The 1500 IBS design does not provide an ideal solution. I have a 12K trailer mounted winch. Grounded the winch cable between the IBS and battery post connector as shown below. This approach bypasses the IBS during winch operation. If winch operation is occasional, this should have minimal impact on IBS function. Another member here and I have used this approach and noted no issues, IBS or otherwise, as yet. One caution, however, depending on winch install, the winch ground cable could provide an alternate ground path via the winch casing and chassis possibly affecting IBS during normal truck operation. In this case I recommend a full disconnect switch or Anderson connector.
The +12v connection uses a Blue Sea marine rated terminal block and 300 amp fuse, along with 450 amp switch disconnect. The +12v disconnect is a safety factor as a backup to the winch control and also to de-energize the winch +12v cable when not in use.
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