Re: Renogy LiFePO4 batteries
Posted: Thu Jun 06, 2019 11:54 am
Bill,whemme wrote:Boy you guys must really like to spend big money on replacement coach batteries. The Renogy 170 amp-hour battery costs $980 each. The Interstate SRM-31 210 amp-hour flooded cell battery costs currently $142/each. My experience running the Interstates in my 2002 BF 26'RSB using a modern 3-stage charger/converter is that my Interstates last at least 5 years of service
With all due respect I need to correct you on something. The SRM-31 has 210 minutes of reserve capacity at 25 amps. This is not the same as amp hours that are specified on deep cycle batteries. To convert to amp hours multiply (210 x 60 x 25)รท3600=87.5 amp hours. You can also take the short cut and divide RC by 2.4. The Interstates are good batteries for most that don't boondock often, but comparing the Interstate group 31 at 60 lbs and 87.5 ah vs a group 31 Vmax which is 75 lbs and 125 ah is huge difference. The Interstates are deep cycle, but still used in the marine world where they need to start an engine so they are a slight compromise compared to true deep cycle. This is why I'm not replacing my Interstates with new Interstates. I boondock at least 50 % of the time and usually for 3-4 days at a time. I'm barely okay with solar to refresh them during the day so going from my 2 SRM-24's at 58 ah each to a group 31 at 125 ah each is a huge difference for me. Bottom line is everyone has different battery needs so we all need to make decision on our individual needs and uses.