Quote Originally Posted by LeighW View Post

You have left a lot out about how DCDC really work, your DCDC charger does not charge at your 14.7V constantly, depending on the SOC of the battery it will start charging at a low value maybe 13V for example ie its current limiting stage, the voltage will gradually increase as the battery charges to maintain a constant 20A in the case of a 20A till it reaches its maximum charge voltage, ie 14.4V@25C, it has to do this to prevent itself burning out. With a 20A charger 14.4V will not be reached until the battery SOC gets to around the 90% SOC point.

The charger manufactures used to argue that lower charge rates were better for batteries when they only had 20A charger, then 25A came along, then 30A then 40A amp, now they can produce higher charger rates they have dropped the argument.
For those playing at home, I hooked-up the BCDC1220 to find out what my Redarc does.

The AUX voltage (bottom) is with the DCDC running for about 5 mins. It eventually lifted the voltage up to 14.6v and then dropped off to its 13.3v float setting.

IMG_7669.jpg

Obviously with my Traxide Isolator the Cranking and Aux voltages hold at the same level.