Group buy for the cheap MagicPower 120W MPD-810H DC-DC PSU

**Telek** · 04-08-2003, 07:32 AM

You do raise a good point, I was very curious about that as well. I wonder if that is real? Does anyone know what the efficiency of the Sproggy is? I wonder if that number is accurate, and if it is, then why is the efficiency so low?

There are a few people in Europe who are intending on getting these PSUs first, I was hoping that we could wait for them to try it out before doing our order. Perhaps then we will have more information.

The guys at Arise in the US seem to be taking their sweet time replying to my emails. Maybe once they do I can ask them for some more information as well as I don't think that the people in Taiwan will understand my request, but I guess that I can try them as well.

Edit:

I just checked, the national LM2587's efficiency rating is 70/80/90% for supplying 3.3/5.0/12.0V with 12/12/10V input. The Maxim data sheets seem to high their efficiency, so I would assume that it would be similar. People claim however that these numbers are pessimistic, but I suppose the only way to tell would be for someone to use an ammeter to tell us. In any case, I asked MagicPower for more info on the efficiency as well, and I am still waiting to hear back from Arise. I'll keep you posted.

**kendrick** · 04-08-2003, 05:13 PM

m

**Telek** · 04-08-2003, 07:36 PM

Originally posted by kendrick
m

Really? how interesting!

I have updated the price for Arise in the top post. $98 for a single unit confirmed, don't know yet about bulk or custom cable order.

**kendrick** · 04-08-2003, 07:48 PM

sounds nice but if its gonna restart when i crank i may as well stick to the inverter or get the opus

**theedge** · 04-08-2003, 07:59 PM

If youre worried about when the cars cranking, a decent cap should take care of that fine.

**Telek** · 04-08-2003, 08:11 PM

yup = tank circuit, if anyone is wondering do a search here to find out more information (basically just a huge cap and a high rated diode). It's not very expensive and will save your computer/radio/whatever from shutting down while the car is cranking (if this is a problem for you to begin with)

**kendrick** · 04-08-2003, 10:25 PM

i built a tank circuit for my inverter setup
that didn't work

**Telek** · 04-08-2003, 10:31 PM

i built a tank circuit for my inverter setup
that didn't work

then you didn't build it right

How did you build it?

**Telek** · 04-09-2003, 03:48 AM

Originally posted by Cadillac_LoungN
This is just me thinking out loud, but doesn't 70% efficiency seem kind of low. I mean for DC-DC, were only talking about like 10% higher than an inverter/PSU combo right. Maybe if it were up in the 90 percentile, like opus then it would be justified...

AH HA! Figured it out. You have to look closely at what the stats for Opus' 150W PSU reads:

Power supply efficiency : greater than 90% *at optimum loads*.

Also check out:

Keypower's DX250H Efficiency : 60% at typical loads
Keypower's DX-250Q Efficiency: 65% at typical loads
Zantek SPS-DX250H (hmm, same as Keypower?) Efficiency: 65% typical
Vox technologies BPS-7004 Efficiency: > 70% at full load
Arise ACE916P Efficiency: greater than 70%

...

So as you can see, The opus power supply stats are misleading.

The actual total efficiency will drop off considerably when you stray away from optimum loads. I think that 70-80% is a more accurate efficiency over the broad range, which is what MagicPower (and others) claim that theirs can do.

I could be wrong here, but I am assuming that the Opus will be no more efficient than any other DC-DC PSU out there.

60% is a pretty typical efficiency for an inverter/AC-DC PSU I think, but even here you see the "choice words". A typical 12VDC-120VAC inverter will give you 70-90% efficiency (note they too say "90% at full efficiency" or "90% at optimum loads"). Most ATX AC-DC PSUs seem to tote a "greater than 65% efficiency". Let's average 80% for an inverter, and 75% for an AC-DC PSU, this gives you somewhere in the neighbourhood of 60%.

So yeah, you're looking at saving around 15-25% efficiency (well, these numbers all have such a large margin of error that this is really hard to tell without hard stats), and this DC-DC PSU is no less efficient than any others.

**PTCruiser** · 04-09-2003, 04:58 AM

Rember that you have a lot off noise in your system using an inverter....

By the way we (www.divx-car.com) are organizig a group buy.

info:
PSU
http://ibelgique.ifrance.com/Cruiser...r/MPD-810H.pdf

Cable:
http://ibelgique.ifrance.com/Cruiser...r/866-810H.doc
or
http://ibelgique.ifrance.com/Cruiser...66-810H-P4.doc

Cost:

Unit: 61 $ + cable + ship -+ custom tax + TVA => ~94$ TTC...
+shipping from us -> you...

Custom tax 9% for the PSU
TVA 19.6%

Telek what's the custom tax in US?

Thread: Group buy for the cheap MagicPower 120W MPD-810H DC-DC PSU

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