yes i have looked at the Chargery website but info is vague. i'm use to a proper wiring diagram, where you can see wiring connections are with proper schematics.
Have you read through the manual and looked at the schematics in it?
yes i have looked at the Chargery website but info is vague. i'm use to a proper wiring diagram, where you can see wiring connections are with proper schematics.
Steve,I suspect some confusion here. the 12V/3A from the BMS to relay (or delay board) is just to activate the relay itself, to close the contactor. These are NO Contactor relays. the 100A / 200A etc ratings are for the amount of amperage they can pass though when the latch is closed. This is DC ONLY ! The relays should be no less than 1.25 times higher amperage than the max load you expect to go through there. So a 100A throughput should have a min of 125A relay. It is better (read wiser) to go above that to 200A so you never reach the max capacity of what the relay can handle, the alternative could be a melted relay or worse should the tolerance not be accurate.
At present I am tinkering without the Delay Board (I got it for "just in case" I had a loading issue that required a further delay mechanism to deal with surges. The documentation on this feature / function is absolutely atrocious, so I have been trying to clarify that with Jason and to possibly come up with a clear English Translation for their docs, especially on such an important detail.
I am NEW to using this BMS and LFP as I am transitioning from an FLA Bank and expanding from there. So it's been a small learning curve for me to absorb this material as well and have spent far too many hours studying various BMS' and their abilities, capabilities & short comings. I looked at many different ones and considered what would work for me and my particular setup and where I want to take my system and felt that Chargery was the answer for me. Once I have more LFP packs with each having their own BMS then things will get even more deeply interesting.... hoping it's just not deep in manure ! I'm now discovering the "joy's of" making FLA & LFP cohabitate (ohhh what fun, ~not~) but I can't just chuck $3200 worth of FLA because...
PS: Sorry I cannot answer all your questions fully, I'm still getting the hang of these.
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.
I went out to the powerhouse to masure them. BMS8TSteve,
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.
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?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
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
My main concern was to protect the batteries from low temperature every other safety feature is a bonus.
Thanks i read those articles last night. Great information.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.
NordkynDesign: Protection and Management of Marine Lithium Battery Banks
MarineHowTo.com: LiFePO4 on Boats
And ideally read this whole series once or twice:
Lithium Battery Systems (6 part introductory series)
thanks for the info.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.
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...www.hammfg.com
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.Yes I'm running charge/discharge relays with the BMS8T. Ya "chinglesh" sucks. It's not that bad. The Chargery is very adjustable. I no longer trust the Daly BMS. Mosfets require heat sinks to work properly. I have seen poor connections with the Daly BMS.
It’s controlled at the “cell” level.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.