mtdoc wrote: »
The Low voltage and high voltage limits in the BMS would simply be a fail safe to prevent damage to your battery bank if the inverter and charger was not programmed correctly. No need for any direct communication between BMS and other components.
Fatawan wrote: »
I have been looking into Lithium batteries recently. I too think they are the future. Cheap solar got me thinking that I should be adding more panels, driving plug-in hybrids, and even storing electric for backup in emergencies. I am thinking large lithium is a better idea than a generator. This company seems to be the cream of the crop:
Not cheap, of course, but looks like a very good product. I think I read something like $1000/kWh maybe??? When you start to compare to a large generator, it's not so bad.
Also, GM/ABB are jumping in with old Volt batteries
stephendv wrote: »
Some Lithium based systems are becoming available in Europe, there this:
http://www.akasol.com/en/storage-for-renewable-energies/neeoqube.html which is the battery and BMS integrated into 1 unit. 3000 cycles to 80% DoD.
And there's a new all-in-one inverter/charger/MPPT tracker: http://powerrouter.com/products/powerrouter-solar-battery-self-use-li-ion which supports charging lithium batteries, but no details on the batteries themselves.
Chuck46 wrote: »
Here is a link to some folks that are living in a bus with LiFePO4 batteries
BB. wrote: »
Is there any Battery Manage System (cell to cell management) with your setup?
peakbagger wrote: »
THis months home power has an article about Lithium Ions with the pros and cons. The big issue that stood out as a con was that the BMS's currently offered lack some critical features
RCCola wrote: »
Thanks for the response, the power router unit is exactly what I am looking for. Off the shelf inverter/charger that is compatible with 3rd party lithium ion battery systems. This one looks ideal and has the added advantage of having the mppt built in. Hopefully they will come up with a 120/240volt unit to sell in the us.
nut17 wrote: »
Hi Bill, I answered this question on my "newbie" thread, but in short, I have no automated monitoring system for cell balance, but now check manually about once per month and the 4 cells are always within 0.01v, which is even better than the supplier said they would be. Cell balance is apparently no longer an issue with the latest versions of this technology.
PNjunction wrote: »
I had to do some digging, but finally found a reference from Shorai stating why they don't use a bms. It is because they utilize quality matched cells, and designed the battery to be operated within the 10 - 80% DOD range on a regular basis. I have purposely taken my Shorais to the limit, and even when operated well into the knees (95% DOD to 14.8v overcharge - testing only, NOT recommended!) they are STILL relatively well balanced. Solution - don't operate at the extremes. It was only until later did I find that info from the factory and was pleased that it agreed with my own testing.
PNjunction wrote: »
What I discovered is this - assuming that one purchases *quality* cells that are closely matched in internal impedance to each other, (you can order them this way I believe) and stays within both the voltage charging specs, and low voltage discharge specs, the balance is extremely close - until you operate in either one of the "knees" above or below the flat charge / discharge profile. Typically this is about 80 - 10% DOD.
I had to do some digging, but finally found a reference from Shorai stating why they don't use a bms. It is because they utilize quality matched cells, and designed the battery to be operated within the 10 - 80% DOD range on a regular basis.
Just charge up to 14.3v, a little bit under a full charge, and repetetively cycle the voltage from about 14.1 to 14.3v - since the battery is not fully charged, this will allow those cells that are a bit low to come up on their own. Interesting! I'm doing that now on a pair of Shorais paralleled together so I can watch the balance delta over time and see how far it may diverge.
the whole balance issue may be overblown and just needs common sense monitoring now and then.