"A capacitor is not a capacitor"
Different microfarads of capacitance react to different frequencies, differently.
A battery more or less is equal to two farads of capacitance. But a battery is indifferent to much of the developed ripple in chargers, alternators, etc. Even INVERTERS send ripple back through the battery feed wires. Use your oscilloscope and confirm this.
A ten thousand microfarad capacitor is the right size for the right job in the right place when placed inline with a single output secondary (low voltage) line. It suppresses ripple from an alternator to the point where the "magnitude" of the waveform is insignificant. Sometime when you aren't busy connect an oscilloscope to your charger or to your power supply output. Then enable AC power to the charger. What do you see? Every damned transistor and integrated circuit that is not switched mechanically "off" sees the same thing.
I'll harp about this again but in a different manner. Devices in an RV have a shorter lifespan than they do on AC power at home. I'm talking about devices with solid state components. Think about this. Why? It's because of inadvertent electronic noise, but more than noise - outright assault by transient voltages. It isn't just the converter that causes transients, it's the chassis alternator, AIR CONDITIONER MAGNETIC CLUTCH, the engine starter motor, and generator starter motor.
If you have no heart issues, stick your finger on the starter motor side of a solenoid, crank the engine then release the key. After you pick yourself up off the floor, switch to the engine air conditioning magnetic clutch and repeat the exercise. These transients indeed "get to" refrigerator solid state components, 12 volt electronics and even inverter internals. The effect isn't instant, it's water dripping on the forehead torture. The greater the amplitude, the larger the area under curve of the ripple the more harmful the effects. I have measured 300+ volts DC from an air conditioner clutch. Use a scope and have your jaw drop to the floor when you see the effect of what a starter motor does to DC power.
I cured Dometic and Norcold board failures, around 80% of them using transient voltage suppression. I clamped hot to neutral with a 180 volt bi-directional device. Where? At the AC heater element voltage supply.
OEM does not address this issue. Why? Because OEM could care less. They do not attach oscilloscopes, they do not monitor entire systems and I can can well guarantee you they are not going to do a thing to extend the lifespan of their devices well beyond the point of warranty.
I cut my teeth on this subject, curing problems with Raytheon and Furuno radar and color sonar electronics aboard commercial fishing vessels. Owners of million dollar vessels do not give a damn WHY their trips have to be aborted, they want the root cause stopped, cold and dead in it's tracks.
The suppression technique using capacitors is not theory. It has been proven so many times it is a joke. When a vessel went from 10K electronic repairs to a hundred dollars over a several year period, and was repeated, vessel after a few dozen vessels, the chance of the capacitor technique being a fluke is reduced to near zero.
Adding a capacitor to a system that already has had its electronic components tortured for years does not guarantee the tortured component will not fail an hour after the capacitor is connected.
To me a 200 mv ripple level is ridiculous. I attached a cap to the new to me WFCO and I cannot detect ripple now.
By the way, take some time and find out CONCORDE BATTERY'S philosophy on ripple. They do not mince words.
Ripple belongs in a trout stream or on the shelf of a wino liquor store. Not in a battery system.
