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Feb 25, 2012, 11:34 AM
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Hello! Thank you all who explained the use of these power supplies to us
I did some testing on the fan control and have come up with these conclusions:
50kOhm resistor gives ~ 2/3 the fan speed
22kOhm resistor gives ~ 1/2 the fan speed
both those connected in parallel give ~ 1/3 the fan speed.
In the attachment you could see a small modification using a DIP switch. I think it's nice to be able to switch voltage regulation ON/OFF (this way you coulld have ~12.3 V at OFF and 12.8-13.8 V at ON position).

Nickolay
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Feb 26, 2012, 11:29 AM
Registered User
Sorry for the double post!
As some have mentioned, for high currents around the limit of 47A, the voltage regulation has to be done precisely. I read that "At 13.4V, the supply is stable all the way to 35A, but unstable at 40A". What does "stable" mean? Maybe stable voltage with almost no drop? Is only the default 12.3V stable?
As i don't have such a big load to test the power supplies, could someone give an advice on what resistor to use between pins 3 and 9 or the desirable voltage? I've put a potentiometer there right now, but would want to do a modification and a resistor would open a lot of useful space.

Thank you!
Nickolay
Feb 26, 2012, 01:26 PM
Registered User
Quote:
Originally Posted by dando
Sorry for the double post!
As some have mentioned, for high currents around the limit of 47A, the voltage regulation has to be done precisely. I read that "At 13.4V, the supply is stable all the way to 35A, but unstable at 40A". What does "stable" mean?
Stable meant the supply could provide the necessary wattage without oscillating. I should have been more specific in my original post. I was doing 6S charges at up to 40A so maxed out at 1008W at the charger output. I did charges in steps of 5A. The only way the supply was stable over the whole range was to leave those pins open (no resistance).

Quote:
Is only the default 12.3V stable?
From the limited testing that I did, yes, only the default is stable all the way up to the limit of the power supply.

Quote:
As i don't have such a big load to test the power supplies, could someone give an advice on what resistor to use between pins 3 and 9 or the desirable voltage? I've put a potentiometer there right now, but would want to do a modification and a resistor would open a lot of useful space.
In my opinion, keep the pot or leave it open. It's the only way to guarantee you can do a charge at the wattage you want and have a stable supply.
Feb 26, 2012, 01:45 PM
Registered User
Thanks for the answer, Frank!
I will charge at low current most of the time.
I was thinking about putting a resistor and a switch in series so I could choose wheter to have default voltage (12.3 V), or, say, 13.4 V (please suggest an appropriate value here). And also leaving two additional pins, so I could connect externally the pot and a resistor in series. This way I'd have three options:
1. default voltage (switch OFF)
2. set voltage (switch ON)
3. variable voltage (switch OFF and the pot connected)

I made some tests and came up with the following results:

Voltage, [V] --- Resistor value, [Ohms]
13 ------------------ 600
13.2 ---------------- 445
13.36 -------------- 360 (standart value)
13.4 --------------- 345
13.45 -------------- 330 (standart value)

Maybe the other close standart values as 390 and 430 Ohms would give around 13.3 V and 13.22 V.
How does that plan sound to you? I just need to find the most appropriate resistor value right now, or just leave it open. Maybe I won't be using that voltage regulation at all that often, but for peace of mind, it's always nice to have an additional feature you might need someday


Thanks!
Nickolay
Feb 26, 2012, 09:27 PM
Registered User

My rig


It is still a work in progress, but I wanted to show off my new rig. I built a charging station several years ago using a PC power supply for 12v power. Worked fine until I starting using 5000+ mah/12s systems for my bigger EDFs and 50cc sized conversions. My chargers kept faulting out when I tried to charge several large packs at the same time.
When my old charging station fell out of my truck and broke apart, I figured it was a omen - time to upgrade. I have been looking for a power supply with sufficient capacity for my needs, when I came across this thread. This was just what I needed.
I used two HP DPS600PB supplies from Ebay, floated one of the DC grounds, and hooked them up in series. I then added some lights, fans for the cooling tubes, a couple of digital volt meters, and this is what I came up with. All the chargers run off the 24 volt side, except the Hitec. The lights are for more than just bling. We night fly in the summer, so having lights available really helps.
I run the fans, lights, and accessories off one 12 volt supply. Both supplies are switchable, so I can run one supply at a time if necessary.
I fly big EDFs and high power setups in Austin, Texas, and I do not like charging packs that are hot, so I use the cooling tubes to cool packs down quickly. They work great, even when ambient temps are in the 100s.
I also added two pull put shelves, just below the chargers, so the batteries do not train the leads when I am charging.
Still working on the drawer, and I have some aluminum angle to protect the corners, but I tried it out this weekend and it worked great.
BTW, we do not have AC power at our field, so I run this station off one Honda eu1000 generator. I know I am pushing the capacity of my generator, but so far it has performed without hiccups.
Also, I would like to say I have the woodworking skills to cut this by hand, but I cheated. I have a 3 axis CNC router mill that does the precision cuts for me.
Enjoy.

Russ
Feb 26, 2012, 09:57 PM
Registered User

My rig


A few more pics.

Russ
Feb 26, 2012, 10:48 PM
Pro beginner
rchelijc's Avatar
Thread OP
Whoa... A turntable, car audio amps and a woofer and a disco ball, all off the 12v would complete it

Seriously nice work...
Feb 26, 2012, 11:46 PM
Registered User

My rIg


I did think about adding a microwave for snacks, but I would have to lug it to the field.
Feb 26, 2012, 11:52 PM
Registered User
Harry H's Avatar
With all that cooling, does it make ice?

Harry

Very nice!
Last edited by Harry H; Feb 26, 2012 at 11:53 PM. Reason: Added text
Feb 27, 2012, 12:30 AM
Registered User

My rig


Quote:
Originally Posted by Harry H
With all that cooling, does it make ice?

Harry

Very nice!
Cubed and crushed!!
Feb 27, 2012, 04:25 AM
Pro beginner
rchelijc's Avatar
Thread OP
Forget microwave, I'm sure that thing powers a 12V bar fridge, you know, for refreshments...
Mar 05, 2012, 11:03 AM
Registered User
Quote:
Originally Posted by dando
Hello! Thank you all who explained the use of these power supplies to us
I did some testing on the fan control and have come up with these conclusions:
50kOhm resistor gives ~ 2/3 the fan speed
22kOhm resistor gives ~ 1/2 the fan speed
both those connected in parallel give ~ 1/3 the fan speed.
In the attachment you could see a small modification using a DIP switch. I think it's nice to be able to switch voltage regulation ON/OFF (this way you coulld have ~12.3 V at OFF and 12.8-13.8 V at ON position).

Nickolay
I heard you can short pin 4 to ground to reduce the fan speed, but this was load related, and it would speed up if required.

Is this true?
Mar 05, 2012, 11:06 AM
Registered User
Quote:
Originally Posted by pgleesonuk
I heard you can short pin 4 to ground to reduce the fan speed, but this was load related, and it would speed up if required.

Is this true?
Yes. The fan speeds up with high load even if you have the pin shorted. I don't think it spins as fast without the pin shorted, though. I've been using it this way for a bit now, but I'm only at high power for 20-30mins.
Mar 05, 2012, 11:29 AM
Suspended Account
As an alternative, the fans are cheap and easily replaced with a nearly-silent version, which seems able to keep up with most any load.
Mar 05, 2012, 11:32 AM
Registered User
Quote:
Originally Posted by ReddiK
As an alternative, the fans are cheap and easily replaced with a nearly-silent version, which seems able to keep up with most any load.
Any chance you can provide a link to some fans known to be silent and work?


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