My alternator might hit 50 amps on a really good day, so a 40 amp DC-DC charger would be plenty. BTW, the usual alternator protectors are 16 or 18 volt Zener diodes. I had occasion to test that once and it did burn the diode up, but the alternator was saved 😊
Joe Della Barba Coquina From: Dreuge via CnC-List <cnc-list@cnc-list.com> Sent: Tuesday, September 14, 2021 1:17 PM To: cnc-list@cnc-list.com Cc: Dreuge <dre...@gmail.com> Subject: [EXTERNAL] Stus-List Re: anyone gone lithium? Hi Joe, I made the change to LiFePO4 this year. And yes, I chose to keep the lead-acid start battery with the alternator directly connected to it. I originally planned on using a DC-DC charger (both w/ and wo/ MPPT solar charging) for charging the LiFePO4 battery. The issue with DC-DC chargers are the limiting charging current, 30A for Victron units, and 50A/60A for others. I have a 120A alternator and to get the most out of it, would require using multiple DC-DC chargers in parallel. My solution was rather simple. Use the existing Blue Sea SI-ARC but in a switched control mode. I first installed a manual push-pull switch and then built an Arduino smart switch which senses the ignition power to control a relay switch for the ACR. I even added temp sensors: one for alternator temperature and the other for the LiFePO4 battery(don’t charge LiFePO4 batteries at temps below freezing). I have it documented on my blog (see links below). I do like Sterling Power’s alternator protector and will likely install one in the future. My recommendation is to focus on the battery system first. LiFePO4 drop-in replacements are economical, but putting together a DIY LiFePO4 battery is simple and affordable. I replaced 2 group 31 deep cycle 110AH batteries with a 560AH LiFePO4 battery. LiFePO4 battery build https://svjohannarose.blogspot.com/2021/06/adding-new-lifepo4-to-house-battery.html Solar System https://svjohannarose.blogspot.com/2021/07/electrical-power-system-w-solar.html - Paul E. 1981 C&C Landfall 38 S/V Johanna Rose Fort Walton Beach, FL http://svjohannarose.blogspot.com/
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