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Small Cabin Forum / Member's Projects and Photos / Creeky's lithium battery build
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# Posted: 1 Jul 2016 10:20

Okay. Canada Day is officially Christmas Day for me.

Woke up at 5. Yup. 5 hrs of sleep and I'm getting dressed and running out through the cold morning dew to the solar shed. 47.6. That's the voltage of my battery pack after running over night.

I test each battery. Each battery reads 47.6. Excellent. All six batteries are installed correctly. It was a bit of a battle getting them all wired up.

The bus bars I use are Nimbus pbts insulated multi tap connectors. I've had them since the first build. Man they make things so easy. And nothing is exposed. It's all tidy in an insulated case.

So. Excited by the low overnight energy use (550 watts). And haven proved the satisfactory installation quality (double checking switches and flashed eeprom settings etc). I turn on the dishwasher.

I go back to bed.

Get up around 8:30. Check the online stats on my computer. 46.7. Everything is working. If I can run my dishwasher and have the fridge go on and off. All is well in Creeky land.

Two thumbs up to Victron. The Victron also runs at 120v. And because you don't have (I'm guessing here) the voltage drop from lead acid, I've noticed the lights no longer dim ever so slightly when the fridge start up surge hits. Praise be the lithium.

Then I notice my controllers are reading "night." But wait. It's sunny out. Off I go again. Flip flip flip. Turn the panel breakers to on. Doh!!!

Ah. Making power began at 8:45. It's now 10:15. I'm up to 47.71. So another hour before I'm back to full charge?

Life is good.

Peace and happiness to all.

# Posted: 6 Jul 2016 13:10

Got my cell log 8m in. After some fiddle faddlin', I found how to measure up to 8 cells at a time direct through the OEM plug.

cell log 8m

I ran a full check on my solar system battery install. There is a maximum of .01v difference between the highest cell and the lowest (one hundredth). And most batteries are like the picture you see above. Those cells are within 6 thousandths of a volt. Or very darn close.

Note: my safety margin .1v. Or 1/10th of a volt.

Finally. There is something quite disconcerting and dissonant to turning on the dishwasher as one goes to bed. At least for a guy who's been off grid for 5 years.

I mean. a 2kw load in the middle of the night. Not with lead acid that's for sure. Or AGM. Or Gel. Or any other horse and buggy whip tech.

Lithium rules! Time to break out the induction cooker!

PS-used 6840 watts yesterday. Recharging after a load test with 5kw. Today I recharged (after using the dishwasher overnight) with 4kw.

# Posted: 6 Jul 2016 13:27

dang fridge and dish washer off grid?? that's impressive

# Posted: 6 Jul 2016 13:45

With modern appliance efficiency you can have A/C too... split mini.

# Posted: 6 Jul 2016 14:49

I am running an a/c unit even as I write. Little 5,000 btu thing. Plus, I just cooked my lunch (grilled chicken sandwich) on the induction hob (english for cooker or stove top).

MtnDon. I've been looking at the 115v minisplits. air source. they're not that expensive and, at least for part of the winter, I could heat with one too. Be nice for the shoulder season to run some heating off of solar.

I'm well suited to ground source too. Which is even more efficient given my location.

I've been resisting (pun intended) looking at a 240 inverter. It's the overhead I don't like. You know. It becomes a never ending monster. Bigger inverter. More idle draw. More idle draw more panels. More panels. More batteries. More power more devices. More devices bigger inverter ...

So I'll probably stick with what I've got. Unless. Unless.

***Also. I don't need a/c for my winter bedroom. It's amazing what you can do with lots of insulation. A good location (tree shaded/cool roof) and open windows at night. It stays quite cool in the bedroom during the day. It's my studio I use a/c in. Not a tremendous amount of insulation. Tin roof (not cool roofed) baking in the mid day sun.***

Thx Sparky30_06.

I guess I'm really exploring what you can do with even a small solar system. I mean 2kw of panels. (In the summer I could get away with 1). Small lithium battery pack. Huzzah. Er. And a small 1200w inverter.

It really doesn't take much.

Lithium report: Another sign (pun also intended) of the lithium benefit is the stove clock. With lead acid it would drop time on surges (fridge turning on). Its now keeping time perfectly.

# Posted: 6 Jul 2016 15:27

Thanks for sharing your build. This is what we will do next when our monster lead acid dies (48 V 700 AH, scavenged from a fork truck).

You can absolutely run everything a normal home would have off grid. We have 3KW array, and do AC (115 V greer mini-split-- works great), electric hot water (diversion load), fridge, freezer, lights, TV, internet, power tools etc.

We are building a home on the same property now, and I think adding another 3-4 KW to the array will cover us nicely (Pico Hydro picks up during the shoulder seasons and winter)

Did you consider TESLA batteries or is the VOLT the best option for a rebuild?

# Posted: 6 Jul 2016 20:31

Rockmtn. Volts are what was available to me. They were a bit complicated to work out. But ... who doesn't love a challenge. And I'm not done yet. Apparently the Leaf batteries are the best for rebuilds. Easier to manage voltages. I think they're 13s. So a true 48v battery. While the Volts are 12s. Or really a 44. I'm going to have to program the BMS too. Everything running on custom specs. Meh.

Tesla batteries should be out new by the time you get to replacing your batts. Hopefully there will be lots of options. I expect Musk will be doubling down on home power now that he controls Solarcity.

With the new high voltage inverter from SMA. You're next battery will probably be 300v.

Or for you. Maybe a titanium/lithium battery pack. 20,000 discharges. Build it for your grandkids.

Ya the Greer minisplit is the one I'm looking at. Did you self-install? The online folks make it look pretty easy.

And I tell ya. Once you've seen what lithium can do. No way you'll ever go back. The efficiency is freaking me out. I'm using 5 kw overnight. Tonnes of power during the day. And just no problems.

Early days of course.

# Posted: 12 Jul 2016 10:27

I had a nice adventure recently. You see I have one bad battery out of the Volt pack I acquired. This 48v battery has one cell at 3.62 while all the other cells come in at 3.83.

What to do?

Well. I went to see John. The rocket scientist. He's a tech from back in the day, when the NRC was launching rockets into space.


Now he's this pushing 80, fit and full of laughter, single fella with his dog. He supplements his pension by fixing radios. Old radios. Radios the size of apartment fridges with fancy wood cabinets and tubes. Radios so old they were made in places like London Ontario or Utica NY.

So who better to call on to see about this wonky celled battery?

In the meantime I had received my "cell log 8M." This contraption lets me measure 8 of 12 cells at a time.

And it shows I don't have one wonky cell. But 3. Yikes.

It also shows that the cells aren't losing power. They are as stable as all the other cells. It's just that they're exactly .2v lower than the other cells.


I won't go on and on with the details . Suffice it to say that John and I start out with a small constant current power supply. Hooked it up to cell 1 and 2. And set it to 2.5 amps.

Well. Two hours and supper and lawn mowing and ... later. The battery cells had risen from 3.62 to 3.75. A bit more than 1/2 way.

Well this won't do.

So John dusts off the beast. A huge ancient unregulated power supply capable of kicking out 20 amps.

He asks me, do you think the battery can handle it?

Yup I say. Not at all sure. But theoretically I should be able to charge at 45 amps safely. And 135 amps if I'm feeling lucky.

Then he gets out the rectifier. We'll put this .5 ohm load in between the charger and the battery for safety. He says.

You can see it on the table in the photo. It's the long white bar
wrapped with ni-cor wire. Or more commonly known as the wire that your toaster uses to burn your toast.

I'm supressing laughter already when we get all hooked up. Only one sparkle event as the attachment clips are so big. Pieces of wood are found to use to insulate between cells.

Alright says John. Here we go. Click. Nothing. He turns the dial and spins the knob. Nope. Nothing.

A short (heh heh) examination of the beastie reveals that the knob screws are loose. So some tightening goes on. Then, as seen in the pic, the "warning light" falls off.

Now that is funny. And we share a chuckle.

Finally, drum roll please, the switch is flicked. The knob is dialed up. Success. The light on the resistor goes on and the cell log begins to show power climbing in cell 3.

So. Long story short. The charge up of the cells 1, 2 and 3 (according to the cell log) is complete. After 2 days they seem to be stable. I will try charging the whole battery now. And we'll see what's what.

The cause of the low cell voltage is a mystery. Bad BMS?

It was a most pleasurable adventure. With drama. Things fixed. Ancient equipment dusted off and put to good service.

Oh. And John shared with me pics from our rocketry program circa 1968. Very cool. There's a good one of him assembling a silver zinc battery. Which he discharged to 0 before charging to the specified voltage (2.something). And used potassium hydroxide for the electrolyte.


# Posted: 12 Jul 2016 15:07

Gotta hand it to you Creeky, you have the gift of writing up an interesting post about tech stuff that is beyond the average guy. (That's a complement!)

# Posted: 29 Jul 2016 10:52 - Edited by: creeky

Thx Wilbour. I'll keep adding.

On with the show

So after 27 days I have now sent 112kw of solar power to the batteries. I have sent 94kw of solar power to my inverter. And I have done some very bad math.

I take an average of 7 days of charging back when I had the batteries under testing. There were days when the batteries being charged for the first time then sat, hooked up to the solar charger, and then topped up the next day.

This average indicates a solar controller daily load of 130w per controller.

Hence, (18kw of loss - 7kw for the 2 solar controllers load) * 92% for inverter/cable loss = 80% system efficiency.

And it would appear the batteries are aprox 91% efficient.

Note: take none of this too seriously. The solar controller(s) load could be off by a factor of 1.5. And there are other problems. Accuracy of the $18 ammeter by ex.

Yet for all intents

However, be that as it may, and all that. Total battery voltage variance is now at .02v.

Cell balancing?

I appear to have found a simple method of using high cells to top up low cell voltage. both lowering high cells and boosting low cells. So cell balancing in a very hands on way. More on that after further testing.

My quest for a balancer/bms continues. I found some really good docs on the balancing/bms chips that the Volt uses. I haven't had time to read them yet.

Update complete!

PS-still gives me a tingle when I, as I did last night, turn on the dishwasher before going to bed. After watching TV or listening to music late into the eve. Huzzah.

PPS-yesterday was cloudy in the a.m. with full sun bursting onto the panels at peak generating time. My "summer angle" set of 1kw of 8 year old panels delivered 965 watts. Interesting given a) age of the panels; b) haze/dirt affecting the solar gain c) the high temp of the panels on a very hot afternoon d) prorated at 20% efficiency loss over 25 years should mean that the panel set is only capable of delivering 930 watts peak.

I would say 965 is full on original power spec given the panel temp and conditions.

# Posted: 5 Aug 2016 08:46

Final update?

Last night I did a full cell voltage test. I let the batteries come to a rest state after a day of charging. I turned off the fridge to avoid sudden surge loads. Gave it a few more minutes to settle.

Began measuring at 10:45. Complete at 11:02.

Results: Cells at
3.96 - 1
3.97 - 29
3.98 - 42

Total = 72 cells.

This indicates that the battery is balanced. A .02 cell variance is perfect. I might get fussy and top up the one 3.96 cell. We'll see.

My lithium battery pack has now been in operation for a full month. Over 120kws through the inverter. Or 4 kw per day. Woowza.

Real world notes:

* Have not used the gas stove in the past month. I use the induction cook top. Dang. I need some new pots.
* Miss the old inverter. I have had one inverter overload shutdown. Hot day. The a/c unit and fridge tried to start at the same time. Otherwise all is fine.
* system continues to show amazing efficiency. Despite the additional 1/2 kw overnight load from the internet being on 24/7 I am typically fully recharged by 11 a.m.

Peace and happiness abounds on a cricket chirping morning here in creeky's swamp bottom farm.

# Posted: 14 Aug 2016 13:33

Did you perform a bottom balance at any point? And if so, what device/method did you use to reduce the voltage of the individual cells?

# Posted: 15 Aug 2016 11:36

MondayCreek. The battery cells had been kept in balance by the Volt bms. I didn't need to balance before installation. All cells were within .016v. And remain that way after 45 cycles.

Personally I wouldn't bottom balance. There's a lot of discussion on this online. As I imagine you know. I prefer a top balance as it's easier to perform.

Active balancing, which uses the high cells to top up low cells and vice versa, is easy to do manually. And in my application, SESS, is not required very often (yet). There are many installations of various Lithium chemistry that run for years without requiring additional balancing.

In sum: I feel the balancing issue is simpler than thought. For SESS I would not insist on a BMS. Exchanging it for a thoughtful initial assembly with balance; monitoring; and of course, generous knees.

It would be nice, for me, to have internet enabled cell voltage tracking. And I'll probably play with that this winter.

***note to all. If you are using my experience for research, please include a reference to my blog at creektreat dot ca or other acknowledgement of source. For publication, I would greatly appreciate receiving a link to the published document. thank you***

peace and happiness.

# Posted: 15 Aug 2016 13:36

thank you sir. You're lithium musings have definitely inspired me to research and consider alternatives to FLA as I seek to complete by solar build.

# Posted: 23 Aug 2016 22:19

I may have located a Volt battery locally. Based on your experience, how difficult would it be to break the 48v sections into 24v sections? My inverter is 24v.

# Posted: 24 Aug 2016 13:11

there will be two 24v sections already.

I don't know your level of experience / competence with electrical. So I hesitate to say "how easy." I could do it.

Other folks have done it. There is a link earlier to montana rv. go look at how they reconfigured his battery to 12v. It's doable.

I don't wish to put info up online where someone could seriously hurt themselves. So I have a blog. Contact me through there if you go through with the idea.

I can say. It's not hard. And the economics are outstanding. I'm over 200kws and all is perfect.

I was going to stay at 12v with my TBS inverter. Which i loved. however the work to take the pack down to that level wasn't worth it. I sold the TBS and bought a 48v Victron.

Sigh. Miss my TBS.

How big a pack are you thinking to build?

# Posted: 24 Aug 2016 21:25 - Edited by: MondayCreek

I definitely respect your concerns with folks hurting themselves. I'll take another look at the montana rv link and see what I can glean.

It would be for a mostly seasonal cabin where short weekend visits are the norm. I'd like to run a 4-6 camera surveillance system 24/7 but that would be the only required non-weekend load. Therefore I'd like available capacity to be between 7-9kw which I think equates to at minimum a 12kw pack (bank?) to allow for longer battery life.

I'll check out your blog and get in touch there if I have any additional questions specific to my build - thanks again for sharing your adventure.

# Posted: 25 Aug 2016 12:18

no worries.

I would like to hear from you. I'm writing a "how to" for sale and could use a beta tester.

# Posted: 14 Sep 2016 15:30

2 month Lithium report

The cells continue to check out exactly at the voltage spread noted in my first test. And verified in my one month check.

I have 1 cell at .02 lower than the highest. Many cells .01. And most cells within .003v. There has been no change I can see.

My 2kw off grid system produced/used has been:

July: 140,210 watts
Aug: 129,710

for a total of 269,920 watts.

Lithium has allowed me to more than double my electric use with no problems.

And just to bug those with lead acid.

I ran my dishwasher and saw voltage sag and recovery of .01v on the 48v system.

Bwahhhh ha ha haaaa

I have seen the future and it is now.

# Posted: 15 Sep 2016 11:22

nice, I've really enjoyed this thread creeky. For my short visits my FLA system is fine for now and still has life left in it, but when I go seasonal full time, I'm sure I'll be following your lead.

# Posted: 15 Sep 2016 13:35

I'd be interested in the "how to" book. I'm gathering all the parts to the puzzle and the last part, the gbs batteries, should be here momentarily.
The panels and combiner box are ready to go. I do have a few questions about proper order in firing this whole thing up. Right now the panel just need the mc4 connectors plugged to together to start the juice rolling.
Thanks for all the help.

# Posted: 15 Sep 2016 18:57

hey Bret, don't forget. all donations on my blog accepted!

and i'll answer any questions privately from there. there are some tricks to set up and charging that might help.

what size amp hr / voltage did you decide on? sounds like you're real close. what an exciting time ya!

also. thanks guys. it was a lot of research. a lot. and many hours of patience expended by my girlfriend.

icing on the cake to see others getting good use from all that.

# Posted: 29 Nov 2016 14:06

Five month update

Well. I've done it again. I bought another Volt pack. From a 2015 this time. I now have 17.1 kw of lithium power to play with. Huzzah. Read about it here.

And the 12kws I installed five months ago? All performing perfectly. The charge cycle is so efficient that I have yet to need supplemental charging. That's right. My genny still sits in a field over by my well.

My longest period without a full charge is 5 days. Needless to say I don't run the dishwasher during this time. I limit power use to 1.5 to 2.5 kw/day.

Recently I had a 3 day weather event. At the end of which, the first sunny day, I ran the dishwasher. It took that day (6kw from the panels) plus another day (4kw) to catch up.

Unbelievable. The efficiency is truly mind opening. And the lack of pressure to keep the batteries at 100% is also lovely.

Creek does it again

Winter approaches and the batts are getting pretty cool. So I'm off to rebuild the battery box and improve the insulation. Cheers.

# Posted: 22 Jun 2017 08:50

1st Year Report:

Just wanted to share this. I am a bit premature (10 days). But to celebrate SPA day (solar power appreciation) I did a cell monitor round on my battery pack.


To wit,
* no cell drift. None. Zip. Zero.
* efficiency far surpassing expectations
* no maintenance other than monitoring
* = happy Creek

lead is dead. Lithium rules!

# Posted: 22 Jun 2017 09:35

Based entirely on creeky's observations LOL I have made the leap. For his sake I hope he is rite and the 500$ thing works thanks creek .On its way to my house from China as we speek. 48 v 20 amp hr

# Posted: 23 Jun 2017 19:50

With charger. Nice.

# Posted: 19 Feb 2018 09:37

Current update? Where can I find creeky's blog? The links in this post return a message saying database error.

# Posted: 19 Feb 2018 12:52

You can find a lot of information on his web site


# Posted: 19 Feb 2018 13:58

Thanks, that is just what I was looking for.

# Posted: 20 Feb 2018 22:36

Yup. Thx bronco_ed.

Creektreat will rise again. I'm traveling and I didn't migrate my blog site properly with ... anyway. So I'm trying to get the database reset. Blush.


Been meaning to update this. So while my Volt modules continue to stay nicely balanced I recently had a report of a fellow's cells going wildly out of balance quite quickly. SO everyone using Volt cells.

Can you let me know if you experience something similar? And check your cells. I know I've gotten complacent about checking as they don't seem to drift.

Btw. This has nothing to do with the fact I have a great BMS for sale now. smile. But, yes, I'm adding a RedWing BMS to my set up this spring.

Also, the fellow borrowed one of my RedWing BMS and within a day he was back in safe territory and after two weeks his cells were within .009.

So nice to know the BMS works well even with wildly out of whack cells.

The cells have remained balanced since. They do seem to shift a bit (he's been .015 to .013 since). Needless to say, he's measuring weekly.

Right. Back to the holiday. Er, traveling for work.

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