Somewhere over the horizon Lithium battery technology, namely, LiFePO4 or a similar inherently safe variant, will come to cruising boats.
This thread is about LiFePO4 technology not any other Li technology. LiFePO4 is a very safe Li technology but is not yet a "drop in" replacement for LA batteries.
I say that, but the reality is LiFePO4 already here. The cost for pre-made factory packs however keeps the "average Joe sailor" away from it currently... I am installing Genasun LiFePO4 batteries next week that are in the 24k range for the entire bank and system..
IMHO this technology is NOT yet ready for "drop in" or DIY level installations. It will eventually trickle down but is not ready for DIY prime time just yet..
Genasun, Mastervolt and Victron are all in the Li arena with good offerings for marine installations but it is very early in the technology and still quite expensive for factory made..
I physically built and engineered my own LFP battery pack but this level of build is a long way from DIY level. I would not advise folks to try and undertake this on their own without a vast knowledge of the technology.
This morning, after a number of testing cycles, I am load testing the bank. The bank is 400Ah made up of four Winston 3.2V 400Ah cells in series.
One amazing thing about this technology is there is virtually no Peukert effect. The Peukert is about 1.03..... The picture below shows the pack supplying a 100A load after a full hour of doing so. The pack voltage is still 12.85V !!!!!!!!
The big benefit to me with LiFePO4 is that there is virtually no acceptance limiting. You charge back to 98% - 100% with ease, if you have the current. This bank could be charged at 3C or 1200A if one had the capability. Once it starts limiting current it does so only for about 20-25 minutes and this is with a .35 C charge current....
With lead acid batteries you can only cycle to 50% SOC or you risk a drastic reduction in cycle life. You can also only ever re-charge, when off cruising, to about 80% SOC due to acceptance and current limiting.
This means the usable capacity of the bank is about 30-35%. You are hauling around 65% of your batteries that are virtually unusable. With LiFePO4 you are only hauling around 20% that you don't use and 80% of the capacity you paid for you can actually use.. Even at 80% DOD they still claim 3000 cycles.
Do I believe this? No, not entirely. Hell Lifeline claims 1000 cycles to 50% DOD on their AGM's yet I see them dead with 100-300 "real world" cycles on a regular basis. Real world and "lab coat" world are usually vastly different. But still guys in the EV world are claiming these cells are actually doing this. I will play the "wait & see"...
The technology is complex, different and requires a battery management system to keep from over charging the cells and discharging to deeply. It requires individual cell level monitoring. The BMS also ensures that no cell can exceed the safe voltage.
These batteries literally charge until full then "hockey stick"/spike in voltage if you don't control the voltage well. This means the voltage rises VERY quickly at the end and can over shoot the safe level and destroy a cell in the process.
My boat systems will need to be modified. I need to have a charge bus and a load bus both controlled and monitored by contactors/relays. The load bus will disconnect the load away if a any cell hits the low voltage threshold. My solar, battery charger and alternator will also all be controlled by their own high voltage cut relays to prevent any cell from going over voltage. Because of the immense energy stored in these batteries the fuse for them is Class T at a bare minimum. I measured the bank last night at over 5200 cranking amps!!!!! The short circuit capability of this bank could potentially explode an ANL fuse.....
This 400Ah bank is also smaller and 76 pounds lighter than our group 31 375Ah flooded bank.. It is also rated for 3000 cycles to 80% depth of discharge (believe that when I see it). I will cycle to 50% - 60% DOD and that puts me over 5000 "rated" cycles (believe that when I see it too)...
This is what the future of batteries on boats may look like... Darn bank is heating my garage right now......! I just checked and at 170Ah's removed from a 400Ah rated battery pack, at a 102-105A constant load, the pack voltage is still 12.79V!!!!!)...
This thread is about LiFePO4 technology not any other Li technology. LiFePO4 is a very safe Li technology but is not yet a "drop in" replacement for LA batteries.
I say that, but the reality is LiFePO4 already here. The cost for pre-made factory packs however keeps the "average Joe sailor" away from it currently... I am installing Genasun LiFePO4 batteries next week that are in the 24k range for the entire bank and system..
IMHO this technology is NOT yet ready for "drop in" or DIY level installations. It will eventually trickle down but is not ready for DIY prime time just yet..
Genasun, Mastervolt and Victron are all in the Li arena with good offerings for marine installations but it is very early in the technology and still quite expensive for factory made..
I physically built and engineered my own LFP battery pack but this level of build is a long way from DIY level. I would not advise folks to try and undertake this on their own without a vast knowledge of the technology.
This morning, after a number of testing cycles, I am load testing the bank. The bank is 400Ah made up of four Winston 3.2V 400Ah cells in series.
One amazing thing about this technology is there is virtually no Peukert effect. The Peukert is about 1.03..... The picture below shows the pack supplying a 100A load after a full hour of doing so. The pack voltage is still 12.85V !!!!!!!!
The big benefit to me with LiFePO4 is that there is virtually no acceptance limiting. You charge back to 98% - 100% with ease, if you have the current. This bank could be charged at 3C or 1200A if one had the capability. Once it starts limiting current it does so only for about 20-25 minutes and this is with a .35 C charge current....
With lead acid batteries you can only cycle to 50% SOC or you risk a drastic reduction in cycle life. You can also only ever re-charge, when off cruising, to about 80% SOC due to acceptance and current limiting.
This means the usable capacity of the bank is about 30-35%. You are hauling around 65% of your batteries that are virtually unusable. With LiFePO4 you are only hauling around 20% that you don't use and 80% of the capacity you paid for you can actually use.. Even at 80% DOD they still claim 3000 cycles.
Do I believe this? No, not entirely. Hell Lifeline claims 1000 cycles to 50% DOD on their AGM's yet I see them dead with 100-300 "real world" cycles on a regular basis. Real world and "lab coat" world are usually vastly different. But still guys in the EV world are claiming these cells are actually doing this. I will play the "wait & see"...
The technology is complex, different and requires a battery management system to keep from over charging the cells and discharging to deeply. It requires individual cell level monitoring. The BMS also ensures that no cell can exceed the safe voltage.
These batteries literally charge until full then "hockey stick"/spike in voltage if you don't control the voltage well. This means the voltage rises VERY quickly at the end and can over shoot the safe level and destroy a cell in the process.
My boat systems will need to be modified. I need to have a charge bus and a load bus both controlled and monitored by contactors/relays. The load bus will disconnect the load away if a any cell hits the low voltage threshold. My solar, battery charger and alternator will also all be controlled by their own high voltage cut relays to prevent any cell from going over voltage. Because of the immense energy stored in these batteries the fuse for them is Class T at a bare minimum. I measured the bank last night at over 5200 cranking amps!!!!!
The short circuit capability of this bank could potentially explode an ANL fuse.....This 400Ah bank is also smaller and 76 pounds lighter than our group 31 375Ah flooded bank.. It is also rated for 3000 cycles to 80% depth of discharge (believe that when I see it). I will cycle to 50% - 60% DOD and that puts me over 5000 "rated" cycles (believe that when I see it too)...
This is what the future of batteries on boats may look like... Darn bank is heating my garage right now......! I just checked and at 170Ah's removed from a 400Ah rated battery pack, at a 102-105A constant load, the pack voltage is still 12.79V!!!!!)...
