A Question on charging

[Clive Moore]

I have just purchased a new charger, its a JP EnErG pro LIPROPLUS 8.

It has two screens that I don't understand.

They are titled:

NIMH sensitivity D. Peak  And NiCd Sensitivity D. Peak they are set to 12mV for NiCd and 7mV for NiMh.

I can change the values up and down from these default settings.

Does anyone know what its for and how I should set it?

I'm having a problem with a new 5000Mah 1.2v cell that I'm charging. When I charge it the charger says that  it has charged to 5500mah (which is an auto cut off level to prevent over charging) when I discharge the cell it only says that it has discharged 3676mah.

Are the above settings causing this or have I got a duff cell or should I turn off the 5500 limit and let the charger keep going?

 Any ideas?

[Piper Cub]

The D Peak (delta Peak) is really just like sensitivity of the cut off charging point for the batteries. Think of it like a room temperature thermostat, the setting of the thermostat determines how long the heating is on before its switched off.

In RC car circles, most racers advise for Nimh, you want a delta peak setting of around 20mv and about 5 mv for nicads. Im not certain what delta peak is best for Lipos. Timbo!?

As regards discharging cells, most charger \ dischargers dont give a full discharg. To discharge nimh \ nicads, you're best investing in a discharger tray to get each cell equally to a cut off voltage of 1.1v. Bear in mind these trays generally only do 6 cell packs so if your flight pack has more than 6 cells, these wont be suitable.

[Tim Mackey]

Many people reckon around 12mv for NiCad, and half of that for NiMh...so your chargers default settings are fine. Remember also that for delta peak detection to work correctly, the charge rate needs to be fairly high so that the voltage rises reasonably quickly and gives the charger a chance to actually detect the fall off.

LiPOos dont work on a delta peak principle, most LIpo chargers simply charge and monitor the pack / cell voltage until it reaches the preset normal figure of 4.2V per cell. The charger then usually goes into a sort of "rest mode" and continnues to monitor the cell voltage. If the cell is able to hold the 4.2V for a reasonable time, charge is terminated, if it falls off almost immediately, then it "pulses" a bit more juice in to the battery until it is happy that it is "full"

So called fast charge programs in some lipo chargers merely work by terminating the charge before the 4.2V is reached, as anything much above 4.17 or so is considered pretty well full.

[Clive Moore]

Thanks guys. (I will get to understand this electrickery thing one day!)

[Tim Mackey]

Well when you do, please let us all know