Even Newer 4 to 24-cell Battery Management System (BMS)

[methods]

I don't know if you are near a Frys Electronics
They sell real nice units for cheap
Come with all three tips
Digital temperature readout
850 degree max

Instant gratification, no shipping, but you have to pay tax.

Recently I switched from an old clunker to a variable temperature and I will never go back! I can solder SMT and 8gauge with the same iron!

-Patrick

 

[boostjuice]

Hi Gary/Fechter,

Could you please post up the BOM (Bill of materials), with or without the Mouser part numbers so the keen amongst us can start sourcing components.

Cheers
Neil

 

[Tom_D]

So, my understanding is that with this relay in parallel to the charger's 120v line, the BMS control circuit would be switched on (via the board jumper) when the charger was turned on, CORRECT ??... and that if I used a Soneil 4808 SRF charger, I could leave it connected all the time to the battery pack when not charging, if you know, CORRECT ??


Thanks, Just trying to finalize all elements that go into the battery box.
Tom_D

Yes on connecting the relay.
Here are the 3 cheapest ones I found on Mouser that would work for the control signal:

655-RT424615
655-RTB14615
893-SCLBWDPDTC120VAC

I believe most of these are PCB mount, but you can wrap wires around the pins and solder directly. Make sure to carefully insulate all the connections! Fat heat shrink or something involving hot melt glue might work well.

Most of these have multiple sets of contacts. You only need one set for the control circuit.

I'm not sure if the Soniel will put a significant drain on the pack when it is off. I don't think it will be a problem, but to be sure, you could measure it sometime.

To be absolutely sure, you could use a DPDT relay and use one side for the control circuit and the other side to disconnect one leg of the charger output. In this case the contacts need to be rated higher than the charger output.

So, Richard,
With the new 3 pin configuration for turning on the BMS control circuit, would you still suggest using the above small 120v coil input relay in parallel with the charger's 120v input if I will be leaving the charger connected? Would I then need 3 ON-OFF contacts coming off the relay? (2 for the BMS and 1 for one leg going to the battery)?

Thanks,
--Tom_D

 

[fechter]

So, Richard,
With the new 3 pin configuration for turning on the BMS control circuit, would you still suggest using the above small 120v coil input relay in parallel with the charger's 120v input if I will be leaving the charger connected? Would I then need 3 ON-OFF contacts coming off the relay? (2 for the BMS and 1 for one leg going to the battery)?

Thanks,
--Tom_D

Yes, I would still suggest using the relay. You could get by with two sets of contacts, one for the power jumper and one for charger negative (you could leave charger positive always connected). When the relay is open, there won't be any drain back into the charger for from the control circuit.

 

[JB_EB]

Hey Gary, please put me down for one board. I need 8 channels. I've got a 30V power supply all built and ready to drive this thing.
Since you are not providing a kit of parts anymore, the BOM would be great so we can start sourcing parts.

Thanks, JohnB

 

[velias]

Yeah, a BOM posted up here would be great so that we can paste it into the Mouser BOM webpage and get the parts delivered around the same time we get the circuit board, instead of having to wait another week for Mouser to send the parts after we get the board.

 

[ejonesss]

it may be possible to overnight the mouser order.

Yeah, a BOM posted up here would be great so that we can paste it into the Mouser BOM webpage and get the parts delivered around the same time we get the circuit board, instead of having to wait another week for Mouser to send the parts after we get the board.

 

[velias]

it may be possible to overnight the mouser order.

It also might be possible to jam a sharp fork into my skull several times.

 

[methods]

Lol. . .

I was thinking it would be a bargain to pay $45 shipping on $30 worth of parts
You mean to say that's not a good deal?
Damn! I have to stop taking advice from people on the internet. . .

-methods

 

[GGoodrum]

I haven't had time yet to put together the BOM file, but I will try to get to it in the next few days.

Mouser ships the day you order, and even using Priority Mail, I've never had an order take more than two days. You could order the parts the same day you order the board, and both could literally arrive at the same time.

BTW, the parts, for a typical 16-channel setup are going to be in the $60 range, not $30.

-- Gary

 

[Patriot]

Gary,

How long do you plan on selling the boards?

I may not have the extra cash to get one for a little while. Maybe a month or two. I'm hoping by Christmas.

 

[methods]

BTW, the parts, for a typical 16-channel setup are going to be in the $60 range, not $30.
-- Gary

Yea. . . But that would not have sounded as dramatic.

-Patrick

 

[wybornd]

I haven't had time yet to put together the BOM file, but I will try to get to it in the next few days.

Mouser ships the day you order, and even using Priority Mail, I've never had an order take more than two days. You could order the parts the same day you order the board, and both could literally arrive at the same time.

BTW, the parts, for a typical 16-channel setup are going to be in the $60 range, not $30.

-- Gary

You should try ordering stuff online and having it delivered to New Zealand not only does it take a month of Sundays , it costs just a little bit in freight and customs ... I wont get into the hassles of trying to import A123 batteries ....

I only wish we had a Mouser type supplier in the country let alone locally ....
Oh well, at least there is the internet.

 

[JB_EB]

wybornd - I share your pain....

Is anyone in Australia interested in piggybacking several orders together to save on shipping costs
I guess if several sets of components were shipped together to say, Sydney, the cost of sending the different sets from Sydney to Melbourne or Brisbane by local post shouldn't be too much??

Although once we see a full BOM, I might be able to source parts locally in Sydney. The higher local cost might still be less than shipping from OS.

JohnB

 

[voicecoils]

wybornd - I share your pain....

Is anyone in Australia interested in piggybacking several orders together to save on shipping costs
I guess if several sets of components were shipped together to say, Sydney, the cost of sending the different sets from Sydney to Melbourne or Brisbane by local post shouldn't be too much??

Although once we see a full BOM, I might be able to source parts locally in Sydney. The higher local cost might still be less than shipping from OS.

JohnB

Possible interest, keep me updated.

 

[disadvantage]

You should try ordering stuff online and having it delivered to New Zealand

Wait a minute; don't you "down under" people have Dick Smith Electronics?
http://www.dse.com.au/cgi-bin/dse.storefront/

 

[boostjuice]

You should try ordering stuff online and having it delivered to New Zealand

Wait a minute; don't you "down under" people have Dick Smith Electronics?
http://www.dse.com.au/cgi-bin/dse.storefront/

Dick smith is a household name in Australia. True, everyone knows the name. Unfortunately they have evolved over the last decade into a franchise that really only sells whitegoods/browngoods (soon to phase out the "Dick smith" name forever in favour of "The Powerhouse"). They have gradually phased out their discrete components to the point where your lucky to find a humble resistor on their shelves.

Jaycar electronics (http://www.jaycar.com.au) is where most dissapointed dick smith customers are reffered to when chasing discrete components. They have a good variety of parts however it is very limited range compared to Farnell and RS Australia. Some of the parts in the BMS are quite specialty (Voltage detectors, opto-couplers, gate driver) and Jaycar dont stock these.

These reliable local companies that i often deal with are;

http://au.farnell.com/ (USA Newark in-One sister company)
http://australia.rs-online.com/web/ (Worldwide company with large stocks in Australia)

Both of these companies deliver overnight if parts are in Australia and 5>10 days if parts must come from overseas warehouses. You pay for local postage only.

If we had a complete BOM that included;

-Manufacturer's part number
-footprint
-Qty

then we could then source these parts from many different electronics suppliers that are easily accessible in our countries, rather than relying on Mouser which holds most of their stock in the USA, despite their international appearance on the web.

Gary, Please remember that you have a large international interest in your board. Mouser doesn't suit everyones needs.

If you can compile a Generic/Mouser Part no. BOM then from this i can compile a Farnell/RS Part.no. BOM for Australians ordering the BMS board. But for this to happen certain things like component footprints must be known. Manufacturers often provide the same Part in different types of physical packages (footprints).

 

[GGoodrum]

The Mouser part numbers basically are the manufacturer's part number, plus a 3-digit code in front, in order to identify the manufacturer. In any case, putting in the complete part number will call up the details for that part, including a link, usually, to the manufacturer's data sheet, in PDF form.

We purposely tried to pick as common and as inexpensive parts as we could, and most will have many substitutions. The exceptions will be the TC54 voltage detector, and maybe the LM431 programmable zener, but the optos, the gate driver, the SCR, all the transistors, the LEDs and even the FETs all are quite common and have many substitution choices available. We also went to great lengths to minimize the different/unique capacitor and resistor values, so that a larger quantity of fewer discrete part numbers could be ordered.

I haven't had time to put the BOM list together yet, as I've been too busy with my "other" job, but I'll try to get to it this weekend.

I've been to several Dick Smith stores, both in Australia and in New Zealand, and I would compare them to a cross between a Radio Shack and a Circuit City. Radio Shack also used to have quite a selection of discrete parts, but not so much anymore.

The board order is in, but because of the larger quantity, it will take 5 full days for manufacturing, and another 2-3 days for shipping. They are due in on Friday,the 31st.

-- Gary

 

[ejonesss]

We purposely tried to pick as common and as inexpensive parts as we could, and most will have many substitutions. The exceptions will be the TC54 voltage detector, and maybe the LM431 programmable zener, but the optos, the gate driver, the SCR, all the transistors, the LEDs and even the FETs all are quite common and have many substitution choices available. We also went to great lengths to minimize the different/unique capacitor and resistor values, so that a larger quantity of fewer discrete part numbers could be ordered.

does this allow us to pull some non critical parts (ones not critical to accuracy in charging and balancing and cut off threshold) to be salvaged from broken electronics (every year tons of electronics go in the landfills) and stuff like vcr's and dvd players have some parts like leds and opto's. leds are used to backlight the buttons and the lcd's on newer environmentally friendly products to eliminate the mercury use.

the opto's are (correct me if i am wrong) used in the power supplies to trip them if overloaded or shorted and voltage regulation.

The Mouser part numbers basically are the manufacturer's part number, plus a 3-digit code in front, in order to identify the manufacturer. In any case, putting in the complete part number will call up the details for that part, including a link, usually, to the manufacturer's data sheet, in PDF form.

We purposely tried to pick as common and as inexpensive parts as we could, and most will have many substitutions. The exceptions will be the TC54 voltage detector, and maybe the LM431 programmable zener, but the optos, the gate driver, the SCR, all the transistors, the LEDs and even the FETs all are quite common and have many substitution choices available. We also went to great lengths to minimize the different/unique capacitor and resistor values, so that a larger quantity of fewer discrete part numbers could be ordered.

I haven't had time to put the BOM list together yet, as I've been too busy with my "other" job, but I'll try to get to it this weekend.

I've been to several Dick Smith stores, both in Australia and in New Zealand, and I would compare them to a cross between a Radio Shack and a Circuit City. Radio Shack also used to have quite a selection of discrete parts, but not so much anymore.

The board order is in, but because of the larger quantity, it will take 5 full days for manufacturing, and another 2-3 days for shipping. They are due in on Friday,the 31st.

-- Gary

 

[ErikK]

That's excellent! Count me in! For a system that can handle 24 cells should I buy one or two units? Will we be ordering on the TPpacks site or how?

Thanks again for all your hard work on this cool project.

 

[cycle9]

Hi,

Just a hearty "me too" for a few of these boards! Thanks again for the great work Gary!

Morgan

 

[GGoodrum]

That's excellent! Count me in! For a system that can handle 24 cells should I buy one or two units? Will we be ordering on the TPpacks site or how?

Thanks again for all your hard work on this cool project.

You would only need one board for 24-channels.

As soon as I get confirmation that the order has shipped, I will make them available on the site.

-- Gary

 

[tomw]

I just stumbled onto this while searching for a BMS for around 50 series connected 200 Ah LiFePO4 cells from China Battery for an EV. Can I use 3 of these 24 cell or 5 of the 16 cell for this application?

Thanks,
Tom

 

[fechter]

Yes, with a bit of modification.

24 series is about the safe limit for the onboard voltage regulator circuit. To use more cells, it would be advisable to use a very small separate 12v power supply to power the control circuit during charge and leave out the onboard 12v regulator. You'd also need to verify the voltage differential between a depleted pack and the charger supply to make sure it does not exceed the rating of the FET. For higher amps, you would probably want to mount the FET(s) offboard on a heatsink. With offboard FETs, you can run several in parallel if necessary to get the desired charge current rating.

200ah cells may take a long time to balance at 500ma. In order to go higher than 500ma, the shunt transistors will need a heat sink, and of course, larger shunt resistors. If the cells are very well matched, the balancing time may be acceptable at 500ma.

 

[methods]

I just stumbled onto this while searching for a BMS for around 50 series connected 200 Ah LiFePO4 cells from China Battery for an EV. Can I use 3 of these 24 cell or 5 of the 16 cell for this application?

Thanks,
Tom

Do you have a link for those cells?

-methods