MP3Car.com - View Single Post

BuNNy-RaBBiT · 11-07-2005, 12:55 PM

Quote: Originally Posted by Nicorolla

what's happening is when you connect the second battery there's a big surge of current going thru the battery with less potential (voltage). This could be dangerous. You need a isolator or you have to leave both batteries connected together at all times (before you do that, charge both batteries to their full capacity).

in details, the battery has a very low internal resistance, therefor if one battery has (for example) 12v and the other has 14, thats a diffrence of 2volts. and since current always travels to the path of least resistance, that 2 volts will flow thru the other battery. To give you an idea of how much current is going thru, say ur battery has an internal resistance of 0.1 ohms. That makes ur current 2 / 0.1 = 20 Amps. The bigger the diffrence and the lower the resistance, the higher your current surge will be.

Ok thanks that clears up.
I connected both fully charged battery`s, and put a diode between the two, now the second battery get`s charged but cant give power to the other battery so it will last longer.
The only draw is that the first battery gives power to the second one so it will eventualy be drawn emty

.

11-07-2005, 12:55 PM	#5
BuNNy-RaBBiT Newbie Join Date: Nov 2004 Posts: 20 My Photos: ()	Quote: Originally Posted by Nicorolla what's happening is when you connect the second battery there's a big surge of current going thru the battery with less potential (voltage). This could be dangerous. You need a isolator or you have to leave both batteries connected together at all times (before you do that, charge both batteries to their full capacity). in details, the battery has a very low internal resistance, therefor if one battery has (for example) 12v and the other has 14, thats a diffrence of 2volts. and since current always travels to the path of least resistance, that 2 volts will flow thru the other battery. To give you an idea of how much current is going thru, say ur battery has an internal resistance of 0.1 ohms. That makes ur current 2 / 0.1 = 20 Amps. The bigger the diffrence and the lower the resistance, the higher your current surge will be. Ok thanks that clears up. I connected both fully charged battery`s, and put a diode between the two, now the second battery get`s charged but cant give power to the other battery so it will last longer. The only draw is that the first battery gives power to the second one so it will eventualy be drawn emty .