Just curious how voltage effects charging.

For instance, can you fully charge a 1000 mah 8.4V battery at 4V, or does the charging voltage have to be higher than the voltage of the pack?

Thanks.

NiCd and NiMh packs are current sinks. Simplistically you control the rate of charge thru current however the voltage must be higher than the pack. Remember you can't have current without voltage they are not separate entities. Voltage = Current times Resistance or Ohms law -> E = I X R

Lead Acid and LPo are voltage dependant. It all depends upon the chemistry of the pack.

John

And this was kind of what I was wondering, why is this so. Is there an easy way to explain it?

Hi, Norton. I remember someone stating that the voltage is just along for the ride, I thought it was good.

Time Pilot,
Batteries are electro chemical devices with different characteristics. About the same analogy can be drawn between bipolar transistors and FET devices. With one it's easier to supply current with the other voltage. You are not going to get a simple explanation as to why beyond that without getting text books and having a chemical background. For some idea take a look at.
http://www.sciam.com/askexpert_quest...B7809EC588F2D7

U-Dud,
Yah it's along for the ride as long as its higher than what you are attempting to charge.

John

It’s the voltage that gives the potential but the current supplies the power. Another way to say it without voltage there is no need for current. So if voltage below threshold of battery the battery will not ask for current needed to charge it.

BTW welcome back John

Rich