@BLUETTI_CARE
I noted some disparity in charging my AC180 power stations. I have 3 units, AC180-1 was purchased over 2 years ago and is pre Bluetooth password capable. Ac180-2 & AC180-3 are approx. 18 months old, purchased together and are password capable.
I have tested all 3 power stations, with the following parameters;
All were calibrated for SOC and depleted in the same manner (a small heater at 800W) to 13% SOC.
Test conditions were in airconditioned environment at 24C.
Each was recharged from a stable grid source at 240VAC. (On roof solar active)
The charge cycle was as follows;
Charged from 13% SOC to 15% SOC in Silent mode, then using the App, charge mode was set to Standard.
Charged to 25% SOC, then charge mode set to Turbo mode until SOC reached 50%.
At 50% SOC, charge mode set back to Standard mode until SOC reached 65%.
At 65% Charge mode was reset to Silent mode until SOC reached 75%, at which time all units were turned off for short term storage.
During testing, the time, in minutes, was recorded for each charging phase and the power in Watts recorded, again for each phase.
I am well aware that each power stations’s BMS will control the level of power input to best manage the battery’s health and temperature, electronics etc may vary. The attached chart of results shows these variations and those marked in green, showing each units results and their differences are what I would assess as acceptable discrepancies.
However, the notable one result in red is something I query. Both of the newer AC180s (AC180-2 & 3) in the 15 to 25% SOC cycle, show 7-800W of input power, whereas the original AC180-1 charged at 1100W during the entire, cycle. Why?
The other point of note is the wide range of input power during the Turbo mode charge and similarly the 50-65% SOC charge in Standard mode. Is there an explanation for this?
Not in the chart is the total charge time for each unit;
AC180-1 = 75 min
AC180-2 = 84 min
AC180-3 = 76 min Also within a consistent time frame, happy with that.
Final point
All 3 unit’s firmware is up to date; IOT for AC180-2 & 3 is 9046.04. ARM, DSP & BMS for all 3 are 2074.08, 2078.06 & 1033.12 respectively. Which raises one final Q. Why does AC180-1 not have an IOT value available in the App?
This behavior sounds like the BMS reacting to temperature sensitivity changes within the cells themselves. You did not specify in your test if you performed a cool down period to ensure cells were balanced as best as possible. For example, a slightly warmer starting temperature on AC180 #1 would result in lower resistance potentially leading to that period where the BMS could sustain 1100W. If AC180 #2 or #3 had hot spots or cooled one, one cell group could heat up faster than the other, leading to the BMS oscillating the charge due to internal resistance.
You can observe if there is an internal resistance difference by performing a voltage sag test between two units each at temperature equilibrium and around 50% SOC. Ideally you’ll want something that purely resistive that turns on instantly at a fixed wattage instead of a space heater where the heating element warms up and the wattage ramps up. Say for example a microwave. Observe how the watts is displayed from shore power. Say it goes from 0W to 1100W within a few seconds. Now you plug it into AC180 #1 and notice it ramps up around the same (accounting for inverter logic as well). Then you notice AC180 #2 and it ramps up to that same 1100W but more slowly. The voltage is sagging more due to the battery pack being not as “stiff”. This will cause the behavior in your chart. More internal resistance will lead to that fluctuating charge (600-1100W). When you do the test, make sure you have SOC at 50% and allow unit to rest for 30-60 minutes so its a fair test.
I depleted all 3 AC180s in the same way, same load on day 1. The recharge was then done, the next day, inside an airconditioned room at the same time, from different wall GPOs. All 3 were stored next to each other in that room overnight, so all would have been at room temperature.
The load was resistive at approx 800W.
AC180-2 & 3 charged mostly at the noted 702 & 830W and occasionally cycled between the noted lower and upper values up to a Turbo wattage, then down to the lower value, before settling at the nominal 7-800W.
Ac180-1 was the "fly in the ointment as it charged at a constant 1100W Turbo mode, when set to Standard mode. (I checked the setting several times)
I’m not overally concerned because, as I have noted many times on the Forum, I charge in Silent mode, wherever possible to maximise battery health. Silent mode appears to be a stable charge, both at a low SOC and a higher SOC and what I expect, sub 300W, or approx 0.25C. I’m not a fan of charging LFP at a full 1.0C or higher.
@BLUETTI_CAREIt’s now 2 weeks since I posted my Qs.
The Q I am most interested in is why one of my AC180s (noted in the first post), when set to Standard charge mode always charges at 1100W. (Which is Turbo charge level).
Hi @Mandp Thank you for your detailed testing and feedback. Regarding the points you raised, please see our explanation below:
The charging power of the device is related to the charging voltage, temperature, and other factors. Under the same conditions, slight differences in the cell voltage between devices may cause variations in charging power. This is a normal phenomenon.
Your first AC180 does not show an IOT version because of the Bluetooth password functionality. The early version of the device’s Bluetooth chip does not support this feature, whereas the newer version of the Bluetooth chip adds this function after an upgrade. Therefore, the IOT version is displayed only on the newer devices. You can use the presence or absence of the IOT version to determine whether the device has Bluetooth encryption functionality.
Thank you for your understanding and support. If you have any further questions, please feel free to contact us.
@BLUETTI_CARE Thankyou for the reponse and the IOT explanation. As mentioned in other posts, I have;
1 x AC200P
3 x AC180
2 x AC70
1 x AC2A
Charger 1
X20 (Bluetti award gift)
1 x Elite 100 v2 (Pre production test unit)
All are working as advertised and very well. My recent questions have only arisen due to my interest in further understanding the above power stations. As I have, in the past, passed my knowledge on to other Forum users, my every question doesn’t just help me, lol.
As an aside, I use the larger of my power stations in grid outages, even though, in the main they are limited to 1,800W inverters. Not whole of house, but enough to cover the basics of lighting, fridge, coms and entertainment. From a capacity perspective I have over 8kWh of battery and multiple charging sources, to even cover lengthy outages.
