The LiPo charger is getting very hot, however, the battery is cool. There is also a high pitched whine coming from the charger. What should I do?

Some details that may be required to make a fair assesment of the situation:

1.) What charger is this? (mocroprosessor controlled 5amps 50Watts (like turnigy or something?))
2.) What is the input voltage to the charger?
3.) What is the input current to the charger?
4.) What is the power supply to the charger being used?
5.) What is the capacity of the battery being charged?
6.) What is the number of cells in the battery?
7.) And finally, at what rate are you charging the batteries (incase you can configure the charging current)

Usually, the most common reason for charger gettin HOT is due to excessive draw of current. (while charging) and dissipation of heat during discharge process across the transistors. (or mosfets)

Saurabh thanks for trying to help. Just give me a missed call/sms on 098640 33027 and I will call you back.

Thanks again.

VC

Check if the whiny sound is coming from the Fan. If not, MOSFET/Coil in some DC-DC converter circuit would be making the sound (which might be evident from the extra heat as well). Please dont try many battery as they might get spoiled if the charger supplies high voltage to the LiPo cells.

Things seem to be OK now. Thanks Ujjwaana!

What changed ?

Really don't know. The only difference was that the charger was earlier connected to a 15 Amp Power socket when it started getting waaaaay too hot. I unplugged it, let it cool down and then reconnected it to an extension cord that was connected to a 5 Amp Power socket. 2 Hours down and both the LiPo's are on full charge now. No problems. I feel there may be some with the 15 Amp wall socket. Any ideas?

I see RED... please be really careful for a couple of up  coming charges. Keep the Lipo in the Lipo safe sack and never leave it unattended. These 'erratic'/Random issues are more dangerous than a permanent failure.

Mild spark at  the Plug may result in the whinny sound, but not heat. Please check the connectors/balance plug on the battery side instead.

Just wondering how this causes problems? Probably too many motors running on this line ? 

  lipo during charging must not leave unattended
do this means that we watch the lipo till it fully charged and turnoff
suddently when fully charged.

what the main reason
does the best chargers have charging cutoff feature when lipos
are fully charged.