Jump to content

DIY Lithium/LifePo4 battery build


Recommended Posts

  • Replies 146
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

The testing is not always done the same. If you test at 90% DoD and 1C discharge currents, the battery will be EOL (defined as having irreversibly lost 20% of its capacity) after 2000 cycles. If you t

I have around 250kWh of Leaf cells running Victron ESS  - not exactly a DIY task job as it all just bolts together.

True. I'm just making a point about how widely the advertised cycles can vary, to the extent that one manufacturer can advertise a number over 3 times bigger than the other, using the same cells 🙂

Posted Images

1 hour ago, phil.g00 said:

If I am correct the 280Ah cell has a 6mm bolt and the 120/100Ah has a 4mm?

Right... the number I spat out is for m8. Winston cells 🙂

57 minutes ago, phil.g00 said:

The SADF tiffies believed in vaseline. ( for battery terminals, that is).

Yup, I've also used Vaseline on flooded lead acid terminals. It works well. Not sure it will work in this application though, need something with a little copper/zinc in it that improves conductivity while preventing oxidation.

 

Link to post
Share on other sites
2 hours ago, JustinSchoeman said:

2) What is the preferred way of routing the balance wires?

a) birds nest (just route directly to the terminals), or

b) channeled wire bundles.

(a) is a lot simpler, and electrically superior (lowest resistance and lowest noise), but does not look great, and is more susceptible to damage if you ever do need to poke around inside the battery.

(b) takes a lot of effort, but looks neat and keeps the wires out of the way, but wires become very long, and long parallel wire runs are very bad for electrical noise.

This would be your own preference.

If you like things neat, then go with option b)

You are constraint with the lengths of the wires, then a) is your only option.

If you are going to cover this up in the case and never look at it, then neither will matter.

 

I was constrained by the wire length during my workbench testing, so a) bird nest was my only optionbatteries.thumb.jpg.312ad6c9136afb79ce569a8494581610.jpg

 

But by changing my battery to sit on it's side and moving the BMS a bit I do have to option of b) and as I like things to be neat I will be doing a cleanup there in the near future. 
My plan is to use small cable ties, so it will be easy to remove if I need to work on something.
image.png.998d3bb81953def5b4fef4f819fa66c2.png 

Link to post
Share on other sites
1 hour ago, JustinSchoeman said:

Doh... 4Nm is the limit for mild steel M6 screws anyway... So may need to consider upgrading those too.

I'll add my experience - I had one cell strip it's thread due to a combination of insufficient thread depth and overtorqing. It's an issue if you are paralleling cells, and stacking the links - and another reason I moved to my own DIY'd copper links.

I managed to fix it with an insert.

Cheers

Ian

Link to post
Share on other sites
20 hours ago, Ian said:

I'll add my experience - I had one cell strip it's thread due to a combination of insufficient thread depth and overtorqing. It's an issue if you are paralleling cells, and stacking the links - and another reason I moved to my own DIY'd copper links.

I managed to fix it with an insert.

Cheers

Ian

TTT had the same problem. Stripping threads. The bolts that came with batteries isn't the best. There thread cut isn't good. You can actually feel how the bolt move inside the battery pole. That's why i went for 6mm stainless allenkey caps. The tolerance and the pitch on the stainless is way better. Same with the hi ten steel bolts. I got all the tools and bits to re tape this stuff. TTT need to do this now with his ones.

The batteries got 6mm thread. 

Link to post
Share on other sites

Maybe these holes are not meant for busbars to be mounted on it. In my understanding they are positioning holes in order to get a nice weld for the busbar adapters. This is what I learned during my search and eventually purchase of LiFePO4 cells. Well, learned... It is what the manufaturer of these cells which is http://www.ecopowerpack.com/ told me.

This is what it should look like:

83975277_Cellenmetdegoedebusbar.thumb.jpg.6f229dccb729ed5cdb33661936e17cff.jpg

Looks way better and there are 2 screwholes per pole.

Edited by RikH
Link to post
Share on other sites
On 2020/08/07 at 12:18 PM, Gerlach said:

TTT had the same problem. Stripping threads. The bolts that came with batteries isn't the best. There thread cut isn't good. You can actually feel how the bolt move inside the battery pole. That's why i went for 6mm stainless allenkey caps. The tolerance and the pitch on the stainless is way better. Same with the hi ten steel bolts. I got all the tools and bits to re tape this stuff. TTT need to do this now with his ones.

The batteries got 6mm thread. 

In hindsight, using studs and nuts might be the safest option to cover all bases?

Link to post
Share on other sites
13 hours ago, Ian said:

In hindsight, using studs and nuts might be the safest option to cover all bases?

Jip. That will be yes. Allen key stud is a good option. There some guys that's doing this. 

Link to post
Share on other sites
12 hours ago, JustinSchoeman said:

That was a looong weekend. Rack ready to bolt in. Lots of bus plates cut, drilled and tapped. Lots of terminal covers printed.  Should be able to start assembling tomorrow.  Lets hope I don't strip anything...

rack.jpg

Looking good!!! Enjoy the build and take your time. 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...