24V Sanyo Denki fans - OK on 12V?

miniyazz

miniyazz

miniyazz

Soldato
Joined
25 Dec 2008
Posts
5,976
Location
Sheffield/Norwich
There's >10 of this Sanyo Denki fan on eBay at the moment (here), model number 109P1224H402. The product description page on the Sanyo Denki site is here.

Before I splash out on a few of these, I'm hoping someone can reassure me as to their efficacy at 12V, as there's no information on the website, and I have no means of giving them 24V at the moment. Obviously I'm not expecting them to push as much air as at 24V, but I'd hope they still push substantially more than a regular case fan. Any thoughts?
 
They'll push substantially less airflow than an equivalent 12V fan. You can buy identical Sanyo Denki fans with the same performance but the motors are wound for 12V rather than 24V. 24V is used as it's a standard DC supply voltage in industrial applications.
 
Thing is, I'll be in need of a couple more fans soon. It didn't help that I accidentally shoved a screwdrive in one last night and broke a couple of blades off one of them. And it's not like these are going to break the bank, at £5 each, whereas their equivalent 12V ones are likely to be considerably more expensive. I might go for them regardless, and just consider getting me an adjustable voltage AC-DC power adaptor if need be.
 
Right so the difference between the 24V and 12V ones is.. that the 12V ones take twice the current?
If the 24V ones are plugged into a 12V source supplying 0.5A (same as the 12V fans are rated for, twice what the 24V ones are rated for), would they still only use 0.25A? Or would they use 0.5A? I'm guessing the former but my electronics knowledge isn't fantastic.

I think I'm gonna get a few anyway, it's not like my radiator'll need high static pressure fans at only 8 fin/inch density!
 
I don't know what current it would use thinking about it. If it was ohmic then 0.25A at 24V suggests 0.125A at 12V.

edit 1: It's not even remotely ohmic.

edit 2: from here it seems likely that it'll turn at 1400 rpm at 12V. You can expect a static pressure of around 13.5 Pa, I don't have a source for this relationship yet so I'm not sure how crude it is.

From here motor torque is proportional to rpm. From here torque is also proportional to current. It is then reasonable to assume (I think, it is 6am though) that current draw is proportional to rpm. As it drew 0.24A at 2800rpm, and I think it'll run at 1400 rpm at 12V, it will probably draw 0.12A at 12V and use 1.44W to do so. This is a quarter of it's power draw at 24V, adding credence to the idea that static pressure varies as the square of rpm.

So, yeah. I still think it'll draw 0.125A, but I now have sources which seem to justify this. As a comparison, mine is a 9G1212H1011 running at 7V, so at 1517rpm ish, with an estimated static pressure of 24Pa. It's blowing lots of air through two 60mm radiators.

The conclusion here is that I think they'll be fine at 12V, but that this particular model is not ideal as it has a lower static pressure than some other ones. But then, I paid 15 quid for mine and 13.5Pa is still rather a lot, a Noctua P12 at 12V is meant to be around 10Pa.

Occurs that I'm contradicting Jokester
Jokester said:
They'll push substantially less airflow than an equivalent 12V fan.
Click to expand...
I think I've been proven wrong every time that's happened so far. :(
 
Last edited:
No, I think you're just argued why they'll push less airflow at 12V. The key thing to remember is that these are just high flow/high noise fans that you're undervolting to give I guess medium flow/medium noise performance at 12V, the only issue is that you won't be able to undervolt them significantly more I would guess. A medium speed Yate Loon fan is likely to give similar performance, but can be undervolted significantly more to give you a wider option for noise and flow if you want and can be bought for less than £5.
 
The 'halving the rpm quarters the static pressure' thing holds true according to different fan rotation speeds from the sanyo denki product page, at least.

Also, an equivalent 12V fan is the same fan but 'wound' for 12V instead of 24V, which would be substantially more powerful than a 'regular' 12V fan. Assuming the static pressure will quarter when the voltage is halved, the static pressure will still be greater than a Yate Loon running at 12V (1.1mmH20 max vs ~1.35mmH20) - and I think the noise levels of the san aces are meant to be lower than most other fans once pushing a similar amount of air? Can't remember where I read that.

I'm sure you're right on the Yate Loons being able to adjust noise levels more specifically using different voltages, though.
 
You must log in or register to reply here.
Back
Top Bottom