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Author Topic: FLA v LiFePO4 (prompted by new Tesla battery thread)  (Read 3655 times)
billt
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« on: May 01, 2015, 02:34:12 PM »

I'm still looking at FLAs...

I was going to use FLA traction batteries, then this thread http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13238&page=1#Item_0 got me doing lots of internet research.

The research convinced me that LiFePO4 were worth using, so I now have 15 400Ah Winston LiFeYPO4 cells and a REC-BMS to talk to the SI8.0.

The LiFePO4 system cost about two and a half times the amount 1000Ah of FLA traction batteries would have, but about the same as a set of Rolls batteries.

LiFePO4 batteries are safer than LA, no sulphuric acid.

They are more efficient 90+% against 80% or less.

No maintenance (watering).

Don't have to regularly charge to 100% or equalise (which is very inefficient in LA batteries.)

Can be left in any state of charge.

In theory lifetime should be much greater than FLA, but they haven't been around long enough to prove that.

Usable capacity is greater, I reckon that 400Ah is pretty much equivalent to 1000Ah of LA. In theory LiFePO4 can be run to 90% DOD, LA shouldn't really be discharged to less than 50% regularly if you want a long service life.

They're much lighter. Not much of an issue but it's much easier to put a 13kg cell in the awkward place that my cells are going than 50kg of FLA.

Over charging or fully discharging LiFePo4 cells will drastically shorten their life, so a battery monitoring system is definitely recommended.
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skyewright
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« Reply #1 on: May 01, 2015, 03:50:56 PM »

The research convinced me that LiFePO4 were worth using, so I now have 15 400Ah Winston LiFeYPO4 cells and a REC-BMS to talk to the SI8.0.
So 15 x 3.2V => 48V?

The difference in weight is certainly an interesting aspect. Hopefully you only move them no more than once in & one out (& that hopefully only in many years time...), but 50kg in a solid block is no joke to shift on anything other than a warehouse like level floor, & that's before considering any floor strengthening (not sure my shed floor is up to a couple of tonnes in that small a space with out a bit of extra help to spread the load).

The LiFePO4 system cost about two and a half times the amount 1000Ah of FLA traction batteries would have, but about the same as a set of Rolls batteries.
~480 euro a piece, plus bits, plus carriage, plus VAT?
Am I on the right lines?

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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
camillitech
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« Reply #2 on: May 01, 2015, 03:51:24 PM »

Would love some regular reports on this Billt and how the SI performs with them. I think a set of LiFePO4 cells would be a good retirement present from my employer  hysteria



Good luck, Paul
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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« Reply #3 on: May 01, 2015, 03:56:52 PM »

a REC-BMS to talk to the SI8.0.
A website that doesn't quote a price? Or am I missing something (PM welcome if you feel it's more appropriate).
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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
billt
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« Reply #4 on: May 01, 2015, 08:58:09 PM »

So 15 x 3.2V => 48V?

Yes. You'ld normally use 16 cells for a nominal 48V pack, but the BMS can only handle 15 cells, but that's within the range that the SI can handle. The usable voltage of the cells is 2.8-3.4, or 42-51V for the pack. The SI can cope with 41-63V.

The difference in weight is certainly an interesting aspect. Hopefully you only move them no more than once in & one out (& that hopefully only in many years time...), but 50kg in a solid block is no joke to shift on anything other than a warehouse like level floor, & that's before considering any floor strengthening (not sure my shed floor is up to a couple of tonnes in that small a space with out a bit of extra help to spread the load).

The issue I have is that my battery shed will be behind the house and the only access is either up a steep bank or down an even steeper bank. Carrying a traction battery into position would be completely impossible. I can get them up there with my tractor, but I haven't laid the concrete floor yet, and putting them up there, then moving them to lay the floor is definitely not on. The lithium batteries can moved into position manually and moved again later if necessary.

~480 euro a piece, plus bits, plus carriage, plus VAT?
Am I on the right lines?

Yes. The total including 21% VAT, terminal links and covers, a contactor and various financial fees was 7250.
The 1000ah traction batteries would have cost 3377. Of course, if my name was Billi, I could have sourced the FLAs for 1000 and the Lithium batteries for 2000!

A website that doesn't quote a price? Or am I missing something (PM welcome if you feel it's more appropriate).

That's not unusual for this sort of thing. http://www.nothnagel-marine.de/index.php?cat=c277_REC-BMS-System.html gives one resellers prices for some of the REC stuff, although not the SMA version.

The REC system was about 560, most of which was ancillary stuff like current sensors (and 22% VAT and bank fees). Rather expensive, but you need something which will talk to the Sunny Island to tell it to stop charging, and I couldn't find any other DIY system which would do it. It would probably be possible to make an Arduino based system which could monitor the batteries and send CAN-bus messages to the SI, but that's well beyond my capabilities and I want something that has a reasonable chance of working.

Of course, it could all go horribly wrong and I've wasted rather a lot of money!
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skyewright
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« Reply #5 on: May 01, 2015, 09:50:50 PM »

Of course, it could all go horribly wrong and I've wasted rather a lot of money!
I have a feeling that you're on the leading edge of technology rather than the bleeding edge.  Wink

Thanks for the info.
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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
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« Reply #6 on: May 01, 2015, 11:11:12 PM »




Yes. The total including 21% VAT, terminal links and covers, a contactor and various financial fees was 7250.
The 1000ah traction batteries would have cost 3377. Of course, if my name was Billi, I could have sourced the FLAs for 1000 and the Lithium batteries for 2000!




Aye Billt, that's broadly in line with my costings a year or two back, 3500 for the Rolls and 7500 for LiFePO4. In the end I went for the FLA's because it's what I'm comfortable with but I look forward to hearing how you get on with the lithium cells.

Cheers, Paul
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
billi
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« Reply #7 on: May 02, 2015, 07:28:59 AM »

Quote
Yes. The total including 21% VAT, terminal links and covers, a contactor and various financial fees was 7250.
The 1000ah traction batteries would have cost 3377. Of course, if my name was Billi, I could have sourced the FLAs for 1000 and the Lithium batteries for 2000!


Ok....                                  Are you talking to me  ?

I have received  quotations ......
A 70 kWh traction battery costs about 3377  , if you take 15 kWh out  = 20 % discharge = 7000 cycles =  3.12 pence per taken out kWh
You have now
 a 20 kWh LifeingPoo  battery        for  7250 , if you take 15 kWh out  = 80 % discharge = 3000-4000 cycles? =  13 pence per taken out kWh
  
 http://www.ev-power.eu/docs/web/2014/GWL-Battery-Bank-WB-Spec.pdf


Ok...

cheers Billi





« Last Edit: May 02, 2015, 07:33:10 AM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
skyewright
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« Reply #8 on: May 02, 2015, 10:51:08 PM »

Aye Billt, that's broadly in line with my costings a year or two back, 3500 for the Rolls and 7500 for LiFePO4.
Just checking we are talking like for like...

In the first post billt wrote:
Quote
The LiFePO4 system cost about two and a half times the amount 1000Ah of FLA traction batteries would have, but about the same as a set of Rolls batteries.
My guess was that meant maybe 24 x Rolls Series 4000 2V ~1000Ah @ C20, S1450, which does seem to work out at over 7000.

I thought[1], you got something like 8 x Rolls Series 4000 6V 400Ah C20 (the "S550" maybe?), but on current prices that would be a lot less than 3500, so I think I must be wrong?



[1] I tried to check your "Rolls Batteries Rock" topic but the as the Navi shop link was broken by the change of shopping cart
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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
camillitech
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« Reply #9 on: May 02, 2015, 11:10:35 PM »

Hi David,

mine are S550s and I've 16,



I'm sure I could have got them cheaper but they come with a seven year guarantee and a 24 hour helpline  Grin I also got a 50% grant under the CCAGS and I'm VAT registered.

Cheers, Paul

PS, I'm looking to come over and collect those panels in the next fortnight if that's OK.
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
billt
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« Reply #10 on: May 03, 2015, 09:49:11 AM »

Yes, my lead acids were the cheapest forklift type that I could find. The nearest Rolls equivalent was the S-1380, which Navitron have listed at 303 each, or 7272 for 24!

Using a billi style comparison, but using sensible figures. Lead acid sensible usable capacity is about 40% of the nominal capacity. Don't want to discharge below 50% and it would seem to be a lengthy and inefficient process to get up to 100%. On quite a few days there won't be enough energy available to do that. It's more sensible to use the 10 hour rate for capacity.

Using that basis the fork lift batteries have a usable capacity of 17.6kWhr, the sellers guess at a life of 2500 cycles to 50% DOD. That gives a billi cost of 7.6p per kwhr.

The Rolls batteries have a capacity of 17.1kWhr, they quote 1280 cycles to 50% DOD giving a cost of 33.1p per kWhr.

Lithium batts have a capacity of 15.4kWhr to 80% DOD and 2200 cycles at 80% DOD giving a cost of 21.5p per kWhr.

Edit. Of course if we were to use billis fantasys we could say that the Lithiums would have a life of 8000 cycles (which I've seen claimed). Then they would be down to 5.9p per kWhr, cheaper than either of the FLAs.

Of course, these calculations are nonsense, because lifetimes are a great unknown, even with well established FLAs and highly dependent on useage and maintenance.

So Lithium is more expensive (what's new!), but the advantages (especially lack of regular maintenance) are worth it to me. Either variety is likely to outlast my lifetime.
« Last Edit: May 03, 2015, 09:53:05 AM by billt » Logged
skyewright
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« Reply #11 on: May 03, 2015, 03:07:45 PM »

mine are S550s and I've 16,
Ah. Twice as many. No wonder my figures were out! I thought 48V x 400Ah seemed a bit small given your set up...

[img]I'm sure I could have got them cheaper but they come with a seven year guarantee and a 24 hour helpline  Grin I also got a 50% grant under the CCAGS and I'm VAT registered.[/quote]
Win win. Smiley

PS, I'm looking to come over and collect those panels in the next fortnight if that's OK.
You'll be welcome. I'll PM later.

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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
skyewright
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« Reply #12 on: May 04, 2015, 11:22:26 AM »

Aye Billt, that's broadly in line with my costings a year or two back, 3500 for the Rolls
So Lithium is more expensive (what's new!), but the advantages (especially lack of regular maintenance) are worth it to me. Either variety is likely to outlast my lifetime.
Paul, on the question of maintenance, you went for the "water miser"/"hydro" caps on your Rolls. Have you been running the system long enough now to comment on the difference they make to maintenance?
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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
camillitech
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« Reply #13 on: May 04, 2015, 02:25:29 PM »


Paul, on the question of maintenance, you went for the "water miser"/"hydro" caps on your Rolls. Have you been running the system long enough now to comment on the difference they make to maintenance?

Hi David,

I've just put 12lt of water in since September so in my humble oppinion, not worth the money. Originally when I costed the system distilled/deionised water was about 1 per liter by the time I got it to Raasay and it had to come from Inverness, now you can buy it in Portree for much less.

Cheers, Paul

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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
billi
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« Reply #14 on: May 07, 2015, 02:05:20 AM »

Billt , do you think  , you are  accurate  ....

Quote
The 1000ah traction batteries would have cost 3377

Quote
Using that basis the fork lift batteries have a usable capacity of 17.6kWhr, the sellers guess at a life of 2500 cycles to 50% DOD. That gives a billi cost of 7.6p per kwhr.

Quote
The Rolls batteries have a capacity of 17.1kWhr, they quote 1280 cycles to 50% DOD giving a cost of 33.1p per kWhr.

The Rolls is rated at  C20   , so  if you compare that with a 1000 ah 48 v forklift  traction battery  , that are rated at C5 ,  that is then  approx  a 60 kWh Battery  @ C20  and at 50% DOD then  certainly closer to   30 kWh !

for those  you get a warranty  of  1500 cycles  at 80% DOD   and still then 80% rest capacity left    - no guessing  Wink -

but  who needs a battery as big   Roll Eyes my forklift one is  approx 12 years old now -7 years with me-  and i assume the  the first owner  with a forklift used them heavily ....

we usually take out  between 2-4 kwh during the night and  at 20kwh , then another charging source than pv has to assist .... so a 25 kwh battery would do us fine, list price for a 10PzS900  24 volt battery is below 1500

the Winston LiFeYPo4  battery  bank  that the guy was  talking about on the green building forum  has
Quote
Operating life    3,000 cycles at 70% Depth of discharge
according  to the specs on the balqon compay website

billi

« Last Edit: May 07, 2015, 09:45:15 AM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
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