I have a off-grid system with Dyness DL5.0 C lithium batteries. The batteries have a built in heating function.
The problem is, that when the batteries hit 0 degrees, the allowable charging current from the BMS goes to 0A. We have at least 4 months below 0 degrees. I would at least need a small allowed current, to keep the remote connection and batteries alive during winter.
Dyness provides no information about the heating, like how it’s supposed to work or be controlled. I have tried to contact them but so far with no result.
Victron remote console has nothing about the battery heating.
I assume Dyness has a way of controlling the heating through CAN. If this is the case, then the problem is that Victron does not support that.
Other way would be to somehow override the low temp limit, to allow for example a small 2A of charge. That wouldn’t hurt the cells.
Does anyone have the same issue or any ideas? If Victron and Dyness don’t help (this is a software problem), the only option that does not void warranty is a small heater that runs on 48V and is controlled by a Victron Cerbo relay.
Yip. And the BMS comms are typically uni-directional with the system managed by the battery, not the battery managed by the system.
Might be a setting required on the battery, but something for Dyness support or the dealer that sold them.
Another option would be to make sure that the batteries never hit 0 degrees by the heating kicking in earlier. That is on Dyness. I don’t know if @OGPS has dealt with this problem.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
5
No, I’m sorry but I haven’t. I’ve never even heard of Dyness batteries before, but I looked them up and they do show up on Victron’s 3rd party supposrted battery list. This is a question for Dyness, though. @latekomuka CCL might go to 0 amps, but have you confirmed that the MPPTs actually turn off or are you only going by CCL=0?
Hi, thanks for all the responses. The MPPT:s don’t turn off. They produce whatever the system uses directly (~10W for Cerbo and internet router) but batteries don’t charge at all under 0 celcius. BMS gives a notification “BMS disabled charging” and CCL drops to 0A at 0 celcius.
@pau1phi11ips@Fideri Dyness provides no information on how the heating works. This is unfortunately a common problem in almost every battery that is sold to the Nordics. They are not tested in cold conditions and a lot of problems have surfaced after being installed here. I could write a separate topic about it, because it’s just unbeliveable what we have found. And normally the data sheets and instructions just say “battery is heated” and charging and discharging temp starts from -20. However they leave out the charging-temp curve and all the relevant heater setting instructions.
On this case, the system is on a island that can’t be reached during some winter months and there is almost zero sunlight for the 3 darkest months so there is simply not enough energy to run a heater.
If the heater is automatic, I would need to know how it’s activated. If the battery heats up during a day when the solar power is less than the heating consumption, then it will kill itself very quickly.
Would it be possible that the battery heating is linked to available power somehow? Technically it would be possible for the battery to know that there is not enough power to start heating. But I don’t think that is the case.
Here is the VRM view. The darkest day in Finland is 21.12, then the amount of sunlight starts to increase again. From 31.12 the battery has been under 0 Celcius constantly. The weather is between -10 and -25. The graph shows that there would be solar energy available, but battery refuses to take in any energy. Not for charging and not for the heating element.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
7
Well, that’s a bummer. I hope you can get Dyness or the distributor you purchased them from to tell you how the heating function works. But, you’re not alone in having to worry about cold temperatures. You are quite a bit further north than most of my customers, but we have to contend with temperatures down to -17° and have to plan accordingly. In our designs we do not rely solely on internal battery heaters. Just this morning we finished an installation of a double stack of inverters and batteries (not Victron) that are internally heated. They are outside in a barn sitting on a concrete floor. The batteries are not directly touching the ground and the customer is building an insulated electrical closet around them to retain heat. If necessary, we will actively condition the space to keep the batteries above 5° w/o relying on the battery heaters. For our customers in Canada, we always use supplemental heat in the electrical closet; even on the west coast where it’s more temperate.
I guess what I’m saying is, keep the environment around the batteries above 5° and use the battery heaters as a last resort means, just like the BMS should not be a primary means of protection, but rather the last resort. The next time you can get to the island, try wrapping the batteries in quilted blankets or some other means to keep them warm.
I’m sorry we don’t have a simple solution for you. This is a design issue and poor communication from your supplier or Dyness. I can only say that as a distributor and installer, we have very specifically chosen the three battery brands we use and sell, we know them intimately, and we don’t install them in environments that fall below 5° or above 32° w/o secondary environmental controls.
Hi and thanks again, this is all interesting to hear.
Lithium batteries have not been used here in off-grid systems before. Mostly because of the climate, the need for heating and the fact that customers and installers are afraid to put the new technology in cold off grid sites. Now we are getting the first real user experiences and I am prototyping on this island. I also prefer finding a good product and get to know it intimately.
The battery in this case is in a fairly small insulated space, with 100mm of foam insulation all around. It would not need much energy to stay warm, but that said, there really is almost zero solar power available.
As a future update, I will set up a small 48V heater, controlled by remote (Victron Cerbo) relay and a thermostat. Keeping at + celcius if it is possible with the amount of solar power available, but making sure the battery never empties itself to heat up.
Have you had the case open? Is there any sort of settings interface like UART or Bluetooth? AFAIK heating should just be a power cable that will heat up the batteries with induction.
They are usually just controlled by the internal BMS, and external power is fed through a power line that is always on. Some batteries might draw from their own current, so if there’s a settings interface I’d have a look there.
I’m working on a cerbo webasto controller to fix this problem. It just senses temperature and energy available for charging (solar or generator) and switches the webasto to keep the batteries at plus temperatures so that they are always over 5°c. It will use much less power than electric heating will.
There is a setting interface directly on the front panel, but there is no documentation on how to access the device.
Webasto and other diesel heaters are great for cold climate off-grid systems, and we use them a lot with remote control to heat the cabin/house 1-2 days before arrival. But it would not work optimally for such a small heating need (small space). I mean, it’s good to burn them at full power for long enough periods to keep them clean and working. In my case it would start, burn for max 10 min and shut off and keeping a steady temperature with that would not be possible in a 1m3 room.
I probably didn’t specify before, that none of this is a problem during periods when someone is on the island. Because then it’s easy to heat the battery space and use generator to charge etc. And the waste heat from inverter alone would keep the space at + degrees. When nobody is there, only charging need is to cover the remote control and battery self discharge.
Oh but then use the cerbo to start the generator. If it’s on then it can provide power to the heater before charging the bank.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
12
We use these 20W heating pads when we have to provide external heat to batteries: Amazon.com: 4 Pcs Silicone Rubber Heating Pad, Heating Blanket Flexible Silicone Heater Mat Rubber Heating Blanket for Industrial Equipment 20W 12V : Tools & Home Improvement I hope that link works for you. If the outer cases of your batteries are metal, you could stick these directly to the case and have the control over heating you desire. If your batteries report their internal temperature to the Cerbo (they likely do) then you could control a relay in the Cerbo using the battery temp reading to turn on/off the relay at your temperature setpoints. Try a temp range of 10-13° or thereabouts to trigger heating before getting too close to low-temp shutdown.
You can use a second relay or a Smart BatteryProtect to switch the current of the heating pads and just the relay on the Cerbo to trigger the higher current SBP. At 48V the current rating of the relays in the Cerbo is too small to switch the pads directly.
100mm of insulation sounds terrific. Do you also have insulation between the floor and batteries?
I have insulation all around. And my heating elements are stuck directly on the cells for best efficiency.
You should have a look inside your batteries, chances are there are already heating elements in them. The generic ones like that usually do.
As a victron forum we encourage best practice.
Cracking a commercial battery without support from the manufacturer will ruin your warranty.
Best to not give advice that could have expensive consequences for the owner.
Yes, which is why I pointed to the datasheet that says they are indeed heated. So just use that.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
16
The OP already knows the batteries are internally heated. The OP just doesn’t know the parameters for how they function because it’s not documented and they aren’t getting any response from the OEM.
