Hi Biljol,
I am installing a large Battleborn lithium bank as well, that is a battleborn BIM I am pretty sure. The picture is pretty grainy when zoomed In on.
From what I recall, the upper left silver bolt is IGN (ignition), the center is gnd (ground), and the right is SIG (signal) which is the “battery boost” I believe. It is all labeled on the BIM. On your current solenoid, since it is not labeled- you are going to have to do some work.
1. Grab your voltmeter and check the small terminals on the solenoid first, as a base line to make sure they are dead/hot until the key is in the on position.
2. Have someone in the coach turn the key to the first click, or ignition position, on one of the wires you should have switched 12vdc. This is your ignition wire. You can have them turn it back off then on a time or two just to make sure this is it, for your own peace of mind.
3. I believe the BIM should have the ign wire fused from what I remember, (5amp fuse?) but do your due diligence, don’t take my word for it. Check, recheck, then check again.
4. The SIG terminal should be the “boost” Feature On your BIM and will be the last small gauge wire on your solenoid. Same process for this, someone in the coach, while you are applying your probe to The old solenoid terminal, have them press the boost switch and when you have your 12vdc- and they release it, it should go back to zero, you have your last connection.
This is all low voltage DC, but high current. Use caution as you normally would and if you don’t feel comfortable- STOP! Get qualified help. Safety first!
If you have any other questions, please feel free to reply to the board or shoot me a message, I am glad to help.
***safety first, this is just a helpful reply, I do not know your technical level and am not responsible for your actions, proceed at your own risk***
Good luck sir,
Nic