I should add: You need to get the "smart" version of the battery protect, so that you can set the cutoff voltage via Bluetooth. Otherwise you have a limited set of choices for the cutoff voltage, and none will be appropriate for what you are trying to do.
I'll dig into this, looking at a setup that includes a Victron Smart Solar MPPT250/70Some of the Victron solar charge controllers have a Load port that be programmed.
SmartSolar MPPT 75/10, 75/15, 100/15 & 100/20 - Victron Energy
Maximize the energy-harvest, driving it intelligently to achieve full charge in the shortest possible time using the SmartSolar MPPT. Learn more now.www.victronenergy.com
I'll dig into this, looking at a setup that includes a Victron Smart Solar MPPT250/70
SmartSolar MPPT 150/60 up to 250/70 - Victron Energy
Maximize the energy-harvest, driving it intelligently to achieve full charge in the shortest possible time using the SmartSolar MPPT. Learn more now.
Well that is unfortunate! Perhaps might able to use one of the programmable relays on the Quattro inverter to achieve this as well..? Battery protect looks like a great option as well though.
Glad to see the $11 controller. Note I'm awaiting the BN Link controller (currently around $34.99) from Amazon.Today I got the temperature controllers installed for my warming pads. All that is left is to clean up the wiring and get the controllers secured.
I decided (for now) to not use the temperature sensor/controller that came with the kit that Ultra Heat created for me. The first controller they provided worked inconsistently. Testing it at home it worked about 50% of the time. I suspect there was an internal wiring issue, but I didn't open it to verify that. The replacement sensor they sent worked every time but the temperature range seemed like it was 30° F to 44° F, not the labelled 35° F to 45° F. I used the temperature sensor from my Fluke 325 meter to check the temperature at the sensor/controller. The Fluke sensor was taped to the Ultra Heat sensor/controller. It isn't clear how accurate it is to tape the two together, but that's all I could figure out.
The new controller I'm using I got off Amazon for $11 based on recommendations from other forum members. It's the LM YN DC 12V Digital Thermostat Module. It has a programmable range, which I prefer to the preset range. Other benefits are that it shows you the observed temperature and the target temperature on the two displays. Each battery now has its own controller. With the Ultra Heat kit, there was only one controller, so it was warming one of the batteries without knowing what that battery's temperature was. Given that the two batteries sat side-by-side and the temp range was conservative there wasn't much risk. With the new setup, there is zero risk.
In the test today, after 40 minutes, the warming pads raised the observed temperature at the top of the battery by 8° F. From ~47 to 53° F. I had to fool the controller by putting the temperature sensor into a gel freezer pack. I could have just raised the target temperature on the controller, but didn't think of that until later.
Each time I checked the current on this circuit, it was no more than 1.68 amps. This was with two warming pads active on a single battery. In my opinion, the results are excellent given the small amount of current that was consumed. The pads must be incredibly efficient.
The temperature reported by the controller was within .75° F of the temperature reported by the BMS's remote temperature sensor. I was pleased to see the two devices report almost the exact temperature. The Victron BMV-712 reported a similar temperature, but it reports only whole numbers. Still, it was close enough to call it accurate. I have both sensors (controller and BMS) taped down together at about the middle of the battery. I used some spare rigid foam to create a hollowed out "cap" over the two sensors so they will be reading the battery temperature without (much) interference from the ambient air. The cap isn't sealed, so this isn't 100% effective.
I checked the backside of the warming pads multiple times during the test. I couldn't feel any heat at all. I used an infrared thermometer and it detected only a 5° F difference between the back of the warming pad and the top of the battery.
The new controller is pretty slick. It's a bit confusing to program at first and comes with no instructions. I found a set of user supplied instructions and cleaned them up. If you want a copy, let me know. I'm going to buy another controller and use it for running a fan to keep the component compartment cool in the summer.
I am following this thread late as I'm exploring battery heater options for my system. I live in a Yurt full time in northern Vermont and travel for a week or two during the school winter break. I watched the same Gimpy Camper video and got a quote from ultra heat for $350. I'm considering other options to save $ but ultra heat is still on the table if needed!
Thank you for responding! So just to be clear, on this quote would you just take the top line item or do I need one of the other items as well to get the wiring?
Thank you for this excellent reply! I'm actually planning not to rack mount the batteries, I'm going to build a single insulated box to keep them in so that they can share heat and be wired together in parallel. I like the idea of using a separate thermostat for each battery, and I've identified two that could work, this one (24v) and this one (12v).
Your option 3 is exactly what I have done on both of my 24V DIY batteries, using those same heating pads and the 24V thermostat you mention in the first paragraph. I posted the builds of both batteries along with lots of data plots about the heating. Let me know of you want the links to those threads.
Amazing! I just ordered one of the 24v thermostats and 4 of the heating pads. Did you use a 24v to 12v or wire your pads in series? Anything else I need to order to get this set up? I'd love links to your builds so I can follow along!
This is helpful to know, thank you. I'm going to try the budget option with stand off heaters - if it does not work well I can get the ultra heat pads and explore a different option but I think this is cheap enough to try!
For my 8S DIY batteries, I used two of the 12V 12W pads wired in series, and the 24V thermostat. It's been working well, and with a well-insulated box it really doesn't take lots of energy from the battery to keep it warm. Two pads in series on a 26V battery will only draw about 1.1A, and for me that would usually run for about 3 hours per 24 hour period to keep the battery between 50°F and 60°F. That's only 3.3Ah drawn per 24 hours.
Very nice! How does your battery compare with my 2 24v 200ah EG4 lifepower batteries? I'm wondering if I should use 2 or 4 of the little heating pads. I ordered 4 with 1 thermostat but can order another thermostat if needed. Did you use a aluminum plate? I'd love to read about your set up if you are open to sharing it!
I helped someone this summer with two Trophy batteries (rack mount, 48V). He put them in an insulated box, although I wish he could have insulated it more. For his system, I got 4 of the 12V pads, put them in series, and put one pad on each side of each battery. In your case, I would put two in series and put those on one battery, and a second pair in series and put them on the other battery. Just tape all the cells to the sides of the battery cases. I think one thermostat should be good enough if the batteries are together (touching).
