More EcoFlow woes: So it goes

Portable power station design apparently isn’t easy. So suggests this engineer’s most recent two case studies, not to mention the long-term history (kudos to Kurt Vonnegut for the inspiration).

My first writeup last month discussed why one battery (or a few) in a larger cluster always seems to drain faster than the others, and how this imbalance would affect the system powered by that multi-battery cluster. The answer depended in part on whether the batteries were connected in a series, parallel or a hybrid combo of the two, to “boost the effective voltage (serial) and/or increase overall system runtime (parallel)”. Here’s how I concluded that piece:

I’m covering today only situations where the installed batteries are either non-rechargeable or are removed for recharging. Multi-battery packs recharged in situ (while installed inside a portable power unit, for example) translate to an even more complicated scenario involving, among other factors, the critical importance (and difficulty) of balancing the various cells within the likely series/parallel cluster.

At that point in time, for readers who wanted to know more about this topic, I referenced a Vitron Energy white paper I’d previously recommended in that same piece for other reasons, which also explored this topic at length. Here’s an example of what I’m talking about in the form of a quote from that same white paper:

If a large battery bank is needed, we do not recommend that you construct the battery bank out of numerous series/parallel 12V lead acid batteries. The maximum is at around 3 (or 4) paralleled strings. The reason for this is that with a large battery bank like this, it becomes tricky to create a balanced battery bank. In a large series/parallel battery bank, an imbalance is created because of wiring variations and slight differences in battery internal resistance.

And later in that section, as further elaboration:

When creating a lead-acid battery bank with a higher voltage, like 24 or 48V you will need to connect multiple 12V batteries in series. But there is one problem with connecting batteries in series, and this is that batteries are not electrically identical. They have slight differences in internal resistance. So, when a series string of batteries is charged, this difference in resistance will cause a variance in terminal voltages on each battery. Their voltages become “unbalanced”. This “unbalance” will increase over time and will lead to one of the batteries being constantly overcharged while the other battery is constantly undercharged. This will result in a premature failure of one of the batteries in the series string.

Again, I commend the entire white paper to your attention, not only because it delves in greater detail into the topics discussed in the two excerpts I selected but also because in doing so, it covers not only lead-acid but also lithium-based and other emerging chemistries such as “flow”.

I wrapped up that prior writeup by saying that “I’ll likely have more to say about these topics in future posts as well.” I didn’t necessarily think at the time that I’d be revisiting rechargeable in situ batteries this quickly…but then again, I also didn’t think that, a short time later, I’d personally experience what I still suspect was the outcome of an unbalanced multi-cell battery bank (along with a couple of other functional hiccups, details of which I’ll also share).

The DOA DELTA 3 Smart Extra Battery

I’ve had my EcoFlow DELTA 3 “stack”, the combo of a DELTA 3 Plus and its companion Smart Extra Battery, for one day shy of a year as I write these words in late April:

Until recently, all’s been well. It had only received a couple of firmware updates, all of which had been drama-free. And although it won’t seemingly power my refrigerator reliably, Xcel Energy’s increasingly frequent (or at least so it seems) power outages have provided plenty of other opportunities for me to tap into its stored-electron stash. The most recent outage (again as I write this …another is sooner-or-later-likely-sooner inevitable) in mid-March thankfully lasted only a bit more than seven hours, not several days, but alas, the “stack” didn’t survive it.

During the outage, I’d dragged upstairs its DELTA 2 base unit-plus-smart extra battery “stack” siblings to run an interior lights and recharge flashlights and various mobile devices:

When the utility company-sourced premises electricity came back up just after midnight, I took the DELTA 2 “stack” back downstairs to the workbench in the furnace room, its normal on-standby location. I’d left the DELTA 3 gear there; the base unit’s front panel display was now illuminated but that of the smart extra battery wasn’t, nor seemingly was the latter more broadly functional any longer. And looking more closely, I noticed an “Error 726” indicator on the base unit display that I’d never seen before:

I hit up Google search for suggestions, which were scant, dubious (I don’t think “turn off the unit and wait a few hours for the cells to rebalance themselves” makes much if any sense, particularly given that the only way to turn the unit off is to unplug it first) and more generally indeterminate save for the revelation that Error 726 indicates that “cell voltage differences are too great”. My next and increasingly common step was to publish a Reddit post. One respondent pointed me toward some Facebook group traffic that I’d already come across. Another noted that he/she had experienced the same issue after a recent firmware update, which I’d also done. And a third offered a “Possible it’s a bad cell” suggestion. Hold that thought.

Base unit BMS reset attempts were ineffective; it was also running the latest-available firmware:

I hooked up a fan to one of the AC outputs to drain the base unit’s batteries, in the hope that a full recharge might resurrect its cognizance of the smart extra battery. No dice; the base unit worked fine standalone but threw an Error 726 with the smart extra battery connected. So, I reached out to EcoFlow technical support, who confirmed that the smart extra battery had gone bad and offered to send me a replacement in exchange for my failed unit.

Two weeks later, the new smart extra battery was in my hands. Connecting it to the base unit initially resulted in the generation of another error code in the latter, the nebulous “Error 014”:

After a brief panic, and acting on a hunch, I checked to see if the base unit needed a firmware update before the two devices could be sympatico. Indeed, that was the case, two update cycles’ worth, in fact:

And, at least as of today, the setup once again seems to be working OK, leaving me with one lingering question: what went wrong in the first place?

• Was it a hardware failure, such as (but not necessarily) an unrecoverable cell-imbalance issue, in my specific original smart extra battery?
• Was there a broader fundamental hardware flaw in initial smart extra battery units, suggested by the prompt to do a firmware update (which I hadn’t seen before) when I plugged in the replacement?
• Did a firmware update to the base unit initiate the failure sequence in the first place, as the comments of one of the respondents to my Reddit post indicates might be the case?
• Or were the firmware-update timings (both prior to the original-unit failure and after installation of its replacement) purely coincidental?

Reader theories (and broader thoughts) are as-always welcome in the comments! And now, speaking of botched firmware updates…

A DELTA 2 double-whammy

Regular readers may recall that I’ve had issues after doing firmware updates on EcoFlow gear before. Generally speaking, I’ve therefore subsequently waited for an appropriate period, combing Reddit and relevant Facebook groups for posted evidence of others’ troubles, before taking the plunge myself. However, when I got prompted for an update to the DELTA 2 in late February, I (over)confidently decided to plunge ahead absent any preparatory research:

After all, the previous update I’d done to the DELTA 2 back in late December had gone well. I was so overoptimistic, in fact, that I updated my RIVER 2 at the same time:

The RIVER 2 survived the update just fine. The DELTA 2 on the other hand…

I admittedly didn’t immediately notice the issue, because it only happened occasionally. With the combo “awake”, everything seemed to be fine (well, mostly…keep reading). But at some random point after the units displays turned off (I stuck with the default “5 minute” setting), the power LED on the smart extra battery would extinguish, the base unit’s fan would kick on and perpetually run at low speed, and it would unceasingly (generally) or cyclically (briefly) draw ~20W of power from the AC outlet connected to it:

Punch either unit’s front panel power switch and the displays would wake up, the fan would stop and the trickle charge would cease…until after the displays turned back off again, that is. Lather, rinse, repeat. The trickle-charge behavior particularly worried me, because I didn’t want to end up with an overcharged, overheated and potentially exploded-and-burning battery situation on my hands. So, after several cycles of BMS resets and draining-then-recharging the battery sets, all of which “fixed” the issue only temporarily, I reached out to EcoFlow tech support once again with the proactive suggestion that a firmware downgrade might be in order.

They agreed. I never received (again, keep reading) their first attempt to “push” me a rollback from v1.0.2.176 to firmware v1.0.2.163, but the second attempt was successful:

The DELTA 2 “stack” is once again stable, at least from a charging standpoint. And although it took a while for another invitation to update back to firmware v1.0.2.176 to appear, leaving me wondering if either my “rollback” package had been customized to suppress the subsequent update or EcoFlow had pulled firmware v1.0.2.176 completely:

Turns out I just didn’t wait long enough (and yes, I declined when the update invitation eventually arrived):

Unfortunately, EcoFlow doesn’t publish firmware version histories for its devices, so I couldn’t check for an answer to my question that way. And customer service’s silence in (non-)response to my repeated queries about this particular topic weren’t helpful either (in contrast, I’m compelled to note, to their overall general excellent support).

Connectivity troubles

While I was in communication with EcoFlow, I also brought up an unrelated DELTA 2 issue that I’d been having on-and-off, albeit seemingly more frequently with the passage of time, with the base unit. After some random time period, hours-to-days after I’d established Wi-Fi connectivity, it’d drop Wi-Fi and revert to Bluetooth-only communication with my controlling smartphone:

Other times, even when Wi-Fi was supposedly still operational:

the DELTA 2 base unit, therefore entire “stack”, became “invisible” when I was attempting to reach it from outside my LAN via the EcoFlow “cloud” intermediary:

EcoFlow tech support suggested that the IoT module inside the unit might be gradually failing. I almost didn’t bother pressing the issue further—returning the unit for repair or replacement is something of a hassle, further complicated by the fact that the included flammable batteries mean that I can’t just drop it off at a FedEx Office location but need to arrange for front-door pickup, and then there’s the delay for a replacement unit to arrive—while the loss of Wi-Fi connectivity is annoying, it’s not a functional “death sentence”.

But then EcoFlow confirmed what I’d already suspected, that the IoT module also implements the Bluetooth subsystem, whose functional loss would completely sever further communication with the unit. Couple that with the fact that I’ve been promised a brand-new (not refurbished) replacement, with a zero-cycle fresh battery pack, and it was an offer I couldn’t refuse. I’m awaiting a return-shipping label as I type these words; I’ll report back on the status of the replacement unit via a posted comment on this post once published.

Design is hard

You may have already noticed a commonality to both primary issues noted in this writeup, as well as those in prior EcoFlow problem-themed coverage from me: the smart extra battery. I’m guessing that it’s relatively uncommon for base unit owners to also have this additional-charge (not to mention additional credit card charge) storage peripheral. As such, the prevalence of user problems is also likely to be uncommon. Therefore, I suspect, it’s relatively easy for smart extra battery firmware-related issues in particular to slip through any EcoFlow pre-release testing cracks.

In no way am I making excuses for the various EcoFlow issues I’ve come across; I’m just striving to be pragmatic about root causes. As I noted at the beginning of this writeup, battery pack design is fundamentally challenging. Make a device increasingly “smart” and the level of difficulty further ramps up. Is EcoFlow unique in this regard? I don’t know. I welcome feedback from owners of other manufacturers’ portable power stations (as well as from both EcoFlow and other manufacturers’ representatives themselves) regarding their comparative reliability. And I’d also appreciate insights from other EcoFlow owners re the commonality-or-not of their experiences. Sound off with your thoughts in the comments, please!

—Brian Dipert is the associate editor, as well as a contributing editor, at EDN.

Related Content

• Single-battery failures in multi-battery arrangements: diagnosing selective cell derangements
• EcoFlow’s DELTA 3 Plus and Smart Extra Battery: Product line impermanence curiosity
• EcoFlow’s Delta 2: Abundant Stored Energy (and Charging Options) for You
• Portable power station battery capacity extension: Curious coordination
• Firmware-upgrade functional defection and resurrection

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