Rob Beckers
18th June 2016, 15:33
We recently started selling Lithium-ion batteries (http://www.solacity.com/product-category/batteries/lithium-ion/), not without some trepidation, as these are expensive and I do not want to sell items that don't live up to the promises. At CAD$7,500 for a 400 Ah 12 Volt battery bank, this is nearly 10x the price of Surrette's flooded lead-acid batteries. Compared to sealed lead-acid (AGM) it would be about 5x the price for Lithium-ion. By the way, that price does include the Battery Management System (BMS), it's build into these batteries.
Even the much-hyped Tesla battery, which incidentally is the cheapest Lithium-ion I've seen so far, is still around 4x the price of lead-acid, and that price does NOT include the absolutely needed BMS.
So, is it worth it?
The claim to fame of LiFePO4 batteries is that they last many more cycles. The supplier we get them from claims 4000 cycles at 80% DOD, and over 6000 cycles at 50% DOD. For most off-grid people that would mean a 20+ year life-span. But does it really last that long?
What is great as well is that there's really no maintenance. These are sealed batteries, you can't do any maintenance, and they are supposed to be insensitive to state-of-charge. Where lead-acid is destroyed if the batteries sit at partial SOC for long periods of time, Li-ion has no problem with that (as far as I know).
There are those that claim a Li-ion battery bank can be sized much smaller than a comparable lead-acid bank. I'm not sure how that is supposed to work. I can see that it can be a little smaller due to the larger SOC swings you can make on a regular basis with Li-ion, but seeing how some installers use Li-ion battery banks that are just a fraction of the size of what a properly sized lead-acid bank would be I don't follow the logic of that.
What I've read about Li-ion batteries is that they do need some baby-ing: Discharge them below 20% SOC and you do permanent damage. Charge them to 100% and let them sit at that does permanent damage. The BMS is supposed to take care of these limits. The BMS also limits charge and discharge currents (as it needs to be able to bypass them).
Li-ion also seems to have a problem with temperatures below 0C; it works, but at much lower charge and discharge currents.
I'd like to hear from others, hopefully those with experience with Li-ion, and find out what's real, what's hype, and ultimately if it's worth the investment. I would like to know how people should properly take care of a Li-ion battery bank; they are expensive enough that I'd hate to see them destroyed due to improper care.
Let's hear it!
-RoB-
Even the much-hyped Tesla battery, which incidentally is the cheapest Lithium-ion I've seen so far, is still around 4x the price of lead-acid, and that price does NOT include the absolutely needed BMS.
So, is it worth it?
The claim to fame of LiFePO4 batteries is that they last many more cycles. The supplier we get them from claims 4000 cycles at 80% DOD, and over 6000 cycles at 50% DOD. For most off-grid people that would mean a 20+ year life-span. But does it really last that long?
What is great as well is that there's really no maintenance. These are sealed batteries, you can't do any maintenance, and they are supposed to be insensitive to state-of-charge. Where lead-acid is destroyed if the batteries sit at partial SOC for long periods of time, Li-ion has no problem with that (as far as I know).
There are those that claim a Li-ion battery bank can be sized much smaller than a comparable lead-acid bank. I'm not sure how that is supposed to work. I can see that it can be a little smaller due to the larger SOC swings you can make on a regular basis with Li-ion, but seeing how some installers use Li-ion battery banks that are just a fraction of the size of what a properly sized lead-acid bank would be I don't follow the logic of that.
What I've read about Li-ion batteries is that they do need some baby-ing: Discharge them below 20% SOC and you do permanent damage. Charge them to 100% and let them sit at that does permanent damage. The BMS is supposed to take care of these limits. The BMS also limits charge and discharge currents (as it needs to be able to bypass them).
Li-ion also seems to have a problem with temperatures below 0C; it works, but at much lower charge and discharge currents.
I'd like to hear from others, hopefully those with experience with Li-ion, and find out what's real, what's hype, and ultimately if it's worth the investment. I would like to know how people should properly take care of a Li-ion battery bank; they are expensive enough that I'd hate to see them destroyed due to improper care.
Let's hear it!
-RoB-