Daly 8s smart bms works! A 250A love story.

[Dhopewell]

I had a difficult experience with the setup. The wire loom comes with 22 gauge or smaller mostly identical wires, and step 1 was to crimp on ring terminals. I considered making them longer, and wish I had. Step 2 was to attach them out of order, and test them and fix them, making critical error of testing the red battery sensor leads to the main negative pole of the battery because the plug was way too small to touch two meter leads to. Step 3 was to check and recheck for correct b+ and go through start up procedure of B-, then leads, then P- to the load, which is a big inverter, 3kw of low frequency Iron Age engineering. Step 4 was to fail, reverse the setup wiring and try again. Several times. Yes, there was the rated voltage at P-, then no to current through load. More steps repeated, over and over several hours otherwise used for work and fun.

What was the problem?
- it was not the hulking 3kw inverter with big sparky caps
- it was not miswiring
- it was not a problem with the Bms
- it was a problem with Daly’s fragmentary documentation
- it was a problem with the black wire ring terminal, which showed continuity in my hand but lost it when cranked onto the terminal (well below the 8N/m allowed torque of the 280s). I believe this was what started the problem
- it was not a problem with the SOC display I put in the light board slot, and which by lighting up encouraged me to continue
- it was not a problem with making topbms run. It recognized the port and displayed the incoming data as soon as there was some
- Finally it was the solution in the topbms software a handy switch called “reset bms”. When I did this the bms actually passed current.

Did you know that inverter caps hold enough energy to power startup for about 7 secs. Now I do. The mysterious voltages people are getting connecting to inverters when the bms is not active is from the caps.

Finally the bms worked. The inverter came on and it stayed on. Cell voltages on display, coloumbmeter running, and parameters to be set and saved in a config file. It was like Christmas

If there’s any interest I’ll run through tests on request. Topbms has a parameter for low voltage charge cutoff. I’m going to find out what happens when it’s exceeded.

 

[Dhopewell]

Daly has graciously offered me a refund after more chasing down of difficulties. There was a lot of back and forth but I give Daly credit for sticking to their protocol and accepting my evidence.

The bms ended up being at least part of the problem. After getting a clean reading of cell voltages (pic1) I started a charge cycle. In pic 2 you can see a comparison of bms pack voltage reading against a fluke 117, with cell 1 reading now reading almost 30mv lower than pre charge cycle on bms (a 50 amp 2 hr charging cycle) and pack reading low by roughly same amount. In pic 3 you can see a substantial negative current displayed even though the negative lead was detached and in frame. I took things apart to check and recheck wiring, setup etc, but could not reactivate the bms when reinstalled.

This episode is over but I’m still curious - has anyone seen similar failure mode and what caused it? Do you think it’s worth opening a bms failure mode thread to document what really goes wrong? FWIW my SWAG is an internal problem with the sensor wire circuit, since the failure looked like what happens when crossing leads.

I bought an electrodacus w my refund and have decided to lay off the FETs for a while.

 

[ttcal]

Where did you locate the Daly software (link)? Thank you.

 

[Dhopewell]

There is a sticky with software. Go to resources and look for titles like “Daly SMART BMS Manual and documentation 3”. They were published in or around May. I don’t recall the exact one I used but there are manuals as well as SW.

 

[ttcal]

Thank you!