I don't recall coming across any other BMS with an internal contactor, have you seen this before?
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200A Smart BMS from LLT Power
- Thread starter simplyshakoor
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I don't recall coming across any other BMS with an internal contactor, have you seen this before?
Ampster
Renewable Energy Hobbyist
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Well, the new Chargery DCC Contactor is Solid State, board mounted with heatsink. Possibly LLT is using similar Solid State Contactors ?
I've opened the DCC and you can't see too much due to the heatsinks and how it's all assembled. I can say, the 300A isn't that big surprisingly and it is bidirectional as well. That's why I think the LLT seems to fit that description too.
Part of the problem I see, is the translation / wording, a tad muddy I'd say. Maybe some carefully worded questions which won't get muddled in translation software hell, could clarify specifically what they mean by contactors and so on.
I've opened the DCC and you can't see too much due to the heatsinks and how it's all assembled. I can say, the 300A isn't that big surprisingly and it is bidirectional as well. That's why I think the LLT seems to fit that description too.
Part of the problem I see, is the translation / wording, a tad muddy I'd say. Maybe some carefully worded questions which won't get muddled in translation software hell, could clarify specifically what they mean by contactors and so on.
Ampster
Renewable Energy Hobbyist
I see a big 10 Watt resistor but no FETs wth Heat sinks. Can't tell if that is a Solid State Relay or a coil based Contactor. My guess is that it is a contactor just because a SSR would have a heat sink to give off the heat they dissipate.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
@AussieSim I assume that is an LLT BMS, could you provide a link to it. If you got any docs, that would be helpful too.
Is that "Box" pre-attached to the PCB or is that your handy work ? I like that solid copper connection, no muckin about there ! The two securing tabs on the black box makes me think it's a factory thing, so it can be moved about to suit any application.
That "black" box really makes me wonder, as Ampster says, no heat sink and an SSR gets hot & would need cooling. The resistor as part of the precharge circuit ? They mention that in some of their adverts for some products. (having actual link to this would help) IMO, every BMS should have a Pre-Charge circuit, sheesh it's such a common NEED and it isn't Rocket Science.
Is that "Box" pre-attached to the PCB or is that your handy work ? I like that solid copper connection, no muckin about there ! The two securing tabs on the black box makes me think it's a factory thing, so it can be moved about to suit any application.
That "black" box really makes me wonder, as Ampster says, no heat sink and an SSR gets hot & would need cooling. The resistor as part of the precharge circuit ? They mention that in some of their adverts for some products. (having actual link to this would help) IMO, every BMS should have a Pre-Charge circuit, sheesh it's such a common NEED and it isn't Rocket Science.
RCinFLA
Solar Wizard
- Joined
- Jun 21, 2020
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There are two things I don't like about solenoid based cutout switch. First is mechnical contact reliability, second is possible relay continuous power consumption.
"latching" does not necessarily mean mechanical bi-state latching. There are three major types of latching relays, including mechanical, impulse sequencing, and magnetic. Mechanical latching relays use locking mechanisms to hold contacts in the last position until they receive information to change state. This is typically done by energizing a second solenoid coil. This is typically done in expensive backup generator transfer switches.
A simple contactor approach that saves some of the continuous current draw is backing down coil drive voltage for closure maintenance state. Only high coil current is used to initiate the contact closure. At least this reduces the continuous power consumption, but you still have the high current mechanical contacts. How much maintain coil current necessary can vary from manufacturing lot to lot of relays. This can be unreliable for high current DC contactors as a high current in primary contact path can create a high enough surrounding magnetic field to cancel out the smaller coil holding magnetic field.
The spec says the solenoid maintain current is 35 mA typ, 50 mA max, so it is not a mechanical latching relay.
It looks like the balancing current ranges from 100 mA to 260 mA. Probably only goes to 260 mA when cell delta voltage is high and there are not too many 260 mA cell balancings going on at same time to prevent too much overall heat buildup.
To be fair, I have issues with most of the cheap Chinese BMS's, not the least of which is the major of them have insufficiently low enough MOSFET active ON resistance to support the current they claim in their spec.
"latching" does not necessarily mean mechanical bi-state latching. There are three major types of latching relays, including mechanical, impulse sequencing, and magnetic. Mechanical latching relays use locking mechanisms to hold contacts in the last position until they receive information to change state. This is typically done by energizing a second solenoid coil. This is typically done in expensive backup generator transfer switches.
A simple contactor approach that saves some of the continuous current draw is backing down coil drive voltage for closure maintenance state. Only high coil current is used to initiate the contact closure. At least this reduces the continuous power consumption, but you still have the high current mechanical contacts. How much maintain coil current necessary can vary from manufacturing lot to lot of relays. This can be unreliable for high current DC contactors as a high current in primary contact path can create a high enough surrounding magnetic field to cancel out the smaller coil holding magnetic field.
The spec says the solenoid maintain current is 35 mA typ, 50 mA max, so it is not a mechanical latching relay.
It looks like the balancing current ranges from 100 mA to 260 mA. Probably only goes to 260 mA when cell delta voltage is high and there are not too many 260 mA cell balancings going on at same time to prevent too much overall heat buildup.
To be fair, I have issues with most of the cheap Chinese BMS's, not the least of which is the major of them have insufficiently low enough MOSFET active ON resistance to support the current they claim in their spec.
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Ampster
Renewable Energy Hobbyist
My KiloVac has an energy saving feature. They call it econimiser because once the contacts close the current need to keep it closed is reduced as you describe above.
The alternative is a SSR and two things I don't like about SSRs is the heat and when they fail, the do so in the closed position. Not something I want for my last fail safe mechanism.
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Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I suspect someone got burned by cheapo or incorrect Relays/Contactors and now just dislikes them with abroad brush stroke.
Wy would EV Makers use them if they are no good ?
Why the heck are they controlling things on Aircraft ?
Neither of them use no name, off brand junk though....
TE/Kilovac, Gigavac, Panasonic (GM & Ford love Pana's) = all top quality hi grade.
But then a $150 Contactor is not like A $25 one is it, and no one should expect it to be.
Want a shock ? Check out what GM charges for their EV Relays ? OMG Heart Palpitation Time ! They have NO SHAME at all !
Wy would EV Makers use them if they are no good ?
Why the heck are they controlling things on Aircraft ?
Neither of them use no name, off brand junk though....
TE/Kilovac, Gigavac, Panasonic (GM & Ford love Pana's) = all top quality hi grade.
But then a $150 Contactor is not like A $25 one is it, and no one should expect it to be.
Want a shock ? Check out what GM charges for their EV Relays ? OMG Heart Palpitation Time ! They have NO SHAME at all !
I ordered this BMS from Alibaba.
200A Smart BMS from LLT Power
Hi! Anyone used this BMS from LLT Power: https://www.lithiumbatterypcb.com/product/7s-to-20s-200a-smart-bluetooth-bms/ Model No: JBD-AP20S002 Looks like a good bargain, what your views?
diysolarforum.com
Externally it looks different to OPs picture, but you can see from this image that it is the same BMS with an updated enclosure.
I have posted all the documentation I can get my hands on on page 1.
200A Smart BMS from LLT Power
Hi! Anyone used this BMS from LLT Power: https://www.lithiumbatterypcb.com/product/7s-to-20s-200a-smart-bluetooth-bms/ Model No: JBD-AP20S002 Looks like a good bargain, what your views?
diysolarforum.com
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Thanks for the links, Isn't that an interesting setup.
Gotta love the docs, geez, that's a bummer.
Gotta love the docs, geez, that's a bummer.
My first 8s 280Ah Xuba shipment has arrived, I parallel top balanced to 3.61V, then assembled into a 24V 8s pack. (Yes they are separate 4p packs, but I confirmed voltages with a multimeter)
For the BMS I might either use a 24V or 48V configuration and didn't want to crimp leads BC6-BC18 permanently, therefore I used a 5 wire wago connector and ran a unified (orange) lead to a M6 crimp Y lug.
For the other leads, I stripped the insulation, left the tinned tips, doubled back the wires and crimped Y lugs (2 red wires for BC20+BC21)
The BMS fired up immediately upon connecting the BMS leads, there was a knocking sound presumably from the contactor/relay, and everything was active - voltages correct on B- and P-. Xiaoxing app connects to the BMS with the password 123456.
Connected a 200A safety switch and my 24V inverter - and it works.
A few observations, the Xiaoxing app I am running asked for GPS permission at startup, I denied it, and my app for some reason has Km travelled in the middle. I belive there is a paid or enterprise version that unlocks settings, but installed app doesnt have that.
In my earlier testing, powering my 2000W inverter with a 30V 10A bench power supply shows an idle inverter consumption of 30-38W. Connecting my LED light uses 15W (shown on the bench power supply) but the inverter's display shows 0 instead of 15W or 15+38W.
Now firing up the Inverter on battery power, Xiaoxing still says 0A 0W, turning on the AC Light via the Inverter - both Xiaoxing and the Inverter display still show 0W and Xiaoxing 0A.
Adding a 250W AC projector load to the inverter now shows in Xiaoxing -'ve A current flow and the Power output (W) to be positive.
The Inverter's display now shows the cumulative Power in watts for the 250W projector plus the 15 LED light.
Xiaoxing diaplays the BMS temp probe to be about 5 degrees warmer than the inverter, given how cold it is I trust the temp displayed by the inverter.
Lithiumbatterypcb have updated their page, showing a different balance lead (only 21 wires), whereas they used to show the same 22 wire instructions from the PDF manual I attached on page 1.
My experience with this BMS so far has been good, the 22 lead wiring was straight forwards, as shown here
Perhaps Lithiumbatterypcb is now shipping a different 21 lead BMS cable as follows
So far the experience with Android Xiaoxiang v3.1.1015 has been good, I can disable the GPS requirement in the app settings by switching to monitoring GUI. There is a built in speaker which beeps on power up, and on saving default settings. Bluetooth range is pretty short, I would say 3-4 meters.
Balancing appears to work as expected, and the balance lead and total battery voltages match my Klein tools multimonitor by +4 mV.
The xiaoxiang GUI appear to show balancing between cells occurring, but I am not sure that passive balancing works that way ?
There are 3 temperature sensors shown in xiaoxiang, #1 I believe is the external wire, and records the ambient temperature to be within 0.5 degrees of my BBQ digital thermometer. (#2 and #3 are presumably on the PCB and record a higher temperature)
After my full charge till 2 cells hit 3.650, the app shows 100% charge and Remaining capacity of 279.99AH.
So far so good with the BMS, only $75 including the Bluetooth module, easy to configure with the free Android app, heavy duty cables, one BMS supporting 7s up to 20s, configurable low temp disconnect - the downsides being the size (enclosure plus cables), the relay (unknown current draw), the external scuffed up aluminium enclosure and the short 3-4m bluetooth range.
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HKZBob
New Member
- Joined
- Nov 7, 2020
- Messages
- 52
Dear all, my name is Bob and I am although testing on a relay/contactor approach.
My contactor is inert gas filled and shall conduct 250A is normally open and it pulls 350mA to pull on hight state.
What is the current consumption of the contactor in this post. Then I have a precharge circuit attached.
Does the attached BMS has a precharge circuit
This is a big downside is if I add a daly BMS to control the contactor it will pull approx 4.2 Watts per hour.
So I think for a permanent use this is to much.
What do you think. I will switch my load off on my high current circuit.
How would you setup a BMS contacter circuit.
Regards
Bob
My contactor is inert gas filled and shall conduct 250A is normally open and it pulls 350mA to pull on hight state.
What is the current consumption of the contactor in this post. Then I have a precharge circuit attached.
Does the attached BMS has a precharge circuit
This is a big downside is if I add a daly BMS to control the contactor it will pull approx 4.2 Watts per hour.
So I think for a permanent use this is to much.
What do you think. I will switch my load off on my high current circuit.
How would you setup a BMS contacter circuit.
Regards
Bob
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Have this hooked up to my 16s LiFePo4 batteries and all battery volts show except cells 1 and 2, main negative balance cables are not connected to charger and battery yet for safety. Anyone else have an issue with a couple cells not reading with all balance leads connected to cells?
Can you post a photo of your BMS leads connections and how you've wired cell 14.
I have the newer model (annodized black extrusion) connected as a 16s battery. All working as expected. All cells show voltage.
A few issues I've noticed :
1) In xiaoxiang the power/current will show as 0 if it is below 2A. For a 24v battery that's about 50W and for 48v that's about 100W. I have a separate battery monitor so can see the battery draw/capacity.
2) cell #1 always reads a few millivolts higher than the actual reading at the cell terminals. This is the same with all 3of my units. (2 x 8s, 1 x 16s). After a few cycles I found which cell tends to hit the cell over voltage limit first, and made that cell 1 - that way it will hit my cell balance threshold earlier.
3) One of my 3 units was faulty, xiaoxiang correctly shows pack/cell over/under voltage protect enabled, and shows charge/discharge Off. However this doesn't work at BMS level and allowed over charging and under voltage, damaging my cells ?. Shenzhen E-Fire have agreed to send me a replacement unit if I pay the shipping.
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Have it wired like this... And this is what shows on the App...
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I haven't had that problem with my units, double check your connections, make sure the BMS leads are adequately crimped and tightly screwed down.
Post a photo if you want a 2nd set of eyes on the wiring.
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