Lipo question

[J Solinger]

How consistant is the output voltage on lipo cells from cell to cell?

Will there be "Magic" cells with a little higher output, or less internal resistance?

My understanding is that lipo cells have proven to be consistant and won't give advantage from one pack to another like selected sub C's verses bulk but my knowledge is outdated.

 

[drobie]

How consistant is the output voltage on lipo cells from cell to cell?
Will there be "Magic" cells with a little higher output, or less internal resistance?

My understanding is that lipo cells have proven to be consistant and won't give advantage from one pack to another like selected sub C's verses bulk but my knowledge is outdated.

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I don't know the answer to that Joe, but it would be a beautiful thing for the hobby.

No more matching. Cool!

If true and you could own stock in Competition Electronics, you might want to be selling it short. B) B)

 

[raptor347]

It will be intertesting to see how consistant they are. I don't know of anybody who's done any testing for variation.

Brian

 

[J Solinger]

Are Lipo cells something that can be run through a standard battery matcher?

 

[Dan Proulx]

Lipos aren't exactly fun to take care of.

I've got a dozens of them and I can tell you that's true of the most current crop. They require very close scrutiny to maintain a "balanced" pack. That is, each cell in a series/parallel pack must be equal to the other cells in voltage or you risk over-discharging the out of balance cells. When I say equal I mean exactly the same voltage.

Last fall I was flying a World Models P51 with a Hacker B50-10L in it. I must have over discharged the pack (I didn't have a controller with the correct low voltage cut off) because a few days later my 5s2p pack of Tanic cells was junk. That's $300.00 down the drain.

Lipos don't "fall off" like nicads or nimhs do. Unless you've got the proper low voltage cut off set in your esc then you'll ruin the pack if you over-discharge it - even slightly.

Another thing that Lipos don't like is water. I was flying a Twin Aventura (float plane) and I got some water in it. The pack got wet - a 3s2p pack of Tanics - brand new - 1st use. The aluminum tabs that come out of each cell corroded and I assume shorted out. The pack "puffed" and it too was junk. That was $120.00 down the drain.

Another thing - LiPos are extremely dangerous. I had a "puffed" pack sitting outside for the better part of a 6 month Minnesota winter.

I decided to pop the cell that was puffed with a very long stick. That pack burst into flames and essentially melted itself into a puddle of...stuff. All that energy still in that pack after all those months and in sub zero whether at times.

More than a few stories exist where people have lost their cars or houses after a LiPo melted down. I store all of mine in metal ammo boxes.

I love LiPos but I'm not sure if they're ready for F/E.

 

[Paul Pachmayer]

Hey Guys,

The water getting on the packs is what gets me. I just heard a story of a 10S pack that got wet and the owner didn't catch it. That's a ton of coin to be loosing because of a little water. Maybe the answer is coating the tabs like an esc?

Paul.

 

[Jim Caldwell]

Dan, was that saltwater on the Lipos/

 

[jstevens]

From what I have read you need different chargers and better care for Lipolys.

Probably the best safety measure was a metal storage box, I think some guys were using surplus ammo boxes. In case a cell decided to granade, then at least, if you were traveling, the cell would not catch everything around it on fire.

Like everything else. It needs to be tested more, the technology gets better and soon enough we will wonder what we ever saw in NiMh.

 

[J Solinger]

Lipo's are a different animal but I belive they are manageable. However, I thought the water alergy thing was either fixed or was never an issue. Thats something we can't realy get around.

 

[RaceCraftBearings]

Doug, Joe , Paul..........

I used to run electric cars way back in the 80's and I now have a Electric tug for retreiveing stranded boats. My question is which SCR would you reccomend if I wanted more Speed/power out an ESC which is rated for 6 or 7 cell. I have some old 1200's that I dug out from the day and they live and perform ok but I think at least a 1500 would give me more what I am looking for or maybe the 1900 or 2400's? What do you think?

Thanks!

Ron

 

[J Solinger]

Ron, if you are looking for some nicads I've got a few packs of CP2400's. They should do well for tugging. I'll sell them for $15 a pack. They still have a lot of life left but I need to replace them with some gp3300's for racing.

 

[Dan Proulx]

Jim,

Nope - no saltwater. Just good old fashioned lake water.

Dan

 

[sjslhill]

Dan,

So your saying that if LiPols just get wet and that's it? Or do they have to sit in the water for a bit? Thanks for the info.....

Steve

Jim,
Nope - no saltwater.  Just good old fashioned lake water.

Dan

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[Dan Proulx]

Steve,

After retrieving the float plane that had gotten water in it I took the pack out immediately - but, did not cut the shrink wrap off of it to insure that there wasn't any moisture trapped inside. Apparently there was.

It took about a 3 days of the pack sitting on my bench before it "puffed".

It's completely my fault for not tearing the pack apart but, who knew?

Maybe a different method of building the packs for boating/float plane flying would eliminate this problem.

Dan

 

[sjslhill]

Oh yes...the water bridged the gap and shorted the cell. You must dry them off.

Thanks for the input

Steve

Steve,
After retrieving the float plane that had gotten water in it I took the pack out immediately - but, did not cut the shrink wrap off of it to insure that there wasn't any moisture trapped inside.  Apparently there was.

It took about a 3 days of the pack sitting on my bench before it "puffed".

It's completely my fault for not tearing the pack apart but, who knew?

Maybe a different method of building the packs for boating/float plane flying would eliminate this problem.

Dan

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