Have you read through the manual and looked at the schematics in it?
) and like others have mentioned there is some videos worth watching on youtube.
Chargery BMS now with Low Temp Cutoff
- Thread starter Steve_S
- Start date
Have you read through the manual and looked at the schematics in it?
) and like others have mentioned there is some videos worth watching on youtube.
tim0shel
Solar Enthusiast
- Joined
- Jan 27, 2020
- Messages
- 464
Steve,
Do you have rough est. dimensions for the display box on this BMS? Proactively looking for a hinge project box that I could install it in.
From the BMS8T manual:
Display module size:96×80×24 (L×W×T, mm) or 3.8×3.2×0.95 (L×W×T, inch)
Main module Size: 122×80×28 (L×W×T, mm) or 4.8×3.2×1.1 (L×W×T, inch)
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Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I went out to the powerhouse to masure them. BMS8T
BMS Control module is 4-3/4" long, 3-1/4 high, 1" thick.
BMS Remote module is 3-3/4" long, 3-1/4" high & 3/4" thick.
Craigmck
New Member
- Joined
- Feb 3, 2020
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i have done my research on this chargery bms8t 300a BMS. After looking at different web pages, you tube videos and looking at Chargery's wiring schematic for the bms8t. Unless you use the relays this bms8t is only a monitor and can balance the cells. I can not see how this bms8t can protect the battery pack from over charging, under voltage, over current, low or high temperature disconnect without using the relays to disconnect battery pack. Battery disconnect is only done on positive side of the battery through the relays. I don't see anyway they can disconnect on the negative side of the battery wiring. What bothers me is Jason from Chargery told me that you don't need the relays for the BMS8t to work. This is how i interpret how this bms works from looking at Chargery's wiring diagram.
please correct me if i'm missing something here.
Watching Wills videos i see that he sometimes does not use a BMS for his battery packs. What do you people think on not using a BMS but bottom balance the cells only.
Being new to lifepo4 batteries and BMS systems their seems to be two schools of thought on running a BMS or not to run a BMS.
My main concern was to protect the batteries from low temperature every other safety feature is a bonus. Now i'm questioning should i even use a BMS ? Thanks
please correct me if i'm missing something here.
Watching Wills videos i see that he sometimes does not use a BMS for his battery packs. What do you people think on not using a BMS but bottom balance the cells only.
Being new to lifepo4 batteries and BMS systems their seems to be two schools of thought on running a BMS or not to run a BMS.
My main concern was to protect the batteries from low temperature every other safety feature is a bonus. Now i'm questioning should i even use a BMS ? Thanks
lmwilco1
New Member
You need some way to disconnect the battery from the load when it is discharged to a minimum voltage to prevent permanent damage to the cells. That is one of the key features of the BMS. You will need to use relays with the Chargery, and you will want two, one for charging and one for your load. If you try to use a single relay then when your temperature goes below the cold cutoff your battery will be cutoff and your heater won't work to heat the battery back up. If your battery voltage goes below the cutoff then it will disconnect the battery and you won;t be able to charge it back up.
I have got around and around on which BMS to use, at this point I am going to go with the bms8t with two relays and the relay delay board to precharge my inverter.
I have got around and around on which BMS to use, at this point I am going to go with the bms8t with two relays and the relay delay board to precharge my inverter.
grizzzman
Photon Vampire
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Well, I agree, no point (in my way of thinking) to have a BMS8T if you are not going to use relays to protect your investment from too hot too cold over charging and under charging not to mention over current protection. Personally, a BMS is cheap insurance for your costly investment. But if that's what you want then go ahead and do not use a BMS. Will is given a lot of stuff to do as he wishes with, plus he makes a bunch of money off his followers. He can easily take a loss. Can you?
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I have also received somewhat unclear mixed messages from Chargery/Jason regarding the relays. The ebay description calls the relays optional, but when I asked Jason directly he said "the relay is for cutting off charge or discharge." Still not a crystal clear answer but I took it to mean, the relays are optional but if you want to be able to disconnect loads/charging they are required. I chalk this up to a language barrier, I believe by "optional" he means "not included in price, and you have your options regarding which relay to use."
This is a somewhat controversial topic, there isn't really an agreed upon answer. Some people feel that specifically with the type of use (fractional C-rates and typical of solar/off-grid a BMS isn't strictly necessary if you have a well designed system and well balanced grade-a cells AND you set conservative charge and discharge limits so there is some cushion/margin for error. But it seems the majority (myself included) feel that a BMS is the prudent thing to do, a balancing BMS is not mandatory, but its prudent to have cell level monitoring/protection, and the cost is not very high for most applications.
Not that there is a single correct purpose for a BMS, but I think you are looking at it backwards. The core purpose of a BMS is fundamentally cell level monitoring/protection, namely low voltage disconnect (LVD) and high voltage disconnect (HVD). If all you truly want is temperature monitoring/protection you could use a BMS or you could use an external sensor connected to your SCC like this one, or climate control of some sort.
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I would read these two articles if you want to get a more well rounded view of LiFePO4 battery protection and system design. In my opinion both should be required reading if you are considering a DIY build.
MarineHowTo.com: LiFePO4 on Boats
NordkynDesign: Protection and Management of Marine Lithium Battery Banks
And ideally read this whole series once or twice:
Lithium Battery Systems (6 part introductory series)
MarineHowTo.com: LiFePO4 on Boats
NordkynDesign: Protection and Management of Marine Lithium Battery Banks
And ideally read this whole series once or twice:
Lithium Battery Systems (6 part introductory series)
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Craigmck
New Member
- Joined
- Feb 3, 2020
- Messages
- 48
Thanks i read those articles last night. Great information.
The problem i have found in the last 2 days of sourcing information on lifepo4 batteries and a battery management systems. There is a lot of miss information out there. Whether it is from a wrong language translation or someone that really does not understand dc voltage. How many people have purchased the Chargery bms8t without the relays and think that they have voltage and current disconnect? i asked Jason and was given incorrect information and it probable is because of a language translation.
Bottom line know that i understand what is needed to run this bms. I'm know ordering the relays and board to run the bms8t successfully.
Thanks all for the information
Solarfun4jim
Solar seduced :-)
@Steve_S
I've noted with several BM shunts that you need to charge the battery pack to 'full' a couple of times per month, so that the units can stay calibrated based on full charge being equal to 100%. I noted on the chargery unit, that you can individually calibrate the shunt for, both the charging at one amperage and the discharging at another amperage, specific to your own usage figures. Would this imply a more accurate calibration set up method which would last over the long term(minimal drift) or would it still require a 'full' charge now and again to 're calibrate' capacity?
For anyone wishing to 'only' run to 90% capacity all the time, the necessity of running a 'full charge' every so often would be a PITA. Thought the chargery might be a better fit than most others, to avoid having to do this?
I've noted with several BM shunts that you need to charge the battery pack to 'full' a couple of times per month, so that the units can stay calibrated based on full charge being equal to 100%. I noted on the chargery unit, that you can individually calibrate the shunt for, both the charging at one amperage and the discharging at another amperage, specific to your own usage figures. Would this imply a more accurate calibration set up method which would last over the long term(minimal drift) or would it still require a 'full' charge now and again to 're calibrate' capacity?
For anyone wishing to 'only' run to 90% capacity all the time, the necessity of running a 'full charge' every so often would be a PITA. Thought the chargery might be a better fit than most others, to avoid having to do this?
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Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Well, as I use Deltec Shunts, I have to recalibrate the BMS for them anyways. They come pre-calibrated for the shunts they supply in the 'kit'. So if you order a BMS8T-300A it comes with the 300A shunt and is calibrated for it. Never had to recalibrate after that.... BUT now my system is about to jump up to a more complex deployment with multiple packs in a bank and more, so I may be headed into that set of possible issues. I will have 2-280AH packs, & 2-175AH packs once I break up the Shunbin Pack I rebuilt which has Paralleled Cells (quite enough of that half assed shenanigan).
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
BTW: I have updated some info on earlier pages but posting this particular bit here too (6 pages later).
The Remote comes with am external buzzer & LED but they are loose and to me that isn't acceptable.
The delay board comes as just a tiny PCB with plugs for the wires and a glued on rubber backing. I don't like that either. So I put them into small project boxes and here it is how it came out. BTW: I used Velcro to attach the "boxed" parts to the remote and same for the delay "boxes".
BMS Remote:
The remote has an external Buzzer & LED for alerts & warnings o 600mm wires. I did not want to deal with loose bits, so I go a small "project box" to put the buzzer & led into (hot glued, so removable) and with a bit of shrink wrap, & double Velcro, voila, nice & tidy and no bits to deal with.
BMS Delay Board:
I also ordered the Delay Board to handle high surges and prevent a cutoff in those instance by allowing a small delay (programmable to 2, 3 or 6 seconds). The board itself has a rubber backing but is exposed and needs to be mounted or something. So again, another project box to put it in and make it wall mountable under the relay set. Keeps things tidy & neat. This also allows me to see the 3 status LEDs on the delay board.
For anyone looking for similar "project boxes" check out this manufacturer below, available in clear & transparent colours, even black ABS. Roughly $6 CAD for the transparent ones.
www.hammfg.com
The Remote comes with am external buzzer & LED but they are loose and to me that isn't acceptable.
The delay board comes as just a tiny PCB with plugs for the wires and a glued on rubber backing. I don't like that either. So I put them into small project boxes and here it is how it came out. BTW: I used Velcro to attach the "boxed" parts to the remote and same for the delay "boxes".
BMS Remote:
The remote has an external Buzzer & LED for alerts & warnings o 600mm wires. I did not want to deal with loose bits, so I go a small "project box" to put the buzzer & led into (hot glued, so removable) and with a bit of shrink wrap, & double Velcro, voila, nice & tidy and no bits to deal with.
BMS Delay Board:
I also ordered the Delay Board to handle high surges and prevent a cutoff in those instance by allowing a small delay (programmable to 2, 3 or 6 seconds). The board itself has a rubber backing but is exposed and needs to be mounted or something. So again, another project box to put it in and make it wall mountable under the relay set. Keeps things tidy & neat. This also allows me to see the 3 status LEDs on the delay board.
For anyone looking for similar "project boxes" check out this manufacturer below, available in clear & transparent colours, even black ABS. Roughly $6 CAD for the transparent ones.
Multipurpose Translucent Polycarbonate Enclosure (1591T Series)
Hammond's 1591T series includes 6 sizes from our 1591 series of plastic project boxes, molded in three specialty polycarbonate colors: clear/transparent, ice blue, and translucent red. With molded vertical PC Board guides, 1591T series is suited for applications where sensors or indicators need...
Hi Steve,
Have you properly wired up the delay board yet? I have some trouble understanding the manual.
My understanding is that instead of connecting the BMS directly to the relais you connect it to the delay board which then connects to the relais. And instead of a charging and a discharging loop you can now have a high and low current charging loop and a discharging loop? If that's the case is there a setting at the BMS to tell it there's 3 relays instead of only 2?
And do you understand what the large power resistor between the high and the low current side (as described in the manual on page 27) is needed for?
Thanks very much for all the information you provide here. You're really an awesome knowledge resource.
Cheers,
Marc
Have you properly wired up the delay board yet? I have some trouble understanding the manual.
My understanding is that instead of connecting the BMS directly to the relais you connect it to the delay board which then connects to the relais. And instead of a charging and a discharging loop you can now have a high and low current charging loop and a discharging loop? If that's the case is there a setting at the BMS to tell it there's 3 relays instead of only 2?
And do you understand what the large power resistor between the high and the low current side (as described in the manual on page 27) is needed for?
Thanks very much for all the information you provide here. You're really an awesome knowledge resource.
Cheers,
Marc
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
This video is a tad long BUT he does a good explanation of how to setup the Delay Board. Have a watch, I think it explains it quite well. I saw another video on the delay board & the Chargery BMS' but can't locate it right now. I am setting up the delay bards a bit later as my packs get built, I am not using a delay board at this time.
Solarfun4jim
Solar seduced :-)
Yeah steve, far better...would probably do something very similar. Glad the shunts didnt need recalibrating during normal use(only for the refit)BTW: I have updated some info on earlier pages but posting this particular bit here too (6 pages later).
The Remote comes with am external buzzer & LED but they are loose and to me that isn't acceptable.
The delay board comes as just a tiny PCB with plugs for the wires and a glued on rubber backing. I don't like that either. So I put them into small project boxes and here it is how it came out. BTW: I used Velcro to attach the "boxed" parts to the remote and same for the delay "boxes".
BMS Remote:
The remote has an external Buzzer & LED for alerts & warnings o 600mm wires. I did not want to deal with loose bits, so I go a small "project box" to put the buzzer & led into (hot glued, so removable) and with a bit of shrink wrap, & double Velcro, voila, nice & tidy and no bits to deal with.
BMS Delay Board:
I also ordered the Delay Board to handle high surges and prevent a cutoff in those instance by allowing a small delay (programmable to 2, 3 or 6 seconds). The board itself has a rubber backing but is exposed and needs to be mounted or something. So again, another project box to put it in and make it wall mountable under the relay set. Keeps things tidy & neat. This also allows me to see the 3 status LEDs on the delay board.
For anyone looking for similar "project boxes" check out this manufacturer below, available in clear & transparent colours, even black ABS. Roughly $6 CAD for the transparent ones.
Multipurpose Translucent Polycarbonate Enclosure (1591T Series)
Hammond's 1591T series includes 6 sizes from our 1591 series of plastic project boxes, molded in three specialty polycarbonate colors: clear/transparent, ice blue, and translucent red. With molded vertical PC Board guides, 1591T series is suited for applications where sensors or indicators need...
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Solarfun4jim
Solar seduced :-)
@Steve_S
Steve, another question on the chargery set up if you dont mind(well more specifically on the use of deltec shunt). I noted in the Chargery 16T spec sheet that the 'suggested' shunt should be equal/less than 75mv. Any idea the reason for this? I like the idea of the deltec, but wondered about using the 100mv/200A version(and recalibrating) to improve accuracy??(larger deviations)
Steve, another question on the chargery set up if you dont mind(well more specifically on the use of deltec shunt). I noted in the Chargery 16T spec sheet that the 'suggested' shunt should be equal/less than 75mv. Any idea the reason for this? I like the idea of the deltec, but wondered about using the 100mv/200A version(and recalibrating) to improve accuracy??(larger deviations)
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With the discharge relays controlled by the Chargery BMS which is fed by a cell balance wire harness are you actually able to disconnect the load from the battery at a specified individual cell voltage or do you need to use a pack total voltage for the disconnect.
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