Scorpion packs
 

FMA Scorpion Packs prices are coming down.

thats a pretty good decrease in price but there still expensive as hell...

Compared with?

impulse 4s 3200s are only $140 and they are 20C.

Scorpions are 20C and 3200MAh 2S 60 Amps continuous with a built in LVC, and built in Cell balancing, and a 3C charge rate for $109.95. Am i missing something?

They aren't true 20C cells :L:, that is if you factor in end temperature.

Your quote?

"-Kokam cells are distributed among a number of vendors. FMA direct is the main one, but there are smaller ones like Watt-Age, Great Planes, and Impulse might be using the 3200mah cells."

Any thing else?

They have excellent burst characteristics, and generally are more safe than most other Lipo cells. How's that :)?

Which cells are you talking about???

The Kokam 3200mah cells.

Unless some one convinces me otherwise "invitation" I am going to pull the trigger on the Scorpion Packs.

In the mean time i need a power supply capable of handeling two chargers at the same time. I found thisKO PROPO Alinco 30 amp continuous power supply that looks real sweet. What are your thoughts?

Expensive... You really don't need that much of a power supply. This is the one I use:
http://www.emtel.com/search/product_...t_id=EMV15012V
It's cheap, pretty small, and works well. Unless you will be charging at 10amps all the time, it should work well for you. Besides, charging a 3200mah pack at 10amps would be over 3C, which would reduce the battery's life.

Papa - I'm with you on this one. I think the Scorpion packs are worth the extra money for the benefits and features they provide. I'm tempted to buy a couple Scorpion packs at the new low price myself. I have the BalancePro packs (the original BalancePro, which is just like the Scorpion except for the cutoff) and they have performed exactly as advertised.

I would not hesitate to buy more FMA/Kokam packs, provided the price is still worth the features and benefits.

That KO Propo supply you list is a decent price for what you get. The power supply that MetalMan links to would also suffice for the Scorpion charger. Mike should be able to get you good pricing on a power supply if you ask him. Lastly, I use a 25A power supply that you can get at your local Radio Shack for $99.
All of these options are valid for a power supply. Choose what you like best :)

I was curius as to what limitation s there where in hooking up multiple packs in series and parallel. The following is the response from Kokam/FMA.

"The Scorpion packs were tested up to 4 in series, making an 8S pack. There should be no limit in parallel configurations, keeping in mind current limitations of the connectors and wire. The ESC and receiver wires are daisy chained through each pack to ensure the LVC works on each pack. The charging must always be done on single pack disconnected from the system. This is due to the common ground of multiple chargers shorting stuff when connected to multiple series packs at the same time.


_____________________________

Visit my Web Hangar at www.gregcovey.com/rc.htm

FMA Direct
Director of Marketing and Promotions"

:cool:

I've had that conversation with Greg Covey before, as well. The "limitations" he mentions are the Deans connectors on the packs. FMA states that the Deans connectors are good for 60A, but just about everyone knows that higher currents are pushed through those connectors daily without problems.
FMA makes this statement as a warning and to cover themselves. Since the Deans connector is rated at 60A, FMA states that the connector limits the pack discharge at 60A. While this is not a true statement, I'm sure it's more of a legal formality and disclaimer than anything else.

Sounds reasonable.

Though the contact area of those deans is not too large, their contact pressure is topnotch.

But i personally prefer the 5.5 BK plugs. It's not that deans rates their plugs at 60A for no reason imo.

The prices listed in the FMA website is actually retail prices, right?
So I guess Mike can get them for a cheaper price, then.

Let's ask Mike? Hello...... I'd rather get them through him.

Well, if I'm using a 9 turn lehner 1950 and I want to go lipo, how many cells am I gonna need to make the motor revs at 32-36000 rpm?!

What does 2s4p mean exactly?

You need to know the KV or rpm/volt rating of the motor.

2 series 4paralel

The motor's kv is 1394 or something.

22.2v multiplied by 1394 rpm = 30946

captain harlock, you will want either 6s or 7s. 7s Lipo will get you to about 36,100 RPM at 3.7v/cell. 6s will take it to 31,000 RPM.

22.2V divided by 3.7V/cell= 6 cells or 6s

Are you following that?

Oh boy. 7s would cost me somewhere between 400-550 dollars and I need two chargers for 168, too. That's alot of money.

No one ever said it was going to be cheap. You could stick with one charger. Do not forget the power supply.

I have a powersupply that gives 30amps with a huge cooling fan and its very compact. When I hook up my futaba cdr-5000 ,which used to destroy many powersupplies, to the new one, I dont even feel the P.S. getting warm. It only costed me 100 dollars or less.

If you got BalancePro packs, then for 7s it would only cost $370 (only, lol). That's for a 4s and a 3s. 6s would cost $322 (2 x 3s packs). Then, you could buy an external LVC device.
Or, you could get the CellPro (standard) packs. 7s would cost $357, 6s would be $291. With the CellPro packs, you use a regular charger and balancer, and a regular LVC.

It is my opinion that packs other than the Scorpion should be used, as their overall value is lower than the BalancePro's or CellPro's. This is caused by the built-in LVC that is like a one-time use sort of thing (think of a disposable camera). Once the battery's life is over, you can't really use the LVC unless you salvage it.

How much are external lvc's? It looks like Fma' LVC for the cellpro / balance pro is about $40. Do you need one for each pack? What is the life expectancy, how many cycles can you expect ?

2s balance pro $113.50
2s cell pro $98.50
2s scorpion w/lvc $109.95

Well, there is this one:
http://66.241.195.91/lithium/lithium.asp?path1=lithium
$25 + $1 for shipping. If you bought 2 CellPro packs instead of 2 Scorpion packs, you would save $23, which means that you would have to spend $3 on the Lisaver. The important thing to remember is that over time, it would be cheaper to get the non-Scorpion packs and just use an external LVC (or a controller with this feature built-in). That is the main point I am trying to make.

plus the built-in LVC is just one more thing to go wrong with the packs and make you have to scrap them prematurely.

Yes but for dummies like me, the ease of the Scorpian packs' plug and play makes it worth it. Not that I even know what's involved in conecting an LVC to other packs anyway. So if everything is allready there and built in on the Scorpian packs, they sound good to me. How common is it for an LVC to go out anyway?

Papa, have you made your decision yet?

Not very likely, unless it gets shorted out or is exposed to extreme heat or is physically damaged.

I see.

FMA now has a two-pack option for the Scorpion 3200 2s pack. It's $215 for two, which saves $5 (a single pack is $110). It's not a huge savings, but it may be what my next purchase is.

http://www.fmadirect.com/Detail.htm?...091&section=32

They actually call it the Monster Truck Pack :)

I am torn between the 3200 packs or the6400packs. I like the idea of the longer runtimes. But do I need it? Must go ten minutes+ ?

Sorry for the double post. They are also listing this power supply for the charger. Nice price.

It depends on how you gear and how much your vehicle demands from the battery. For instance, I used a Dynasty 19T brushed motor with a Novak GT7 in my XXX-4 with the 2s 3200 pack. That buggy would easily go 15 minutes racing, and I'm sure it would be the same with a mild brushless system. However, if I went to a 10T brushed or aggressive brushless, I wouldn't expect much more than 8-10 minutes.
I geared for racing on the track I run at. I needed no more than a 19T motor, so that's what I ran. Speed is great, but it kills parts quick when you have more speed than you can handle on the track. I gear for overall performance over speed when racing.

Well the xxxt has novak 5800ss, geared per the manual. The Super Gmaxx has the 1940/6. Its just been on my mind.

The 5800ss should easily make 12 minutes or so. Drop a tooth on the pinion and you'll get closer to 15 minutes, I'm sure.

The 1940/6 is another matter. I would think you'd get a good 10 minutes with the 3200 packs, but it does depend on gearing.

I have two of the 6400 packs for when I run with the nitros this coming outdoor season, but I don't run them with other electrics since they weigh more, require modification to the battery mounting setup (the packs are about 5mm taller than a nimh pack), and just aren't needed for a 5-minute race.