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

invento123

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So I have a question on all this. I have a yeti 1250 I would love to, at the very least, lighten up but still use. It is currently being used out in my workshop combined with a 90 watt solar panel to run the lighting and electrical in the shop.
I've been looking into upgrading to a LiFePo4 battery (with a built in BMS of course) like you did but am curious about a few things.

First, will the built in charge controller be able to properly charge the LiFePo4 battery? As in, will it keep from over charging it with an equalization charge or such?

Second, will the charger actually fully charge the battery or will it only charge to lets say 80% as the charger thinks the battery is full due to the voltage difference between a fully charged lead acid and a fully charged LiFePo4? In addition, will it only discharge the battery to say 20% once again because of the voltage difference from a lead acid to a LiFePo4?

Any input or advise is greatly appreciated as I would love to keep my Yeti running with a new lithium battery!
 

Bob142

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First, will the built in charge controller be able to properly charge the LiFePo4 battery? As in, will it keep from over charging it with an equalization charge or such?
I've had no problems fully charging either of my LFP battery solutions (the drop-in and now the DIY) using the built-in charger. The Yeti charge profile is set up for an AGM lead acid so there's no equalization charge.

Second, will the charger actually fully charge the battery or will it only charge to lets say 80% as the charger thinks the battery is full due to the voltage difference between a fully charged lead acid and a fully charged LiFePo4?
It fully charges it for me. The absorption voltage in the built-in Yeti charge controller is at least 14.4V so there's no issue as that's more than sufficient to charge LFP.

In addition, will it only discharge the battery to say 20% once again because of the voltage difference from a lead acid to a LiFePo4?
No such problem exists. You can completely drain your LFP battery to your heart's content. ;)

Good luck!
 

Daedalus

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Hi all, Have some modding plans for my Yeti 150 :). Question for the OP and others. as most of the GZ kit runs SLA bricks although the newer stuff is now lithium. As the charging is PWM, how are you getting around the issue of the LiFePo cells needing more battery management than SLA??
I've seen another yeti 150 having the LiFePo upgrade but seen nothing of battery longevity with being changed by SLA circuitry. Or does the additional MPPT unit providing that?
 

invento123

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Hi all, Have some modding plans for my Yeti 150 :). Question for the OP and others. as most of the GZ kit runs SLA bricks although the newer stuff is now lithium. As the charging is PWM, how are you getting around the issue of the LiFePo cells needing more battery management than SLA??
I've seen another yeti 150 having the LiFePo upgrade but seen nothing of battery longevity with being changed by SLA circuitry. Or does the additional MPPT unit providing that?
As a matter of fact I just upgraded my yeti 1250 to LiFePO4! Basically from what I've learned and now experienced, because the batteries being used in the yeti's are AGM deep cycles, their charge voltage works great for LFP (LiFePO4). The max charge the yeti will give a AGM battery is right around 14.4 volts, right around where a LFP is at full charge. Once the LFP battery reaches full charge, just like an AMG battery, it will stop charging.

You will have to get a battery with a battery management system (BMS) built in, in order to keep the LFP cells balanced and just to make 100% sure the yeti doesn't somehow over charge or over discharge the LFP. From what I've seen almost all premade 12v LFP batteries have a BMS built in as its basically a requirement. You will however need a new way of measuring the LFP batteries state of charge as the yeti's built in battery meter can't accurately show the LFPs charge level. I highly recommend a shunt meter as that's what I'm using and so far it's been working great!
 

Daedalus

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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 😊
GZ do have nice enclosures. I do like whats been done on this forum where the units are gutted to improve even beyond the current GZ offerings. My next upgrade is a GZ 400. Already have a Sherpa 50 running the upgraded cells like Sherpa 50 battery upgrade and currently modding the Yeti 150 to enable chaining like the bigger 400 with anderson connectors (run time over sheer wattage). The yeti lid is getting a QI charge option too. I have seen a guy online Yeti 150 Bioenno LiFePo upgrade. This LiFePo battery only sports 15Ah so i do question the capacity benefit over the SLA version of the cell. That said its a drop in unit and can be connected to the SLA charge circuit.
 

invento123

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In my opinion, the older generation lead acid Goal Zero generators were and still are somewhat better than their current lithium offerings. Not only were the batteries user replaceable thus allowing for lithium upgrades, the generators were rather bulky so adding stuff like a shunt meter for monitoring a lithium battery and adding extra ports or integrating a QI charger is something you could do.
Looking over Goal Zeros current offerings, especially compared to similar generators from other brands, it doesn't seem like Goal Zero is worth the higher price anymore.
 

Ely

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Goal Zero works as aspected. If the inverter is specified to give 1000 watts it gives you 1000 watts (and a bit more) until the battery is empty. Same with Jackery.

If someone buy a all in one plug and play system it should be working without issues.

I have here some GZ units, old lead acid and some from the actual Yeti X for mobile use. And two Jackery. All of them are working perfect, no issues about many years.
 

Daedalus

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Goal Zero works as aspected. If the inverter is specified to give 1000 watts it gives you 1000 watts (and a bit more) until the battery is empty. Same with Jackery.

If someone buy a all in one plug and play system it should be working without issues.

I have here some GZ units, old lead acid and some from the actual Yeti X for mobile use. And two Jackery. All of them are working perfect, no issues about many years.
i do like the GZ for what they are, i do begrudge the pricetag and have bought both mine as used/openbox. That said i find them good quality. Next purchase will be a 400 unit. Seen alot of people going for lithium upgrades of the older units. previously seen the Bioenno drop in cell and various incarnations of 18650 packs which shed alot of the weight out of the older tech.

Does anyone have voltage specs for the 150/400/1250? GZ weren't overly helpful in sharing those....... whilst we cant remove the SLA/AGM charge circuit we can at least build BMS in-between to stop the lithium's going funky. But also wary we can abuse AGM but Lithiums are cranky when they get too discharged.
 

corerolla

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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.
Hi @Bob142, I have a victron blue smart 12v 30a charger and when attached to the chaining port there is no current pushed to the battery, but when I hook it up directly to the battery is only when I get 30a charge. Has anyone come across this? This is with the 100ah agm battery as I didn’t receive a charger with my used yeti 1250 and figured the victron would be able to allow me to monitor the charge via bluetooth. It is just odd the victron only will charge when attached to the battery directly and not by chaining port.
 

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corerolla

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Hi @Bob142, I have a victron blue smart 12v 30a charger and when attached to the chaining port there is no current pushed to the battery, but when I hook it up directly to the battery is only when I get 30a charge. Has anyone come across this? This is with the 100ah agm battery as I didn’t receive a charger with my used yeti 1250 and figured the victron would be able to allow me to monitor the charge via bluetooth. It is just odd the victron only will charge when attached to the battery directly and not by chaining port.
disregard, chain port fuses blown. i will change these and see if it works again.
 

invento123

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i bought the 1250 used and the fuses external at the chaining port were purple 3a fuses. ah wth, so these are 50a fuses?
LMAO yes the original fuses were 50 amps each, total of 200 amps. Not sure why they went with such a high value, I personally swapped them out for 30 amp fuses as if the internal lifepo were to short on that chaining port, I'd like to limit it to 120 amps
 

corerolla

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LMAO yes the original fuses were 50 amps each, total of 200 amps. Not sure why they went with such a high value, I personally swapped them out for 30 amp fuses as if the internal lifepo were to short on that chaining port, I'd like to limit it to 120 amps
thank you @invento123 for the knowledge! super appreciated.
 

Supervstech

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LMAO yes the original fuses were 50 amps each, total of 200 amps. Not sure why they went with such a high value, I personally swapped them out for 30 amp fuses as if the internal lifepo were to short on that chaining port, I'd like to limit it to 120 amps
Unless the fuse size is maxi, blade fuses aren’t made above 40A…
 

Will Prowse

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