LI-PO Charging Question

[bacala600]

I'm hoping the experts on this forum can clear up some issues I'm having, I am having a hard time understanding the maximum charge voltages on my LI-PO pack and others like it, I have a align 3s 11.1volt 2100mah pack please tell me what is the maximum voltage I should be charging each cell to I am assuming that each cell should not be charged to more than 3.7 volts per cell, but I was reading some threads saying that at 100% charge you should be at 4.2 volts per cell making the pack a 12.6 volt pack please clear this up for me, Also I currently own a Venom Power 2-5s Balancing Charger it has a output of 1.5 amps and will shut off when each cell balanced to 4.2 volts, their is no switches or knobs to change this output can I safley use this charger on my align packs I will be investing in a better charger soon like the estation bc6, or the cellpro 10s but till then I whould like to use this one, again please help me better understand this I am new to lipos and just don't want to make any mistakes. Thanks

[ChasHeliCop]

Max voltage is 4.2 v/cell When you run the pack or discharge do not go below 80% of the pack capacity.

[Mercuriell]

Yes standard charge of lipos is to 4.2V per cell so 12.6V for 3S - the working volatge of the cell is nominally 3.7V for a lipo. Discharge UNDER 3V per cell likely to wreck the pack. 80% discharge maximum recommended which works out to about 3.5V per cell.

Best to charge at no greater than 1C ie the packs capacity you could safely charge your 2100 pack at 1.5A which would take about 50 mins.

[bacala600]

THANKS guys for the replys, that helps clear up some uncertainties I have to LI-PO battery packs. As of right know the charger I will be using Venom Power doesn't have the means of measuring the voltage levels in each cell before or after using the pack so I can only guess:thumbdown: so for know I will keep my flight times on my Trex 450se v2 to about 5-6 min then recharge that should keep the cells above 3.5v

[Pinecone]

BTW that 3.5 volts per cell for 80% is UNDER LOAD. If your pack is 3.5 volts percell after youfly, and take the pack off and it srests a bit, you have probably gone too far.

I use a timer and a lipo alarm to make sure I don't overdischarge the packs. Efliernz here in HeliFreak (PM him) makes nice lipo alarms.

[bacala600]

Thanks for the advice Pinecone I will for sure be looking into a LIPO alarm.

[charlieh]

4.2V per cell is a safety limit suggest by most lipo and charger manufacturer. Some did push the limit to 4.22~4.23V per cell for extra performance without deterioration of battery life, but only work on good quality batteries. Also when charging up to 4.22V per cell, extra safety precaution like thermal cut-off is critical.

The discharge side is more prone to accidental damage of battery. It is better to have a flight plan, stick to the time and try not to discharge over 70%.

Most accident occur during charging is not simply over charge the cell, it's the run away escalation of temperature. IMO a temperature cut-off function is a must.