Daly K-Series BMS

Background

The Daly BMS addresses two shortcomings with the ANT BMS, specifically the lack of controller capacitor precharge, and there being no way to disable the discharge MOSFETs without using the phone app.  This latter deficiency is a major hindrance for any off-road motorcycle.

Daly is a large company with a confusing array of offerings.  It was not easy for me to narrow down the most suitable candidate.  It seems Daly's method is to have you chat with an applications engineer (assistance appears to be available 24/7).  But I'm never willing to do that until I know enough to ask intelligent questions.

Daly's website is very polished.  Videos are their preferred way to convey information.  I suppose that makes the most sense for an international market, but I'd rather have a concise manual that's searchable.

I managed to work out the following definitions (which appear to be common among the Chinese offerings): 

• A Hardware BMS has no interface for monitoring/setup 

• A Smart BMS utilizes Bluetooth to a phone app for control and monitoring

• A Relay BMS switches on the high side via a contactor

This lead me to Daly's K-series.  You then select a unit for a specific cell chemistry (3.7V or 3.2V nominal) and the exact number of series cells in your pack.  Of course there is a choice for the continuous current rating.  I chose the smallest (40 A) version because it was just an evaluation unit and I had no real application for it in mind.  Wire leads are optional on the lower-current variants.  I prefer terminals.

I also ordered Daly's USB-UART interface for a Windows PC, as it seemed that was the only way to configure the unit to support a physical On/Off switch and enable capacitor precharge.  More on this later.

Prior to placing an order, I acquired Daly's Windows software and the PDF manual for it.  This manual is very good.  Unfortunately, the PDF user manual for the BMS itself is horrid.  It appears to be blurry copy of the printed version that accompanies the product.

The BMS is potted, so I won't be photographing its internals.  Below is a screenshot I captured from one of Daly's YouTube videos.

At first, these flashing sequences may seem arbitrary, but they are not.

I remember the meaning of the Off, Slow, Medium, Fast flashing rates based on how much energy the BMS can afford to spend flashing the LED.  From least to most: Sleeping, Idle, Discharging, Charging.

This is a good place to mention the BMS's current draw.  During Sleep, I measured a mere 660 uA draw.  This can be further reduced to about 425 uA by unplugging the Bluetooth module.  When Idle, the unit draws approximately 8.8 mA.  All these numbers will likely vary somewhat depending on battery voltage.

Below is the wiring diagram.  It appears to be quite simple -- and it is.  But it's not really complete either.  It would have been more realistic to show two wires for the Load and Charger connections instead of merging them into a single line.   Similarly, I would have used ellipses (. . .) to indicate there can be more cells in the pack.

Key Switch Button

Daly offers an optional key switch for $5.  That seemed expensive for a BSM that cost me $24.  I assumed I would have the proper connector on hand.  Nope.  It's a very small JST GH with a 1.25 mm pitch.  Nothing I had available was even close.  Not wanting to wait for the proper connector to arrive for a test, I used a tiny tweezer to short the two outer terminals together.  This proved the switch would do what I wanted.

Although the description of the Key Switch Button says you must use a computer interface to program that functionality, it's also possible to do so via the Android app.  There are four choices, in addition to “Disable.”  I selected “Control discharge MOS and sleep.”  With the switch contacts open, the BMS opens the discharge MOSFET and goes to sleep.  The BMS consumes very little current in this state.  Closing the switch contacts wakes the BMS and allows the battery to discharge.  After acquiring the proper connector, my testing with a SPST switch proved the expected action.

Controller Capacitor Precharge

This is an area of great concern to me.  The oscilloscope capture below shows that the Daly exhibits the proper behavior.  BMSs that do not provide capacitor precharge certainly do work.  The question is, for how long?  Although the BMS itself can be damaged by a high surge current, it's an inexpensive item.  Replacing a costly proprietary controller in a motorcycle is a much more daunting prospect.  I suspect getting the proper controller may be difficult for some e-motorcycles even during the 10-year period mandated by law.  And motor controllers certainly are not inexpensive.

Observations

1. These observations represent my best understanding at the time of writing, but there may be errors.  You should consider the manufacturer's reference material as the definitive source.

2. At the time of ordering, you must specify the proper number of cells.  This makes connection simpler and more foolproof, but you lose flexibility.  The cell connection wires are fairly short and very thin compared to the ANT BMS.

3. The BMS is completely sealed.  This is great for heat transfer and keeping water out, but there is no possibility of repair.  And it is certainly an impediment to the curious.

4. The BMS has two UARTs.  They are available via 6-pin connectors, only 5 of which are used.  Both UARTs can function at the same time.

5. The USB-UART module for communication with Daly's Windows software is optional and costs ~$10.

6. The BMS awakens via communication from either UART (and via the optional On/Off switch).  The UARTs default to 9600 baud, and will not “autobaud” to a different speed.  19.2k, 38.4k, 57.6k and 115.2k are options listed under the Windows software. 

7. Daly has two variants of the Windows software.  The one that specifically supports the K-series is fairly unpolished. Although the other variant excludes the K-series, it's much more refined.  But due to hardware limitations of the K-series some features won't work.  The most vexing problem is an inability to read the history log.

8. Each software application has a different password (listed here for reference). The Android app version 3.1.4 is 123456.  The PC app (BMS Tool) version 1.14.61.2 is 12345678.  The PC app (BMS Monitor) version 2.4.16 is 20211115.

9. The Android app asks you to create an account by entering an email address and a password.  I'm not exactly sure how I got around that, but was able to make the app work on a tablet without having a Daly account.

10. By default, the Android app only allows to you monitor the BMS.  The password must be entered prior to each session for which you want to do control or settings functions.  Although the password can be changed, I don't think it can be eliminated entirely.  This is great for an OEM, but it's an inconvenience for the experimentalist.

11. The Bluetooth module may be located remotely.  This is good for a battery enclosure that must be metal by FIM regulations.

12. Generally, I prefer the ANT's Android app.  But Daly uses better technical English, and is therefore easier for me to understand. 

13. When the NTC thermistor(s) are not installed, the BMS disables both charging and discharging functionality. 

14. When first using the BMS, the battery needs to be charged to 100% to calibrate the SOC.

15. The default sleep time for the BMS is 3600 Seconds (1 hour).  If you want to cancel sleep mode, a value of 65535 (largest 16-bit number) should be entered.

16. Although Daly claims to offer technical support, none was forthcoming.  My request for tech support was answered within 24 hours and forwarded to a technical person (Lin).  However, it's now been over a week and I have not received an answer (despite sending a follow-up email).

History Log

The history log proved to be a source of aggravation.  Although it may be viewed via the Android app (which takes a long time to display), I could not find any way to write the history log as a file to the tablet.  Daly's method is for you to supply an email address to which the log is forward via their server.  This I was successfully able to do.  Supposedly, the file is formatted as .CSV (comma-separated values) using the UTF-8 character set.  However, I could not read it into an OpenOffice spreadsheet.  It just made gibberish.  I then tried opening it using a text editor.  The text editor did not like it at all, but I was able to read “Java Excel API” near the beginning.  Ah-ha!  I refuse to use Excel, but a friend was able to read and save it as a standard .CSV file for me.

Clearing the history log was also a problem.  I could not see any way to do that via the Android app.  The only method appears to be via Daly's older BMS Tool.  The newer BMS Monitor will not do it.

Bottom Line

I expect most users will find the Daly a better choice than the ANT for an off-road vehicle application.  Neither company responded to after-sale technical support questions.   For me, the requirement of controller capacitor precharge is non-negotiable.  I also greatly prefer having a physical On/Off switch rather than using an app. 

 At some point in the future, I may review the QUCC BMS, but it won't be anytime soon.