Hi.
With either a 100A fuse or a 60A fuse I'm getting about 25A charge on my van's victron smart LiFePO4.
Before I head to a garage to get the alternator function tested (I don't think it'll be that as I'm getting similar with two different fuse ratings) is there anything else I should try? At the moment the neg in to the 12/100 is 50mm² connected to the battery terminal, would connecting it straight to the chassis ground like the starter battery is make any difference?
The input current is electronically limited to approximately 90% of the fuse rating. A 100A fuse, for example, will therefore limit the input current to approximately 90A. A 60A fuse will limit the input current to approx 54A. Both of these are well above your stated 25A charge. I seriously doubt you will see much more then 25A anyway.
One of the primary functions of the 12/100 is to protect the alternator against overload in case of a high capacity LFP battery bank (most 12V alternators will overheat and fail if running at maximum output during more than 5 minutes).
Your battery may not need any more than 25A if it is near a full charge. Personally, I’d be happy with a 25A charge since it would charge a fully depleted 100Ah battery in 4 hours. That is a high charge rate and much higher is not recommended for LiFePO4 anyways without battery degradation.
You did leave out some pertinent information regarding your battery capacity and number of batteries so I’m just making some assumptions based on what information we have been told.
