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  (#166)
silentbob343
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03.19.2011, 03:04 PM

Quote:
Originally Posted by mistercrash View Post
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.



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.
   
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  (#167)
Overdriven
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03.19.2011, 10:53 PM

[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.


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  (#168)
mistercrash
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03.20.2011, 09:35 AM

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.


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  (#169)
Metallover
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03.20.2011, 05:38 PM

Just cleaned up my unit



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  (#170)
silentbob343
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03.20.2011, 09:23 PM

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.


Last edited by silentbob343; 03.21.2011 at 01:39 AM.
   
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  (#171)
silentbob343
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03.20.2011, 11:26 PM

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



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.

Last edited by silentbob343; 03.21.2011 at 12:27 AM.
   
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  (#172)
snellemin
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07.05.2011, 11:13 PM

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.





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  (#173)
JThiessen
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08.07.2011, 11:26 PM

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.

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  (#174)
Ola
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12.14.2011, 05:01 PM

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?


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  (#175)
snellemin
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12.14.2011, 07:27 PM

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.


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  (#176)
Ola
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12.15.2011, 03:27 AM

Quote:
Originally Posted by snellemin View Post
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..


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  (#177)
Ola
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12.15.2011, 03:36 AM

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 :)


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  (#178)
snellemin
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12.15.2011, 10:10 AM

27.6V......sweet.


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



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  (#179)
BrianG
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12.15.2011, 10:18 AM

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.
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  (#180)
Ola
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12.15.2011, 11:22 AM

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..


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