Sterling DC-DC Battery Charger 40A- Bidirectional

Smart Alternator/Euro 6+ compatible
- Ignition feed or Vibration Sense modes
- 6 preset battery types
- 6 self recovering protections
- Low temperature trip for Lithium Ion batteries

Benefits of BB installation with EV
- The BB1240 has a maximum current draw of 40 Amps. A good estimate is to rate your BB to approximately 25-50% of the current rating of your alternator. This allows the converter to provide the power to run your obligatory loads (steering, lights, stereo, air con etc) and surplus to go in to your 12V house battery. If all of your alternator capacity is being used by all ancillaries the voltage shall drop across the 12V system and the BB shall naturally reduce performance and eventually turn off during that episode when there is a high power demand. The BB shall turn on again when the voltage climbs.
- Charging lithium batteries directly from the alternator could either burn outyour alternator of trip the batteries BMS. The benefit of the BB is that it shall reign in the current to whatever BB you choose.
- You shall get the correct charge voltages at the 12V auxiliary battery. Some DC DC converters shall sit at 14.7V all the time, which may be too high!

Reverse Charging Feature.

The BB1240 can charge in both directions. Provided there is over 13.2V on the leisure battery (13.5V if lithium) and the starter battery is below 13V the BB shall allow approximately half current (~20A) to flow back to the starter battery up to about 13.4V (float voltage). It simply allows the starter battery to remain topped up when there is surplus energy in the domestic battery. This feature will NOT drain your domestic battery - it simply takes surplus. Once your alternator / engine turns on or you provide the BB with an ignition signal the BB reverts to normal charging of the house battery.  This mode can be disabled, but is on as default.

This is ideal for allowing the starter battery to remain topped up when you have solar / wind / charger - charging up your house battery.

A video on the reverse charging feature can be found here

Installation Manual