Yes, with your DVSR mod you can just drop in a LFP battery, but you have to remember to turn the DVSR off when you stop to float.
Check out
@WiskyDan ’s posts in this thread;
DVSR help... On how he tied his DVSR positive into a fuel pump hot for a simple way to operate the DVSR without a second thought. I know of at least one other person who set up their DVSR that way and I think I had told WiskyDan about it and he emulated that set up and wrote his post about it.
As far as the number of 100Ah LFP batteries you’ll want to have on board, LFP batteries have almost three times the amount of Ah / KWh of energy storage compared to a lead acid battery. I can’t stress enough the addition on the Victron Energy smart shunt, they are small and easy to install. No worries on tossing out the 50% number, a lot of people look at the voltage to determine battery state of charge, but to use voltage to determine SOC on lead acid batteries they need to be disconnected and at rest for 24 hours.
The Victron app for your smart device works with all Victron devices. I have two of these smart shunts installed on my boat, one for the trolling motor battery bank which is an isolated system and one for the house battery. The shunt also has a start battery tap that will measure voltage only on your start battery, I used this tap on the house battery shunt to see the voltage on my start battery. I’ve found on my boat the connext screen voltage reads low, usually .5 volts when in the lower voltage range, I’ve verified this with my fluke meter as well as the smart shunt, the shunt and my fluke (multimeter) read the same while the connext screen voltage reads up to .5 volts low.
My boat will read voltage on the connext screen (as well as the shunt) in the 14.2 to 14.4 range when cruising when the batteries are charged up, so yours were still low on your cruise back. Speaking of charging, LFP batteries charge five times faster than lead acid batteries so this is why LFP batteries are a great marriage to our alternators, as all of the output will be going into the LFP battery. Your boats alternators put out roughly 13-14 amps each when the rpm’s are above 3500 rpm, and approximately half of that at idle. This five time faster charge rate is where automotive style alternators (variable magnetic field or VMA) have issues with LFP batteries, but not with the alternators (permanent magnet alternators or PMA) on our boats.
You will also need to replace your on board 5x2 charger with at least a 10x2 as LFP batteries require 10A minimum. I had MinnKota 10 A chargers originally but have since switched to Victron IP67 chargers. The IP67 chargers are user configurable to any battery chemistry via the same Victron app and Battle Born customer service can walk you through the set up or I can help you set them up the way BB wants their batteries charged. The IP 67 chargers are capable of charging from 3A up to 25A. I have my trolling battery bank, 3-100Ah BB batteries, at 25A each, that reduced my trolling motor battery bank recharge time from 14 hours to 3.5-4 hours.
My suggestion for your set up would be to install one group 27/31 100Ah BB battery, the smart shunt,
@WiskyDan ’s DVSR fuel pump hot mod and run that set up until such time you see via the smart shunt you are running short on capacity, if you reach the point where you need more capacity then add another 100Ah BB battery in parallel to double your storage capacity. These batteries are expensive so no need to install a second LFP house battery until you need it.
So far we’ve just talked about performance of these batteries another big factor is the weight savings, a BB 100Ah battery weighs half of a similar size lead acid battery, and LFP batteries weigh 1/5 of the weight of a lead acid battery bank of the same useable storage capacity. The other really big thing is these batteries they last 10 times as long, they come with a 10 year warranty, I expect to get 15 years out of my batteries and I use mine a lot more than the average boater as I have been averaging 35-40 boating days and 12-14 hours each outing a year. While I absolutely love my boat, there’s a good chance I may move to a larger boat with a bit more protection from the elements in the future, if and when that day comes, my MinnKota chargers and a new set of lead acid batteries will go into my boat for the sale and the LFP batteries and chargers will come out and go into the new or new to me boat.
Not sure if you read the thread I mentioned above;
Conversion to LiFePo batteries Or not yet but I highly recommend that as well, I spent a lot of time researching this subject before I moved ahead with this project,
@mrcleanr6 was exceptionally helpful with his suggested questions which allowed me to ask questions of the manufacturers, which is how I arrived at BB being the only choice. BB has excellent customer service and all their sales people are tech support as well and BB sells and fully supports Victron products, if they don’t happen to answer the phone leave a message and they will call you back pretty quickly. ReLion also has people you can talk to, but I could not use their heated batteries in series for my trolling motor bank. Dakota lithium has sales people you can talk to but if you have tech questions it’s a 24-48 hour response time and from what I’ve seen they balk at warranting their products, I helped a member here get his Dakota lithium battery replaced. Can you find less expensive LFP batteries? Yep, but you get what you pay for, and in the case of LFP batteries the BMS (battery management system) is vitally important to protecting the battery from over voltage charging, low voltage cutoff, high amperage in/out, low/high temp cutoff, allowable amperage in/out etc.. BB also uses a type of cell that is different from the other battery manufacturers that enable their batteries to continue working if one cell stops working where the other brands will stop working. This video is linked in the conversion to LiFePO batteries thread,
it’s a bit long but well worth the watch.
And lastly and also important to me is that other than a printed circuit board that is produced in China BB are designed and manufactured here in the United States.
