SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jun 08, 2004, 05:59 AM
Registered User
CustomPC's Avatar
Australia, NSW, Cherrybrook
Joined May 2004
1,576 Posts
Any Experiences with ST Model Lithiums?

Hi,

I contacted a prominent hobby store here in Australia about lithiums. I originally wanted to purchase a 2S pack of E-Tec 1200's, possibly a 2S2P.

The sales assistantant said that they also had some other cells made by ST Model in 1600, 1800 and 2200 sizes.
His opinion was that the ST Model packs were constructed stronger than the E-Tec's.
He also said some of his customers had E-Tec's catch fire but to date he had heard of no such problems with the ST Model packs.

The ST Models present better value when considering capacity for dollars spent.

Does anyone have any experience with the ST Model lithium packs.

They'll be used with a speed 400 with 2.33:1 gearbox. Currently running 8 cells and 8x4 with 7.2v motor and draw 4.5A static (measured).

I Will change to a 6v motor and increase prop to 9x4.5 with a 2S lithium pack. MotoCalc estimates me i should draw about 7A with this setup for slightly more thrust.
CustomPC is offline Find More Posts by CustomPC
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 08, 2004, 08:17 AM
Uh Oh Jungo
ParkJeff's Avatar
Australia, WA, Perth
Joined Feb 2003
784 Posts
I've used the ST Models packs. They are prismatic Lithium Ions and not Lipos which basically means instead of the cells having a plastic bag "casing" they are encased in metal like Nicads and NiMHs. They are usually heavier for the same capacity when compared to Lipos although chemistry is the same or similar.

I have an 1800mAH 3S pack and the cells are good for about 8A. If you're only drawing 7A WOT then you should be safe with the 1800s. I'm using my pack in a GWS TM400 with a S400 geared 3.4:1 and a 9x5 prop.

Ask about the weights of the packs first as that may or may not be an issue for you.

Cheers,
Jeff
ParkJeff is offline Find More Posts by ParkJeff
Reply With Quote
Old Jun 08, 2004, 08:59 AM
Registered User
CustomPC's Avatar
Australia, NSW, Cherrybrook
Joined May 2004
1,576 Posts
Quote:
Originally Posted by ParkJeff
They are prismatic Lithium Ions and not Lipos which basically means instead of the cells having a plastic bag "casing" they are encased in metal like Nicads and NiMHs.
I have an 1800mAH 3S pack and the cells are good for about 8A.
Cheers,
Jeff
That's Interesting. I didn't realise they were metal cased. You can't tell from the pic's on the web site.

When you say the cells are good for about 8A do you mean that's the best you've been able to achieve or that's all you run them at? 8A is only about 4.4C. They claim they can be discharged at 6C constant and 8C bursts (10.8A - 14.4A).

Hmmm...... What to do?
I think i'll stick with my original plan to get Lipo's. Would it be wise to stick with some well known brands like Kokam, TP, E-Tec and irate?
CustomPC is offline Find More Posts by CustomPC
Reply With Quote
Old Jun 09, 2004, 12:18 AM
Uh Oh Jungo
ParkJeff's Avatar
Australia, WA, Perth
Joined Feb 2003
784 Posts
Yes I was a little miffed when I got them as I thought they were Lipos too. Guess you get what you pay for. I've tried a 1800 pack in a plane that was drawing about 12A WOT (probably 10A average) and it lasted maybe 20 flights. That's why I only have one pack left .

If you have the means go for the Irates or the new Gen 2 TPs which are 10C cells. Watch out for width with the larger (>= 1800) Irates as it could be a problem fitting into narrow fuses. The TPs are nice and expensive.

Jeff
ParkJeff is offline Find More Posts by ParkJeff
Reply With Quote
Old Jun 09, 2004, 03:32 AM
Registered User
Brisbane Australia
Joined Nov 2003
805 Posts
If you are looking for true 10C performance then you need to go with Tanic / Irate / TP / Apogee / Polyquest. Getting them to OZ is the only issue. I have had batteries shipped from Tanic, Irate (cheap battery packs) and Aircraft World. I have also purchased other items from parkflyer motors and all provide cost effective and reliable shipping down under.

The only catch is finding the correct size cell to fit yuour aircraft / application.

I have a single ST pack (came with my 3D CAP II) which was woefully underpowered for the 9.5 AMP draw on the standard power plant.

If you are looking for cheaper solutions the E-Tec cells are OK if you keep within their comfort zone (<8C). Make sure you get the packs with the PCB not the older solder the wires to the tabs versions.

With 2S you will drop around a volt under load from your 8 cell pack so the performance will drop off and you will need to prop up.

Michael
mjdoz is offline Find More Posts by mjdoz
Reply With Quote
Old Jun 09, 2004, 06:57 AM
Lipoly not Lipo-suction
Cranky1's Avatar
Brisbane Australia
Joined Nov 2003
229 Posts
How about giving a local Lipo retailer a go. PM me or check out my new web site.

Cranky
Cranky1 is offline Find More Posts by Cranky1
Reply With Quote
Old Jun 09, 2004, 07:24 PM
Registered User
Brisbane Australia
Joined Nov 2003
805 Posts
Cranky - sent you a message via your web site

Michael
mjdoz is offline Find More Posts by mjdoz
Reply With Quote
Old Jun 09, 2004, 08:14 PM
Registered User
CustomPC's Avatar
Australia, NSW, Cherrybrook
Joined May 2004
1,576 Posts
Quote:
Originally Posted by Cranky1
How about giving a local Lipo retailer a go. PM me or check out my new web site.
They are interesting prices Cranky. Do you make up packs in 2S or 3S or do you leave that to us? Any intructions about how to do it?

Seriously thinking about cancelling my order for a 2S2P E-Tec pack (@ $105) and getting 4 of your cells.
CustomPC is offline Find More Posts by CustomPC
Reply With Quote
Old Jun 09, 2004, 11:15 PM
Lipoly not Lipo-suction
Cranky1's Avatar
Brisbane Australia
Joined Nov 2003
229 Posts
I was in the same boat as you guys, buying my lopo's over seas. So I bit the bullet and opened up shop. I haven't advertised packs yet but I'm thinking of 2s for $32 and 3s for $45 (the 3s are a bit more fidly) They'll have JST leads so they can plug into my adapter for paralleling :-)

Cranky
Cranky1 is offline Find More Posts by Cranky1
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Any experiences with Rimfire motors? flying evader Power Systems 7 Feb 27, 2007 11:12 PM
Question Any experiences with Hooobby.com? MikeReilly Trader Talk 1 Jan 02, 2007 05:46 PM
Any Experiences with Jeti 45 kelvin Electric Plane Talk 2 Apr 11, 2002 12:12 PM
Any Experiences with Shrouded Prop Designs? sticktime Electric Ducted Fan Jet Talk 7 Nov 15, 2001 02:02 AM
Any Experiences with Shrouded Prop Designs? sticktime Power Systems 3 Oct 22, 2001 02:17 AM