Hi,
I was thinking of getting some low power (14W) vivarium heating pads and putting them under my Smart Lithium Batteries then using a thermostat to control them (set at say 10°C) to prevent them getting lower than 5°C over the winter.
Anyone have any experience or comments?
I am making a small (closable) additional outlet on my Webasto heater to the battery bay and I can switch the powersource of the battery from housebank to bowthruster bank (which a tradditional battery bank). The last is being trickle charged from a multiplus.
I have done just this. I have four batteries and 4 x 15W Silicone Rubber Heat Mats.
There was a good article linked from a Victron Blog entry earlier this year that is worth a read.
@Bathnm,
Would you mind to share the brand of rubber heat mats and possibly a few images how you wrap them around the SmartLithium?
Are the heat pads thermo controlled in any way, internally or externally?
@Stefanie, I used these https://www.thermosensedirect.com/acatalog/silicone_rubber_mat_heaters.html
I basically put them under the batteries, so that heat can rise up around the batteries. I also installed some aluminium faced bulb wrap between the bottom of the cupboard to act as an insulator from below and an aluminium plate on top to spread the heat. So I have a bulb wrap, heat pad, aluminium plate sandwidch.
The black circles are the locations of the heat mats and the batteries then stand off the floor so there is a small air gap under neath the batteries.
I need to work out how I shall control these. I may write some code for the Cerbo to control relay 2 based on a temperature probe value, or purchase a small dedicated control board
@Bathnm,
great info! Thank you very much. Looks really nice and something I was thinking about for long time now, but didn't came to a long term solution.
Are the Heat Mats 12V or 240V and how much power?
Yes, they need to be temperature controlled for when you're not on the boat.
For the moment I'm using a simple ceramic 240V/750W heater, powered from shore and controlled manually but remotely via SignalK. Basically a virtual switch controlling a YDCC-04. I wired a temperature sensor from Cerbo directly to the side of one of the SmartLithium and switch the heater on when I feel necessary. Additionally I monitor bilge (I learned that the SmartLithiums internal temperature is always equal to the bilge temperature when not charging) and saloon temperature and base my decision to start the heater on them.
@Stefanie They are 12v and 15w, so with 4 of them on max that would be 60W. I am aware that the internal temperature is always higher than the exterior, so would look to turn them on at around 6 or 7 degrees and turn them off again at 8 or 9 degrees. I might also install some form of battery protect in the circuit so that if the battery voltage drops it will shut off. As I am only onboard at weekends I need something that I can ideally monitor and control through the Cerbo.
When on board in the winter I will have the Eberspächer heater keeping things warm enough, but need to ensure that when there is solar to top the batteries off that it can be used.
@Bathnm,
wonder if 15W is enough to increase internal temperature at all when it really gets cold. Please keep us updated as your solution seems to be the best I've seen so far.
I'm at least 2 or 3 days a week on the boat although I'm able to control all and everything remotely. In the end I (have to) trust that the BMS will cut off chargers at >5°C and so far it does (tested). Then I only need to take care of loads so that batteries don't get drained too much.
I have 60w as there are 4 of these heat mats. We will see as we go through this winter. Have a read of this article article. The batteries internal temperature is likely higher than the ambient temperature. So it won't take much heat input to keep it above the 5 degrees C.
