[Max]

Originally Posted by cloudniner

. Just make sure one reads the instruction manuals and/or consult someone with knowledge of the dangers and what not to do.

Agreed!!!

PS- whenever I meet a new flier at our club that is just starting with electrics, I always caution him about safe charging. The first words out of my mouth is: "These batteries are safe if you are careful and charge them correctly. If you charge them incorrectly, YOU WILL BURN YOUR HOUSE DOWN!"

They usually pay attention after that.

[gixerfien]

Originally Posted by cloudniner

"I find this statement very hard to believe. Not that the fire didn't happen"

Max

I will send you the details via a PM. I don't want to go into details here. Just make sure one reads the instruction manuals and/or consult someone with knowledge of the dangers and what not to do.

Come on, share the story.

I know myself, I am very interested in knowing what happened and I'm sure others too.

Originally Posted by Max

Agreed!!!

PS- whenever I meet a new flier at our club that is just starting with electrics, I always caution him about safe charging. The first words out of my mouth is: "These batteries are safe if you are careful and charge them correctly. If you charge them incorrectly, YOU WILL BURN YOUR HOUSE DOWN!"

They usually pay attention after that.

Hey max, could you or anyone want to chime in on this aspect.

What about the temp probes that every single charger I've seen these days has. Most even come with the probes. I've always used mine when charging as a precautionary. I can see when guys are using parallel boards and have multiple batteries charging but even besides that fact, I NEVER see anyone using these at the field EVER and this really surprises me to be honest.

Was wondering if it's just too much trouble?, is it too late by the time it works?, or because you should always be watching them so it doesn't need it?

For me I just always assumed, it's there so why not use it.

[davidmc36]

Originally Posted by gixerfien

....
What about the temp probes that every single charger I've seen these days has......

The funny thing about the temp probes. The first charger I ever bought the temp probe was shaped in a semi-circle housing that was magnetic for attaching to the side of a NiXx battery. That was the only charge program that gave a warning about temp probe not connected when you initiated charge sequence.

LiPo are supposed to be Endothermic while charging.

[Max]

Originally Posted by gixerfien

Hey max, could you or anyone want to chime in on this aspect.

What about the temp probes that every single charger I've seen these days has. Most even come with the probes. I've always used mine when charging as a precautionary. I can see when guys are using parallel boards and have multiple batteries charging but even besides that fact, I NEVER see anyone using these at the field EVER and this really surprises me to be honest.

Was wondering if it's just too much trouble?, is it too late by the time it works?, or because you should always be watching them so it doesn't need it?

For me I just always assumed, it's there so why not use it.

Sure.
This is what I go over with my students:

Rule 1: USE A LIPO CHARGER

When lipos first came out, people were ignorant on their use. People would use Nicad and Nimh Chargers on Lipos. VERY BAD. This caused a lot of fires because the behavior of a Lipo as it charges is very different from the behavior of a NiCad or NiMh Battery. Result: NiCad/NimH chargers do not lower the current on the LiPo as the LiPo gets to fully charged, leading to a lpo fire.

Also, to answer your question about temperature sensor- Unless I am mistaken, this is only used for Nicad/NiMh batteries, as they tend to heat up as they reach their peak voltage. Lipos don't warm up at all if you charge them at 1C. (as you should be doing most of the time)

RULE 2: USE A SMART CHARGER:
A smart charger has better capability of detecting your battery's start voltage and knows when to stop better than the cheap-o lipo chargers that come with RTF RC planes. These either fail or malfunction. That leads to fires. I've read enough on various RC forums to make me fearful of them. When my brother bought his first RTF plane and came to my house to show it to me, I promptly smashed that piece of junk charger on the driveway as soon as I got my hands on it..LOL

RULE 3: CHARGE IN A SAFE PLACE:

• Charge on the concrete floor in your garage or basement
• Charge on a metal table
• Use an ammo can
• Use a cinder block
• Charge in a shed
  Etc.....

KEEP IT AWAY FROM COMBUSTABLES like wooden tables, plastic containers, etc.

Rule 4: USE THE BALANCER BOARD
The balancer board is what tells the smart charger the condition of each cell in your pack. If one cell is bad, a smart charger will know and shut down the charge process and warn you.
WHY THIS IS IMPORTANT:
Say you are charging a 3S pack. The end voltage is 12.6V (4.2V per cell, or 4.2+4.2+4.2).
The charger will keep charging until it sees 12.6V.
But what if one of the cells was low? If you aren't using a balance board, you could be in a situation where one cell was low. Lets say for this example, 3.0V. Now your charger starts pumping in the voltage to the pack and its looking for 12.6V. The 3.0v cell stays low, but the other cells start taking more voltage. Now you are in a situation were the charger has not reached 12.6V yet, but lets say its presently seeing 12.4V. It will keep pumping volts into the pack because its waiting to see 12.6V.
But what is really going on is:
The low cell is still at 3.0v, meaning if the charger is seeing 12.4V, the other 2 cells are 4.7V. This is well over the 4.2 limit, which means your battery ins now prone to bursting into flame at any time!!!!

So use the balancer board!!!

The balancer board allows your charger to work the safest when you charge your lipo in "balance" mode, but repeated balance charging tends to lower the life-span of the pack. For noobs, I tell them "ONLY BALANCE CHARGE"- its safer that way. Sure the pack doesn't last as long but for the price of a new pack, the increase in safety is a worthwhile trade off. Remember we are talking noobs here.

For more experienced users, you can charge your battery in "Charge" mode, and if you use the balance board, the smart charger still monitors the cell status so that it will warn you if anything is wrong with any of the cells.

RULE 5: CHARGE AT 1C WHEN POSSIBLE

The faster you charge your battery, the faster things can go from bad to worse to fire.
My rule is 1C for all charging when I have time; 2C is the most I will go if I am in a hurry.
I know of some packs that can charge at higher rates, but again, where I have read of experienced people having lipo fires, its when they are charging at high C.

RULE 6: STORE AND HANDLE THEM CAREFULLY
A fully charged pack that gets punctured will spontaneously burst into flame.
Keep batteries in a container that will prevent them from getting banged about during transit or handling.

RULE 7: DONT TRUST A DAMAGED BATTERY

If you crash or damage the battery during a flight or through handling (ie dropped onto concrete) treat it as a ticking bomb. Place it in a cinder block or ammo can on a concrete slab in your back yard and leave it for 24 hrs. Inspect it carefully after 24 hrs and check the voltage. Sniff it. If it smells like nail polish, you have a punctured pack. Treat it with care and dispose of it as recommended (Discharge to 0 with an automotive light bulb, short leads, send it to recyclers)
IF so far the pack checks out after 24 hrs, dont let your guard down. Charge it with extra care and remain vigilant with it until you have put several flights on it. Only then can you assume to treat it like any other regular battery.

RULE 8: DONT LEAVE THE ROOM WHERE YOU ARE CHARGING IT (unless its outside)
Keep an eye on your batteries that are charging. You should never leave them unattended. Have a plan to handle a lipo fire.
Ask yourself: what will I do if this battery suddenly burst into flame?

• Can I get it outside?
• Can I toss it into a big metal pot to contain it?
• Will it safely burn itself out in my Ammo can (or cinder block).

Have a plan and have the means to deal with a lipo fire "just in case"



Phew! Well, that is what I usually cover with a new student. If I missed anything, please chime in and I will add to my list. Might be worth circulating in our next club's newsletter

[wilf]

when I first entered the hobby with a HZ supercub I had the crappie over priced HZ batteries that come with the cub. one of the puffed quite a bit. not sure why. So I thought I should slice the case on the battery to let the pressure out as they are a very poor fit in the cub to start with. So I took a utility knife and sliced the case open. really never let any pressure out and stayed puffed so I taped it back up and used it till it craped out.
Bought some hobby king batteries still did not fit the cub well but I still use them and they are going strong. Blew one up when I hooked the leads from the esc to the battery backwards. Pluged the battery into the esc and it made no noise and the lights did not blink. I thought this strange. Switched on the tx and the battery went pop.
Wilf