Daly smart bms high cell disconnect

[John Frum]

I have an overkill(jbd) bms.
On high cell disconnect the charge path is blocked but the discharge path is still active.
This can be observed by administratively disabling the charge path from the android application.
There is a slight <1volt drop in system voltage but the system voltage doesn't drop to zero.
The discharge path is still active.

If you have a Daly smart bms please do the same test and report back.

My hope is that that the Daly disables both paths and the system voltage drops to 0.
Would like confirmation before I spend money.

 

[Ampster]

My hope is that that the Daly disables both paths and the system voltage drops to 0.

I am curious why you would prefer to have the discharge path disabled? The first thing I would want to do on a high voltage event is bleed off some energy.

 

[John Frum]

I am curious why you would prefer to have the discharge path disabled? The first thing I would want to do on a high voltage event is bleed off some energy.

This idea is to use 2 BMSs
The primary BMS will be in the current path
The second BMS(the Daly) won't be in the current path but will control a relay.
That relay controls a dumb charge source.

Its really hard to find a 24 volt charger with proper charge termination and enough current for my setup.
Victron makes one but I could get decent inverter/charger cheaper.
BTW I can't use an inverter/charger because my very atypical usage model prohibits it.

 

[Pim57]

My Daly has the same behaviour. The CHGMOS is turned off and the DSGMOS stays on.

And I agree with Ampster that in case of a high voltage I really prefer to lower the voltage asap.

 

[Ampster]

I assume you are only using the second BMS to control just a relay and no other BMS functions. Have you looked at just a programmable relay or do you need high cell cutoff?

 

[John Frum]

My Daly has the same behaviour.

Sorry not clear to me how your Daly behaves.
Does the voltage drop to zero or does it just drop a bit?

 

[Pim57]

I have a common port Daly with two sets of mosfets. One for charge and one for discharge.

As the discharge mosfet stays on (in case of a HV disconnect) the full voltage is present.

 

[John Frum]

I have a common port Daly with two sets of mosfets. One for charge and one for discharge.

As the discharge mosfet stays on (in case of a HV disconnect) the full voltage is present.

That won't work my use case.
Bummer.
Thanks.

 

[DJSmiley]

This idea is to use 2 BMSs
The primary BMS will be in the current path
The second BMS(the Daly) won't be in the current path but will control a relay.
That relay controls a dumb charge source.

Its really hard to find a 24 volt charger with proper charge termination and enough current for my setup.
Victron makes one but I could get decent inverter/charger cheaper.
BTW I can't use an inverter/charger because my very atypical usage model prohibits it.

What do you call 'with enough current'?

34A: https://www.jameco.com/z/PB-1000-24...ttery-Charger-28-8-Volt-34-7-Amp_1954341.html

55A: https://www.jameco.com/z/RPB-1600-2...nt-Single-Output-Battery-Charger_2251479.html

110A: https://www.jameco.com/z/RPB-1600-2...nt-Single-Output-Battery-Charger_2251479.html

All can be configured to 2 or 3-stage charging and voltages can be adjusted, so perfect for LFP.

If 110A is still not enough you can parallel 2 units to get 220A charging...

 

[John Frum]

Its an 1p8s 280ah battery so...
280ah * . 2c = 56 amps minimum
280ah * .5c = 140 amps maximum

 

[John Frum]

@DJSmiley thanks for the links those look like contenders.
Looks like the 2nd and 3rd link are the same unit.
Is that cut and paste issue?

 

[Diysolar123]

yep, thats how the daly works so that no current will flow into the battery, but the battery can still be discharged so you can drain those little angry pixies out of it.

if you want to control a relay based on what the daly(or jdb) is doing, you could just get the data you want from the serial ports of the BMS.
Use a cheap esp32 or a pico raspberry pi and control anything you want!!!

 

[John Frum]

yep, thats how the daly works so that no current will flow into the battery, but the battery can still be discharged so you can drain those little angry pixies out of it.

if you want to control a relay based on what the daly(or jdb) is doing, you could just get the data you want from the serial ports of the BMS.
Use a cheap esp32 or a pico raspberry pi and control anything you want!!!

Is it as simple as polling in a loop for the key/vals that I'm interested in?
I'm guessing there is no event subscription mechanism, confirm?

 

[Diysolar123]

Is it as simple as polling in a loop for the key/vals that I'm interested in?
I'm guessing there is no event subscription mechanism, confirm?

its a simple protocol, you can just grab all the data and,well, do what you want I guess hehe
The spec is on this site and it is readable without learning mandarin (although learning that would probably help with a LOT of manuals!)

 

[John Frum]

its a simple protocol, you can just grab all the data and,well, do what you want I guess hehe
The spec is on this site and it is readable without learning mandarin (although learning that would probably help with a LOT of manuals!)

View attachment 46217

That is not at all clear to me.
I am guessing there is a pile of context missing.
I assume its a polling interface.

BMS life is expressed in 1 byte, whut?

 

[Diysolar123]

the entire spec is on this site, its a standard protocol interface...
You send a command byte with appropriate headers and format, and you get a response block.
hex 0x93 sent returns a 8byte block with the data as shown inthe table, which in this case is the state of the charge and discharge mosfets.

 

[John Frum]

the entire spec is on this site, its a standard protocol interface...
You send a command byte with appropriate headers and format, and you get a response block.
hex 0x93 sent returns a 8byte block with the data as shown inthe table, which in this case is the state of the charge and discharge mosfets.

Link please.

 

[Diysolar123]

oops, forgot to add the mystery that is "BMS life"... which is just a translation issue...
"BMS life" is what we would call the BMS heartbeat upcounter.


this site has a great collection of resources besides the forums!!

here is the daly smart bms resources:

Daly SMART BMS Manual and documentation

UPDATES: 5/19/2020 - Added CAN Protocol Documentation 5/20/2020 - Added RS485/UART Protocol Documentation To get to the manuals, click on the "Go to download" button in the upper right corner To get the Daly PC SW for configuring the Daly...

diysolarforum.com

 

[John Frum]

Is there an example that demonstrates a set/get transaction?
It appears to be transactional but no session, confirm?

 

[John Frum]

Actually since I already have an Overkill bms is there a equivalent spec for the overkill?