EG4-LL 12v V2 vs Electric winch and windlass

[Recollect]

Ive been looking at the EG4 V2 12volt as a candidate to replace my house AGMs on a 39 foot catamaran. Id go 24v but dont want to toss out perfectly good electronics, so 12v it is.

The 12v v2 BMS is rated for 200A continuous, 220A for 30 seconds and up to 380A for 3 seconds.

Anyone tested one of these with a windlass or electric winch in the real world? Would 2 or 3 in parallel leave enough headroom for worst case loads?

Windlass specs seem reasonable:

• Voltage: 12V DC
• MotorWage: 1000W
• Max Pull: 1200 lbs (545 kg)
• Work Load (SWL): 275 lbs (125 kg)
• Amps Work Load: 100A
  • Amp Draw: 60-100A
• Circuit Breaker: 110A

Winch is harder to quantify.
According to the manufacturer, anywhere from 50 to 250 amps depending on the pull load.

I know the current can vary greatly depending on the loads encountered by the winch/windlass.

Thank you!

 

[AnarchyJet]

If I understand correctly, your windlass runs off the house bank. Which is currently agm and supplied by a 110 amp breaker.
How many amps is your house bank pulling when the windlass isn't running?
I would suggest a dedicated agm bat for the windlass, fed by a small DC-DC charger. Then size your LFP house bank for your desired capacity.

 

[BobR]

I prefer to use the engine starter battery for the winch. The engine is usually running while using the anchor winch; so will be charging the winch/starter battery.

 

[Recollect]

Thank you for the replies.

Currently the windlass runs off the house bank, so does the winch. Aside from those high draw devices, house loads are generally low, less than 30amps at any given time. I live in the Pacific Nothwest and use diesel for heating and cooking. I dont not use an inverter and there is no shore power. I have 2kw of solar to keep the batteries charged, even in the winter. Boat engines are 2 x mercury 25hp outboards with 15 amp alternators. If I understand your recommendations correctly, it is to keep the AGM bank separate from the Lithium via a DC to DC charger going from Li to AGM. Moving the very high amp surge loads from the windlass/winch to the AGM, all the rest on Lithium. Forgive the simple diagram, trying to keep things high level:





I was debating this setup however began to wonder if its even needed, which is what prompted my post. With the higher capacity BMS (200A up to 380A) on the lithium, I was hoping to avoid running dual banks. I guess it comes down to how well the BMS handles those surge loads. For peace of mind I can see going with the split AGM set as they are known to take those loads reliably.

 

[AnarchyJet]

I'm guessing if you had 2 batts in parallel with 200A BMS, and only used either the windlass or winch it would be ok. Does each outboard have a dedicated FLA starting battery? You will need a DC-DC charger from each alternator to the LFP to limit current if you want that as a charging method. A diagram of the boats current config would be helpful to give you ideas.