Thanks @Sea Change do you have any links for Rod Collins?
Why insist on 15 years? The degradation of lead within 5 years even when treated exceptionally well is well documented and understood. When not treated exceptionally well and looked after lead can fail or degrade within weeks. With price/usable capacity equalising (and with good AGMs lithium is now cheaper per usable Ah) lithium would only need to match the 5 years, for which there is extensive evidence even on these lowly forums and a cursory look outside these walls shows plenty of much older installs with little to no degradation.
He has a website (Marine How To) but I found the following on the Facebook group 'lithium batteries on boats' (info on cycle life and degradation is at the end):
Happy 13th birthday to my LiFePo4 battery bank(5/10/2009)!
Back in 2007 the first lithium iron phosphate battery cells were just beginning to be manufactured and become commercially available. I dove in & began researching everything I could about lithium iron phosphate. Unfortunately back then there was scant white papers and scant research available. Anything that was available was behind a pay-wall at some university. I decided if I wanted to learn about lithium iron phosphate I needed to buy some cells & start experimenting. That was the only way I was going to learn. My first cells were small 100 Ah thundersky cells because they were relatively inexpensive and I didn't really care if I ruined them. being this early into a new technology I knew I was going to get some arrows in my back being a pioneer.This was all before cylindrical LiFepo4 cells even existed.it would've been much easier to destroy a few $10 cylindrical cells than cells the cost me $200 a piece.
I wound up destroying those initial cells pretty quickly experimenting with charge voltages, how deeply you could cycle them & such. I quickly found out that they didn't really care how deeply you discharged them other than going below about 3.00 VPC. I quickly learned that the cells did not need to charge to anywhere near 3.65 V to attain 100% state of charge. I also learned that they did not like to be absorbed for longer than is absolutely necessary. On those early cells these batteries were quickly degraded if you left them on absorb for too long a duration. After all this testing and experimenting I finally decided to order a set of 400 amp hour Winston cells for my own vesel. It may sound hard to believe, that back in 2009 we had a lot more availability in battery management systems. Genasun was actually building a BMS Clean Power Auto had one and there are a number of others mostly designed for EV use but that can be modified for marine use . Other than Genasun the only BMS that was specifically designed for marine application was made by a company called Clean Power Auto. Demetri the owner of that company is now is the engineer at Lithionics.for perhaps 2000 cycles I use this clean power auto BMS. At that point I switched to a REC BMS.
For my own banks charging I decided on 13.8V @ roughly a .4C charge rate with a 30 minute absorption and no float. The primary charge source for this bank has been the alternator and a Balmar MC 614 regulator. While we had plenty of solar solar it remained off most of the time. We used this bank with just 30 minutes of engine runtime a day. This is pretty easy in Maine with the light winds we have in the summer. Doing all the charging from the alternator worked out perfectly. If we needed to stay at anchor for more than three days I would simply flip on the solar array just to slow the discharge. The original charge regime I set up for this bank back in 2009 has worked amazingly well. Today the battery has over 2300 cycles on it with almost every cycle going to at least 80% depth of discharge purposely. As of the last discharge capacity test the bank could still deliver the full 400 amp hours of capacity (Technically a little bit over). So, for those who say LiFePo4 hasn't been around long enough to see how long it actually lasts, I'd say 13 years & 2300+ cycles is pretty good data so I am personally sold.
I fitted brand new lead acids when we left the UK. On our Biscay crossing I ended up taking them down to 12.2v a few times running the autopilot in challenging conditions overnight (the boat wasn't yet properly set up, Hydrovane, lithium, and most of the solar were aboard but not yet installed).
Thanks I'll enjoy reading.
The same seems to be true in reverse though, to be fair. Just like with anchors. AGM is the new CQR and the holdouts will be hoarding them in years to come!
Who said I was insisting on 15 years? It was a figure that was 50% greater than the life of my last set of bog standard lead acid batteries. I am hoping to get 12 years out of my current AGMs, but we will see.
I thought Torqeedo motors were 100% waterproof? I read on these pages that in an incident where the driven boat sank or became entirely immersed, its Torqeedo continued running long after, either hampering or helping recovery.
I make most of my living fitting lithium and solar for cruising boats and probably have to tell more people not to fit it than to fit it. I finished a boat the other day and the neighbour in a weekend cruising mobo that never goes more than 30 miles and only anchors out for a night in nice weather asked if I could do LifePo for him too because he'd heard it was great. After ascertaining his use profile and the cost to make a good conversion I persuaded him that at most he needed a second leisure battery - LA - for £100, plus a bit of cable and 45 minutes of my time...
Delivery is definitely a factor.
For just the battery, lithium is already the cheaper option (unless you're insisting on buying Victron batteries etc). DIY lithium is already just as cheap as leisure batteries, per useable Ah. Drop-ins aren't that much more expensive, probably cheaper than AGM.I'm starting to really like the sound of Lithium. Cost for bottom end Lithium is the same as top end lead acid. You can consistently charge them to 100% and deplete them to 0%. All of the other kit you need to convert to Lithium, fuses, B"B or whatever seems to be free too, as no one mentions that when making a comparison. Excellent stuff
Not confused at all. You made a statement that is not supportable.
