The BMS (battery management system) controller has two 12 volt inputs. One when the key is on (load power) and the other when the vehicle is being charged (source power). The [[http://saturn.lynnautorepair.com/BMS%20Elithion%20Lithiumate|Elithion BMS]] needs to know which condition or mode it is in.

Mas Tech Road Pro

Mastech and RoadPro AC/DC converters
During charging, it will, if commanded control the charger, record amps and watts in, give warnings etc. To supply 12 volts during charging one could
1. run off the 12 volt vehicle battery
2. turn on the DC/DC unit
3. supply power from a 120 volt AC cord
Right now with my setup I am doing the last.
The power supply has failed. (one of the little .5 amp plugin converters also failed or never worked, when I first set this up) It was a Roadpro AC/DC converter part #RPSL-7000. After using it to power only the BMS which I tested it’s current draw of .280 amps, it has lost control. It’s output was 3 volts with a AC hash to -.5 to 2.5 volts. I checked the wall voltage is correct at 125 AC volts and the same at the cord end. I ran 13 volts to the BMS from my Mastech Powersource and the controller is OK.
I ordered a little Mastech AC/DC power supply from [[http://stores.ebay.com/automationtechnologyinc|eBay]] It is a model #HY152A. Maximum output of 2 amps and voltage is controllable from 1.5 to 15 volts. It has a voltmeter (analog) and on and off switch. Cost was $40 with shipping.