Hello, I am trying to setup an unusual battery charging system for my RV.
I have a DC/DC battery charger connected to the alternator of my vehicle. The charger takes nominal 12v dc in and then controls its boosted output to provide “two stage” charging. The charger adjusts the output voltage to ensure that it will not draw more than 30 amps on the input (this is stage one), then as the battery charges and the current draw goes down it will limit the output voltage to approx. 13.4v (this is stage two).
I would like to have this charger feed into a Xantrex C60 PWM charge controller which then feeds the battery. The reason is that the batteries never really get fully charged if the max output voltage of the DC/DC charger is set to basically a float voltage, also it takes a very long time to complete the charge since the voltage is relatively low. My intention is to bump up the output voltage of the DC/DC charge controller to say 16v and then let the C60 PWM controller ensure that the batteries are fully charged without overcharging them.
I have confirmed with the manufacturers that the C60 is fine with virtually any DC source up to 60 amps, and the DC/DC charger can be set to output up to 17v.
I have bench tested this setup and it works reasonably well except when the battery gets near the end of its charge and the current get less than about five amps. At this point the DC/DC converter starts to buzz due to the PWM of the C60. Once the C60 decides that charging is complete it shifts to “float” mode where the voltage is kept around 13.2 volts and the current can be as little as 50ma. At this point the output voltage of the DC/DC charger starts to swing wildly and buzzes quite loudly.
I need a filter between the DC/DC charger and the C60 PWM charge controller to smooth out the PWM. I have placed a 4700 uF 25v capacitor across the inputs of the C60 and this reduced the buzzing somewhat as well as fully stabilized the voltage at all currents. I also tried up to six of these capacitors in parallel, but performance was exactly the same. This is an OK solution but I’m wondering if using an inductor as well might make a better filter. I really don’t know much about filter design. I don’t have a scope so I don’t know what frequency the PWM is operating at.
It’s a strange setup I know, but any assistance would be appreciated.
I have a DC/DC battery charger connected to the alternator of my vehicle. The charger takes nominal 12v dc in and then controls its boosted output to provide “two stage” charging. The charger adjusts the output voltage to ensure that it will not draw more than 30 amps on the input (this is stage one), then as the battery charges and the current draw goes down it will limit the output voltage to approx. 13.4v (this is stage two).
I would like to have this charger feed into a Xantrex C60 PWM charge controller which then feeds the battery. The reason is that the batteries never really get fully charged if the max output voltage of the DC/DC charger is set to basically a float voltage, also it takes a very long time to complete the charge since the voltage is relatively low. My intention is to bump up the output voltage of the DC/DC charge controller to say 16v and then let the C60 PWM controller ensure that the batteries are fully charged without overcharging them.
I have confirmed with the manufacturers that the C60 is fine with virtually any DC source up to 60 amps, and the DC/DC charger can be set to output up to 17v.
I have bench tested this setup and it works reasonably well except when the battery gets near the end of its charge and the current get less than about five amps. At this point the DC/DC converter starts to buzz due to the PWM of the C60. Once the C60 decides that charging is complete it shifts to “float” mode where the voltage is kept around 13.2 volts and the current can be as little as 50ma. At this point the output voltage of the DC/DC charger starts to swing wildly and buzzes quite loudly.
I need a filter between the DC/DC charger and the C60 PWM charge controller to smooth out the PWM. I have placed a 4700 uF 25v capacitor across the inputs of the C60 and this reduced the buzzing somewhat as well as fully stabilized the voltage at all currents. I also tried up to six of these capacitors in parallel, but performance was exactly the same. This is an OK solution but I’m wondering if using an inductor as well might make a better filter. I really don’t know much about filter design. I don’t have a scope so I don’t know what frequency the PWM is operating at.
It’s a strange setup I know, but any assistance would be appreciated.