Rmack1 wrote:
This 'emergency power supply' thing has jumper cables, but they are suppose to be used for charging up batteries. Will it work backwards?
Generally the jumper cables connect DIRECTLY to the battery inside the box.. (Though I've seen some with a switch or a breaker).. So yes, they will work backwards.. The only 'Danger' is that your converter is capable of way way way too fast charging of that AGM battery.. Odds are the AGM battery inside the box is at most 25-30 amp hours. and though LIFELINE says you can hit theirs with 3 times their AH rating (75 to 90 amps for the sizes I mentioned.. IF THEY ARE THAT LARGE) my converter is 80 amps. and that 3x only applies to LIFELINE, other makes its more like 1/3 amp hour rating.
SO have the AGM fully charged when you first parallel it with the house batteries.. That way the house batteries will suck up the excess amps when charging.