EcoFlow Delta PRO Extra Battery review
_EXTRA BATTERY TESTING_
When I first got the Extra Battery, I had to decide if I would leave the factory firmware of the Extra Battery or update it to latest available at the moment which was 1.0.0.96 (this means updating any of my two Delta PRO to latest as you can’t choose which version you want).
I had one Delta PRO with 1.0.0.85 and the other one with the original factory firmware so in the end I thought that it would be interesting to first test with original factory firmware and switch to latest if I would detect any kind of problems.
Since all the EPS fiasco I’m extremely reluctant to update, especially my factory firmware Delta PRO which has been running without ANY issues (apart from the ones I’ve described here and here).
So I connected the Extra Battery with factory firmware to BALROG (port #2 so EB would never update even if I made a mistake) which also has factory firmware and I’m happy to report that it has been running flawlessly 24/7 for the past 3+ months and the maximum drift apart I’ve seen is 4% but they usually stay within 1% to 2% while charging/discharging and I very rarely have to do my “30s recalibration method“.
A week after I got my first Delta PRO (January 2022), I started developing/coding a complete server solution that pulls, processes, analyzes, and saves to database a total of more than 9.000.000 datapoints per day and all my findings in this and other articles are based on this precise internal data of Delta PRO and Extra Battery.
When you connect an Extra Battery to the Delta PRO, they will try to balance each other by mainly matching their internal battery voltage to be as close to each other as possible. In my case the maximum drift that I’ve seem was 4% that was immediately fixed with my “30s recalibration method“. The normal behavior (in my case) for the Delta PRO <-> Extra Battery is to be between 0% and 2% which is negligible. I’ve done multiple tests with sub 100W loads for more than 8 hours in a go to see if I could catch a big drift but in the end it never happened (max onetime was 4%).
I’ve also done the opposite by putting 3.2KW+ loads for a while to see if I could force an imbalance but the maximum I could see on the LCD was a 1% difference. After reading so many bad reviews, even from allegedly knowledgeable people, I was expecting to face multiple problems but to my surprise and as of this writing, I haven’t faced any kind of issues; it’s as plug-n-play as it gets :).
Please be advised that when you are charging/discharging, you might see a difference in % because of the way the Delta PRO + Extra Battery charge/discharge; what I’ve observed is that sometimes the Delta PRO will split the AC load (discharge) evenly between the Delta PRO and the Extra Battery but the Delta PRO will add to itself the 55W+ internal consumption (40W inverter + 15W internal electronics/fans) so in the end you would see a discharge ratio of 55%/45%. When it gets a little bit away, the trend will invert and the ratio will become 45%/55% to compensate and rebalance the battery packs voltage by increasing the discharge rate of the Extra Battery.
Be aware that it will first try to balance/match the voltages as best as possible. When discharging you should see that the Extra Battery has a higher percentage (in my case not higher than 2%) than the Delta PRO and when charging you should see that the Delta PRO ends up being higher percentage than the Extra Battery. As both batteries start to reach around 51V when charging, you should see that they are getting close to each other or even the same percentage; the Delta PRO will start to charge on a slower rate while providing the rest to the Extra Battery until both reach around 52V where they should stop charging. You might even see that one of them has stopped charging while the other is still charging.
You should think of it as a turn-based balancing scheme instead of a perfect real-time balance. This sounds great but sometimes both units will get out of whack when the algorithm that calculates the internal watts capacity (based on voltage) has a discrepancy and ends up guessing that the watts capacity is less than real one (example 3.480W instead of 3.648W = 95% instead of 100%) so you might end up with same internal voltages but different % capacity due to mismatched volts-2-watts capacity.
When both unit’s battery voltage is the same, due to the flat discharge voltage curve of the LFP4 chemistry of the battery, which makes it a challenge to correctly guess the real capacity left, the Delta PRO will fall-back to the watts capacity that the algorithm of both units is calculating in real-time, but what happens is if the initial watts capacity has been wrongly calculated, the error will compound and the percent to real capacity will be wrong and you would see a high % imbalance between the units. There’s no easy fix except to maybe modify the charging algorithm to do a slow top-off to (BMS) battery voltage cutoff and then reset the calculated watts capacity by also taking into account battery aging (# cycles) with an internal “volts-cutoff-to-expected-capacity” table but maybe that’s too much for the ESP-M SOC….? All in all it still ends up being a guess work at best.
I personally did not suffer this kind of issues (thanks to my access of all internal data in real time) as I would use my “30s recalibration method” and have both watts capacities in sync with the voltage so I would advise anyone that has issues to try my recalibration method as it only takes 30 seconds and you don’t have to dumb-drain you batteries till shutoff.
This last month+ I’ve noticed that I don’t even need to bother with calibration anymore as the units watts capacity is quite precise and the drift doesn’t go above 2-3% but remember that I’m using original factory firmware (so newer firmwares might behave differently…?). My other Delta PRO that is running 1.0.0.85 needs a little bit more love from me but nothing serious.
I see on your You Tube vid about fan noise that you’ve modified your Delat Pro to drop the noise to 40dB. Can you detail what the mod is? I’ve considered replacing the fans with “Arctic” brand low noise fans but would like to hear your ideas first.
Thanks!
Hi George.
This is what I wrote on YT in respect to the fans:
Hi There,
I wish I had discovered your forum sooner. I purchased the EF DP in September 2022 from Amazon along with a Solar Panel (of which I am yet to use). I had been using the unit to run large appliances during peak times and charge the unit during off peak periods via AC. I use the “Slow/Custom” switch and control the charge voltage in the app. I reside in Australia. The system has 4x 230V 10A sockets along for output. Generally, I am able to operate a dishwasher at 75 degrees C (167F) for 2hrs 10 mins and a 2hr 35 min load of laundry in my front load washing machine using cold water. Then the battery would be be at 1%. I purchased the EF DP Remote Control and immediately was disappointed that the screen kept timing out at 60 secs max despite it being connected to an always on USB-C cable. I had contacted EF Support to address this, they took an exceptionally long time in trying to help resolve the issue. I had to provide video evidence of what had been occurring. They said it was definitely faulty and they would be sending me a replacement. After the replacement had arrived, I had set it up and paired it successfully with my DP and connected it via Ethernet to perform a FW update on it. I immediately noticed that the issue was still present and called them out on it. They said this time it is a limitation of the FW and there is nothing further that they could do. I still have the other EF DP Remote with me and they have not requested it back – What gets me is why get me to go through the hell of trying to demonstrate an issue with their expensive remote control when they were already aware of it?? The eventually emailed me asking if I wanted to keep it or they would refund me for the purchase. I didnt reply as I thought whats the point, I would have to post one back to them and pay for shipping.
I recently purchased the EF DP Extra Battery for the insane price of $4369 AUD and have successfully connected it to my DP. I noticed after I had reached a charge of 100% (which both units were displaying), the app indicated a FW update was available and I updated thinking this is the correct thing to do. I am now sitting on V1.0.1.18 and V3.0.1.11 (WiFi) as displayed on the app.
My first operation was to run a full load of laundry in my clothes dryer with X-Boost turned on, running a Dyson Purifier Fan and a Dehumidifier at the same time and I had observed the Extra Battery was matching the output of the DP of 2500W+ at one time.
A week on using the EB I am not satisfied. The Extra Battery when in operation with the DP running the same load as before does not match any longer. The EB seems to max out at 1100W input to the DP and doesn’t assist the DP when its almost out of juice. I feel load balancing is a problem as it clearly cannot achieve this. I’ve also found that despite the EB having a higher charge remaining the DP continues to output a charge to “top-it-up” where as it should be doing the opposite and providing a charge to the DP.
I am currently charging my DP from 43% to 100% at 2000W (the max output from my outlet is 2300W, but sometimes trips the breaker). Whilst charging it is outputting 794w to the EB at the same time and both capacities are almost identical.
I only wish the EB would function as it was marketed to me as. I am somewhat happy with the EF DP however these FW issues are bugging me. I wish there was a was to reset back to stock FW. I have my unit connected to the internet and use it via Bluetooth when the internet goes down.
Appreciate your thoughts?
Thanks for reading.
– Daniel
Hi Daniel!
The EB & DP wil never be identical because of how voltage/charge transfer works.
When charging, the DP has a higher internal (battery pack) voltage than the EB so the EB can charge from the DP and the opposite is true when discharging; the EB will have a higher internal (battery pack) voltage than the DP so the DP can take energy from the EB.
What I’ve observerd is that the BMS (Battery Management System) will try to keep both battery packs (DP/EB) within 0.10V of each other
What you see on the LCD as % of charge is basically a (best case) guess when the battery (DP or EB) have had a full charge + state reset (State of Charge); the computer that manages the battery has an internal table of data that correleates voltage, temperature, cycles to an approximate, user facing percent of charge that will get out of sync (looses precision) the more you use the DP but the full battery capacity is stil there just not reported correctly to the user.
This past week, I’ve observerd an issue with my EB where after charging to 100% from solar, when disconnecting from solar, it would not share the load with the DP so the DP drained 20% while the EB didn’t budge (0 watts).
The only way to kick it out of it’s slumber was to drastically increase the drain on the system (DP+EB) from 200W to around 1.500W which finally woke up the EB and started draining 3:1 vs the DP to try and catch up (took a long time to almost catch up).
TLDR: It’s a BETA product that needs some nursing where you’ll have to jump in when an issue arises to fix it and go back to normal. The disparity between what is reported (%) and reality can become big with time/cycles and the only way to fix it is to reset the counter (check my articles for the 15 seconds procedure to reset it).
As for the REMOTE, it was an issue with early FW because it wasn’t coded properly so they finally took the time to implement it and then used the DP to reprogram the REMOTE so it wouldn’t turn OFF at 60 seconds __BUT__ you NEED to have the remote connected via ETHERNET/NETWORK cable when doing the FW upgrade and when using the device or it will revert to 60 seconds.
I have my remote via ethernet cable and it is on for 16+ hours a day since the last 9 months or so.
Hope this helps!
Take care.