Blue Sea ACR (humm)

[JWL]

I have a Blue Sea ACR in my 2020 Hawk Shell. Last year I installed a 100 AH Lithium in the camper. Knowing that the AGM in the truck and the LiPo4 charge differently I disconnected the wires at the truck batt and at the ACR. I have minimal power usage in the camper and the 200 watt solar here in the South has never not been able to keep up. I did anchor the wires from the truck and the camper in case I needed to get a recharge sometime while driving and reconnect them. The other day while in my garage I heard a high pitched hummmm. (At my age ear ringing is not unusual) I thought it was from the fluorescent lighting, but no. In the camper I discerned it was coming from the ACR. Bat was at 13.27 v, camper power/relay switch was off and everything seemed as usual. So, is the ACR dying? Is it trying to connect to a nonexisting battery? (Although in the last year we have never heard it) Is there something wrong with my thinking on leaving it partially connected? We thought maybe because it was so quiet that is why we heard it but I just wanted to make sure there was not a problem lurking.
And yes I know the best solution is to get a DC-DC charger, but I’m not in a position to replace the wiring and as stated our needs don’t justify it.
Thanks!

 

[rubberlegs]

Do you need to charge the battery from your truck any more? It sounds like you are doing fine just with solar. Maybe you could just disconnect your camper-truck connector.

 

[Jon R]

If you want to leave the ACR in place partly connected in case you ever want to connect it for a truck charge, I would suggest one additional disconnection step:

Disconnect the ground wire to the ACR by pulling its in-line fuse. On my Grandby it’s around a 16 gage wire that is yellow, and it has a rubber covered in-line fuse holder right near the ACR. Pull that fuse. That will prevent the relay coil from being energized and it will depower the control electronics, which are probably the source of the noise. Save the fuse for reactivating it later if needed.

 

[Vic Harder]

Is the small little ground wire still connect to ground?