EEVblog 1707 - REPAIR: Goal Zero Yeti 400 Lithium Battery

[EEVblog]

Dave's Goal Zero Yeti 400 lithium ion battery failed. Repair time.

00:00 - Goal Zero Yeti 400 Battery failure
01:32 - Hiccuping
03:28 - Teardown
04:47 - Failure hypothesis and potential solution
05:37 - The mains inverter PCB
06:43 - The control PCB
07:36 - Dual battery connectors
08:09 - Measuring the dual battery connections to make sure they are in parallel.
08:58 - The lithium ion battery pack
09:24 - Measuring the battery pack voltage, and the under voltage lookout protection
10:49 - Re-powering just the controller board
11:38 - Progressive system module power up with the battery, isolating the mains inverter
12:23 - Measuring the battery again to see if it's accepting a charge
13:20 - Winner Winner Chicken Dinner
15:34 - No electronics repair needed
15:54 - Goal Zero battery physical design
17:03 - Back from the gym, what's happened?
18:33 - Fault summary

[Bemused2020]

Great video, Good info, Thanks
... According to a variety of folk on the internet ... Try a reset. "Press and hold the Units, Light and Info button simultaneously for some seconds until the battery reboots"
 This may turn off the current hungry ac inverter which appears to be trying to turn on during start-up.

... Maybe (once you get it running of course), it would be a good idea to check in settings to see if unit is set to automatically turn ac output "on" when charging power is connected?

... Suspect software isn't disabling AC Inverter prior to attempted restart hence power-brick is cutting out under load. (Most power-stations should disable AC - output when battery flat)
Maybe connect a power source with higher current capacity if you're feeling brave?

... It might sound odd but I suspect you will have un-balanced cells and the fail-safe BMS attached directly to the battery has tripped before the main-board battery diagnostics has triggered a normal shut-down. I have seen similar several times.

... I seem to see a lot of BMS's (in domestic and, sadly, professional gear), that mysteriously allow cells to get out of balance when the battery pack is a few years old, can't imagine why a manufacturer would want that to happen...!

... Many power stations can take firmware updates to solve problems ... but often these require loading dubious / invasive apps... Not my cup-of-tea!

[Per Hansson]

Followup video 1:


Followup video 2:

[electr_peter]

W.r.t. to Rigol DL3000 DC load - it has many unsolved FW bugs with the last version of FW being 5 years old. Rigol simply doesn't care about FW support Also, current waveform shape is not terrific at all

On battery app start, DC load sometimes (~10-30% chance) passes very small amount of current - practical solution is to change current limit while ON, then it goes to the right current.
Regarding short at inputs, try enabling/disabling SHORT functionality via buttons and via settings - it is implemented somewhat back to front in FW. Although some units fail shorted when AC power is applied (possibly digital board failure).

At least one positive is possibility of improvement (dl3021-to-dl3031-conversion-discussion) as it's OK robustness and thermal wise as ~350W load. Otherwise get something else.

[J-R]

I ran some tests on my DL3021 running as a DL3031A and I was able to reproduce both of the issues.  Selecting the battery test, playing around in the utility menu, then exiting back out results in it frequently changing to the 0.1A current limit.

Entering battery test mode and quickly pressing the On/Off button multiple times results in the load staying on at the previous current level even though the display shows 0.0A and the button isn't lit.  And also sometimes it goes to a full short.  But on my unit I'm able to simply press On/Off again, wait a few seconds, then turn it back off and it works fine.  Definitely something that could be fixed via software update.

Definitely new buyers should avoid this unit.

[EEVblog]

I ran some tests on my DL3021 running as a DL3031A and I was able to reproduce both of the issues.  Selecting the battery test, playing around in the utility menu, then exiting back out results in it frequently changing to the 0.1A current limit.

Entering battery test mode and quickly pressing the On/Off button multiple times results in the load staying on at the previous current level even though the display shows 0.0A and the button isn't lit.  And also sometimes it goes to a full short.  But on my unit I'm able to simply press On/Off again, wait a few seconds, then turn it back off and it works fine.  Definitely something that could be fixed via software update.

Definitely new buyers should avoid this unit.

Several people in the youtube comments have also confirmed this. Seems to be a difference in firmware and FPGA versions, with some people not seeing it with certain older version combo's.
This is nuts, definitely a unit to avoid.

[J-R]

I have ben reading the comments on YouTube.  I have firmware v00.01.05.00.01 from 2020-12-01 and FPGA 2.03.  It shipped from Rigol with this combination.

When it goes into the short failure mode, it is a "true" short.  It took everything given from a current limited power supply while set for 1A.  Which lines up with what is seen in the video (battery pack protection kicks in), and it's not just the lower current of the DMM.

The failures could be somewhat rare to bump into, depending.  I've used this unit a bunch for battery capacity testing and never saw these.  But that is because I just turned it on and started the test.

The load remaining "on" while the indicator light is off happens about one out of five times when rapidly pressing the button.  But I could never get it to happen when ensuring a delay of a few seconds.

My Keysight EL34143A is my main bench electronic load.  This Rigol is mostly for field work so I won't have to shed any tears if it gets broken.

[bergenhut]

After seeing Dave's video and also owning a Rigol DL3031 electronic load, I hadn't noticed the issues with the battery load test with my unit in the past when testing batteries. I then replicated the settings and test that Dave done and had no issues what so ever. It behaved correctly. I've had my unit for approx. 6 years with no updates done.
Software 00.01.04
FPGA 01.02
Boot 01.011
Hardware 01.00
James

[J-R]

After seeing Dave's video and also owning a Rigol DL3031 electronic load, I hadn't noticed the issues with the battery load test with my unit in the past when testing batteries. I then replicated the settings and test that Dave done and had no issues what so ever. It behaved correctly. I've had my unit for approx. 6 years with no updates done.

When in the battery test app, if you quickly and repeatedly press On/Off, does it ever misbehave?  Using a bench power supply set the current to 1A on the load but 2A on the power supply.  See if it ever draws the 2A from the PSU.

Just wanted to confirm whether you tested in that manner.

[bergenhut]

J-R, In the battery test app using a current limited supply at 2A and the Rigol load set to 1A, it only drawes a max. of 1A with the load on, and no current from the supply with the load channel off, even  swithing it on/ off  quickly. The resistance test of the load terminals with the unit mains powered but the load channel off read 253kohm.
What I did find that I hadn't seen with my unit before now, was that if I did switch it on/off/on fast, 30% of the time it wouldn't load to the full 1A, only 15ma, as in Dave's video. If I just turn the load channel off and then back on usually fixes this.

[Cyclotron]

I ran some tests on my DL3021 running as a DL3031A and I was able to reproduce both of the issues.  Selecting the battery test, playing around in the utility menu, then exiting back out results in it frequently changing to the 0.1A current limit.

Entering battery test mode and quickly pressing the On/Off button multiple times results in the load staying on at the previous current level even though the display shows 0.0A and the button isn't lit.  And also sometimes it goes to a full short.  But on my unit I'm able to simply press On/Off again, wait a few seconds, then turn it back off and it works fine.  Definitely something that could be fixed via software update.

Definitely new buyers should avoid this unit.

Several people in the youtube comments have also confirmed this. Seems to be a difference in firmware and FPGA versions, with some people not seeing it with certain older version combo's.
This is nuts, definitely a unit to avoid.

Well, I suppose this one is off my list.  I have a BK8500 that's driving me up the wall. I'll pursue a Chroma unless there's reason to be concerned about them, too.

[J-R]

I've e-mailed Rigol.  I think if we all contact them about this, maybe they will be convinced to work on a firmware update?

[electr_peter]

I've e-mailed Rigol.  I think if we all contact them about this, maybe they will be convinced to work on a firmware update?

Rigol doesn't care about FW updates unless DC load catches fire or something.

[J-R]

Latest is that Rigol states that the faults in Dave's video were due to an outdated FPGA.  Which best I can tell can't be updated and requires replacing the board.
They essentially ignored the issues I mentioned finding with my unit despite having the same versions as their currently shipping units.

So I suppose if you can get the base model for cheap and unlock it, the result is something that perhaps is difficult to beat price-wise, but be sure to test everything with a current-limited power supply to see what issues your unit will have.  I've used mine to test a bunch of batteries without incident, so I'm happy enough I suppose.

If your unit doesn't have the latest FPGA but is still under warranty, maybe try to get it replaced while you still can.  Although some problems still persist.