When an Orion smart dc-dc charger, isolated is used to charge a low impedance battery does the INPUT current get limited to match the power capacity of the charger?
I have a fuse limited supply, (20A at 12V), and would not like to blow fuses on this line. Is it safe to use a 120W charger, (nominal 10A draw), on this supply or will it overload when charging a near flat battery?
The smallest isolated charger you can get is the 12-12 18A. That is capable of 25A on the output. You really need a 50A circuit, 40A at least on the input. You can look at the non-isolated Orion XS. You are able to limit the charge current. I have the 12-12 18A and measure about 22-23A going in to get 18A out at 14.2V.
Owen,
Thanks for the information, always good to get real world verification of current flow.
I need the isolation unfortunately, (due to another appliance having a charge cycle using PWM on the negative leg).
I think I may look at an isolation DC-DC step up to say 19V and then using an MPPT controller, with charge control, to charge the battery. Two boxes instead of one, pity, but it might be the simplest, safe way of limiting the charge current and hence inflow current.
You’ll need more than 19 V going into the MPPT if your battery bank is 12 V. Most MPPTs need about 5 V above the battery’s charging voltage to start, so with a 12 V bank charging at 14–15 V, you really want at least 19–20 V under load. A boost set to 24–48 V will give you more headroom, which helps avoid issues if the voltage sags. I’ve run a 12-48 V isolated boost into an MPPT for a 36 V trolling motor battery, and it worked well, but I later went back to a straight 12 V setup. The main point is that if the boosted voltage is too close to the battery voltage, the MPPT may not start, or it’ll drop out.