Converter/Battery question

[Lonestar]

When connected to shore power does the converter supply the 12vdc to the trailer, or does the converter just charge the battery and the 12vdc is supplied from the battery? I'm assuming there must be some form of isolation between the converter and the battery. Sure wish I had a schematic of my electrical system.

[ncitro]

When connected to shore power does the converter supply the 12vdc to the trailer, or does the converter just charge the battery and the 12vdc is supplied from the battery? I'm assuming there must be some form of isolation between the converter and the battery. Sure wish I had a schematic of my electrical system.

No isolation. The converter is in parallel with the battery and the main DC bus. Technically (I hope I get this right) the loads in your system will be fed by whichever has the highest voltage, but in practice it works to picture it like everything runs off the converter as it will almost always be at the highest voltage.

[Lonestar]

OK. But if they are in parallel they would always both feed the trailer at the same time it seems, regardless of the voltage of either. There would have to be some form of isolation for just one to be the source.

But if no isolation, if the converter were to go belly up, would not the battery backfeed into the converter? That is, unless there is diode protection. Or, maybe it just doesn't make any difference. I've tried to find some info about this circuitry on the web but nothing has popped up.

Having had trailers for 40 years I just never thought about how the converter and battery interfaced.

[ncitro]

If I remember my physics right, voltage leads current, so it will flow from the highest voltage to the lowest. That means that unless your battery is at a higher voltage than the converter your loads should draw the converter down before they tap into the batteries. Anecdotally I can tell you in practice that’s the way it looks like it works. Also why if anyone suspects a bad converter the first thing you look at is the voltage.

[Country Campers]

In my RV the converter feeds the power panel and then travels to the battery. The converter is closer to the power panel than it is to the battery. The converter and battery work together to power the 12 vdc circuits. I have learned that even plugged into shore power that if the battery voltage is low the converter has a hard time powering slides and the jacks by itself. The battery needs to have a good charge and be in good shape to perform by itself and with the converter. There is no isolation between the battery and the converter other than the battery disconnect switch , depending on how it may be wired.

Brian

[TedS]

Current will not flow from battery to converter because of diodes in the converter. The fuses on the converter will blow if the battery is momentarily connected backwards. Since connected in parallel, the batery and converter will have the same votage. Current will flow to lower resistance whether its converter to battery or converter and battery to lights, motor, whatever.