diy solar

diy solar

Deciding to DIY my solar battery was one of my worst mistakes ever

kolek said:
And if I ever have to fix it, I'll be in a much better position than if I had bought finished batteries.
Click to expand...
I thought the same when I found out my cell #15 was defective in one of my 10kWh rack batteries. Got the replacement cell(s) as warranty and DIY the whole job even they offered I could get it changed professionally for free if wanted. Plug&Play. Really easy to do because those busbars were not laser welded. I was mentally ready to deal with laser welds, so I'm quite sure I could have managed those too if needed. While at it I Installed Neey 4A smart balancer which made top balancing super easy but took some 30 hours. Next time I'll get 8A version or even bigger one to make it not only super easy but fast too.

I know now I could DIY battery if needed but there's no economical sense for me to do so as I can get premade cheap enough.
 
42OhmsPA said:
-At least double whatever capacity you think you need.
Click to expand...
exactly. I remember when I thought a rack of 6 100a ah batteries was enough , lol.

by DIYING I was able to double my capacity to 57kwh for less than one rack and it has many benefits.
  • lower charging and discharging c rate
  • lower gauge, less expensive wire
  • cycling the batteries less
  • less stress and less heat on everything
now I'm spoiled. If my batteries even get down to 50% soc I start getting antsy
 
@42OhmsPA or anyone else who might know torque on these bolts...

Thanks for your feedback. Just wanted to clarify, it's the torque on these bolts, the ones that add compression, that I'm asking about, not on the battery terminals. (Note this is not a picture of my battery, it's a picture I found on this forum).
 

Attachments

  • torque-here.png
    torque-here.png
    511.5 KB · Views: 34
kolek said:
@42OhmsPA or anyone else who might know torque on these bolts...

Thanks for your feedback. Just wanted to clarify, it's the torque on these bolts, the ones that add compression, that I'm asking about, not on the battery terminals. (Note this is not a picture of my battery, it's a picture I found on this forum).
Click to expand...
There’s like a 100 page post where folks argue, debate, and rehash that.
 
kolek said:
@42OhmsPA or anyone else who might know torque on these bolts...

Thanks for your feedback. Just wanted to clarify, it's the torque on these bolts, the ones that add compression, that I'm asking about, not on the battery terminals. (Note this is not a picture of my battery, it's a picture I found on this forum).
Click to expand...
Personally I'd go finger tight turn plus a turn but I know others will have differing opinions.

I'd also add a plate or piece of angle from one side to the other to spread the load, wood will change over time. (I know it's not your build).
 
1201 said:
exactly. I remember when I thought a rack of 6 100a ah batteries was enough , lol.

by DIYING I was able to double my capacity to 57kwh for less than one rack and it has many benefits.
  • lower charging and discharging c rate
  • lower gauge, less expensive wire
  • cycling the batteries less
  • less stress and less heat on everything
now I'm spoiled. If my batteries even get down to 50% soc I start getting antsy
Click to expand...
Good point, I still have a pack pulled out that I need to replace a cell in. I could probably revive the cell, but it’s going into the 12v pile for a future trolling battery build.
 
42OhmsPA said:
Personally I'd go finger tight turn plus a turn but I know others will have differing opinions.

I'd also add a plate or piece of angle from one side to the other to spread the load, wood will change over time. (I know it's not your build).
Click to expand...
Oh, don't worry. lol. I'm using a solid 11mm thick sheet of aluminum for the end pieces.
 
kolek said:
Oh, don't worry. lol. I'm using a solid 11mm thick sheet of aluminum for the end pieces.
Click to expand...
Nice. That's what I had planned for mine too, half inch aluminum plates. Until I tried to put them in my toolbox case and found that I measured all wrong. And that's where I instantly converted to the no compression team.
 
hwy17 said:
I am posting this for humor and not with the intention to ridicule anyone. It is based on my own experience.
Click to expand...
Perfect, yep, the "virgin" dude fits my personality to a "T."
Is that your original artwork?
 
hwy17 said:
Nice. That's what I had planned for mine too, half inch aluminum plates. Until I tried to put them in my toolbox case and found that I measured all wrong. And that's where I instantly converted to the no compression team.
Click to expand...
Hey, you can't do that! Are you saying you switched from the "virgin" team to the "chad" team just like that?! lol

But in all seriousness, I really question if the "chad" team really ends up with a decent result in the end. Maybe they do, I just don't know.
 
kolek said:
Hey, you can't do that! Are you saying you switched from the "virgin" team to the "chad" team just like that?!
Click to expand...
At multiple points in my build I went chad. Sometimes by choice, sometimes by error and frustration.

I was originally planning to have automatic precharge with automatic offline recovery. Now I have manual precharge with manual recovery. My next one probably won't even have manual precharge, and will rely on the other batteries in the bank for the precharge.
 
My "workshop" is a mess (garage) and I need to finish the bottom of my box (overengineered and underengineered at the same time, oh well). I did the stupid and am making my own bus bars because the ones that came with the cells are too dinky IMO (another mistake on my end I guess, more DIY).

My biggest issue is while I love DIY, I don't have a lot of the resource called TIME. I have 3 kids 5 and under. When am I going to have time? :ROFLMAO: 🤪
 
Different strokes for different folks…find what works for you and get better at it..
In any case try to have fun whatever you choose.

J.
 
I am sorry that you experienced such extreme challenges on assembling your battery pack. I found it to be a very rewarding experience. First off, the compression thing is not for me. My Cells are not compressed and are doing fine. Top balancing wasn't for me either. It just seemed like a complete waste of time. I have had more years in the electronics field than some of you have been alive, so putting together this system was a walk in the park for me.

My philosophy on putting together my 128 Cell pack was to make it easy on myself. Yes, I had to play whack a mole with the Cells until they were top balanced, but the time spent was a whole lot less than connecting the pack up in parallel. I could not even begin to imagine what it would be like to top balance 128 cells. I can see why you would be frustrated doing it the hard way.

I just connected the pack together in the way that I designed it and then dealt with the Cells that had a bit too much of a charge. Now I look at my data once a week and daily make sure that the pack still has enough power to last the night.

We told CMP to shut off the power in February. Typically, we can run for about 3 days or so without the big bright object in the sky that produces such wonderment in our world.
 
kolek said:
I'm trying to figure out the correct torque figure for the battery fixture I created.
Click to expand...
My understanding is that few prebuilt batteries have any "compression". Rather, they just tape the cells together or use foam between the cell and outer case to hold the cells "securely" in place. Consequently, if you are happy with that level of prebuilt "compression", no need to worry about proper "compression".

As for my 4s1p DIY build, in a mobile environment, I fabricated a simple fixture using two 3/4 inch boards and four 1/4 inch threaded rods; with the nuts tightened just enough to keep the cells from falling out when I pick up the fixture.
 
Something I don't really follow is that people keep mentioning that DIY batteries are only 10% cheaper than pre-built ones... how is this the case?

For reference, I can get 600ah of pre-built batteries in a rack for $7,700

96 prismatic 105ah cells (16s x6 for 605ah total) is $4,000 shipped. 6x 100amp daly 16s BMSs is a total of $459 shipped.

Grand total to DIY the batteries without any enclosures or racking after taxes and shipping is $4,459

... this is ~46% cheaper for 5% more capacity (630ah vs. 600ah)

What am I missing here?
 
Shinzul said:
What am I missing here?
Click to expand...
The case/rack, bus bars, fuses, cables, switches, terminals. Perhaps most importantly, your time. I enjoy doing this stuff, but if I take my "hourly rate" into account, I have a really, really expensive battery (and overall solar set up), and it's not even done yet!
 
Shinzul said:
Something I don't really follow is that people keep mentioning that DIY batteries are only 10% cheaper than pre-built ones... how is this the case?

For reference, I can get 600ah of pre-built batteries in a rack for $7,700

96 prismatic 105ah cells (16s x6 for 605ah total) is $4,000 shipped. 6x 100amp daly 16s BMSs is a total of $459 shipped.

Grand total to DIY the batteries without any enclosures or racking after taxes and shipping is $4,459

... this is ~46% cheaper for 5% more capacity (630ah vs. 600ah)

What am I missing here?
Click to expand...
Battery prices are dropping quickly so people may be using last year's prices who knows? But yes in my case diy was less than half the price of prebuilt
 
offgrid-curious said:
The case/rack, bus bars, fuses, cables, switches, terminals. Perhaps most importantly, your time. I enjoy doing this stuff, but if I take my "hourly rate" into account, I have a really, really expensive battery (and overall solar set up), and it's not even done yet!
Click to expand...
Wood case $12
Bus bar $50
Breaker $30

Cables you need with either pre build or diy.

My time is free spare time because I would be on this site anyway so it's a quick couple of hours break from the forum 😲😆
 
kolek said:
Even for pro-level handymen, to do this right, with all the research required, the fixtures and compression and flexible busbars and sizing and building the box and top balancing and the BMS and the fuses and wiring... etc. etc. this is a really big project. For the record, I happen to be a pretty crappy handyman. So maybe for some of you this is a walk-in-the-park.
Click to expand...
Man, I was just planning on using no compression and laying the cells out on a HD rack (like that dewalt one). It's gonna look ugly af, but I know I am no carpenter.
 
You must log in or register to reply here.

Similar threads

Mattb4
What was your worse DIY solar mistake ever?
5 6 7
Replies
169
Views
8K
42OhmsPA
4
R1200GS
Does DIY route make $ense for a rooftop system?
Replies
2
Views
260
R1200GS
R1200GS
4
Optimistic solar breakeven calculation
2
Replies
30
Views
1K
millsan1
millsan1
C
Should I connect this EK-24S4EB balancer to my Gobel DIY battery box?
Replies
2
Views
196
caesarv
C
K
Planning my first DIY build
Replies
18
Views
779
RyGuy
R

diy solar

diy solar
Back
Top