Posted on 4 Comments

Unknown PIN or password

If you are using the Android app version 3.1.1026 or the one from google play, there is a conflict with the newer BMS firmware version 2.1.

The BMS does not have a password function, but the app still expects it to be there. It will send the blank PIN (000000) and get a negative response from the BMS, and the app gets stuck in this loop.

This has been resolved in the iOS app.

We are also coming out with our own new android app soon that will solve this problem.

For now, you can try the older version of the android app 3.1.1015, or try the iOS app, or the desktop app via USB. Links to these applications can be found here: https://overkillsolar.com/support-downloads/

If you need to use the USB desktop app to fix this, you can email support@overkillsolar.com and request a free USB module.

Note that the existing Android app version 3.1.1026 will never work with BMS firmware 2.1 even if you reset the password.

We apologize for the inconvenience.
-Steve

Posted on 1 Comment

Password Reset , communication failure.

Starting with firmware version 0x17 sometime in 2021, JBD added a password function to the BMS firmware, without telling anybody.

The BMS doesn’t have a physical reset button, so there really isn’t a practical way to implement password protection. (without risking a permanent lockout)

This has caused some of our customers to be locked out of the settings on their BMS if an unknown password is set.

The basic monitoring functions are unaffected, however the JBD android app will not display the basic info without the correct password. The iOS app and the desktop app(s) will still display basic info without the correct password, but will not display parameters.

This is sometimes reported by the app(s) as a communication error because the BMS is not returning the requested data, only the “bad password” message.

The solution may be a password reset

The newest version of JBD’s desktop app includes a tool to clear the password, which actually makes the whole password function useless at best.

There is a screenshot included in the zip file with instructions, since the app does not display english labels on that page.

You can now use our release of Eric Poulson’s BMS-Tools desktop app to send a password reset command.

Either way, You will need a USB communication module.

Find the application download links here: https://overkillsolar.com/support-downloads/

What’s next

After the next version update, the xiaoxiang-bms iOS app will have a password reset tool.

We do not know when a new version of the JBD android app will include the reset function.

Posted on 6 Comments

How to charge LiFePo4

LiFePO4 does not need a multistage charging profile.

The manufacturer of our 100 ah cells, and the MFG of the common 280ah cells specifies charging at a rate of 0.5c up to a maximum voltage limit of 3.650 per cell.

Based on the LiFePo4 charge curve the cells will reach nearly 100% charge at 3.500v per cell, so this is our recommended target voltage (14.0v per 4-cell battery, 28v per 8 cell battery).

Note that there is no mention of “float” charging. This is only applicable to lead acid yet most charger designs include a float setting for LiFePo4, usually 13.2v for a 4 cell battery.

Why is this a problem? Because at 13.2v the battery will be significantly discharged, and so you will observe the battery going through a deep cycle after every full charge, even though it remains plugged into shore power.

Therefore the ideal charger for LiFePo4 batteries (in our opinion) is a current limited power supply set to 14.0 to 14.2 volts.