I saw that. That's weird. Thanks for clarifying that up for me. I understand now.

Here's mine all done

http://img.photobucket.com/albums/v6...6/IMAG0039.jpg

That blue right thur is gansta. Looking good man.

Hot swap and IIRC the 208B requires 18v to support 350w.

I see Brian already answered the 17v question.

I haven't read all the posts in the thread so sorry if this has been discussed. I have read in here that if you go with two server PS to have a 24V power supply, the two can't be touching because you have to remove the AC ground on one of the units. I hope I understood correctly. This guy here says that he removed the DC ground on one of the units instead retaining the AC ground on both units so the boxes can touch with no problems.

http://i177.photobucket.com/albums/w...g?t=1300561628

http://i177.photobucket.com/albums/w...g?t=1300561660

Maybe someone with more knowledge than me can confirm that this way of doing it is safe.

http://www.rcgroups.com/forums/showt...1369612&page=2
Plenty of guys have purchased his kit and I haven't heard of any issues.

[QUOTE=mistercrash;401698]I haven't read all the posts in the thread so sorry if this has been discussed. I have read in here that if you go with two server PS to have a 24V power supply, the two can't be touching because you have to remove the AC ground on one of the units. I hope I understood correctly. This guy here says that he removed the DC ground on one of the units instead retaining the AC ground on both units so the boxes can touch with no problems.
QUOTE]

I just finished reading the entire thread from the link posted above. The only thing that's a little scary is on page 4. But the scenario described is also easily prevented. I'll quote the important bit here and save you some thread searching.

"The power supplies have 4 terminals, two for each power supply. You can use a jumper between the two middle terminals to put the power supplies in series and use the outer two for 24v (47amps) or you can jumper both the red and blacks to each other and put the power supplies in parallel mode where you have 12v (94amps).

You can also wire for series and run one charger on the outside posts, then plug another charger into each power supply to get 12v.

The only thing you need to watch for is that plugging a charger into each power supply while in series mode makes one charger's chassis ground for one power supply but also DC+ for the other which means that setting it on top of the charger can cause a short.

Because of this It is recommended that you only use the grounded power supply for 12 while in series mode.

Now that I'm thinking about it, I should probably make a diagram to mail out with the kits." See link in previous post on page 4 for diagram.

http://sites.google.com/site/tjinguy...ts/diy-24v-47a

This is where I found the info I posted, I don't think it has anything to do with that guy on RC Groups. Unless it's the same guy.

Just cleaned up my unit

http://i345.photobucket.com/albums/p...1/IMG_0551.jpg

http://i345.photobucket.com/albums/p...1/IMG_0552.jpg

Almost finished with mine,

Was also wondering if I should use rubber grommets on my aluminum angle to reduce the possibility of a short should the post shift and contact the aluminum.

Here is a picture to demonstrate what I am referring to. Once the back half is on and the nuts are snugged over the post it seems secure, but I would hate for the posts to touch the edges of those holes if I were drop the PS or have some other jarring force act on it.

http://home.comcast.net/~silentbob343/posts.jpg

Figured out the pinout on the hot swap board. 10 pin IDC connector just like on your USB motherboard headers.

http://home.comcast.net/~silentbob343/pins.jpg

Time to scavenge a spare USB plug.

Couldn't find any USB motherboard headers so I used a dead ESC lead and two of those tiny motherboard speakers to get enough wires with the contacts already crimped/soldered on. Also managed to desolder the connector from the swap board, but will need some CA or epoxy to keep the pins from falling out of the connector. Both bottles of CA were dried solid, so it looks like I'll have to finish tomorrow.

I was lazy and bought me a kit from this dude on rcgroups. It's a pretty good kit, if you don't have much time to custom make your own 12v-24v PSU. You basically just lift the ground off one of the legs on the second psu. Cut some wires and connect everything.

http://i189.photobucket.com/albums/z...u/DSC06248.jpg
http://i189.photobucket.com/albums/z...u/DSC06247.jpg
http://i189.photobucket.com/albums/z...u/DSC06245.jpg

Just got mine hooked up and running tonight. I wanted something encased for taking on trips in the RV, and to keep debris out of the fans. After turning my garage inside out trying all the different cases I had, I noticed one in the downstairs "theater room to be" that I had walked past a hundred times in the last two months. Its just a basic Stanley plastic case, but it did not have any dividers or divider channels inside it. I didn't really want to used plywood, but it was handy, I had really gotten tired of overthinking this thing.
I put a base of 7/16" ACX down and screwed it in place to firm up the whole case. I then used 3/4" veneered plywood for the dividers (the center one has a 1.25" wide tee on the end of it to keep the supplies from sliding - although I doubt then will ever come loose. Next, I just cut a top piece out of 3/4". I used bar clamps to hold the entire thing together for putting the screws in - and predrilled the holes to keep them from splitting. But.. when running some screws in from the outside (to keep the "box" secured), I didn't use a big enough bit, and split one piece of wood (you can see it where the two cable clamps are screwed in for the input power cords).

I also used a STSP switch to to be able to turn it off and on. It fit nicely under one of the lid latches (however, it only turns red when off - its supposed to also show green when its on. Dont know what I did with the wiring on it....
Also drilled a bunch of holes for ventillation, and drilled two larger holes on the output side so that I dont have to open the lid to plug my charger in.
Turned out ok - if anything, I'd like to go back and make the plates out of nylon instead of plywood - but no reason to spend that money on it.

[IMG]http://i244.photobucket.com/albums/g...7111855-00.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111855-01.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111856-00.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111856-01.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111856-02.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111856-03.jpg[/IMG]

[IMG]http://i244.photobucket.com/albums/g...7111857-00.jpg[/IMG]

Just put together a PSU based on this thread! HP 47A psu`s in serie, making 24V 47A..

Not alot of work, and works great so far with a 206B 20A charger, while i`m waiting for my Powerlab PL8 in the mail..
Ill post pictures of the portable "charging case" im building when the PL8 gets here..

But the noise...

Anyone that has solved this without rebuilding the psu completely? Does it need all the airflow to stay cool?

Well, I'm pulling close to 47A @ 24V with the Powerlab 8. You just have to live with the noise when pulling all that power.

I was afraid so..

But i did find how to slow the fan down though.. Short pin 4 to ground, is supposed to slow the fan down to the minimum setting..

I`ll try it today.
I might get away with it if i adjust the output voltage some. Seems like it can handle up to 13.8V, but i`m not sure if the PL8 and my iCharger handles 26-28V though.... I`m emailing them about it now..

Hehe, just by looking at ad`s, it seems like the 206b can take 28v input, and the PL8 up to 32v.. So i think i can get away with bumping the PSU output up to 27.6v :)

27.6V......sweet.


This is what I was pulling this morning charging my ebike batteries.

http://i189.photobucket.com/albums/z...8/DSC01752.jpg

FYI: These supplies generate quite a bit of heat when driven near its max for a while. Despite the high efficiency of these supplies (~85%), outputting ~550w generates close to 100w. So, that fan is needed when they are driven hard.

If you are enclosing them in some kind of charger station case, you could probably use a larger fan (which doesn't need to spin as fast for the same CFM) as long as the air is directed through the power supply. Then you could do that fan speed reduction mod. IIRC, you can't simply remove the fan because the supply needs to see some rpm or it won't function.

I do agree.. But i`m wont be pulling full amps for that long time with every charge..
I also have max 5s batteries, so the charger will charge at 850w maximum.. Thats approx 970w at 0.85, so theres still a good margin up to the 1150w maximum on the PSU`s.. And thats at stock 24v... Wouldnt it be producing less heat at 27v, being more efficent?

I`ll do some testing and measure temps to see how it works out..
I think i will be installing a switch for the fans as well.. for minimum + maximum settings, in case i want more cooling :)

At 20A charging, the air coming out of the psu`s are cold as the outside air hehe..

Thats so cool! :D Couple years ago, i would laugh at you if you said that you`re going to charge batteries with 1150w power :lol:


Btw, i love youre e-bike project..!

It's just crazy at what power level we can charge batteries now. Would be nice if I had 230Vac in my garage, so I could use all three Powerlab8 at the same time. Oh well, maybe one day.

My ebike is nice to commute with. Very low key. Most people thing that the ESC is a audio amplifier. Currently running 16s2p lipo(32mph max). Just too cold at times to go 40mph.

How big is the power supply? (one PS LxHxW )

The fan may need to be a high pressure fan at any cfm. The cases are very constricted. A 2-sp switch would be nice like mentioned above.

I got 3x32A 230v to my garage heheh.. And we have several 10-16A circuits 230v at our hangar at the airstrip, so were all good :na:

I modifies the PSU`s this evening :yes: I didnt have resistors to make absolute max output voltage, but i did make 27v still.. I reckon it drops some at load though, but alot better than the 24.3 i had.

i also soldered a 13Kohm resistor on the fan control circuit to slow down the fan`s.. I tried to shorten those pins, but that made the fans run WAY to slow.. I think i found a good mid level, and its very easy to put a switch into the circuit to make full fan speed if its necessary.. Test`s at 40A will show :intello:

The aluminium suitcase i`m using for charge-box, is vented in both ends of the PSU`s now, and all thats left to do with it, is making a 230v input socket for the PSU`s on the outside of the box.. Pic`s will come when i get my PL8 :yipi:

12x3x2.75

Well, here`s my take on a portable charge case :)

http://www.br-motor.no/bilde/diverse...adekoffert.jpg

Nice :yes:... that looks pretty good...

Im planning on doing the dual power supply, but I have a question: In my garage (where i plan to use the power supply) the neutral and ground is bound together in the pannel box. So is removing the ground prong on one of the power supply cords going to even do anything?

Neutral and ground are electrically the same point in any US panel box for 120v mains, so that's nothing new. However, if you don't float the ground wire in the PS units, you get problems because you are paralleling the input, but series connecting the output.

Cool, thanks Brian

I made a 12V/24V power supply from two HP PSs. I installed an ON/OFF switch on the little wires I used to connect the three little pins of each PS and it worked fine. Then I decided that instead of having two power cords (one for each PS), I wanted the two to merge as one so I did that. I made sure to have one PS grounded and the other ungrounded. So now the switch doesn't work. Is there a way of wiring the switch so it can turn the power supplies on or off when the two power cords are merged together.

Thanks

Oh yes, the pics. Some in here like pics. I went for the compact look.

http://i177.photobucket.com/albums/w...no/24v_ps1.jpg

http://i177.photobucket.com/albums/w...no/24v_ps2.jpg

Here is how it was wired with the switch. It worked fine shutting off and powering on both PSs. But when I merged the power cords together, the ungrounded PS would always stay on and the grounded PS would always stay off no matter where the switch was.

http://i177.photobucket.com/albums/w...er_supply1.jpg

Switch the merged 120v
 

Mr.MC 1st I floated the 12 and 120 on one unit. Then I ran a single 120 cord into a 120 light switch (mounted on my charge box) then split out from there to feed a switched 120 to both units.

Edit: After looking at your pic of your nice and compact ps you don't have a place for a 120 switch. Oops my mistake.

Here is a pic of the last one I made.
[IMG]

Thanks for responding, I know I can easily put a switch on the power cord but my PS is self contained and not part of a bigger case. That is why I wanted a way to put a switch on the small wires used to connect the pins together, so the switch can be small and be part of the small box I made for the two PSs. Maybe I'll end up putting the thing in a case, yours looks real good by the way.

Thanks,
That's a good question. I'll stall now for someone else to chime in....

IIRC, the switch attached to those small wires simply grounds them to turn it on (similar to how ATX PC supplies work with the green wire). Since you floated the grounds on each supply, I'm surprised it even works at all.

What I would do is use a double-pole single-throw (DPST) switch and have the small wires on each supply hooked to each pole. That will allow you to turn both supplies on at the same time, yet only use one switch and still have them isolated. A DPST switch is basically two SPST switches in one package.

However, a DPST switch may be hard to find, so just use a DPDT switch and just don't use two of the contacts: http://www.radioshack.com/product/in...ductId=2062499

I'm going to have to try that. Thanks Brian.

I haven't been in this thread in a while. I now feel wholly inadequate about the size and performance of my power supply:cry: The cases are cool:yes:

Mistercrash- BG gave you an example of a dpdt switch, but scroll down and read the reviews, that particular one appears to be crap. Hopefully you can source a better one:intello:

edit: 57 pages of them on fee-bay http://www.ebay.com/sch/i.html?_from...All-Categories

Well, I can say that I've personally used that switch on a number of projects and they all still work. Maybe the reviewers don't understand how to use them, or are using them in applications where more current is drawn than the switch can handle? Maybe there was a bad batch? Maybe it's a combination of user stupidity and normal number of DOA units?

In this case, the switch is passing very little current so it should be fine. But at the very least, it was an example of a DPDT switch.