Silent charge or float?

[hwse]

I have a Magnum MS1212 2000w / 100A 12v inverter-charger in my motorhome. By batteries are a couple of drop-in 460Ah packs for a total capacity of 920Ah

I am trying to decide which charge profile to use with I am plugged into a full hookup site. I have two programable profiles that should work for my PFL.

• Three phase - bulk, absorb float - use 13.8v for bulk and absorb with 30-minute absorb time and then drop to 13.4v float. In this profile the batteries will be held constantly at 13.4v and all service loads will be provided by the Magnum charger.
• Silent - bulk, absorb, off - charge pack to 13.8v for bulk and absorb with 30-minute absorb time and then turn off all charging until pack voltage drops to the customizable "re-bulk" voltage. In this profile the batteries will be held charged to 13.8v and then all service loads will be provided by the battery which will drop down to re-bulk (thinking of somewhere around 12.2v) and then be recharged to repeat the cycle.

Opinions?

 

[hwse]

For some more info, most of the big loads are AC and will be supplies by the 50A 240v connection. These include refrigeration, floor heat, cabin heat water heating induction cooking, air conditioning, computers and TV's and of course the battery charging.
The DC system runs lights, hydronic furnace pumps and blowers, and that is about it. In silent mode, the batteries will take most of a week to drop to the re-bulk voltage.

 

[Ampster]

Generally float is not considered good for Lithium batteries but some have used it when charging from solar and when there are small loads. That way the batteries end the day with a full charge and Float takes care of the loads from when Absorb ends and solar end. It is more about your use case. I have done both and in my case it depends on the season. If you are not concerned about the cost of using AC then use the two stage process to be easier on your batteries. I assume at a hookup your power is a fixed fee or included in the site rental? You can always top off your batteries from the grid before you depart.

 

[hwse]

Generally float is not considered good for Lithium batteries but some have used it when charging from solar and when there are small loads. That way the batteries end the day with a full charge and Float takes care of the loads from when Absorb ends and solar end. It is more about your use case. I have done both and in my case it depends on the season. If you are not concerned about the cost of using AC then use the two stage process to be easier on your batteries. I assume at a hookup your power is a fixed fee or included in the site rental? You can always top off your batteries from the grid before you depart.

The AC is a part of the campground fee so does not matter and this coach is a huge energy hog. I got the 920Ah capacity because that will give me 2.5 to 3 days of off-grid energy without solar. It is an all-electric coach so uses a lot of 110v AC.

Your comments are in line with with my thinking. I can float at any voltage I want so could drop it to something lower for the weeks or sometims months that I am connected to power but that does not feel like it would be good for the cells. A slow discharge and then recharge feels like the better choice.