BMS and Victron MPPT Confusion - Low Temp Cutoff?

[loverofpeace]

Hi guys,
In the process of building my first system with a Xuba 280Ah and 200-260W of panels. I've been trying to soak up Will's site and videos like a sponge but am still unclear about the BMS/MPPT issue.
On his site he recommends a Victron MPPT because of the ease of programming and the low temp cutoff (if you buy the sensor). Does anyone here have one and can confirm that the low temp sensor works for this purpose? If I buy a BMS that already has a low temp cutoff like this one that he recommends do I still need the Victron MPPT with the low temp cutoff or can I get a cheaper MPPT that doesn't have it and let the BMS do its job?

Thanks in advance!

 

[loverofpeace]

@Will Prowse would I still need a Victron MPPT with the Low Temp Cutoff if I buy a BMS like the one you reviewed that has it already? Thanks!

 

[Craig]

No you would not need a victron if BMS has low temp cut off. Of course I never see the need for a Victron lol

 

[Will Prowse]

Yeah, its unnecessary if you have BMS with low temp protection. If I was building $30K+ system with victron, I would install redundant temp safety methods. But BMS protection is plenty for most people.

 

[KG6S]

I don’t have a BMS with low temp cutoff (Daly) but I do have the Victron temperature sensors. I like having the additional telemetry data and logs. This best thing of the temp sensor is that it amplifies the Victron Bluetooth signals.

 

[loverofpeace]

I don’t have a BMS with low temp cutoff (Daly) but I do have the Victron temperature sensors. I like having the additional telemetry data and logs. This best thing of the temp sensor is that it amplifies the Victron Bluetooth signals.

Thanks for the response, have you tested whether the sensor works? I am honestly leaning to a similar combo in order to avoid programming troubles with other mppts.

 

[loverofpeace]

Yeah, its unnecessary if you have BMS with low temp protection. If I was building $30K+ system with victron, I would install redundant temp safety methods. But BMS protection is plenty for most people.

If you wanted to save a few bucks would you rather cheap out on the bms (something like Daly without the low temp sensor) or mppt ( still a good one but not victron)?

 

[KG6S]

Thanks for the response, have you tested whether the sensor works? I am honestly leaning to a similar combo in order to avoid programming troubles with other mppts.

I love the Victron MPPTs and entire VE eco-system with the battery monitors and temp sensors. The Victron Connect blue-tooth VE buss is really nice. I must say, though, I couldn't afford the inverters. And I got an absolute killer deals on the other components...like-new on EBay and Amazon (open box, not even used). Since I don't know anything but Daly, I can't advise on the BMS.

The Victron MPPTs are really easy and intuitive to program, and the data logging is a nice feature. You can see the historical data watt hours. It tickles my Geekiness.

Download the IOS or Android app and run in simulation mode, if you haven't yet done so.

YMMV.

 

[loverofpeace]

I love the Victron MPPTs and entire VE eco-system with the battery monitors and temp sensors. The Victron Connect blue-tooth VE buss is really nice. I must say, though, I couldn't afford the inverters. And I got an absolute killer deals on the other components...like-new on EBay and Amazon (open box, not even used). Since I don't know anything but Daly, I can't advise on the BMS.

The Victron MPPTs are really easy and intuitive to program, and the data logging is a nice feature. You can see the historical data watt hours. It tickles my Geekiness.

Download the IOS or Android app and run in simulation mode, if you haven't yet done so.

YMMV.

I'll check it out. Have you tested out if the Victron low temp sensor works and actually stops charging below the threshold?

 

[KG6S]

I'll check it out. Have you tested out if the Victron low temp sensor works and actually stops charging below the threshold?

Yes, I set the cutoff temp quite high this winter (in TX) and they stopped charging.

 

[loverofpeace]

Yes, I set the cutoff temp quite high this winter (in TX) and they stopped charging.

Awesome, thanks for the info I think I'll get one, the price difference isn't as great as I thought it'd be especially since other brands don't have the bluetooth connectivity typically priced in.

Now I just need to figure out if the 75/15a one will be good enough for 200w worth of panels.

Thanks for the info and I tested out the app as you suggested by the way. Looks really clean

 

[Dzl]

Now I just need to figure out if the 75/15a one will be good enough for 200w worth of panels.

75/15 would be safe with a 200W panel at either 12v or 24v. If 12V it might be just slightly undersized (12.8 x 15a = 192W) so you might lose a bit of charge current, but if you are flat mounting your panels or its overcast or any number of other things it wouldn't be a factor. I wouldn't worry too much about it if money is really tight, but moving up to the 100/20 would give a bit more breathing room.

 

[loverofpeace]

75/15 would be safe with a 200W panel at either 12v or 24v. If 12V it might be just slightly undersized (12.8 x 15a = 192W) so you might lose a bit of charge current, but if you are flat mounting your panels or its overcast or any number of other things it wouldn't be a factor. I wouldn't worry too much about it if money is really tight, but moving up to the 100/20 would give a bit more breathing room.

Thanks! I ended up buying the programable bms Will recommends so I may just buy a cheaper 20a instead of the victron. As long as programming won’t take me all day I’ll be happy.

 

[Dzl]

Thanks! I ended up buying the programable bms Will recommends so I may just buy a cheaper 20a instead of the victron. As long as programming won’t take me all day I’ll be happy.

What alternatives are you looking into?

The Victron controller's are quality units, and the cost is not too much more for some of the smaller SCCs. Probably won't make a huge difference either way, but I like the Victron App and interface (good balance between customizable and simple), and like how all their devices play well together (not important if the SCC is all you will be using) and I have more faith in them as a company (warranty, tech support, documentation, knowledgebase, quality, etc). Just my 2c, as I said for a small system, probably won't make too big of a difference either way.

 

[loverofpeace]

What alternatives are you looking into?

The Victron controller's are quality units, and the cost is not too much more for some of the smaller SCCs. Probably won't make a huge difference either way, but I like the Victron App and interface (good balance between customizable and simple), and like how all their devices play well together (not important if the SCC is all you will be using) and I have more faith in them as a company (warranty, tech support, documentation, knowledgebase, quality, etc). Just my 2c, as I said for a small system, probably won't make too big of a difference either way.

The Renogy Rover 20a sells for around €64 here and seems to have good reviews while the 75/15 victron is about €122. The 100/20 is €162. The Renogy doesn’t have Bluetooth though and I’m not sure if that’s necessary for programming it.

 

[Dzl]

The Renogy Rover 20a sells for around €64 here and seems to have good reviews while the 75/15 victron is about €122. The 100/20 is €162. The Renogy doesn’t have Bluetooth though and I’m not sure if that’s necessary for programming it.

Would be something to look into (total package cost). Sounds like Renogy is about half the cost but make sure accessories won't bring the prices closer together, if they do think harder about the Victron. I don't know a ton about the quality of Renogy products, I've heard they are mostly a branding company and don't produce any of their products but that's second hand knowledge, what I do know about Renogy is that their documentation and their quality of tech support leaves something to be desired. This is not necessarily a reason not to go with them, but it is something that should enter into the equation and be researched.

 

[loverofpeace]

Would be something to look into (total package cost). Sounds like Renogy is about half the cost but make sure accessories won't bring the prices closer together, if they do think harder about the Victron. I don't know a ton about the quality of Renogy products, I've heard they are mostly a branding company and don't produce any of their products but that's second hand knowledge, what I do know about Renogy is that their documentation and their quality of tech support leaves something to be desired. This is not necessarily a reason not to go with them, but it is something that should enter into the equation and be researched.

For sure. I'm looking at this as a long term investment so eventhough I'm a cheap ass I prefer to take the highest quality cheap method hehe if that makes any sense. I do like the victron 5 year warranty and you figure a company like them will be around in 5 years to honor it. Not that sure about renogy.

Is there any danger in buying the 75/15 renogy and let's say my panels somehow magically hit their max production 5.56a each. Would it somehow damage the charge controller or would it simply only take in the 15a to the battery?

 

[Bob142]

The Renogy Rover 20a sells for around €64 here and seems to have good reviews while the 75/15 victron is about €122. The 100/20 is €162. The Renogy doesn’t have Bluetooth though and I’m not sure if that’s necessary for programming it.

Renogy sells a Bluetooth dongle for use with the Rover series. (I’ve got a Rover 30 with the BT dongle). If you go with Renogy you definitely want to get it so you can use the app to program and monitor it.

I also have a Victron 100/20. I prefer it over the Renogy for all the reasons Dzl points out.

 

[Dzl]

Is there any danger in buying the 75/15 renogy and let's say my panels somehow magically hit their max production 5.56a each. Would it somehow damage the charge controller or would it simply only take in the 15a to the battery?

No, with Victron Controller's, its safe to exceed the rated output. What's important from a safety standpoint is staying below the max input voltage (75V) and max input current (15A). The max output current rating limits your usable power, but its not a safety issue (at least not with Victron). So your hypothetical 5.56A x 2 would be well within the controllers ability to handle. I recently learned (I believe it was Bob who showed me) this is not the case with some cheaper controllers, so be sure to do your research and read the manual with other brands.

This article from Victron does a good job of explaining the basics, scroll down to the section 'oversizing a PV array'