Re: What to do with LiFePO4 batteries when the boat is layed up?


Rudolf Waldispuehl
 

Hi Joerg

 

Hope you are doing well and all is fine on Kincsem. Where are you now?

 

Sorry to step in so late but I just finished my strategy with moving to LFP. I was also concerned about to lay-off the boat for a longer period.

My strategy is to keep 2x100AH of Lead Acid In the system and charge them by Solar (or Shore) when away from Boat. Therefore the Bilge pump and another small consumer can be active during absence. AND I have a Backup for the Starter- Batterie as well, which is always on and charged.

 

Your LFP can be switched off (no longer on the 24V bus) and the internal BMS is automatically switching off after 24h without any activity.

Mastervolt told me today that in this scenario I can keep the batteries for more than 6mt. untouched because there is no internal currency drain.

They said that it could go even up to one year or more, ….  but it depending of the SOC at the time of lay-off. Hope it’s not just Marketing 😉

BTW:

The Hybrid idea is not mine, I got from Dean (SV Stella) who just finished to build a Hybrid System with Lead Acid and LFP for similar reason and more….

I always had the idea to combine the 2 technology, but Dean gave me the confidents that it works.

 

Best regards

Ruedi

SY WASABI

A54#55

 

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Thanks very much everyone.  Based on Thomas’ suggestion, I‘ve now programmed an event for my 60A charger which switches it to float at 80% state of charge.  The voltage of the batteries at 80% with the charger off and minimal load (2A) is a little less than 26.8V.  So this may be the way to go - but I have an email into MV support to confirm.  Their advice quoted above strictly speaking only applies if all loads are off which won‘t be the case for me since the bilge pump and galvanic insulator will be on although the loads are minimal for a 600Ah battery bank.   It may also not be necessary to have this event if the charger never goes back to bulk with such a small load.  

Scott, given that MV recommends to charge the batteries to more than 80% at least every 3 month, I suspect that it‘s not good for them to be kept at 50% as you suggest.   

Joerg

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