Warren Holybee
Active Member
It was asked I post about my Lithium planning, and why.
Currently, I have 2 group 27 batteries for house(230Ah total), and a group 24 for starting, in the factory location under the quarter birth. With each of those in its own box, and all the wires for the battery switch, and buss bars, shunt etc., there just isn't enough room for any more battery there.
I need to replace my batteries before I continue cruising. The 230Ah of Lead Acid I have now were frequently drawn down to 50% or less, and while on passage often not recharged 100%. I got about 3 years out of them. They are still somewhat serviceable, but no way would get me back to California. I considered an alternate location, in particular there is alot of space under the port side cockpit locker. But that is a lot of work, and additional expense. I live on my boat now, and no longer have access to my garage, table saw etc., so it would be a challenge.
With Lithium, I can have more usable capacity in the current space, with 1/3 of the weight, and expect 10+ year life. As expensive as they are, if I were to otherwise buy 400Ah of lead, and build a new cabinet location for them, and all the new heavy wire etc. It really isn't that much more expensive. It's much less considering a 10 year life.
The question the is, what lithiums. I am looking at drop-ins over a DIY at this point, which also have the advantage that if one of a pair of drop-ins fails I still have power just at reduced capacity. I have made some interesting observations. Most drop ins seem to use prismatic cells, with a few notable exceptions.
Renogy seems to use pouch cells. Looking at Will Prowse's (on youtube) teardown they appear tightly packed in a metal case. What happens when they swell? It otherwise seems a decent product, and I like that there is an inexpensive panel that will allow battery monitoring without the need to use a BT app. I hate needing to use my phone for everything instead of having a panel meter. They have a short warranty I think 3 years.
Battleborn and Dakota both use cylindrical cells. Cylindrical cells have the advantage of better cooling, and if a cell dies the whole battery doesn't fail. In fact, if my math is correct, a whopping 34 cells could die and the battery would still make 80 of rated capacity. (each cell is 2.3Ah so 8 cells in each 3.2V block could fail) This seems a huge advantage, and interestingly Dakota and Battleborn seem to be the only 10+ year warranties. Neither Battleborn or Dakota have a way to monitor the internal BMS.
Most drop in's, and all DIY use prismatic cells. If a single prismatic cell dies, you lose the whole bank. They do seem to be very reliable, with some reports of early Lithium on boat adopters now more than 10 years in service and still test as new.
Right now, I am leaning toward Dakota, being slightly cheaper than Battleborn, an 11 year warranty, and including a lithium charger (albeit a small one). I will also be adding a Renogy 60A DC-DC charger, so that my Alternator will be connected to my start battery, and the Renogy charger will charge the Lithium from that. That isolates the Lithium bank from the alternator and protects both the alternator and battery from damage. And, I will be adding a Victron battery meter to monitor the Lithium bank, sold by Dakota and they provide the programming details to make it accurate.
Currently, I have 2 group 27 batteries for house(230Ah total), and a group 24 for starting, in the factory location under the quarter birth. With each of those in its own box, and all the wires for the battery switch, and buss bars, shunt etc., there just isn't enough room for any more battery there.
I need to replace my batteries before I continue cruising. The 230Ah of Lead Acid I have now were frequently drawn down to 50% or less, and while on passage often not recharged 100%. I got about 3 years out of them. They are still somewhat serviceable, but no way would get me back to California. I considered an alternate location, in particular there is alot of space under the port side cockpit locker. But that is a lot of work, and additional expense. I live on my boat now, and no longer have access to my garage, table saw etc., so it would be a challenge.
With Lithium, I can have more usable capacity in the current space, with 1/3 of the weight, and expect 10+ year life. As expensive as they are, if I were to otherwise buy 400Ah of lead, and build a new cabinet location for them, and all the new heavy wire etc. It really isn't that much more expensive. It's much less considering a 10 year life.
The question the is, what lithiums. I am looking at drop-ins over a DIY at this point, which also have the advantage that if one of a pair of drop-ins fails I still have power just at reduced capacity. I have made some interesting observations. Most drop ins seem to use prismatic cells, with a few notable exceptions.
Renogy seems to use pouch cells. Looking at Will Prowse's (on youtube) teardown they appear tightly packed in a metal case. What happens when they swell? It otherwise seems a decent product, and I like that there is an inexpensive panel that will allow battery monitoring without the need to use a BT app. I hate needing to use my phone for everything instead of having a panel meter. They have a short warranty I think 3 years.
Battleborn and Dakota both use cylindrical cells. Cylindrical cells have the advantage of better cooling, and if a cell dies the whole battery doesn't fail. In fact, if my math is correct, a whopping 34 cells could die and the battery would still make 80 of rated capacity. (each cell is 2.3Ah so 8 cells in each 3.2V block could fail) This seems a huge advantage, and interestingly Dakota and Battleborn seem to be the only 10+ year warranties. Neither Battleborn or Dakota have a way to monitor the internal BMS.
Most drop in's, and all DIY use prismatic cells. If a single prismatic cell dies, you lose the whole bank. They do seem to be very reliable, with some reports of early Lithium on boat adopters now more than 10 years in service and still test as new.
Right now, I am leaning toward Dakota, being slightly cheaper than Battleborn, an 11 year warranty, and including a lithium charger (albeit a small one). I will also be adding a Renogy 60A DC-DC charger, so that my Alternator will be connected to my start battery, and the Renogy charger will charge the Lithium from that. That isolates the Lithium bank from the alternator and protects both the alternator and battery from damage. And, I will be adding a Victron battery meter to monitor the Lithium bank, sold by Dakota and they provide the programming details to make it accurate.