Lithium battery charge profiles

[mahendra]

ok so its not just any lithium then?

[Cniemand]

Lithium batteries vary greatly. That is why people are fearful of them. Such as lithium cobalt or lithium manganese with catching fire. Those early laptop batteries.

I'm not aware/have direct knowledge of the other lithium chemistries. The Lithium Iron Phosphate LiFePo4 ones are those I use. They are pretty stable when kept in their voltage ranges.

They are the ones that show 2-3000 cycles for 80%dod. I believe that the data suggests the cycle life changes quite a bit better when only using say 70% or less.

[mahendra]

thank for the info

[jimbo]

Any updates on the Lithium?  Prices from http://www.balqon.com/energy-storage/ seem very reasonable.

[tecnodave]

BYD of China , the largest manufacturer of LiFePo4 cells , is building a huge assembly plant in Lancaster, California to build city transit busses for the American Transit Industry. These buses are to be powered by LiFePo4 cells.

This is going to change the whole picture as to pricing/availability of these cells. Last I have heard , full production in 2015.   (Assembled busses, not batteries)

Real game changer,

td

[mahendra]

that's great news if the price is going to really drop significantly. Hope we can get hold of a few too.I have sourced lithium batteries such as sinopoly and calb directly from china prices are really good ,shipping is really unfriendly. Don't know why but its really high to any part of the world

[cpm]

I still don't get it.

24v/380ah in AGM L-16 form costs me something like $2K in big round numbers

24V/400ah in LiFePo4 would set me back about $3.6K in big round numbers, and last 4 to 5x as long, and not be a toxic mess.
(and have 5x the warranty).

So, Why is it that lithium is still considered too expensive?

I'm confused.

[tecnodave]

Just bought 24 volt 380a.h. Flooded lead acid $840 delivered  good quality industrial set.
Best quote LiFePo4 200 a.h. 24 volt set, $3000 with BMS.  Price getting better but were not there yet.
400 a.h. Complete about $6995. F.O.B. Fremont ,Calif.  BYD cells , assembled in CA.

another two years they will be more reasonable as BYD ramps up for the demand.

td

[mahendra]

well they are considered expensive because it is difficult to fork out that kind of cash for a set,but that s just my opinion

[tecnodave]

I'm in the same boat there, I like the idea of lithium but the cash is not there right now. I think that they will be a better solution as you get rid of the toxics, explosive gasses, etc. What intrigues me most is the long life. I get real good life from FLA but that is where my experience is. I did a winter in Fairbanks Alasks working for Alaskan Husky Battery Company building batteries that work at 70 degrees below so I have lots of experience with FLA and regularly get 10-12 years from a well maintained set. I just bought a set of Rolls S-530 RE L-16's headed to the scrapyard for $20.00 from a person who did not know how to maintain them.  Two weeks on a solar trickle charge with high voltage panels direct connected ( no cc only a reverse flow blocking diode ) they are coming back nicely....all cells within .012, and I find that to be typical.  I think that a good 50% of batteries of all types die from "LOM"  ( lack of maintaince )  now if installers could educate buyers about maintaince!
I think that most consumers believe that unlimited power will come out of an outlet regardless of circumstances.

Maybe if I win the lotto I will buy LiFePo4 batteries and a new EGO inverter and maybe another Classic or two.....LOL!

[jimbo]

So what is your secret to getting good life out of FLA?

[tecnodave]

Jimbo,

Glass float hydrometer!  Better ones count! Must be able to resolve .005 s.g.
Chart the result....I have a notebook that I log my weekly hydrometer readings for each set

Don't run them down too much! And don't use only the top few % of capacity
Chargers must have proper profile or your eye on it in case of old school bulk charger
Heat kills batteries, keep them cool, use chargers that have thermal feedback. (BTS) inverters/chargers should have BTS as well
Good source of distilled water, it's not all the same!  Minerals will kill a battery quickly!

Biggest mistakes I see, too low a voltage for job ,too high current, too big of inverter for job

It's all about maintaince. I am very mechanical so it's just my nature.


If I have a set in trouble I correct the problem before it gets worse, if I am getting low readings on one cell maybe down .020 from the others I pull that set from service and charge with a high resistance source. Right now I'm using some Cadmium Telluride panels at 92 v.o.c. directly connected through diode to 24 volt set. This provides high enough voltage to burn sulfation from cells but will throttle current to a safe value. I am just looking to wake them up, not a hard charge, sometimes I will let them sit at a charge only a few percent of the 20 hour rate for several weeks.

There are many little things that add up and count.

td

[jimbo]

Thanks for the advice.

Don't run them down too much! And don't use only the top few % of capacity

Any figures you like to use?

[tecnodave]

Jimbo,

I use mostly L-16's and don't charge set until at least down 20-25% more like 45-50% unless I'm in summer foggy season and almost never go below 70 % total A.H. capacity.  I have two separate banks for my household (32 foot Tioga Motorhome and tiny cabin) and two more for my 40 foot shipping container workshop and use one set or the other switched with 300 amp marine switches so I'm using "A" bank and charging "B" bank...way better control.....but then I have been tinkering electricity since the early 60's....am commercial electrician for a living....AC and DC...."A" bank are bought new and "B" bank are all recycled from my work

Note:  this will confuse the Classic using WBjr. it's seeing discharge from one set and charge on other set.  I use separate BTM on each set and switch them to set being

Too complicated!

td

[jimbo]

Oh ok, my 1600 amp, 24v Raylites get a much easier time then that. The previous owners had the generator kicking in automatically at around 80% SOC but i have since dropped that down to 65-70 % SOC.  I try to test the SG every 60 days and so far they are all very close. Hopefully i will get a few more years out of them (currently 6.5 years old)