Re: Converting my Amel 54 to lithium batteries: what I did, what I like and what I don't like (after one year of full time live aboard use)


Scott SV Tengah
 

Colin,

Good to hear from you! I guess you guys aren't selling Island Pearl II then? We are in San Blas now and planning to transit the canal and head to the Galapagos within a month. Slowly but surely making our way to your part of the world :)

Do you have any idea of the amp hours you're putting getting out of your solar/wind array? I am very jealous that you have that production capacity and I'd love to see numbers.

Since you're barely running the Victron 230v chargers, you don't have to worry about this, but others may want to think about it: lead batteries can only take full current at low SOC. I seem to recall around 65% SOC or so, the charging current tapers quite a bit. With LFP, the batteries will take full current up to 99% or so. That means your chargers are running at full capacity and generating lots of heat for longer periods. 

Related to that, if you haven't already, think about your 24v alternator and the regulator attached to it. I am not sure what alternator is fitted on the SM, but we have a Mastervolt 110amp which Mastervolt says is OK for the long periods of full current that LFP will require of your alternator. For good measure, I installed a temperature sensor that will instruct the Alpha Pro II regulator to taper output if the alternator gets too hot. Finally, make sure your alternator has a LFP charging profile and just as importantly, the Battery Management System (BMS) can shut down your alternator when there is an over voltage or over temperature condition in one of the cells. Note that you can have acceptable overall bank voltage but one of the 32 cells that will comprise your system may be over voltage. If your system doesn't stop charging, it could irreversibly damage that cell. 

Finally, keep in mind the Dolphin chargers don't have a LFP profile. At least the ones in the 54 did not. There's a 54 owner out there who installed 1200 (!!!!) AH of LFP and fried them in short order - I believe because he charged them using the wrong profile.

After your install, you will get a 25% boost from your already massive solar/wind array on charging because with LFP, you don't get the 25% charging inefficiency you get with lead. BTW - I've run the aft AC all night on battery/inverter and our 450 amp hour bank was more than enough.

Hope this helps.

--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

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