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 <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 <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/ > On Sep 14, 2021, at 9:27 AM, Della Barba, Joe via CnC-List > <cnc-list@cnc-list.com> wrote: > > My batteries are about shot and I am thinking of going to lithium batteries. > I have to say I thought I knew this stuff and it seems massively confusing > with a ton of directly contradictory information. One big issue seems that if > the BMS disconnects for any reason, that will do a lot of damage to your > alternator and perhaps other equipment too. Add to that my regulator does not > have a specific lithium setting, I would need to get into the custom menus > and try and make one. > What seems to be the best bet is just to connect the alternator to the start > battery and use a DC-DC charger to charge the lithium bank. Some of them also > take solar input, so that saves me buying a solar controller with lithium > settings, which is something else I don’t currently have. > > Joe > Coquina > Thanks to all of the subscribers that contributed to the list to help with > the costs involved. If you want to show your support to the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
