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HelicopterAlignOther › 2 in 1 regulator voltage
12-03-2007 05:15 AM  10 years agoPost 1
rcadd1ct

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Richardson, Texas

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In the instructions it says it is for a 2 cell lipo. It never gives the max voltage it will take.

I would like to use A123 cells with this regulator.

I know two will work, but when you use A123's people say to add one compared to lipo's.

So the question is, do I use a two cell or a three cell A123 pack to power the align 2 in 1 voltage regulator?

-RCA .......... Making Cuisinarts Fly!!!!!!!

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12-03-2007 06:15 AM  10 years agoPost 2
motowncali

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Napa, ca

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Assuming that the A123 cells are just lithium-ion cells, just use a two cell.

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12-03-2007 06:57 AM  10 years agoPost 3
MolokaiBoy

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Lahaina, Maui,Hawaii USA

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Well a 2cell lipo has a nominal voltage of 7.4v and fully charged at 8.4v.

I'm not sure what the exact voltage per cell are for the A123 cells. So I would assume if 3cells will not exceed 8.4v fully charged than I would go with 3 cells if not go with 2.

Hope I made sense

Les
Maui RC Modeler's, Big Island RC Helis, http://www.facebook.com/mauirc

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12-03-2007 02:46 PM  10 years agoPost 4
rcadd1ct

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Richardson, Texas

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lipos are 3.65v under load.
A123s are 2.85v under load.

So a 2cell lipo is 7.3v.

A 2 cell A123 is 5.7v. A three cell is 8.55v.

I think I need to go with the three cell, but I don't want to push the regulator by over volting it.

I am using the fully loaded voltage numbers, but they are for use in scaling battery packs for scale heli electric conversions, not for RX duties.

-RCA .......... Making Cuisinarts Fly!!!!!!!

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12-03-2007 03:05 PM  10 years agoPost 5
Topher

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Rochester, Michigan

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Most Vregs have a pretty large voltage range. A typical 5v Vreg will usually go up to 16v although at that voltage it may not be very efficient. I think a 3cell A123 pack will be fine.

will wash your heli for a quarter

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12-03-2007 03:29 PM  10 years agoPost 6
MJWS

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Airdrie, AB - Canada

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Your 2s a123's will stay around 6.2V under the loads seen here, you have to take them over 40A to get them to 2.85V per cell. The regulator will have a drop accross it of ~.5V depending on the regulator they used. You'll be very close to 5.8V with the reg doing very little work. I ran a different reg this way for a while. Took a second to figure out why it wouldn't run at the full 6V it was set too.

Most of us just run direct off the 2s A123 packs for 6V servos as it is pretty much in the sweet spot of a 5cell nimh pack. The curve only moves from 6.3-6.1V over about 90% capacity.

Have fun,

Mike

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12-03-2007 03:59 PM  10 years agoPost 7
rcadd1ct

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Richardson, Texas

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Do you worry about cell balance on a two cell A123?

-RCA .......... Making Cuisinarts Fly!!!!!!!

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12-04-2007 04:13 AM  10 years agoPost 8
MJWS

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Airdrie, AB - Canada

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I don't balance A123's. There are a few guys running them that have found the odd cell that goes out of balance a little. But it seems that even if they are slightly out they equalize very quickly when any type of load is applied as the start and end of the curve is so steep. There is no danger from overcharging if one cell is a little out, so I don't sweat it.

Pretty much the only way to kill these is to physically damage them. I've sucked 150A from them, charged at over 40A, only time they complain is if I crash and punch the ends in somehow.I tend to judge them by capacity of a charge, which I always monitor, and how they hold voltage under high load. Occasionally I cycle them at a decent rate to see if they are still performing. None dead in many cycles (1yr) most at over 50A all are still performing nearly perfect. Btw as they die their iR actually drops and they get better with just a loss in capacity. There are some very long abusive test cycles (~2000) on rcgroups.

If you have a balancing charger and the taps handy, put them on. It can't hurt. I have 40 cells set up as 2s rx packs and multiples of 4s, none have gone out of balance. YMMV.

Mike

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12-04-2007 05:44 AM  10 years agoPost 9
rcadd1ct

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Richardson, Texas

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OK.

Thanks.

-RCA .......... Making Cuisinarts Fly!!!!!!!

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12-04-2007 07:12 AM  10 years agoPost 10
motowncali

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Napa, ca

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I just saw an A123 ad and was surprised by the 3.3 voltave rating. These cells actually sound similar to the original Duralite packs. No regulators needed, just a 2 cell pack. Didn't realize this technology was still around, thought everthing had become 3.7 volt lithium cells.

Mo

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12-05-2007 12:59 AM  10 years agoPost 11
MJWS

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Airdrie, AB - Canada

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These are based on nano-phosphate technology. Nothing at all like the older duralite or other li-ion cells. The good news is the generic players are starting to come into the space. Not matching the specs of A123 yet, but I'm sure they will come close in time.

Mike

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HelicopterAlignOther › 2 in 1 regulator voltage
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