That's cool. I have all my equipment out in an uninsulated power shed at our hunting cabin. Been up a few times when it's been down to 0F (not sure what that equates to in Celsius?).
How well do the batteries heat themselves while discharging?
Is BIG BATTERY full of Crap??
- Thread starter ghostwriter66
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How well do the batteries heat themselves while discharging?
Hedges
I See Electromagnetic Fields!
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Probably just as well. You wouldn't want that self-heating on a hot day.
If you were to epoxy a power resistor onto each busbar and daisy chain them, you would have a heater you could power from DC or AC, with good thermal path to interior of battery. Do the wiring intrinsically safe - silicone tube around a small gauge wire which serves as its own fuse. Control it with a thermostat and a signal "I'd like to charge now", such as PV voltage.
www.digikey.com
(1.6 ohm, 10 watt, one per busbar might be about right for DC heater)
If you were to epoxy a power resistor onto each busbar and daisy chain them, you would have a heater you could power from DC or AC, with good thermal path to interior of battery. Do the wiring intrinsically safe - silicone tube around a small gauge wire which serves as its own fuse. Control it with a thermostat and a signal "I'd like to charge now", such as PV voltage.
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Ulmo
New Member
The one I received stopped charging when I put the temperature sensor in dry ice, but it still allowed discharge. I posted here about it:
BigBattery 170Ah PowerBlock low temp cutoff does something for charging, but not sure at what temp or what happens with discharging
Test results video at end of post with description. Regarding Will Prowse's review of these nice batteries: Then Will commented on that video with this update: "Correction to this video: Unfortunately, I was correct about questioning the low temp charging protection on the powerblock...
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Ulmo
New Member
Ulmo
New Member
I think it's obvious heaters need to be designed into these things along with the BMS and cells. It would do as you say: divert charging current to a pad, not charging the battery until it is to spec temp (let's say over 35ºF), and then ramp it up properly according to the spec sheet and state of charge. Heck, that's what Tesla car packs do already.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I will forward this suggestion if you really want to cover the bases and make a great / outstanding product. As a Northerner (deep north Canada) and having lived in every extreme from Deep Hot Desert to the Arctic circle I have a slightly different perspective. I've lived & worked in places that can hit -50C (actual, not windchill) and up to the high +40C temps.
Consider the BMS' you are using ! What they Can & Can't do and why they should do the things needed by most folks.
Have a SERIOUS LOOK at these two models, then explore the rest of this companies offerings and realize there are more advanced devices out there than what your people / engineers or what have you, have had experience with. Also, appreciate the complexity increases significantly as the number of packs within a battery bank increases and the need for equipment interfacing comes into play. This is where "drop-in" fall down as they are not really intended for ESS level systems unless they are designed to interact with each other & the equipment they are driving.
BesTech Power Co.,Ltd Battery Management System (BMS) with Communication protocol for 4~16 cells in series
Part number: HS-019:
DIRECT LINK to above: http://bestechpower.com/communicationbms/HS-019.html
Then 100A-1000A + more goodness Part number: HS-015 NOTE COOLING/ HEATING drivers.
Direct Link to above: http://bestechpower.com/communicationbms/HS-015.html
Also heads up notice, from the tradies rumour mill, the USA is about to get an LFP Recycling facility within the next two years. Specializing in LFP, up to and including breakdown, recovery of materials and regenerating it into new cells. Likely a company to get "hooked up with" one the public announcements are made (expect anytime now).
Ulmo
New Member
I was trying to delete those posts, but there's no delete button.
That is correct behavior. Lithium batteries can handle discharging below zero, it is charging that is the problem.The one I received stopped charging when I put the temperature sensor in dry ice, but it still allowed discharge. I posted here about it:
BigBattery 170Ah PowerBlock low temp cutoff does something for charging, but not sure at what temp or what happens with discharging
Test results video at end of post with description. Regarding Will Prowse's review of these nice batteries: Then Will commented on that video with this update: "Correction to this video: Unfortunately, I was correct about questioning the low temp charging protection on the powerblock...
Ulmo
New Member
Yes.
What's a good way to control the exact temperature applied to the sensor from my dry ice? I don't want to put the dry ice's full (lack of) temperature on the probe, just incremental amounts either way. I don't quite know how to do that. I would need my own sensor to know what the other sensor is saying. But how would I group the two sensors to read the same amount? Tape them together? Where can I get such a sensor?
Edit update: apparently getting cryogenic temperature sensors requires specing them out. But then the cheapest way at those temps is to make them yourself out of wire, maybe; currently watching this:
Edit update 2: oh, there's lots more involved. Sigh. https://www.brighthubengineering.co...hat-is-a-thermocouple-how-thermocouple-works/ I might not do this myself right off depending how much of this I can scare up out of my shack.
Last edited:
Hedges
I See Electromagnetic Fields!
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(thermal) resistor divider. Ice mixed with water is zero C, dry ice is whatever CO2 evaporates at. Two layers of material separating them would divide the temperature between them (assuming its thermal conductivity doesn't vary drastically with temperature.)
My Fluke 325 multimeter has a temperature probe that came with it. I used it this week to watch the temperature when I put my warming pad sensor in an ice pack.
Ulmo
New Member
Ok. Bought one for $277.95, arriving Nov 24-27.
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Here is a simple, independent battery box heater design that works well for me.
Notice that it operates completely independently from the rest of your system
Should I put this in resources?
Notice that it operates completely independently from the rest of your system
Should I put this in resources?
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Done
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Welcome to the New Year.
After all the great discussion on this tread, I did purchase the BigBattery 24V 170Ah LiFePO4 Power Block
The box did not come with any documentation at all. I have made numerous requests via live chat and emails to BigBattery (including @MrGreen ) with only one response saying that they have no digital version they can email.
So I am looking for the configuration parameters for my charge controller (using GroWatt 24v 3000W unit). These numbers should be applicable to any other charge controllers I would think. In addition the voltages would help with the Solar Battery Monitor as seen in this video
I am using @Will Prowse published settings for these all-in-one units, but it still calls for specifics for the battery being used.
My requests/questions are:
Referenced Links
BigBattery 24V 170Ah LiFePO4 Power Block
GroWatt 24v 3000W unit
AiLi Battery Monitor Voltmeter
After all the great discussion on this tread, I did purchase the BigBattery 24V 170Ah LiFePO4 Power Block
The box did not come with any documentation at all. I have made numerous requests via live chat and emails to BigBattery (including @MrGreen ) with only one response saying that they have no digital version they can email.
So I am looking for the configuration parameters for my charge controller (using GroWatt 24v 3000W unit). These numbers should be applicable to any other charge controllers I would think. In addition the voltages would help with the Solar Battery Monitor as seen in this video
I am using @Will Prowse published settings for these all-in-one units, but it still calls for specifics for the battery being used.
My requests/questions are:
- What is the low voltage disconnect of the BMS?
- What is the over voltage set at?
- What is the Floating Charge Voltage?
- What is the Bulk Charge Voltage?
- For a Battery Monitor Voltmeter, what is 100% SOC volts and 0% volts?
Referenced Links
BigBattery 24V 170Ah LiFePO4 Power Block
GroWatt 24v 3000W unit
AiLi Battery Monitor Voltmeter
Attachments
Thanks, but that really does not give me the information that I was asking for.
- What is the low voltage disconnect of the BMS?
- What is the over voltage set at?
- What is the Floating Charge Voltage?
- What is the Bulk Charge Voltage?
- For a Battery Monitor Voltmeter, what is 100% SOC volts and 0% volts?
That seems ridiculous. In this day and age, I can understand companies not including full physical paper documentation, but for them not to provide--and beyond that to claim they don't even have a digital version, seems ridiculous.. Are they writing users typewriters? a printing press? How is it possible to not have a digital version available? Maybe it is a simple misunderstanding, I can't really judge.
Below are educated guesses / inferences based on the specs in the image posted above by @laseradam
Possibly 2.125V (8.5V / 4 = 2.125V) -- [see: "working voltage range"]
Possibly 3.750V (15V / 4 = 3.750V) -- [see: "working voltage range"]
This is not a BMS parameter, generally speaking the most common recommendation seems to be ≤3.400V (≤13.6V)
Not a BMS parameter, but it looks like BigBattery recommends ≤14.6V -- [see: "charge voltage"]
Not sure. Your battery monitor documentation would be the place to start. Is this a voltage based monitor or a shunt or hall sensor based monitor capable of counting coulombs?
This general resource on selecting and understanding system voltages may help with some of your questions:
Beginners Outline for selecting System Voltage.
To get the paper, click on the orange button at the top of the screen. One of the first decisions when designing a system is what the system voltage will be. This paper attempts to help sort out all of the different factors in deciding system...
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