Recharging LiPos in a refrigerator

[vulture27]

It doesn't sound totally crazy but, I have a small dorm frig in my basement. I was thinking about using it as a safe haven to recharge. It might help limit the damage in case of fire or explosion. Also would it be advantageous to cool the battery during recharge?

:hug:

Let's hear from some of those who are not electron challenged.

[R1R 7humbs]

I don't know if condensation would be much of a problem. Also, I've heard that Lipos actually cool down while charging.

I don't want to take the thread off topic... but I want to mention that a few engineers mentioned that you can use a microwave to charge a battery (they do it). They were referring to cell phone batteries but I'm not going to try it.... apparently it charges them in 10 - 15 minutes. :bomb:

[nitrohog]

I have had no issues in several years and thousands of charge cycles with fires or even heating up. Why not just use a lipo sack or some sort of ammo box?

[jaywhy]

Because using a fridge is hard-core! ;)

[vulture27]

Besides...it makes my microbrews taste better! LiPo Beer. MmmmMmmm!

[helisforfun]

It doesn't sound totally crazy but, I have a small dorm frig in my basement. I was thinking about using it as a safe haven to recharge. It might help limit the damage in case of fire or explosion. Also would it be advantageous to cool the battery during recharge?

:hug:

Let's hear from some of those who are not electron challenged.
Probably not a good idea as lipos are effected by temperature they will take on and hold more power when charged in the cold fridge but once you remove it from the fridge and get to room temp it could enter an overcharged state and puff or burn etc. It is more ideal to charge and discharge at close to the same temperature.

[Bigglesworth]

-------------- Also, I've heard that Lipos actually cool down while charging.---------

Not the experience I've had.
I embedded an LM35 temp sensor into a pack I made up.(22V 4.4Ah - 6s 2p)
After an 80% flight and a short walk back to the office (3 min), my pack was 55 deg C and cooling.
When it was down to 25 deg C (room temp) I charged it with my Thunder power setup @ 3Amps and watched the temp slowly rise to 30 deg C. When the current started to drop back down so did the temp.

The sensor was in the center of a wrapped pack, on the outside I couldn't feel any temp rise.

Just some info I had, See you in the air.
Phil

[Ginvent]

if you charge a cold lipo to the 4.2 volts per cell you could damage the lipo. The FMA cellpro has a feature that if your charging in the cold the charger will only charge to 4.18volts per cell.

charge in the fridge is a BAD idea.

storage in the fridge however the jury is still out on

[blueviewlaguna]

if you charge a cold lipo to the 4.2 volts per cell you could damage the lipo. The FMA cellpro has a feature that if your charging in the cold the charger will only charge to 4.18volts per cell.

charge in the fridge is a BAD idea.

storage in the fridge however the jury is still out on
FMA advises that you can store lipo's 90% charged and under in the fridge.

[wlfk]

They're right - this is a b-a-d idea and could cause a LiPo fire, rather than preventing or containing one.

Secondly, LiPos don't explode. They flare quite spectacularly, and fairly briefly, but they don't go 'bang' - except perhaps initially when the covering is breached. Have a look at LiPo fires on youtube.

If you're concerned about LiPo fires - and it's very reasonable to be - then you could charge them in a lipo bag, or a pyrex bowl, or in the middle of a concrete floor. Another thing about a fridge is that the insulation might actually be flammable, so you might be causing additional problems.

K

[Pinecone]

The problem is, the lipo bag (the actual cell) doesn't explode, but if you contain it, then the outer container CAN explode.

Ammo cans are a BAD idea. There is a thread on RCG wehere guys had an ammo can explode, with though it had a 3 inch vent hole. They were delirately overcharging (for testing purposes) a 6S 4500 pack or so.

[thedrill]

Its between 40 and 50degrees in my garage! should I be bringing my lipos in the house to charge ? Is that too cold?

[Azathoth]

I have fully charged a few outside the fridge at room temp and then put them in a fridge. I thought this was great as it gets really hot here and I may not fly them for a week, so I thought the lower temp would slow discharging and overall degradation of the pack (which also happens quicker due to the fully charged state and heat).

However I was then told that the maximum safe voltage lowers with temperature. So putting them in the fridge suddenly means they become overcharged and damaged. My thoughts however is that the voltage drops with temperature as well preventing the overcharged state? Any thoughts?

It's cool in the fridge. :cool:

[Ginvent]

I have fully charged a few outside the fridge at room temp and then put them in a fridge. I thought this was great as it gets really hot here and I may not fly them for a week, so I thought the lower temp would slow discharging and overall degradation of the pack (which also happens quicker due to the fully charged state and heat).

However I was then told that the maximum safe voltage lowers with temperature. So putting them in the fridge suddenly means they become overcharged and damaged. My thoughts however is that the voltage drops with temperature as well preventing the overcharged state? Any thoughts?

It's cool in the fridge. :cool:

Chargeing a pack at room temp to a full charge then sticking them in a fridge is BAD the max you want a cold cell is 4.18volts. Haveing them at 4.2volts will cause more damage then god for your cells your better of leaving them in room temp.

With the Cellpro 4S if your chargeing in the same envirmonet as your flying FMA has a temp sensor that tell the charger to only charge to 4.18 volts per cell. BUT your lipos being cold will drop voltage faster under load and not supply the current the should wicth would translate to you being more likely to overcurrent your pack and damage it.

It is good practice to charge at room temps (anything above 65 degrees). And to try you best to keep the cells warm untill takeoff. The discharging of the pack should keep their temps up. When storing lipos store them about 50% charged and at room temp or in the fridge, never chill fully charged lipos, never charge a cold lipo