EcoRenovator  

Go Back   EcoRenovator > Improvements > Solar Power
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 07-03-16, 09:19 AM   #31
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

Thanks NiHaoMike. I have been into the endless-sphere and diyelectriccar sites. Lots of info there. (where's the head spinning icon?)

I like this BMS the best so far. Based on the TI bq 96940. I don't know that they are actually shipping it. I would like to find someone who would sell me 1. These guys seem to want sales in the 1,000s.

Bigmouse on diyelectriccar posts pics of his reading of the OEM BMS. I can see how that might work.

IamIan pointed out a great idea for me. And I will be looking at this simpler solution. Thanks again IamIan. Took awhile for what you wrote to sink in. Super appreciated.

Initially of course I'm going to monitor cell voltages. If, as it appears is the case, all the voltages remain more or less in balance. I will keep to a more manual course.

I'm traveling a lot this summer. Which is getting awkward. I just started the system and already I'm away for three days. Would kind of like to be closer at hand to monitor and correct. Oh well. Fingers crossed. "Cloud" monitoring is probably next.

I'm trying to leave some loads (the fridge, internet 24/7, lights) on the batteries so they don't remain too fully charged. Trying for that 5,000 discharges range. Smile. And on that note, I have found some graphs/charts that indicate it's best to keep your discharge to 3.4/cell for longest life. I am set up at 3.2. Will be keeping an eye on that. Of course, to date, my lowest discharge is 3.8.

Looking forward to charting solar watts in/power out and voltages with more data points than day 1.

__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Old 07-05-16, 10:24 AM   #32
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

Introducing the cell log 8

Initially I clipped the wrong fin and had inserted the dang thing upside down. And for this reason the reader didn't work? Okay. Well. I clipped the other fin this time. And looked carefully at the picture of the fellow on endless-sphere using his cell log 8. Voila.

I can now measure up to 8 cell voltages at a time. My plan is to take pictures with my camera. And then track. Certainly should speed monitoring.



Here's a pic of the "bad" battery readout. Turns out 3 cells are low by .2v. That's a lot really. Yet the cell voltage isn't dropping and the cells seem unharmed by the crash. Was there a problem with the OEM battery charge/monitoring? Who can say.

So I am going to charge to balance and then exercise the battery some to see if I can return it to normal function.

That would be 2.125kw of sweet.

Note: this battery is not part of my install.
__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Old 07-05-16, 01:58 PM   #33
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,479
Thanks: 1,113
Thanked 369 Times in 300 Posts
Default

Very nice progress.

I'm not sure if they ever fixed it, but the cell log 8 does not pull evenly from all cells (assuming 8 are connected). I believe cell 7 and 8 are not drawn off of, so it will create an imbalance over time. There is a modification online to fix this and it is pretty easy to do.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is online now   Reply With Quote
Old 07-05-16, 03:17 PM   #34
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

Thx for the tip on the draw. I didn't buy the 8s. I bought the 8m. It doesn't log. Just gives the voltages. Appears accurate right out of the box. Short term use and manual monitoring. Don't want to do that long term.

Update: Ran a load test yesterday. Basically ran my loads, (a/c on; TV; internet; lights; fridge) for a full day from the completion of the absorb cycle around 11 a.m. to 9 a.m. today. Took about 5400 watts to fully recharge (includes daily use). Voltage went from 48.32 to 45.48 overnight and back to 48.32.

That's pretty close to 2 days of "winter" use. So have to say I'm happy with the results of this test. 5kw draw down and recharged by noon. That'll do.

The Victron inverter is too small. Watching TV (49" cfl based LCD tv) with the a/c running, internet on (700w load): when the fridge kicks on I got a "beep" from the laptop running the Netflix movie. Everything keeps going. But it probably indicates a load max.

Time for a led lcd tv I guess. Really could use a bigger inverter. Say 2000w. Or 2200. I love the no load draw on the Victron. I mean 10 watts/hr? But a bit more surge for the fridge would be nice. Waiting for Victron or similar to do a 60hz model.
__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Old 07-05-16, 10:11 PM   #35
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,131
Thanks: 15
Thanked 249 Times in 235 Posts
Default

What about multiple inverters? Dedicate a 100V/50Hz unit to motors and that will reduce power usage of those loads by about 17%.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 07-06-16, 11:51 AM   #36
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

That's what I've been thinking about. Multiple inverters. Not sure how to isolate the two inverters tho.

Guess i need something else to research. Or wait until somebody releases a parallel inverter for 60hz.
__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Old 07-07-16, 07:53 AM   #37
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

Ran my first full pack voltage monitor. The widest variance on cell voltage between all six batteries (72 cells) is .01v. This is within an acceptable range.

Most of the cells are within .003 of each other.

Will monitor weekly and track. Very nice that I've been able to plug in the OEM cable and read from that with the cell log 8. I take a pic of each battery readout and then compare at my leisure.

Have adjusted my float voltage. Still not quite right. So will be adjusting that.

Continuing to note exceptional efficiency. Have not used the gas stove as I have the induction stove top going. Very efficient. Coffee was ready this morning in record time. A/C running from 2 till 8-9 pm. Internet on 24/5 now.

Had a wonderful adventure with making a mess of port forwarding. I would like to be able to monitor the batteries remotely. Well. Let's just say after two hours I was relieved to be back where I started.
__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Old 07-13-16, 10:07 AM   #38
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

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 Canada's NRC was launching rockets into space.



Beasties

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.

Huh?

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 wonky cell 1 and 2. 7.45v. 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. Pretty sure. Theoretically I should be able to charge at 45 amps safely. And 135 amps if I'm feeling lucky.

Then he gets out this lovely long piece of plastic. 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 3 days the voltage remains stable. I will try charging the whole battery now. Early impressions are that the battery is stable and the problem lay elsewhere.

Which is great 2.125kw news. 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.

Neat.
__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
The Following 2 Users Say Thank You to creeky For This Useful Post:
pinballlooking (07-13-16), stevehull (07-13-16)
Old 07-13-16, 12:03 PM   #39
pinballlooking
Super Moderator
 
pinballlooking's Avatar
 
Join Date: Jun 2013
Location: SC
Posts: 2,836
Thanks: 165
Thanked 537 Times in 440 Posts
Default

Nice story. I really like this project.
__________________
Current project Aquaponics system , Passive Solar Greenhouse build

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Solar Install 12.5 Kwh-
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Mini Split installs -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

EV Chevy Volt -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
pinballlooking is offline   Reply With Quote
Old 07-29-16, 09:57 AM   #40
creeky
Journeyman EcoRenovator
 
creeky's Avatar
 
Join Date: Jun 2011
Location: a field somewhere
Posts: 301
Thanks: 63
Thanked 44 Times in 31 Posts
Default

Thx Pinballlooking. Its been a pleasure reading your journey as well. (One thing I noticed about the Volt batteries, as posted above, is there were 3 low cells on one battery. After charging and watching they've held up perfectly. Leading one to wonder why they were so low. And even more so, consider if it was the BMS or volt charger at fault. Something for Volt owners to wonder at also.) smile.

On with the show

So after 27 days I have 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.

__________________
Current projects
Chevy Volt battery pack conversion

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Blog that is down right now but will return
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Business where I sell solar stuff
[url]https://www.bobolinksolar.com
creeky is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 11:59 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design