Lipo Facts

[SouthJersey-FE]

I figured A thread on this subject would be a good idea. We all know what the voltages are and what mah equal. But there are now what...3 diffrent types of lipo packs? Can the the aircraft cells be used in boating? What about the Team Orion car cells? I have seen a single 6000mah pack. Will that make running 2 packs a thing of the past? I'm sure there are lots of issues that need to be adressed.

[BoatDoc]

there's been lots of talk, lots of confusion, and lots of learning going on when it comes to lipo. they have many advantages, and a few shortcomings as well. the cells are physically more fragile than a nimh pack. but, they are lighter and have higher voltage. they also have a higher initial cost than a nimh pack. word on the street is that they will last about 10x longer than nimh (or more). the rules to allow them are still being worked out. there are some who want "open" cells or boats within voltage classes, and other's (me included) who want certain limitions in place. we'll see how it comes out in the end. from what i've learned, here's what i can offer:

use 20C packs (that means they can be discharged at 20X their rated capacity...a 5000mah pack can go 100amps for example), you can use a lower C rating, but you'll want to make sure you don't over draw the pack

use high grade, high current wire and connectors (5.5 mm bullets, and 12ga wire are considered minimum)

WATERPROOF YOUR BOAT

a good rule of thumb is the 70% rule, don't draw more than 70 percent of the battery's rating, and don't use more than 70% of the capacity

use a balancer when charging

use a good charger (hyperion is a brand that has been recommended to me)

last thing...i'm not running lipo's at the moment. i'm in "fact finding" mode, just trying to learn what i'll need to do to make the switch. the above are some general rules that have been shared to me.

for cells, check out cheapbatterypacks.com

[Kirker]

The biggest thing: Lipos WILL explode if overcharged! Smoke, flames, shrapnell, the whole nine yards! Go to youtube.com you can find videos of "ya-hoo's" blowing them up on purpose. Lipos WILL EXPLODE! Make sure you know what you're doing!

:eek:

[SouthJersey-FE]

Most informative. I have a duratrax ice charger. It is rated to charge lipos. I would have to buy a balancer. I personaly would like one more season of nihm. That would @ least give prices time to drop. Not to mention let the technoligy develop and be better adapted to our sport.

[BoatDoc]

these new cells are getting safer and safer. some guys tried to pop a pack a while back, and believe me...it took effort to do it! that doesn't mean that you shouldn't be safe and follow the mfg's guidlines, it just means that they are safer than the older cells.

[TSDavis]

"Lipos WILL EXPLODE". Can we agree instead that LiPo CAN explode?

Those youtube clips give no parameters. Which cells were they? How many amps were they crushing into them? Were they puffed before they were overcharged? Were they new cells? Had they ever been discharged below 3 volts per cell? Were they ever in an impact? How long did they stand there and watch them puff up? Was that in 2 minutes or 2 ours? What type of charger?

The newer cells are built so much better than the old ones. To overcharge a 20c rated 3700 pack you would need to charge at 7.4amps + on a non peaking charger or just the wrong charger all together. The pack boatdock was refering to was a newer generation 20c pack charged at 12 amps and it took forever to pop the cells. Now if they were damaged it may have been different.

Yep, ingnorance will get you hurt. I've seen NiMh burst under huge amp draw. Seen them sizzle at 8 amps on a chargers too. Unattended charging. Ignorance can be expensive. NiMh combined with brushed motors can cause your hull to explode. Very rare but I've seen it. Anybody up for a nice speedo blaze? On the water? Been there done that. Burned some up on the bench. Got smarter. So did the makers.

Nitro and gas burn. Can even explode under the right circumstances. So you take precautions to be safe. If we treat LiPo as a volatile fuel we should be okay. The difference being that we've all been exposed to volatile liquids our whole life. We're conditioned. Gas burns! duh! I guess that's kind of obvious. The tendancy is for folks to think "batteries er' batteries" Not so. Manufacturers and retailers have learned more about the technology and are doing a better job of educating the customers now.

Plus, when that video was filmed the "LiPosack" was not even available. The sack works great. I even store my LiPo right in the sack. Cheap bit of safety.

T.S.Davis
NAMBA FE Chairman

[BoatDoc]

at the Sardine Classic back in july...all the "pops" and "poofs" belonged to Nimh cells and one very unfortunate ESC. as my assistant and i were pulling up along side a boat to recover it after a heat, the hatch suddenly burst off, flames and all! turned out to be the speed controller :eek: i know of 3 nimh packs that popped during the event...one of them went in the middle of a heat and cost my buddy the win in N2 hydro. another went due to a charging issue, and a third also popped, but i don't remember how/why.