine? With a relay I suppose?

What happens if the relay failed or even the fan then it wouldn’t turn on? 

[PaulJ]

12 minutes ago, Clanky said:

What happens if the relay failed or even the fan then it wouldn’t turn on? 

I suppose you could fit another higher temperature switch with alarm if you was worried about it.

 

Edited March 21 by PaulJ

[Peanut]

23 hours ago, Clanky said:

How long is the cable from the alt to the lead? Extend it more to create more resistance or wait till the solar fills the lifepo4 up and the BMS turns them off before running the engine😂

Surely, Clanky is right. A longer wire will give you a greater resistance, reduce the charging rate, and hence the load on the alternator.  That in turn will lower the alternator temperature. The whole object of having the long wire to protect the alternator in the first place. As suggested, a fan will introduce another point of failure.

[Roberto Conigliaro]

20 hours ago, Peanut said:

Surely, Clanky is right. A longer wire will give you a greater resistance, reduce the charging rate, and hence the load on the alternator.  That in turn will lower the alternator temperature. The whole object of having the long wire to protect the alternator in the first place. As suggested, a fan will introduce another point of failure.

As I mentioned the long wire didn't work for me - as suggested by PaulJ, I will install a temperature switch with alarm, which is very affordable, so in the unlikely case the fan / relay would fail, I should be covered.

On 21/03/2024 at 19:09, PeterF said:

If you want to run it off the ignition switch then you need a 12V relay, connect a lead from your ignition switch to the positive coil on the relay, negative coil goes to battery negative. Then connect from the battery positive to one side of the relay switch, the other side of the relay goes to positive on the fan then from the fan negative to battery negative. The fan could be wired to either engine battery or domestic battery, the relay keeps the fan circuit isolated from the engine electrics. Do not forget fuses.

Thanks so much, very helpful! Would you be able to advice on where I should connect the relay on the ignition switch? I have got an ignition switch like the one below. I'd assume to the connection 75 (radio / cigarette lighter)? or the to 83 (auxiliary)? 

[Tony Brooks]

15 or if it turns on and off with the ignition 83

[Roberto Conigliaro]

8 minutes ago, Tony Brooks said:

15 or if it turns on and off with the ignition 83

Thanks! The idea is to have it on only when the engine is on, so I'll connect it to 83, which luckily is also free.

[Tony Brooks]

15 minutes ago, Roberto Conigliaro said:

Thanks! The idea is to have it on only when the engine is on, so I'll connect it to 83, which luckily is also free.

 

You can't do that with the ignition switch, you need to add a rising oil pressure switch to the engine, but terminal 15 feeds the warning lamps and instruments you are unlikely to leave the ignition on with the engine not running. Check 83 because it may stay on, once the ignition has been on, until you turn the switch off and take the key out. if it works like 15 then it will be fine to use, but remember both terminals will stay live if the ignition is left on.

[Roberto Conigliaro]

4 minutes ago, Tony Brooks said:

 

You can't do that with the ignition switch, you need to add a rising oil pressure switch to the engine, but terminal 15 feeds the warning lamps and instruments you are unlikely to leave the ignition on with the engine not running. Check 83 because it may stay on, once the ignition has been on, until you turn the switch off and take the key out. if it works like 15 then it will be fine to use, but remember both terminals will stay live if the ignition is left on.

Thanks for the clarification Tony, I am still little confused sorry though - what can't I do? 

[MtB]

1 hour ago, Roberto Conigliaro said:

As I mentioned the long wire didn't work for me -

 

How can it not work?!! 

 

If the long wire is not reducing the charge current, it either isn't long enough or it is too fat. 

 

 

[Roberto Conigliaro]

7 minutes ago, MtB said:

 

How can it not work?!! 

 

If the long wire is not reducing the charge current, it either isn't long enough or it is too fat. 

 

 

I did try with a 16mm x 4 metres and still overheating - my alternator has a high voltage output, could that be the reason? not sure.. 

[MtB]

10 minutes ago, Roberto Conigliaro said:

I did try with a 16mm x 4 metres and still overheating - my alternator has a high voltage output, could that be the reason? not sure.. 

 

Thia seems unlikely unless the regulator in the alternator is busted. But busted regulators usually result in lower-than-correct voltage output. 

 

It's probably better to judge the regulating effect of a "long wire" by measuring the current in it using a clamp meter. The alternator temperature rather depends on the continuous current it is supplying and if the alternator is still overheating, lengthen the wire and measure how much the current reduces by. 

 

That way, you get a clearer understanding of the effect of your particular "long wire".

 

 

Edited March 23 by MtB

[Tony Brooks]

12 minutes ago, MtB said:

 

This seems unlikely unless the regulator in the alternator is busted. But busted regulators usually result in lower-than-correct voltage output. 

 

 

 

Or it is a battery sensed alternator with the sense wire missing or open circuit. That would cause the alternator to produce a high voltage, as would an open circuit field diode.

 

51 minutes ago, Roberto Conigliaro said:

Thanks for the clarification Tony, I am still little confused sorry though - what can't I do? 

 

You said that "The idea is to have it on only when the engine is on" which is rather ambiguous, but I assume that you mean "only when the engine is running" rather than "all the time the ignition switch is on".

 

You can't use the ignition switch on its own to only turn your fan on when the engine is actually running, with the fan stopping as the engine stops. What you can do, and is the easiest, is to have the fan on whenever the ignition is on. On most modern boats a buzzer screams at you if you leave the ignition on with a stopped engine so it is almost, but not quite, what you want.

[Roberto Conigliaro]

5 minutes ago, Tony Brooks said:

 

Or it is a battery sensed alternator with the sense wire missing or open circuit. That would cause the alternator to produce a high voltage, as would an open circuit field diode.

 

 

You said that "The idea is to have it on only when the engine is on" which is rather ambiguous, but I assume that you mean "only when the engine is running" rather than "all the time the ignition switch is on".

 

You can't use the ignition switch on its own to only turn your fan on when the engine is actually running, with the fan stopping as the engine stops. What you can do, and is the easiest, is to have the fan on whenever the ignition is on. On most modern boats a buzzer screams at you if you leave the ignition on with a stopped engine so it is almost, but not quite, what you want.

I see, sorry confusion came from the fact that 'ignition on' and 'engine running' for me occur always at the same time, but I see your point - they are two different things, and I appreciate the clarification