Author Topic: Changing from SLA to LifePo4 batteries  (Read 6704 times)

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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #45 on: June 13, 2021, 10:51:23 pm »

Thanks LH,
The 5a active balancer is doing a surprisingly good job keeping the 'new' half of the bank's cells even.  The smaller 1.2a active balancer on the 'old' half of the bank struggles to keep things even. 
I'm almost ready to add the 5a shunt balancer setup to the 'new' half, after which I will remove the individual small bms' and 1.2a active balancer from the 'old' half, parallel all those cells, then connect the 'old' half's cells to the 'new' half's cells, completing the paralleling of the whole bank. (whew!)  It will truly be one large battery at that point.  The combination of the 5a active balancer plus the 5a shunt balancer should be able to handle whatever happens....

I've been running a narrow charging range; only up to 54v(3.375v/cell) until all the above was done.  Once done and settled in, I'll start bumping the top voltage up some. Hoping to get to 56v (3.5v) while still maintaining cell balance.  I'll be happy with 56v.  I do fine with 54v, just think I can squeeze a little more capacity out of this big bank.

As far as low voltage goes, I have no plans to run below 48v.  Mainly because powerjack inverters start losing the nice sinewave below 48v.  Also the lfp batteries drop voltage quickly below 48v.  So I put an alarm on the bank that sounds when it dips below 48v.  It's only going to happen in winter (or other unsual circumstances - like several consecutive stormy days).  Then I have to switch over to (ugh!) grid power.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #46 on: August 05, 2021, 12:28:08 pm »

Haven't had much to post about for awhile.  Long summer honey-do list plus 100F+ temps since early June have limited my productivity. (It's not that great anyway!)  I have managed to get the cells paralleled on the 'old' half of the bank.  Removed the 4 daly bms' and the small active balancer from that side.  The bank is now balanced better from just being paralleled than it was with all the small balancers in use.  Guess I'm continuing to learn.
Also did the wiring for the 5a shunt balancer setup.  It's ready to mount.
9092-0
Once it's up in place I can start hooking it into the 'new' half.  I'll let that half settle in a few days before paralleling in the 'old' half.

Other than that stuff, the 15kw powerjack is humming along, doing an excellent job of running the house 24/7.  Sadly, those 100 degree+ daily temps have forced me to run the central air, which means paying Idaho Power to run it on grid power.  I never planned my system to run the ac because we typically only need it 14-15 days per year.  It'll be closer to 4 solid months worth this summer.  I'll pay it, because we're not willing to be miserable to avoid paying.  Not worth it and not the point.
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Offline lighthunter

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Re: Changing from SLA to LifePo4 batteries
« Reply #47 on: August 05, 2021, 02:17:06 pm »
Hi Doc! I removed our central AC about a year after buying the place when i realized it needed recharging. I didnt want the annual service bill that comes with many of those. So we run two 8Kbtu window ACs 24/7, they both cycle a fair amount, keeping everything between 70-74F. Love the setup and easy to manage with solar powerwise We have a large home but is insulated well. I leave 3 oscillating fans on 24/7 one in garage and one each near the AC units. Weve been using around 25kw daily from the solar and since i dont have that much storage the solar switches to grid 8-9pm every evening and switches back at similar morning hour. So 12 hrs on grid as hot its been used about. 700kwh from grid in july so guessin you still got me beat HA. Without the heat load the solar normally lasts till 2 or 3 in the morning dropping the grid use to 350kwh (electric range, dryer and DHW) Theres room for better utilization here since the 6kw of panels could do 50kwh most days. But hey its miles ahead of doing no RE at all. One of my future ambitions is to drive to work on RE. With the butheads running our gov gas will probably be pretty expensive.
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LH

Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #48 on: August 05, 2021, 05:47:05 pm »
Wow LH, you keep the house hot. 70 to 74 F wow. Where we live if the house gets to 21C (69.8F) we open the door to let the house cool down a bit.
Seems odd to me that we see people in Summer who want their houses to be freezing cold then in winter they want their houses to be hot.
I reckon that our blood has thickened a lot and consider it to have the viscosity of molasses now. We don't have AC because we only get a couple of days a year that go above 25C (77F) which we consider hot. On those days we keep to the shade.
Cheers
Pete

Offline rossw

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Re: Changing from SLA to LifePo4 batteries
« Reply #49 on: August 05, 2021, 09:07:12 pm »
we only get a couple of days a year that go above 25C (77F) which we consider hot. On those days we keep to the shade.

Wow Pete, that's barely above frozen!
Summer here we regularly see 45C and on odd occasions 2 or 3 more than that.
Fortunately, to us "cold" is anything below zero, we get a couple of days a year around -3C, and every few years we hit -6 or -7C


Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #50 on: August 05, 2021, 10:03:28 pm »
Hi Ross, you have much more extremes than we do. On the mountain we live on we have winter days with between 1 and 8 degrees, summer usually 12 to 25 degrees C.
On very rare occasions we get heatwaves of 28 here. In Launceston it gets hotter, but we are usually 5 degrees less than those lowlanders.
Nights well not much below -3 , outside.
Cheers
Pete

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #51 on: August 08, 2021, 09:46:27 am »

Hi guys!
LH, I do have a window unit ac that I haven't put in a window yet.  I should get around to that....
I'm glad I'm not the only one getting hot temps Ross. Misery loves company.   Jealous of your weather, Pete.  It' supposed to be cooler here this week.  Only up in the 80s(cold snap!-hah!)

Getting the shunt balancer connected up.  Got a new phone, so new camera.  Not my idea.  Sprint says, "Your iphone 5 won't work after January, but boy we have a deal for you!  Free phone!" I took it but still waiting for the other shoe to drop. (One would think I'm not a trusting person!)
Anyway, pics are higher res so take longer to upload.  Still being rotated to the left 90 degrees when I upload so must be my computer doing it.  Before uploading, if I view a pic, rotate it 90 then rotate it back, then resave it, it uploads fine.  No idea.
Still figuring out the new camera, so here's a pic of partially connected shunt balancer.
9094-0
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Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #52 on: August 08, 2021, 05:34:24 pm »
Looks nice Doc, How many villages are you going to be powering?
Maybe it is time for us all to look at moving underground. Seems that there are giant fires in the US, and Greece.
A few feet of dirt all over the house would be good insurance.
I hope your batteries last for a long time Doc, sure seems like a lot of work you have put in there.
Pete

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #53 on: August 08, 2021, 06:04:03 pm »
Thanks Pete,
I could definitely power more than I am now.  It's wintertime's short days and long nights I'm trying to provide for.  But yeah, a lot of work.  Hope it will be worth it in the long run.  Hoping these batts last a long time too.
Fires are a worry.  One reason I'm not in california any longer.  Lost my house to the big 03 fire there.  Fires in Oregon and Idaho are a long ways from here, luckily.  Not too many trees here in the immediate neighborhood.  Grass fires I'll just have to deal with if they come.  Hope not.

The shunt balancer is wired up to the 'new' half of the bank.  Pic is pretty good.  You can zoom in and read the cell volts of each cell.  Old camera wouldn't have been clear enough. 
I'll have to wait a few days to wire up the 'old' half.  Not enough wire.  Had to order some more.  Using 14ga stranded hi temp wire. 
Balancer won't do much until both halves are connected and I bump up the charging from 54v to 56v.  Kicks in at (i think) 3.55v/cell.  Each balancer cell is individual.
Wish I had put this one in first thing.  Spent a lot on small balancers, BMS', and active balancers that couldn't handle these batteries.  Learning as you go gets expensive.  I think this setup will do the job properly.  Time will tell....

9096-0

Should have waited to take the pic until I had dressed up the wires, but oh well.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #54 on: August 19, 2021, 03:22:54 pm »

Ok, everything is connected, all cells are paralleled on both halves of the bank.

Been watching for a couple of days and gradually increasing charge settings.  Float is now 56v and bulk is at 56.8v. Balance isn't bad.  Charging has been hampered some by sporadic sun and smoke from west coast fires.  After a windy night blew some of the smoke out, getting a good charge today at 95a.  Had to fix a couple small things, but now the balancer seems to be doing it's job.  The fan/temp control is doing it's job keeping the heatsink cool.  Still have 3 cells not quite coming up to the rest at this setting, but improving daily.  Will give it a couple more days at this setting and see what I get. 
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Offline lighthunter

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Re: Changing from SLA to LifePo4 batteries
« Reply #55 on: August 20, 2021, 09:25:59 am »
Hi Doc!  Lookin real good. You do nice work!
It is enjoyable when it all works like it should.   New LFP prices are about 1/2 what i paid a few years ago.  $500/kwh 2016 vs $500/kwh today. Now its a thinker between FLA and LFP on price. FLA still beats LFP on up front cost but the value brings LFP ahead. Do you have any statistics on your used cells DOC? Are they 5yrs? 10Yrs old? Roughly how many cycles and i think you said the capacity now is like 70%? That info may help others make decisions but i realize it may not be available. I plan to do a capacity check on my 5yr old cells to see how they are holding up and will report that soon.

Iphone i know nothing about but do know my phone camera has a setting if i want picture saved by orientation sensor or left original.
Health Warning: May contain traces of nut!
LH

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #56 on: August 20, 2021, 04:49:35 pm »
Hi LH,
I don't know how old the BYD modules are.  There was no info available.  No labels with any dates.  (might be in chinese!)
I just had to take a chance based on the cheap price.  Hoping they will last long enough that prices to replace them will be much more realistic.  As you point out, the prices are already dropping.
To my knowledge, There are no more BYD modules available anywhere.  Right after I bought my second set they all disappeared (at least online).

Also figuring the large size of my battery bank will help extend the lifetime by reducing severe cycling.  Guess time will tell.
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Offline lighthunter

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Re: Changing from SLA to LifePo4 batteries
« Reply #57 on: August 21, 2021, 12:32:12 pm »
Hey Doc! Thanks 4 the feedback. You did really well with your storage setup. Very few have capacity like you do now.
I was looking at the cell monitors you have, (cellmeter) do those have an output contact or audible alarm for low/hi cell volts?  The cellog8S has this but they no longer make it. Too bad seems wierd they discontinue popular products like that.
Health Warning: May contain traces of nut!
LH

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #58 on: August 21, 2021, 10:52:31 pm »
Hi LH,
As near as I can tell, the cellmeter8 has no alarms at all.  It supposedly has a way to test a servo, if you could make that usefull. 

The translated instructions are terrible, so not really sure if it is trying to balance or not.  It wouldn't have much effect on my batteries anyway.
I bought them as cheap real time voltmeters and (approximate) state of charge readouts.

Also have a ISDT BG8s meter.  Costs 3x more than cellmeter8. Cooler display.  Shows all cells on one screen.  Actually seems to do some balancing.  No alarms that I can see.
Sorry, not much use to you seems like.

Funny how test equipment changes over time.  Many years ago I used to use a Simpson 260P multimeter working on navy ships.  Was considered the best you could get.  It cost way more than I could afford then.  Bought one in great shape last weekend at an estate sale for $8.  With case.  This weekend got an Amprobe clamp-on ammeter for $6. Also with case.  Couldn't afford one of them back then either.  Digital meters have displaced them, so guess I bought them out of nostalgia.
The meters we're using today won't last long enough for someone to find (still working!) at an estate sale years from now.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #59 on: August 22, 2021, 10:28:47 am »
Have to correct my earlier statement.
The ISDT8s does have a settable, audible  low cell voltage alarm.  No high voltage though.
We're all going to DIE!  (eventually)

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