I have a rather large 44ft toy hauler with two Victron 3000 Multiplus, 700aH of BattleBorn LiPO, 1900w of solar on the roof and a 70A Victron Charge Controller. I run the two Mulitpus inverters in stand alone mode. This way I can shut one down when not needed.
I live in the southwest region of the United States. Around Arizona, Utah & Nevada. Temps in region during the summers can get rather warm in the 100F - 120F range. I will frequently hit campgrounds with a 30A connection. My rig is a 50A rig with three Air conditioner units. I do love my Victron setup. It works really well in almost any environment except where I need to set the shore power limit down to 29A to prevent a circuit breaker pop on a 30A connection in a hot climate.
During hot climates, I can easily reach the Lithium charge shut-off temp (High Temp Battery Cut-off) at the most inconvenient times. Particularly when I want to get that 3rd AC unit operating, but the battery temps are reporting too high. This forces the solar charger to shut off even when I just need a direct from solar to Multiplus assist and do not need to charge the battery. Instead, what happens is the solar charger shuts off and now all the “Assist” demand now must come from the battery bank, rather than solar. This only exacerbates the heating problem on the battery bank as the solar no longer helps with the load. I get it, the solar charger is just protecting the battery in hot weather from attempting to charge. But, It seems to me that with some intelligent programming, especially if your Multiplus, Battery Monitor, and Solar Charge controller are all connected that it should be able from software to ascertain whether any solar energy is going into the battery bank. If it is, just turn down the solar energy until it does not attempt to charge, but still provides direct energy to your Multiplus inverter load. This would allow my rig to collect and use solar energy direct to my load during the hot weather and then return to a normal mode when temps drop later in the day. It would also prevent my battery from having to carry any load during these times when you would rather not lean on the battery. I’m getting enough solar, especially here in the southwest. I just need to solar charger to cooperate and not shut-off. Am I making any sense?
You are pretty much unlimited with what you can do with Victron gear. I dont see a GX device, but you could do something with Node-RED. I haven’t used any temperature sensors on Victron gear because I have mostly used Lithium. I have not had to deal with overheating. The temperature is mainly used for charging adjustments for lead-acid batteries.
Who set the system up? What temperatures are you talking about? Lithium is good up to about 45°C, then you will have some problems. Charging at high temperatures will shorten the life of the battery.
I think you could do something with the temperature besides shutting down the MPPT. For example, you could set the charge current to achieve the desired power on the inverters.
You will also need some logic to check for very high temperatures and still disable charge and discharge.
Thanks for the reply. I installed the system myself. Not shown, but further to the right is my Cerbo GX. Ambient temps alone can reach 46c to 47c. Cabinet temps inside the RV can get even warmer adding an addition 2 to 3 degrees, even with no load. I do understand not attempting to charger the battery bank during these mid afternoon times when temps are too high for safe charging. However, what I would prefer is the solar charger not turn off during these times either as without any solar power available, all the Assist power for my Victron’s must come from the battery bank. The thing is, I only need a slight assist about 400w from either solar or battery. The solar could supply this energy and just feed the Victron inverter and prevent any attempt to charge the battery bank by simply getting the Battery Monitor info. All my devices are setup on the VE.Smart networking data link. So, they can share data.
What needs to happen is the solar should stay on, feeding energy into the system until the Battery Mon indicates a zero load. The solar charge controller can throttle from there. Throttle up when demand goes up, but only until the battery monitor no longer shows a negative number indicating a drain on the battery. By keeping the battery monitor at zero, no discharging or charging is occurring allowing the battery to remain essentially neutral. In this manner, I get the real time solar power from my panels, without an attempt to charging the battery. When temps drop down to below 45c, normal charging can restart.
I’m an Electrical Engineer by trade with circuit design experience and I’ve designed all kinds of electronics like this, so I know with a little bit of software work it can be done. If I spent an hour with the software engineers that write the code for the solar charge controller, I’m confident this would work and could be sent out as an update.
Shane, What diagnostics are you using to confirm that the mppt is being told to not charge he battery because the battery is too hot, vs the mppt derating to zero because itself (the mppt) is too hot?
We never get those temps in NZ, so i’m out of my depth, but would a little of the cold air from the AC being diverted to that box resolve the whole issue, and keep your batteries happier?
It’s easy enough to do with Node-RED. You can adjust the MPPT power by reducing the charge current to match the load on the inverter. I can help if you want, just let me know.
Hi RP, yes I have the temp sensor connected up to the battery monitor. The battery monitor shares this data with my Charger controller. Anytime the charge controller gets a temp report of 50c or higher, it shuts off the battery charger. This exascerbates the issue as prior to the solar shutting off, only a small portion of the assist load was coming from the battery. Most was coming from solar. However, once the solar shuts off 100% of the assist load now comes from the battery making the battery heat up even faster. Routing some cool air is difficult as it’s an outside compartment.
What I’m suggesting is a simple software fix. Instead of outright shutting off the solar charge controller at the threshold temp. Just throttle back the solar charge power so that none goes into the battery bank. If in the case like my setup, I’m not getting enough solar to supply the entire need from solar, then essentially the solar would stay on as none of it’s going into the battery anyway. If a load should shut off, and suddenly there is a surplus while the battery is reporting above the high temp shutoff, simply throttle back the solar charge controller power until only the load gets power. If there is no load, then the solar charger can go to zero. My explanation might not be all that well, but if I spent an hour with the software engineer who writes the solar charge controller code, I could fix this issue.
Just an extra line of code. If the battery high temp shut off is reached, check one more input. If the battery is in (-Neg) discharge cycle, don’t shut off the solar it’s not charging the battery anyway. If the battery is in (+POS) then throttle back solar power until the battery bank = (Zero)
Have you considered simply circulating the cabin’s cooler air through the installation area? Or even installing a dedicated cabinet cooling system — which is fairly standard practice in many electrical setups?
It seems that the root of several issues could be addressed by bringing down the installation temperature. Improved cooling would benefit everything, especially the battery’s performance and longevity.
I have considered a dedicated cabinet cooling system. Though that will require extra power by itself though. Routing cabin air into that compartment is definitely a challenge as well. I was able to relocate the battery temp sensor from the bus bar gang connection out to an individual battery post instead. Turns out the batteries themselves are not nearly as warm as the (POS) bus bar. Combine that with simply opening up the cabinet and setting up a fan to blow outside air in there was enough to keep everything on and happy.
