What is the preferred choices for replacing batteries? 3 large batteries? 2 large batteries, 1 starter & 1 house? 2 large house batteries and a small starter battery?
What are the preferred battery chemistry? Firefly, Mastervolt Odyssey TPPL, Lifelife 31T? Lithium Ion anyone?
Has anyone fitted the inch longer Firefly battery into a 109? How did you change the mounting?
Replaced our batteries a year ago. We do a variety of overnight races and find having 3 group 31 batteries to last very long (2 house; 1 start). They are so good that we probably could get away with just two. I am uncertain as to whether downgrading to group 27 would be beneficial. What I can say is Trojan AGMs batteries are great. Make sure you set up your charging system correctly for proper chemistry. This is addressed in an earlier post.
https://www.practical-sailor.com/issues ... 244-1.html
Will likely switch to AGM for my next batteries.
I was able to fit two Firefly batteries in the stock location. I am running one regular Lifeline AGM as a reserve and two Fireflys as the house bank. The Fireflys will fit if you put them in the aft two locations. Then I changed the positive wiring to retain the 1 BOTH 2 positions. The Fireflys have a lot of capacity. So far we are very happy with their performance. Excuse the blurry pic.
sweet caroline # 239
Something for me to share, I rewired everything so that the starter battery & starter are isolated from the house & house load, so that starting the engine doesn't spike the electronics (probably not a problem with 2 firefly batteries !)
To do this I
1. Ran a new 9 foot red electrical cable from the engine compartment to carry the alternator output direct to the house batteries, by connecting it to the same post on the electrical switch as the house battery. No matter where someone turns the battery switch, the alternator output goes to the house battery (protecting the alternator diodes.)
2. I disconnected and taped the wire in the engine compartment that bridges the starter and the alternator (Be sure to first disconnect batteries and shore power before doing this, there are no fuses to stop an arc if you accidently touch engine)
3. I moved the Starter wire from the common lug to the #1 battery lug. Now the starter battery and starter are connected together. Unfortunately the Off position on the switch has no effect of cutting off the engine key. In the future I will install a BlueSea e-series switch (4 lugs) and then that will allow me to have an off position that also cuts off the starter.
Note that the house batteries wired in parallel as pictured above are done incorrectly. Putting the boat leads to one battery and then piggy-backing two off to the second battery will cause a small, but critical, voltage drop to the second battery. The charger will slightly and then eventually continuously over-charge the first battery, damaging it. (This happened to me: charger started running constantly, first battery was bulging, quite warm and held no charge, second was fine.) It's best to put one boat lead to each battery to keep the voltage levels identical. There are detailed treatises on this topic online.