Goal Zero Yeti 1250 – Great platform for drop-in LiFePO4 upgrade

Bob142

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What’s This Post About?
I got the portable, LiFePO4-based solar generator I wanted by combining an old-school Goal Zero Yeti 1250 with a Lion Energy Safari UT battery.

This is not the best system for everyone, but it fits my requirements almost perfectly. It’s also straightforward to achieve:
  • Buy a used Goal Zero Yeti 1250.
  • Buy a Lion Energy Safari UT LiFePO4 battery.
  • Replace the lead-acid battery with the LiFePO4 battery.
  • Enjoy your full featured, high capacity, portable LiFePO4 solar generator.
For those who want more of the story, read on.


Background

I wanted a portable, relatively large capacity, lithium-based solar generator that had room for expansion. In looking at the full-sized offerings on the market I found I didn’t really love the big Li-NMC systems. My concerns were fewer max capacity cycles, lack of easy expansion, and battery chemistry safety compared to LiFePO4. I looked to see if any vendors offered a LiFePO4-based system but didn’t find anything I liked. I figured I’d have to go the route of others and build my own portable system (I’m amazed at how cool the systems in Show and Tell are). Then I remembered a solar generator I had first looked at way back in 2012 but always dismissed as not truly portable: the lead-acid Goal Zero Yeti 1250.

Go here for Goal Zero Yeti 1250 info


The Conversion to LiFePO4
The Yeti 1250 is a monstrously heavy 103 lbs (46.7 kg) unit with a group 27 100Ah AGM lead-acid battery at its core. The good news is that Goal Zero designed this system to have a user-replaceable battery. The battery accounts for over 60 lbs of the Yeti 1250’s weight, so I thought if I found a LiFePO4 drop-in replacement that was light weight and could fit in the battery compartment I might have something to work with. (The original battery measures 12.9" x 6.8" x 8.7".)

Enter the Lion Energy Safari UT 1200. Coming in at 21 lbs and offering more effective capacity than the lead-acid it would replace, I figured it would make the Yeti 1250 light enough to lift and make it actually portable (where my definition of portable is that I can lift it myself and put it into a vehicle for remote use). The Safari UT physical dimensions of 10.2” x 6.6” x 8.8” seemed workable in theory. In practice, it fits and has worked great so far.

Replacing the battery was straightforward, and Goal Zero even provides a seven-step procedure in the user manual. Here’s a YouTube video of how to replace the battery.

After replacing the battery, the whole system weighs about 60 lbs.


Charging
  • The old Yeti 1250 has a 20A MPPT charge controller built in! And unlike the MPPT module Goal Zero sells now for their Li-NMC models, you can put 12V panels in series because the input is rated at 16-48V (the Yeti Lithium 25A MPPT module input is rated at 15-22V which means you will be putting your 12V panels in parallel).

    There are two types of charging ports, (2) 10A 8mm and a 20A Anderson power pole port for a combined input power rating of 240W.

    [The website (320W) and manual (240W) have conflicting information, so I contacted Goal Zero customer support to confirm what the actual max input wattage is. The answer is max input of 240W, regardless of whether that all comes in through the Anderson power pole input or split between that and the 10mm input ports.]

  • You can also use the chaining port (described below) to jack in whatever charge controller/charger you want. I use this to connect a Samlex 30A grid-power charger. I may also use it for a higher rated MPPT charge controller down the road.

State of Charge Monitoring
Note: I haven’t yet decided what I’m going to do long-term for state of charge monitoring since I assume the built-in monitor is calibrated for lead-acid. Stay tuned.

(Edit: Dec 21, 2019) First attempt at SoC monitoring is to use this Drok meter with hall effect sensor. (More details below.)

(Edit: June 9, 2020) The Drok is a bust as it does not provide accurate SoC. I'll work on a shunt-based solution.

Output Ports
  • 1200W continuous/1500W surge AC inverter (pure sine wave) with three outlets
  • 3 – USB (2.1A)
  • 2 – 6mm 12V DC (6A)
  • 1 – Cigarette lighter style 12V DC (10A)
  • 1 – Anderson power pole 12V DC (33A)

Expandability
The Yeti 1250 has a built-in chaining port (Anderson SB175 connector) on the back that allows users to add additional batteries in parallel. Perfect! I can attach more Safari UTs if I need to get more run-time, and since they only weigh 21 lbs a piece I can still load the whole setup into my SUV in pieces and reconnect at my destination. With the Anderson connector, adding or subtracting the additional batteries is a snap.

(Edit Mar 6, 2020) Example of chaining extra batteries can be seen in this post below.

Availability
  • Yeti 1250 – Find a used one on eBay. Goal Zero customer support told me that they have discontinued the Yeti 1250 (shortly after I bought a refurbished one from them).

  • LiFePO4 Battery – Buy a Lion Energy UT 1300 (or any LiFePO4 battery that fits the dimensions stated above. Or go the DIY LiFePO4 route).

    Note: Lion Energy discontinued the UT 1200 shortly after I bought a couple. Hmm, a pattern. The universe seems to be trying to tell me something. However, they are replacing it with a UT 1300 that is the same physical size, only 23 lbs, and reportedly will be 105 Ah (vs. 90 Ah for the 1200)

The Cost
Your mileage will likely vary from mine, but here it is for reference:

  • Yeti 1250 - $700 for an “open box” Yeti 1250 from Goal Zero. I was able to sell both the lead-acid battery, and the Yeti roll cart (you may want to keep this depending on your situation) which brought my cost down to $550.

    I’ve seen used Yeti 1250s sell on eBay for between $475-$650 recently.

  • Safari UT 1200/1300 – $650 for a UT 1200 from Costco’s recent clearance sale. This is an atypically low price, so you will likely spend closer to $800-900 for a battery that fits into the compartment.

  • Drok meter for SoC monitoring - $29 (Edit: June 9, 2020) Don't buy the Drok.

  • Chaining cable for extra battery capacity - $25 on eBay for a 2’ long 4 AWG cable: eBay chaining cable

Total cost for my base system: $1,200 $1229 (Edit: Dec 21, 2019)

For reference, that is virtually identical to a Goal Zero Lithium (NMC) Yeti 1000 w/MPPT module.
 
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Will Prowse

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Holy cow that's awesome! And the price you got the safari ut is out of this world. I have never seen them that cheap before, you found a bargain!

And you would get 4-8x the rated charge cycle life. Very nice. And non combustible chemistry. Love it!
 
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eddie1261

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I'm confused. The Goal Zero 400 lithium is $599. The differences would be a PWM controller and storage/output values of 428Wh 10.8V, 39.6Ah. I could buy 2 of these for that $1200. I don't know what I am missing here. Also remember as you formulate a reply that I bought this strictly for my CPAP and to power a small TP-Link portable router that eats almost nothing.

One this I DO wish this had was chaining capability, but it is what it is. $600 was my price point. It IS good to see that the battery swap out is possible though.
 

Will Prowse

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I would personally use that safari battery with an all in one unit and call it a day. Mppt, pure sine wave inverter, ats, charger etc, for much cheaper. But I love the idea of hacking a goal zero. If you have one laying around collecting dust because the AGM failed, and you can get a LiFePO4 for cheap, you can toss it in there. Pretty neat 😊
 

Bob142

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Eddie, I don't think you're really missing anything. The GZ lithium 400 sounds perfect for what you need it for, while my system is not well suited for you. For me, it's all about fitting the system to your use cases. My converted 1250 has over twice the Wh as the GZ lithium 400, along with an AC inverter that's 4x as powerful. It's also 4x heavier than yours. The intended use for my system is much larger scale than yours. I need to be able to power a full-sized fridge and a home heating system for potentially a couple of days during power outages.
 
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eddie1261

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My converted 1250 has over twice the Wh as the GZ lithium 400, along with an AC inverter that's 4x as powerful. It's also 4x heavier than yours.

That's what I missed. OVER twice the performance of mine.

I beat it up a lot testing it when I first got it. Different combinations of appliances, duration to 50% of charge using those different combinations.... The learning curve is steep when you first wade into this area. Between the CPAP, 12v fan, 12v lights, 12v charging..... I ran things for 2 hours at a time and noted the amount of storage used. Then charged back to full and did it again with a different combination..... Played with it for like 12 days with the "A, B and C", then A, B and D", then B,C and D"... and so on, each with a charge in between. Fun stuff and a good way to learn.
 

Bob142

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Will, I thought about going the all in one route, but at 12V I only saw an 800W inverter model. I also need to be able to throw the whole thing in my car and deploy it at different sites and felt the self-contained nature of the Yeti 1250 fit the bill better (handles!).
 

Will Prowse

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I love the yeti 1250 case. Goalzeros look good. And yesz that inverter is so small. Drives me crazy.
 

eddie1261

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Where you guys take things one step further is that you even thought to do that. Never would have occurred to me.
 

Bob142

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Quick update for those interested: I finally got around to installing a SoC monitor and have updated the OP with the info. I went with a Drok meter w/hall effect sensor as the first try. So far I'd say it's good enough for my purposes and infinitely better than no battery monitor.

Note: I tried to figure out how to get the AiLi shunt-based monitor into the system but so far haven't come up with a way to cram it in the very limited space (doesn't mean I'll stop trying).


Longer story for those who have time on their hands: Here's a little bit of show and tell.

Installation
I was JUST able to get all the wires of the Yeti 1250 through the hall effect sensor and get everything connected back up. If anyone else tries this, there are three distinct cable bundles for the positive side that are loosely shrink wrapped together. I had to pull the group apart and thread them through one at a time. Here's a pic of the initial test install with the Yeti top off:
img_2300-jpg.3731


Initial Test
I plugged in my kill-a-watt meter and a lamp with an old fashioned 60W light bulb to do a test.

It's a little hard to read all the meters in the picture, but the Yeti and the kill-a-watt are measuring about 66-67 watts while the Drok reads 85.8 watts. I know that that Drok is reading power consumption pre-inverter and the GZ and kill-a-watt are post-inverter. So if the Drok is somewhat accurate, it suggests the GZ inverter is about 80% efficient.
IMG_2298.jpg

Charging Tests
The Drok looks reasonable compared to the internal meter when charging from one of the standard inputs.
IMG_2301.jpg

And it knows when the system is being charged by an external charger via the chaining port, where the built-in monitor is blind to it:
IMG_2303.jpg

I did notice that the Drok current measurements were consistently slightly high compared to external clamp meter readings. For example, when the external charger was pushing 30A, the Drok measured 30.7A.

The Button Up
I'm not sure this will be the final solution so I didn't go too crazy trying to come up with a slick way to integrate the meter. I decided the best plan for me was to install it inside the storage compartment of the lid.

IMG_2305.jpg

IMG_2307.jpg
 

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Supervstech

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I have been using that meter, and it is so inconsistent with measurements. Fine for gross checking, but not helpful when exact soc is needed. Every time you move the meter, or orientation changes, the readings change. By A LOT...
I decided to setup their shunt based meter, and will be integrating it soon.
 

Bob142

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I have been using that meter, and it is so inconsistent with measurements. Fine for gross checking, but not helpful when exact soc is needed. Every time you move the meter, or orientation changes, the readings change. By A LOT...
I decided to setup their shunt based meter, and will be integrating it soon.
Thanks for your input and for sharing your experience with the Drok. I agree that it's not ideal, but so far it has performed well enough for this use case. Especially since I had no real SoC indicator prior to this. As indicated at the beginning of my post above, my preference is to get the AiLi shunt-based monitor installed but I've got space constraints I need to figure out how to work around. I use the AiLi on my cart-based system and it has been rock solid so that's ultimately where I want to end up with the Yeti.
 

Bob142

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Here's an example of extending the Yeti's run time by chaining extra batteries. I built a DC subsystem crate (details in this thread) to hold the extension battery bank (shown below connected via the Yeti's Anderson SB175). The crate has its own AiLi capacity monitor so I don't have to reprogram the Yeti's Drok monitor whenever I use the extension bank.

IMG_2563.jpg
 

Bob142

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I have been using that meter, and it is so inconsistent with measurements. Fine for gross checking, but not helpful when exact soc is needed. Every time you move the meter, or orientation changes, the readings change. By A LOT...
I decided to setup their shunt based meter, and will be integrating it soon.
After 6 months of using the Drok hall effect meter I have to completely agree with @Supervstech's assessment. It is not suitable for this application, so I don't recommend it. It has become a source of frustration since the readings are constantly all over the place. Ultimately it hasn't really improved my ability to monitor state of charge. I'm going to revisit installing a shunt-based meter.
 

Bob142

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Time to level up? The battery bay in the Yeti 1250 is sized perfectly for 4 280Ah EVE cells and an Overkill BMS... Mwahahahaha!

Coming soon: the Yeti LFP 3000.

IMG_3293.jpg

(That's gonna blow up my whole one-person-able-to-lift-it portability. Gonna need to buy back that Yeti roll cart I sold...)
 

Kbighair

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I’m just about to give the Yeti, lithium battery switch a try. Everything is sitting here, ready to go but thought I’d check back to see if you’ve any last-minute tips?
 

Bob142

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I’m just about to give the Yeti, lithium battery switch a try. Everything is sitting here, ready to go but thought I’d check back to see if you’ve any last-minute tips?
Cool. All info in this thread is up to date. It’s worked great for me.

And welcome to the forum!
 
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Bob142

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Time to level up? The battery bay in the Yeti 1250 is sized perfectly for 4 280Ah EVE cells and an Overkill BMS... Mwahahahaha!

Coming soon: the Yeti LFP 3000

The drop-in replacement chapter has ended. The story continues with the new EVE 280Ah cell upgrade...

 
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