LiPo Sack Question

[bigwaveohs]

Does the Velcro burn so snaps are better?

"Just so you know.. we have found HUGE advantages to snaps over Velcro when it comes to lipo sacks."
Grim

[DPeterson]

Save your money - skip this lipo sack crap.

You guy's that are using lipo sacks - How are you monitoring your cells during charge? Are you continually opening the sack and putting your face close to the opening to visually monitor? That would be the only method I can think of unless the lipo sacks are see through. Man O man!

We need some well thought out safe lipo handling and charging procedures spelled out and soon.

So far here is where I am at: Leave the cells in the boat - the boat offers at a minumum a containment vessel to hold the fire suppresent powder, will hold water if you so chose to throw water in it, and will work well under a fire retardent blanket. Furthermore the cells are not designed for repetitive handling - why are guy's tugging away on them constantly - damaged cells are the problem cells. The boat (containment vessel) also offers a means for which to handle or remove the cells from the area that may effect other equipment or people.

All pit areas must be supplied with Fire extinguishers of the sufficient size and type, and or buckets of sand, and or fire retardent blankets, and or buckets of water for the brave ones.

Damaged cells for any reason must be removed from the area and contained in a fire proof vessel for disposal later.

All charger cables must be covered all the way to the tip with non-conductive material - no open charge cable ends allowed.

All charging will require balancing features and must be utilized.

No unattended charging. Not sure how this works at a race. We all have to pit for racers.

Fire away - no pun intended.

Doug

[bigwaveohs]

Interesting...the very first rule in the recent AMA Alert (http://www.towerhobbies.com/help/ama_lipo/index.html) regarding charging guidelines for LiPos says:

1. Store, and charge, in a fireproof container; never in your model.

And please, no railing on the messenger...I'm just posting what the AMA is recommending...

BTW, The only type of Fire Extinguisher that will work on LiPo Fires is the new Class D (Yellow) Extinguisher. The problem is they are vary expensive. They average around $400.00 each.

You can use an ABC class to keep the fire from spreading but they won't have any effect on the LiPo fire.

[DPeterson]

I am aware but remain in disagreement. IMO - this fire proof containment requirement comes for the manufacturer for liability reasons. It does not justify that this is the safest procedure.

AMA as well as other organizations contradict themselves. They suggest to charge in a fire proof container and then say you must also monitor the cells. I find it difficult to do both in a safe manner.

[LuckyDuc]

Most boat hulls are made of the same material as the lipo sacks. Fiberglass cloth. I don't see why charging the packs in the boat is any more dangerous than charging outside in a sack. It is easier to grab a boat with a burning lipo in it than a burning lipo sack(In the event that the fire needs to be moved)

I'll post a pic of a damaged lipo wire that resulted from the constant removal and insertion for charging purposes.

[Grimracer]

Doug,

Our chargers are fully capable of monitoring the pack/s. Why would one need to open the sack during charging?
Regardless of safety, I really don’t see any "REAL" reason to lose a boat to fire when it CAN be avoided.
We store, transfer, carry, use WAY more lipos then all of the members on OSE combined and a fire be it in the plane, heli, boat or whatever is never taken lightly.
Besides the bad things that lipos are capable of come as no surprise when we are “using them” its when we are not using them that “things” come as a surprise.

Everybody.. just use your head and be safe!

Grim

[bigwaveohs]

My boat costs a lot more than my LiPo sack...and all I really wanted to know was why Grim preferred snaps to Velcro.

[LuckyDuc]

My boat costs a lot more than my LiPo sack...

The point that Doug is trying to make with charging in the boat is that the lipos get damaged as a result of constantly taking them in and out of the boat to charge. I have to pull on the leads in some of my hulls to remove the packs. This damages the pack over time.

[DPeterson]

My charger doesn't detect lipo temperature, lipo puffing or a potential wire short. Time for an updated charger. :)

[Doug Smock]

FOLLOW THE MANUFACTURES RECOMMENDATIONS!!!!!!!!!!!!!!!!!!!!!!
I'll leave the "charging in the boat" alone, FOR NOW.

Doug

[T.S.Davis]

Does anyone know what the AMA's requirement is based on? Doug's point is valid too. Isn't it when we assume all our equipment is working flawlessly that accidents happen? If your charger wigs out and your cells are inside a fire "proof" container you don't know they've gone all blood sausage until they burst.

I have to make a special tool to get the cells out of some of my boats. Think shoe horn. It's a nightmare. It will wreck the cells if I do it multiple times. Basically I'm scraping a flat edge across the bottom surface of the cells. Not all my boats are like that though. If the cells come out without too much trouble I pull them.

I understand not wanting to lose a boat. Maybe the AMA figures you would be charging inside a plane with a 7' wing span and you can't relocate it easily. Boats are a little different IMO.

If taking the cells out of my boat in my opinion (who better I built it) is going to damage my cells I can't see following the recommendation. Damaged cells because I followed the recommended practice?

The bag is for containment. They're not a waist of time. Just not sure they're THE answer like some think they are. I wonder how they hold up to a 10s pack. I like that fire blanket idea. Just in case sort of thing. Remove a burn (somehow?) and toss the blanket over it.

Mike, what do you think made the snaps better? Think I missed it. Stay closed better?

Doug, I need your email address. PM or whatever.

[DPeterson]

Very sorry for highjack bigwaveohs.

I have a back ground in risk management and loss control and am really struggling with so called safety rules that are a little more than a feel good procedure.

I hope you get your original question answered and maybe on the side we can hash out some safe procedures that are actually intended for their purpose.

Terry - I PM'd my e-mail to you.

Doug

[Grimracer]

we did a bunch of testing.. i wish I could find the videos..

Anyway.. with snaps one has a tendency to lay the bag with the snaps up. when and if a fire happens the flames shoot out over the top of the bag and not the sides (like a Velcro one).

We tested this with a large cardboard section under the bag.. when using a velcro sack the cardboard started on fire.. with snaps it did not..

We also found that the snaps did not lit go even in high heat or under large pressures. I have seen a 4S 4200 go up and the pressure of/from the fire is DAM SCARY! (like a blow torch).. nukes whatevers in the flames path.

We had a 300mah pack go up one time.. WOW.. that little sucker was NASTY doing its thing.. We quick closed the ammo box it was in and it sealed the box so hard (vacuum) we could not get it back open..

Anyway.. I will state again.. use your head and just be safe..

BTY.. I have a buddy that put chimney liners on their side and against a block wall in his basement.. Based on what I have seen this is about as good a system as you can get for "in house" charging and storage.


Grim

[Doug Smock]

Sorry for the hijack also.
Lots of good reading here so you guys know what you'll be exposing your friends and family to when your boats burn.

http://www.plasticmaterials.net/msds/msds_plastic_materials.html

As if the burning LiPos aren't bad enough!
So much for feel good.

Doug

[Doug Smock]

we did a bunch of testing.. i wish I could find the videos..

Anyway.. with snaps one has a tendency to lay the bag with the snaps up. when and if a fire happens the flames shoot out over the top of the bag and not the sides (like a Velcro one).

We tested this with a large cardboard section under the bag.. when using a velcro sack the cardboard started on fire.. with snaps it did not..

We also found that the snaps did not lit go even in high heat or under large pressures. I have seen a 4S 4200 go up and the pressure of/from the fire is DAM SCARY! (like a blow torch).. nukes whatevers in the flames path.

We had a 300mah pack go up one time.. WOW.. that little sucker was NASTY doing its thing.. We quick closed the ammo box it was in and it sealed the box so hard (vacuum) we could not get it back open..

Anyway.. I will state again.. use your head and just be safe..

BTY.. I have a buddy that put chimney liners on their side and against a block wall in his basement.. Based on what I have seen this is about as good a system as you can get for "in house" charging and storage.


Grim

Mike,
Post us up a MSDS sheet on your LiPo sack please sir.
Have a great weekend fellas!
Thanks,
Doug