awesome power supply

[AZ ChopperCam]

I got this not too long ago after cooking a crappy Pyramid power supply

"iota 55" is what it goes by. Do a search on ebay for them. You can get them for $100.

I'm running my 1010 charging 10s at 5 amps and 2 tritons charging 3s at 2 amps as well as a Simprop charging my 9.6v TX pack at 1amp.

The Iota is not even warm.... in fact I just touched it and it's room temp! I hear these things have been known to have two 1010's running full blast on two 10s packs and it just gets lukewarm.

I've burned up 2 other powersupplies before finding this one and the price makes it so great!

http://www.rvupgradestore.com/ProductImages/iota/dls55_10.jpg

[Skiddz]

Nice.. I paid almost that for a 12v 25A supply...

[askman]

very nice switching power supply. good deal for the money. I've been running 32/36 amp pyramid that I got for 120 bucks. regs work hard in a linear supplies, especially if you try to run them near 12v. I run mine at 14.5volt and it starys pretty cool with extra fan on the heatsink. luckily, my charger can handle 15volt.

[Skiddz]

FYI: RV supply stores are selling these things for as much as $300. My dad is very active in the RV community (He writes for FMCA, does safety seminars etc) and I've put him on the hunt for the distributor to see if he can find some good deals. I'll post any results I get from his hunt. (If I know him, he'll BS his way into a few at less than cost.. heheh)

[Brett Horton]

Where can you get them for $100?
The best I have found on ebay was $135

[AZ ChopperCam]

they come up all the time

here's one
Item number: 250036752855 $100

this one for $89
Item number: 250037948713

just gotta do some looking

[Brett Horton]

Those are just starting bids.
I just bought one from the "$100" guy, a placed a bid of $110, was out bid, placed a bid of $130, was outbid. Went to his Power store and "buy it now" for $135. Got one on the way
The $89 was also a starting bid..
Still a great price for that much amprage.
Thanks for the heads up.
The total with shipping and handling was $147.00

[AZ ChopperCam]

nevertheless they can be had for $100 with patience as I got mine for that price (plus shipping of course)

even at $150 they are the best bang for the buck! you'll love it!

[Brett Horton]

I don't have much patience :)
again thanks for the info

[Teej]

While it would be nice to have a proper power supply...I'm just not in a hurry to charge lipos at home...at least not yet. If I grow to have multiple helis and lipos coming out my ears like you and need to charge 5-6 sets a day, then I might be interested in a high-current p/s.

For now...My scavenged PC power supply is good enough for the lipos and I've got wall warts for the radio gear.

[askman]

I am setting my fleet up with a123M1 cells. I spent 500 bucks and ended up with 3-10S and 4-5S packs. I will be running 5S (equvalent to 4S lipo) on my qj8 and btcp, 10S on my swift/logo10 and 15S on my eraptor. I can charge at max power (my tme extrema charger can take 20amp at full power) and triton can use 8amp. that is why I have 35amp PS. 55amp would be even better. since a123 can fully charge in 15-20min at 8amp, I can fly almost continously with 3packs.

[Skiddz]

OK, Pops struck out. None of the distributors he or his RV pals deal with carries that unit. Interesting since almost all the google hits show it to be an RV converter/charger.

Looks like E-bay is the way to go...

[Teej]

As much as I like the fast charge ability of the A123 cells, I couldn't make the $ or weight calculations work in my favor.

The way I figure it, the packs are half the capacity for the same weight as what I'm flying. So I can either cut flight times in half or carry 4.5 pounds of batteries instead of 2.25.

The $/pack is lower with your (Andrey) quoted #s, but it's the same $/minute of flight time.

The remaining benefit is charging speed which isn't as great as it sounds when you consider that a full charge will take 20 minutes with those packs vs an hour with mine.

With my lipos, if I show up with 3 full packs, I can fly for 39 minutes the first hour and 13 minutes each hour afterwards.

With 123/moli packs, I could fly for about 25 minutes the first hour, and about 20 minutes per hour after that. (Charging 1 pack at a time means charging 3 packs per hour giving ~ 18-20 minutes flight time per hour)

So up until about 2.5 hours or so, I'm ahead. After that, the fast charge packs will walk away from me.

Now given that the 123/emo cells are cheaper, my early advantage with lipos could be negated making things about even after the first hour and a 7 minute per hour advantage to the other cells after that.

However....I don't need to land and change packs as often, I didn't have the hassle of building packs myself, and the charger/balancer combo works better with lipo.

[Wild Moose]

This is a very descent power supply. Popular with CB'ers, IIRC.

My friend and I have had great results with the 55A unit running four 1010's charging 6S packs @ 1C each and the P.S. gets warm to the touch. The fan really didn't kick in to high speed until just before the chargers hit the CV phase.

We did find out the limitations for this unit at a recent fun fly, five 1010's and two AF 109s all charging simultaneously. The power supply hit the wall so-to-speak and crowbar'd the output, resetting all chargers in the process. I believe that when the 109's entered phase three, the pulse charging algorithym drew enough (peak) current to overload the IOTA thus tripping it.

We just completed a portable 'power grid' with two IOTA units and a 2KW Honda generator for major flying days. Should never have any more problems charging at the field :twisted:

[askman]

actually, I get almost 10 min on my 10S A123 pack on my logo and 8min with 15S a123 on my eraptor. this is enough for most of my light AP flying. only downside, is that the voltage dump quickly at the end, so if I see power dropping, I land immediately. on my logo, I was getting 13-14min on 8S3600 pack if I drain it, and I usually only fly 11-12 min on it to save the pack. 10S A123 has bit less initial headspeed compared to 8S lipo, but holds headspeed better(as it holds the voltage better) you cannot compare straight mah of pack, as it does not tell the whole story. these 2300mah A123 cell is really equal to 3000/3100mah lipo. (or even tiny bit more as I don't dare use more than 80% of lipo pack as I worry about cycle life) with weight of 3700mah cells.

[Teej]

Oh, please don't think I was knocking your setup - sounds very nice, especially on the Logo.

I still wouldn't mind experimenting with such cells myself if I found the right deal and equivalences. But even so, you're getting 8 minutes with 1500 grams, whereas I'm getting 13 minutes with just over 1000g.

I do know that 11s on the a123s would give me about the same voltage I've got now...12-13s would be a bit better but then it's a whole new charging question. :P

edit: err...I think I have the voltages wrong. I was thinking 3.3 on the a123 but some of the sites I see show lower #s.

What works out to ~ 42 peak and 37 nominal volts with a123s?

[askman]

each cell is 75 gm (with shrink/wire) 10pack is 750gm and 15cell is 1100gm. bare cell is about 70gm. 5Sa123 equals 4Slipo in practical term. my cell hits 2.8v and stays there throughout the pack at 20amp or so until it dumps. 42v nominal at 15S. at rest/1c, it is at 3.3v and charges to 3.6v. my lipo would sag to about 3.5 at 20amp load and go down from there. Do you get 13min flight with 20% reserve? also, is it 20C pack? for myself, I won't use full pack on lipo. killed too many packs that way in low number of cycle. even with 20% reserve, I only get 100-150 cycles before I see a big drop in capacity.

for comparison, 20C 2200mah lipo is about 60gm I will use 3.3v for lipo, as its discharge curve is fairly even slope between 3.6 and 3.0 when it cuts out.
lipo : 3.3v * 2.2*0.8=5.8watt/cell or .098 watt/gm
A123 : 2.8v *2.3=6.44wat/cell .092watt/gm

not much difference when comparing similiar sized cell, but the lipo have advantage in bigger cells like tanic 20C5000.

lipo: 20C5000mah is 120gm
3.3v*4=13.2watt or .11watt/gm or 20% more capacity given same weight.

I don't deny lipo is better in terms of power density. upto 40% better, but in practical term, this goes down to 20% in practical terms. at 150buck vs 500, I will take a123 anytime.

anyway, that is my reasoning. I could run 10S2P and get 11-12 min on my lipo at 1500gm, but 8min is good enough for me. add in durability, quick charge and 1000cycle life, it was easy decision on my part.

[Teej]

No, my packs are not 20C but they don't need to be. They're 10C continuous, 15 burst which works out to 50 / 75 amps. I draw about 18 average in hovering flight.

Yes, that's 13 minutes with reserve. I put an 8.5 minute run on it and put about 2600 into the pack....so the 13 is estimated but likely.

I only have a 500 gram scale and each 5s just barely exceeds its range.

I do expect my heli's endurance may drop slightly when I go fully operational. I've got a few ounces of weight that can come off but unfortunately I have more to put on. :)

Sounds like I need a 15 cell setup if I try a123s also.

T

[Brett Horton]

Got mine in today, looks heavy duty enough!
I will let you guys know how I like it.