<<< POWER SUPPLIES >>>

safe

safe

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<<< POWER SUPPLIES >>>

We have a lot of threads that talk about building chargers (circuits for limiting them) and balancers, but there is often little said about where the power might come from. This thread is (hopefully) going to thrash out this question (endlessly, since this is after all the "endless sphere" :wink: ) until we arrive at an answer to the question:

"What is the most cost effective power supply?"

...and whatever other variations we might come up with.
 
Example

http://www.xoxide.com/casegears-black-steel-480w.html

xoxide_1986_57023273.jpg


:arrow: Price - $18.99

Total Wattage: 480W
Current:
+3.3V: 28A
+5V: 34A
+12V: 18A
-5V: 0.5A
-12V: 0.8A
+5VSB: 2 A

So doing the math we get:

$18.99 / 480W = 4 cents per Watt

Can anything beat 4 cents per watt?

(using a price per watt metric will make a better comparision base than trying to deal with volts and amps individually)
 
Example

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3285

Automatic Smart Charger (0.5A) for 3.0V (1 cell, 3.8V cut-off) LiFePo4 battery Pack

LiFePO4_char_new_1.jpg


Output: 3.8V
Charging current: 500mA

Total Power Output - 3.8V * 500mA = 1.9 Watts

Price - $19.99

$19.99 / 1.9 Watts = $10.52 per Watt

So if we compare the BatterySpace product to a Computer power supply the individual charger is:

$10.52 / $0.04 = 263 times more expensive! :lol:
 
Example

http://electricmotorsport.com/store/ems_ev_parts_chargers_zivan.php

zivan.jpg


Zivan Chargers are Unique because there can be programmed for just about any battery chemistry. This allows you to have the optimal charging Algorithm for your particular pack of batteries whether you are using AGM, Gel, Flooded SLA, Ni-Cad, NiMH, Lithium or any other rechargeable battery that may come on to the market in the future.

Power - 1 kW
Price - $499

$499 / 1000W = 49 cents per Watt.

Power - 2.6kW
Price - $925

$925 / 2600W = 35 cents per Watt.

Power - 4.3kW
Price - $1,285

$1,285 / 4300W = 30 cents per Watt.

Since this product also has advanced internal logic and it's price point is pretty good it's got a lot going for it. However, you still really need to implement individual cell cutoffs or balancing to really do this right, so you aren't "there" with these right out of the box. But for this thread we are first just discussing the price per watt.
 
Example

http://www.cy-model.com/product_info.php?cPath=23&products_id=343&osCsid=d2a147cb1100b75427537adfa78855ad

MEGA POWER INFINTY-960SR

Mega%20Power%20Infinty%20960SR%2012S+A123m.jpg


Charge/Discharge power:
max. 180/50W

Price - $291.50

$291.50 / 180W = $1.62 per Watt
 
Power Designed For Safe

http://www.xoxide.com/safe-power-400w-psu.html

"Safe Power 400W Quiet Power Supply"

xoxide_1991_39607683.jpg


Maximum Power: 400W
Current:
+3.3V: 32A
+5V: 40A
+12V: 20A
-5V: 0.5A
-12V: 0.8A
+5VSB: 2A

Price - $14.99

$14.99 / 400W = 3.7 cents per Watt!
 
DC-DC :mrgreen: 10$ on ebat for 150W.

they have auctions every weeks 6.6cent per watt

BXB150-48S05FLT.jpg


and SMALL!!

Doc
 
DC-DC isn't the same idea. Power Supplies mean that you can plug them into your wall plug at either 120VAC or 240VAC and get some kind of DC voltage from it. DC-DC is the wrong category.

Let's stay focused on "Power Supplies" and pricing.

The concept is simple, but finding the products is work... (but I like your enthusiam :) )

The Zivan Chargers that Patrick has over at Electric Motorsports look very good at their price point which is consistent with them being very smart guys. :wink:
 
safe said:
DC-DC isn't the same idea. Power Supplies mean that you can plug them into your wall plug at either 120VAC or 240VAC and get some kind of DC voltage from it. DC-DC is the wrong category.

Let's stay focused on "Power Supplies" and pricing.

The concept is simple, but finding the products is work... (but I like your enthusiam :) )
Click to expand...

Ok ooook.. :p

maybe a AC-DC... they made many modules that accept 150Vac input... but i agree they are difficult to find on ebay :|

Doc
 
Doctorbass said:
...they made many modules that accept 150Vac input.
Click to expand...
:arrow: Do you guys in Canada use 150VAC?

In America it's 120VAC or 240VAC. Or were you just saying you knew of things that could accept extra power so they were more durable?

What do the Europeans use?
 
PC power supplies are an inexpensive way to create a bench power supply, however the way you are pricing them per watt is perhaps flawed. It will be a strange beast indeed where you can hook up all those outputs and use them effectively to charge batteries. More realistically will be using either the +12V rail or the +5V rail to feed your project, so you should really be using just those numbers in your calculations. Also, based on testing it is rare to find a PC power supply that can put out its nominal amperage on a rail (see tomshardware's torture testing for example). You may want to look at the nominal numbers as "peak" numbers, and back off from there.

So the 400W PC power supply you listed claims to provide 40A at +5V. Lets say it can achieve 30A continuous (which may be generous), and you get 150W of usable power from the power supply.

$14.99/150W = $0.10 per Watt.

It's still an inexpensive power source, but about 3x the price per Watt in your calculation.
 
OneEye said:
It's still an inexpensive power source, but about 3x the price per Watt in your calculation.
Click to expand...
I've got two extreme points to somehow make converge. If I buy 12 Thundersky cells @ 3.2v * 40Ah that equals a 1C charge rate of:

12 * 3.2 * 40 = 1536 Watts

...but Thundersky cells are rated 3C for charging so:

1536 Watts * 3 = 4608 Watts

Now if I work backwards from that and ask how many power supplies I might need to do either 1C or 3C then:

1536 Watts / 400 watts = 4 to 6 power supplies

4608 Watts / 400 watts = 12 to 18 power supplies

...I'm not going to really want to have 18 power supplies, but I might be okay with 4 so reverse calculating (and derating slightly) I get:

400 watts * 80% (a guess) * 4 = 1280 Watts

C Rating for charging becomes: 1280 / 1536 = 0.83C

I could live with that... (for about $80) :)

And we have to remember that the power supply is just the first part of the charging system. You still need to deal with individual cell charge cutoffs, so there's a whole bunch of stuff that has to happen after the power supply.
 

Attachments

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Don't forget you have to get that power from the wall socket somehow. A typical wall circuit is rated for 15A/120V, or 1800W. Your conversion efficiency may only be 80%, so you have 1440W available charging. That's almost enough to get your 1C charging rate.

Some wall circuits have heavier wiring and are on a 20A breaker, so that becomes 2400W at the wall or 1920W at 80% effective.

If you want to get to 3C, you will need to pull from a dryer circuit, 240V @ 30A = 7200W at the wall, or 5760W at 80% effective.

Maybe you want to look at non-US (European/Asian) power supplies that take 220V/240V?
 
OneEye said:
A typical wall circuit is rated for 15A/120V, or 1800W. Your conversion efficiency may only be 80%, so you have 1440W available charging.
Click to expand...
That's about all I wanted. In my garage I've got two separate wall sockets with independent 1800W ratings. So if I were to get 4 power supplies at 400W each then I should be able to get 800W from each circuit. I've got breakers on the wall sockets for things like power tools and they trip when overloaded. I've been able to operate a heater and a charger at the same time, so it should okay.

:arrow: 1200W is about the limit before you have to get fancy... using 800W per circuit should be okay.
 
You bought the fancy house with the upgrades if they put multiple separate circuits in the garage. Most places will wire all the sockets in the garage on a single loop to a breaker in the panel.

I'm envious. I couldn't afford the upgrades. I had to run around the attic in the summer to install ceiling fan/light fixtures in all the kid's bedrooms (I HATE the lame switch controls wall socket wiring that is so typical these days). I could have died of heat exhaustion.
 
OneEye said:
You bought the fancy house with the upgrades if they put multiple separate circuits in the garage. Most places will wire all the sockets in the garage on a single loop to a breaker in the panel.
Click to expand...
I was flush with dot.com cash and California real estate cash and splurged on a better house in a cheap part of the country. (Missouri) For $182K I got a house with a four car (2x2 square) garage and circuit breakers. I'm happy with the decision, but I'm kind of stuck with it now because nothing sells. It's the best garage I've ever owned. :) (but since it's so damned cold in winter I can only use it 8 months out of the year :( )

99c.jpg


http://www.cpsc.gov/cpscpub/pubs/99.html
 
The GFCI's are usually in addition to the arc-fault/overcurrent circuit breakers in the panel. Be sure each wall socket is on a different panel breaker, otherwise they are still limited to the single breaker limit at the panel (15A or 20A).

Of course as you have stated only 1C charging is your goal a single circuit may just be enough anyway.
 
My house was owned by a guy that used the garage as a place to work on cars. There were deep oil stains that I ended up renting a wire brush machine to grind off to get back to white cement. He had wired a high powered line for use with an Arc Welder as well as a second line. So I have at least two power lines (at the circuit breaker box) going to the garage. All this was one of the main reasons for buying the house in the first place because having a really well configured garage was always a dream of mine. Most people will have to make do with a single circuit and so going above about 1000W is probably not possible.
 
Example

http://www.mpja.com/prodinfo.asp?number=17413+PS

5V @ 200A LAMBDA/EMI POWER SUPPLY

17413.jpg


5V * 200A = 1000W

Price - $149.95

$149.95 / 1000W = 15 cents per Watt

(not bad and you might be able to get away with just one power supply this way)
 
Example

http://www.mpja.com/prodinfo.asp?number=12922+PS

5V @ 13A AUTEC POWER SUPPLY

12922.jpg


5V * 13A = 65W

Price - $9.95

$9.95 / 65W = 15 cents per Watt

Buy 10 for $8.95 each - 14 cents per Watt.
Buy 25 for $7.95 each - 12 cents per Watt.

(this might be good in that you could have one per cell. It eliminates the multiplexing issues)
 
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