PD or Iota for my upgrade?
I'm thinking about a converter and battery upgrade. The batteries will be wet cell lead acid 6 volt Possible T-105s or the 230AH, EGC2 from Sam's club. I'll probably go for four. (Does nayone have...
Forum Discussion
You're right, the converter knows it must increase voltage to get 60A out. Those who took measurements of their PD have recorded max output voltage of around 14.1 to 14.2V during the initial stages of charging. The converter never gets to its rated current. Why?
We both agree the PD should be raising its output voltage further, but it doesn't. The failure of the PD to increase voltage results in reduced, or sub-par output current.
I, and others have measured battery resistance. It's in the neighborhood of 10 to 20 m ohm. The converter load (battery) has 10 times less impedance than the resistive load Wayne used.
Why can the PD output 60A at 14.4V with a 240 m ohm resistive load but falls short when charging a battery that has 10 m ohm resistance? What's the difference between the two scenarios?
Sal
We both agree the PD should be raising its output voltage further, but it doesn't. The failure of the PD to increase voltage results in reduced, or sub-par output current.
I, and others have measured battery resistance. It's in the neighborhood of 10 to 20 m ohm. The converter load (battery) has 10 times less impedance than the resistive load Wayne used.
Why can the PD output 60A at 14.4V with a 240 m ohm resistive load but falls short when charging a battery that has 10 m ohm resistance? What's the difference between the two scenarios?
Sal
DryCamper11 wrote:Lets do some load resistance calculations.
To drive a 60A PD with a resistive load, it take:
R = 14.4V / 60A = 240 m ohm
When driving the same converter with a battery that's at 12.2V, it takes:
R = Vconv - Vbat / 60 = 14.4 - 12.2 / 60 = 37 m ohm
The PD can't deal with the 37 m ohm load.
The second is the model resistance when modeling a real world battery as a perfect voltage source and a .037 ohm model resistor. But from the point of view of a DC output voltage charger, it never sees that 37 m ohm model resistance. All it knows is that it has to increase the output to 14.4 volts before 60 amps will flow.
