EVE 280Ah LFP cells in a Goal Zero Yeti 1250

Bob142

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Thanks to what I've learned from so many people on this forum I've been able to level up my modified Goal Zero Yeti 1250 again. This time I took out the Lion UT1200 LFP battery and put in 4 EVE 280Ah LFP cells that I got via @Craig, and added an Overkill 120A 4s BMS. Goal Zero must have seen the future because the cells fit into the battery bay perfectly with just enough room to the side for the BMS and battery monitor.

Some highlights for me on this build:
  • Finally put together a DIY LFP battery. Now that I've done it I don't know what took me so long.
  • Made my own busbars out of 1/8" x 1" 110 copper bar stock (thanks to @backwash for the link). Didn't have a drill press so I bought this WEN for $89 and it worked well for me. I made three busbars for the battery cell connections and two long ones for top balancing in parallel. (Wish I saw @Bob B's comment about using a center punch a little earlier. Will do that next time.)
  • Followed @FilterGuy's top balancing tutorial and charged the cells in series with the BMS first, then used a 15V 40A lab power supply to finish the job with the cells in parallel. (There should be zero drama doing it this way if you follow the instructions carefully. It also goes fast compared to just putting the cells in parallel.)
  • Added a TF03K shunt-based battery monitor because the GZ internal monitor uses voltage for state of charge since it was a lead acid system originally. (I tried a Drok hall effect battery monitor in the initial system customization and it turned out to be useless.)
  • Learned that the Overkill BMS short circuit protection works... and that I shouldn't let my guard down in my exuberance to finish a build.
Here are the pics:
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(Yes, I fixed the red balance lead that got pulled a little too taut.)
 
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Bob142

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Currently running a test of what may become the dedicated grid/mains charger for the Yeti. It's the $40 IOTA DLS-30 12V 30A charger @HaldorEE tipped people off to in this thread. I'm not using the IOTA IQ-LIFEPO IQ4 "smart" charge controller module as it's actually kind of dumb. Thanks to a heads up from @carlos1w I'm using the dual voltage plug to make the charger voltage 14.2V. (See other thread for more details.)

Charger is connected to the Anderson SB175 chaining port on the back of the Yeti. The third pic shows the little dual voltage plug connected to raise the output voltage to 14.2V. I'm satisfied with that as my absorption voltage. I'll be monitoring charging so I can terminate it when the pack reaches 14.2V so it won't hold it too long.

As long as the IOTA behaves well in tests, I'll sort out some form of mounting to the roll cart handles or maybe I'll use my go-to milk crate solution like I did to add a 3rd party SCC to the Yeti. I'll post the solution(s) when I get to them.

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tauren

New Member
@Bob142 This looks great! I'm a total solar and power newb with a Yeti 1250 that I bought in 2013. Original deep cell battery is dead and will cost $250 to replace. I've been debating if I should use that $250 to upgrade to a new consumer Lithium system instead of getting another lead acid (and maybe sell the Yeti as parts?). But I love DIY and if there's a good way to leverage my existing Yeti, I'd love to give it a try.

Do you have full build instructions somewhere, parts list, etc? I'm comfortable with low power DIY, but never dabbled with higher power solar/batteries/etc. So any hand-holding would help.
 

Bob142

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@Bob142 This looks great! I'm a total solar and power newb with a Yeti 1250 that I bought in 2013. Original deep cell battery is dead and will cost $250 to replace. I've been debating if I should use that $250 to upgrade to a new consumer Lithium system instead of getting another lead acid (and maybe sell the Yeti as parts?). But I love DIY and if there's a good way to leverage my existing Yeti, I'd love to give it a try.

Do you have full build instructions somewhere, parts list, etc? I'm comfortable with low power DIY, but never dabbled with higher power solar/batteries/etc. So any hand-holding would help.
Welcome to the forum, @tauren!

If you haven't already, take a look at my original Yeti mod that used a Lion Energy LFP drop-in battery. Depending on what your use cases are and your appetite for DIY, that might be a worthwhile and sufficient upgrade to the system. It spares you the DIY battery part of the build so is a faster upgrade. Costco occasionally runs great deals on the Safari UT1300. You'd also need to install a battery monitor like I did in this thread to get an accurate state of charge for the LFP battery.

If you decide that you'd prefer to go the DIY battery route as I did in this thread, you'll need to do a little homework on the size of the currently available large LFP cells. When I did this build the EVE 280Ah cells were ubiquitous, but those have dried up. Most people seem to be getting the Lishen 272Ah cells now so you'll need to figure out if those cells will fit in the battery bay of the Yeti 1250. I suspect a quick search of this forum will get you the answer. I recommend you reach out to @Michael B Caro to get your cells. I believe his suppliers are providing grub screws, serrated washers, and double busbars so it's a nice package (for this build I had to make my own busbars and procure the screws and washers separately.)

The first post in this thread has links to all the major components that I used, so that's your starting point parts list. I can provide guidance on particular questions you may have in a PM (conversations in this forum - the envelope icon up top). I've been doing that for others and it's working well.

Good luck and I look forward to another Yeti 1250 LFP conversion!
 

tauren

New Member
Thanks for the response. It feels like I should go the DIY route with 4x280ah batteries, but I'm not clear what the practical differences are between the two builds. Can you clarify a couple things?

- Based on cost alone, which solution is less expensive? The UT1300 appears to cost $900 (not available at Costco right now) vs about $300-400 for the EVE/Lishen (I've reached out to @Michael B Caro for more accurate pricing). But what other costs will there be for the 4x280ah solution that aren't also in the UT1300 build?

- Based on performance alone, which solution is superior, has more power, charge cycles, longevity, least amount of maintenance, etc?

It looks like the Lishen and EVEs have essentially the same size:

In this video he says the Lishen 280ah is actually listed as 272ah, so I think the two items are basically the same dimensions:
 

Bob142

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Based on cost alone, which solution is less expensive
The costs of the two solutions are almost the same if you get a good deal on the UT1300 at Costco.

But what other costs will there be for the 4x280ah solution that aren't also in the UT1300 build?
The cost of a BMS and a power supply to top balance. Those costs can vary quite a bit depending on which model of each item you buy. Search the forum and you'll find plenty of good options and advice on each.

Based on performance alone, which solution is superior, has more power, charge cycles, longevity, least amount of maintenance, etc?
  • The Yeti system has the same power no matter which battery solution you go with.
  • 280Ah > 105Ah so you get much more runtime with the DIY battery implementation.
  • The DIY battery build takes a lot more time compared to dropping in the UT1300 (that time includes months waiting for the cells to arrive after ordering).
  • Both the raw cells and the UT1300 marketing material promise thousands of charge cycles (read the fine print on the raw cells and you'll see you need to provide compression. I didn't do that in my build).
  • The UT1300 provides a warranty. There is no warranty with the DIY battery build.
My preference is obviously the raw cell DIY battery build, since I upgraded from the drop-in UT1200 to it. I only brought up the other option so you and others reading this can compare the two and decide how much DIY you are willing to take on based on your use cases.
 
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