Smartsolar max voltage

[blackrose]

14 hours ago, nicknorman said:

 

I think the Smartsense thing is under £100.

 

I paid £32 inc VAT and postage.

[nicknorman]

1 minute ago, blackrose said:

 

I paid £32 inc VAT and postage.

Bargain!

[magnetman]

Does it work? 

 

It will be a while before temperatures start dropping a lot. Would it be worth changing the compensation thing experimentally to a large value and see if the max voltage changes correspondingly? 

 

Just as an experiment to ensure the arrangement is working correctly. 

 

 

[blackrose]

14 hours ago, magnetman said:

 

There will also be choice supportive bias associated with this kind of topic. Obviously. 

 

 

I love a bit of choice supportive bias. Its brilliant. Also known as post purchase rationalisation. 

 

Its a wonderful phenomenon. 

 

Surely the opposite is also true? There are plenty of people who don't want to spend money on equipment, who rationalise that it doesn't work or that the effects are too insignificant to bother with? That can also involve a supportive bias phenomenon. We see it with people who refuse to fit anodes for example, because they don't think they work.

 

For me, battery temperature compensation and anodic sacrificial protection are both supported by science.

Edited July 13 by blackrose

[magnetman]

 

Also interesting to know how the Victron app calculates the voltages. 

 

On the 'trends' page there is definitely smoothing (clue is in the word 'trends') but on the history page there is a maximum. I suppose the question to ask Victron is what is the time period used to get this value. 

 

 

[blackrose]

2 hours ago, jonesthenuke said:

The compensation works for temperatures above and below 25C, higher voltage when temperatures are low and lower voltage when temperature is high.

With the cells at 21C, you should have increase in charging voltage of 4*30mV so 120mV. This assumes you have the compensation set to -30mV/C, can you confirm this?

 

Yes it's set to -30mV/C

[magnetman]

1 minute ago, blackrose said:

 

Surely the opposite is also true? There are plenty of people who don't want to spend money on equipment, who rationalise that it doesn't work or that the effects are too insignificant to bother with? That can also involve a supportive bias phenomenon. We see it with people who refuse to fit anodes for example, because they don't think they work.

 

For me, battery temperature compensation and anodic sacrificial protection are both supported by science.

 

I agree but of course spending one's own money on something does introduce a psychological element. 

 

Someone who does buy something has made a judgment and taken a financial risk. 

 

Someone who doesn't has made a judgment but not taken the financial risk. 

 

So the person who bought the item is more likely to need to justify it than the person who didn't. 

 

The question, which @Tony Brooks did allude to earlier, is whether the temperature compensation thing is actually worthwhile on ordinary canal Boat installations. 

 

I don't think anyone is arguing that it is desirable in large scale battery systems like UPS and telecoms but these systems also have other complex arrangements including automatic topping up of the water. 

 

 

 

 

 

 

 

 

[blackrose]

1 hour ago, Tony Brooks said:

...but a similar charge of being a lover of complex systems with little consideration of cost can be levelled at you. 

 

Every piece of battery charging kit I've ever bought has been supplied with a temperature compensation thermocouple cable - battery chargers, alternator controllers. That was until I bought an Epever MPPT controller and had to buy the cable as an extra for £12, but it's hardly complex equipment! 😂

 

When it came to the Victron rather than a physical connection it was a little blue Bluetooth box which you stick to one of the batteries (Smartsense) so it's slightly more complex but essentially it's doing the same thing as the thermocouple cable. It also has battery terminal connectors so it provides slightly more accurate voltage information to the MPPT.

 

16 minutes ago, magnetman said:

So the person who bought the item is more likely to need to justify it than the person who didn't. 

 

 

That doesn't seem to be the case based on the strength of argument here on both sides. It seems to me that both sides are equally psychologically biased in trying to justify their positions.

Edited July 13 by blackrose

[magnetman]

If you change the figure to 300mV instead of 30 for a short time will the upper battery voltage increase/decrease appropriately? 

 

That would be a way to ensure that the thing is working properly. 

 

Assuming the top voltage shown in the history page on the app is correct. 

 

 

[blackrose]

2 minutes ago, magnetman said:

If you change the figure to 300mV instead of 30 for a short time will the upper battery voltage increase/decrease appropriately? 

 

That would be a way to ensure that the thing is working properly. 

 

Assuming the top voltage shown in the history page on the app is correct. 

 

 

 

I will be testing it. I think the first thing I'm going to do is make sure I understand which voltage reading is giving me the correct information because the MPPT is showing slightly higher voltages than my shunt battery monitor or my Smartgauge. So I'll take some voltage readings at the batteries with my fluke multimeter - assuming that's reading correctly!

[magnetman]

7 minutes ago, blackrose said:

 

 

 

 

That doesn't seem to be the case based on the strength of argument on both sides. It seems to me that both sides are equally psychologically biased in trying to justify their positions.

It makes no difference whatsoever to me if it works or not because I don't own any lead based batteries.

 

I am just idly questioning whether it is worth having this sort of system. 

 

Maybe it is. Being 'right' or 'wrong' makes no difference to me. 

1 minute ago, blackrose said:

 

 fluke multimeter - assuming that's reading correctly!

They are usually pretty good. 

 

With any luck ! 

[nicknorman]

15 minutes ago, magnetman said:

 

The question, which @Tony Brooks did allude to earlier, is whether the temperature compensation thing is actually worthwhile on ordinary canal Boat installations. 

 

 

Depends on the type of batteries you have. If cheapo “dual purpose leisure” then probably not worthwhile. But then again for £34 it’s not a huge decision. If quality semi-traction lead antimony then yes. And also yes if you have gel or AGM because the correct voltage is more critical  - slightly too high and they dry out, slightly too low and they sulphate (although more slowly than lead antimony).

[Tony Brooks]

1 hour ago, nicknorman said:

also described my own personal experience with this particular type of battery and how in winter they definitely needed a higher charge voltage, otherwise they rapidly sulphated. But it seems you didn’t bother to read that bit. I’m not going to repeat it, it is still there for you to read if you can be bothered.

 

Yes I did, but that does not mean that temperature compensation is the only way to do it, if the controller in use has custom settings then that is another way of setting a higher winter charging voltage You could also run an equalisation charge now and again, in fact many solar controllers and battery chargers do that, be it in a less than perfect way. This shows that you have not read or understood what I am saying/asking. I think @magnetman man is saying something pretty similar. If you can't provide real world evidence from several examples, then it is fair to conclude that you MIGHT be providing a biased view because you bought the kit and will find it difficult to acknowledge that you may have wasted your time and money. I go along with Magneman in questioning exactly how many of the benefits are theoretical in real world use and use by marketeers to sell product.

[nicknorman]

1 hour ago, Tony Brooks said:

 

Yes I did, but that does not mean that temperature compensation is the only way to do it, if the controller in use has custom settings then that is another way of setting a higher winter charging voltage You could also run an equalisation charge now and again, in fact many solar controllers and battery chargers do that, be it in a less than perfect way. This shows that you have not read or understood what I am saying/asking. I think @magnetman man is saying something pretty similar. If you can't provide real world evidence from several examples, then it is fair to conclude that you MIGHT be providing a biased view because you bought the kit and will find it difficult to acknowledge that you may have wasted your time and money. I go along with Magneman in questioning exactly how many of the benefits are theoretical in real world use and use by marketeers to sell product.

I didn’t buy the kit. I don’t have a solar system and I have never bought a Smartsense. I don’t even have lead acid batteries any more. So I have no dog in the fight, other than the science and the truth, and I do understand the principles and I have seen the need to vary charging voltage according to temperature. And although you are correct in saying that you could manually adjust the charging voltage according to your estimate of the battery temperature, why bother when to have it done automatically without scope for human error costs £34?

Edited July 13 by nicknorman

[jonesthenuke]

1 hour ago, magnetman said:

If you change the figure to 300mV instead of 30 for a short time will the upper battery voltage increase/decrease appropriately? 

 

That would be a way to ensure that the thing is working properly. 

 

Assuming the top voltage shown in the history page on the app is correct. 

 

 

Or cool /warm up the smart sense module. For example holding it in your hand for a minute should warm it significantly? Or apply an ice cube

[Tony Brooks]

17 minutes ago, nicknorman said:

I didn’t buy the kit. I don’t have a solar system and I have never bought a Smartsense. I don’t even have lead acid batteries any more. So I have no dog in the fight, other than the science and the truth, and I do understand the principles and I have seen the need to vary charging voltage according to temperature. And although you are correct in saying that you could manually adjust the charging voltage according to your estimate of the battery temperature, why bother when to have it done automatically without scope for human error costs £34?

 

Does that include the smartphone/tablet/another piece of kit that Blackrose seems to think he needs to get this £34 think working correctly?

 

If it was simply plug and play with simple set up I would agree that a boater may as well have it as not, but In another topic we have had questions about getting the radio signals this type of kit seems to need through steel bulkheads and the length of a variety of boats. None of this says it is not worth doing, but I question how much benefit it gives the majority of boaters. Remember it seems Blackrose, who I consider as being fairly clued-up and practical, needed five days and lots of advice to get his set-up to his satisfaction.

[blackrose]

2 hours ago, magnetman said:

I am just idly questioning whether it is worth having this sort of system. 

 

 

The chances are if you have a MPPT, a 3 stage battery charger, a charger/inverter combi or an external alternator controller, then you (and Tony) already have this sort of system. 

 

The complex temperature compensation algorithms are already built into the charging equipment which you've already paid for. The only difference between us is that you haven't connected yours up. 

Edited July 13 by blackrose

[nicknorman]

2 minutes ago, blackrose said:

 

The chances are if you have a MPPT, a 3 stage battery charger, a charger/inverter combi or an external alternator controller, then you (and Tony) already have this sort of system. 

 

The complex temperature compensation algorithms are already built into the charging equipment which you've already paid for. The only difference between us is that you haven't connected yours up. 

Exactly. The MPPT “out of the box” does temperature compensation, the only problem being it only knows the temperature of the MPPT not of the batteries, so no good if the batteries and the MPPT are in different spaces at different temperatures.

[blackrose]

36 minutes ago, Tony Brooks said:

Remember it seems Blackrose, who I consider as being fairly clued-up and practical, needed five days and lots of advice to get his set-up to his satisfaction.

 

I'm not really clued up when it comes to digital equipment. I'm only clued up after I've installed it and then I suddenly feel like I'm an expert! 😋

 

It could be that it's working perfectly and I'm making a fuss about nothing, but I'd just like to make sure. The difference between me and some other people is that I install things myself and then I question how it's all working. Many other people don't bother, they just fit and forget.

[blackrose]

3 hours ago, magnetman said:

If you change the figure to 300mV instead of 30 for a short time will the upper battery voltage increase/decrease appropriately? 

 

I just tried switching temp compensation off while it was in absorption mode at 14.97v and it immediately went down to 14.82v so it looks like it is working. The trouble is that every time I try that I can only do it once because when I try turning temp compensation back on for some reason it goes into float mode. 

 

You have to catch it while it's in absorption mode in order to observe the results of any changes. The trend graphs in the app don't really have enough resolution or adequate axis unit detail to see what's happening. I'm a bit nervous about setting it to 300mV in case it shoots up to some ridiculous voltage and I can't switch it off quickly enough.

[cuthound]

4 hours ago, magnetman said:

I don't think anyone is arguing that it is desirable in large scale battery systems like UPS and telecoms but these systems also have other complex arrangements including automatic topping up of the water. 

 

 

 

Typically batteries used for telecoms, data centres, etc are in temperature controlled rooms, so no need for temperature compensation.

 

Also they have phased out wet cells since around 1980 because of the labour costs associated with either topping up or maintaining the automatic systems.

 

Typically they use Valve Regulated Sealed Lead Acid batteries (AKA AGM's) as these are relatively cheap and known to be reliable, rather than Lithiums batteries, although I expect this will change in the near future as Lithium battery costs continue to fall.

[nicknorman]

1 hour ago, blackrose said:

 

I just tried switching temp compensation off while it was in absorption mode at 14.97v and it immediately went down to 14.82v so it looks like it is working. The trouble is that every time I try that I can only do it once because when I try turning temp compensation back on for some reason it goes into float mode. 

 

You have to catch it while it's in absorption mode in order to observe the results of any changes. The trend graphs in the app don't really have enough resolution or adequate axis unit detail to see what's happening. I'm a bit nervous about setting it to 300mV in case it shoots up to some ridiculous voltage and I can't switch it off quickly enough.

Can you not turn off the charger using the App, then turn it back on again at which point it goes into bulk?

[blackrose]

1 hour ago, nicknorman said:

Can you not turn off the charger using the App, then turn it back on again at which point it goes into bulk?

 

Yes it does. I can also isolate the panels and switch them back on again. It starts the charge cycle again but it doesn't stay on absorption for very long. Is it because the batteries are already fully charged?

Edited July 13 by blackrose

[magnetman]

There are voltage settings in the 'expert mode' on the Victron app. 

 

 

One always disables the charger when changing settings. Enabling the charger after this will usually put it into Bulk charge unless of course the voltages are being altered by another input. 

 

 

[blackrose]

13 hours ago, magnetman said:

There are voltage settings in the 'expert mode' on the Victron app. 

 

 

One always disables the charger when changing settings. Enabling the charger after this will usually put it into Bulk charge unless of course the voltages are being altered by another input. 

 

 

 

Yes I've set the voltages in expert mode. I didn't realise charging was disabled while doing this. 

 

Anyway, temp compensation is definitely working and is responsible for the "high" absorption voltages I'm seeing. 

 

Absorption voltage was at 15.0v this morning, so I switched off temp compensation and it immediately went down to 14.82v. I switched it back on again (and reset it to -30mV/C) and it immediately went back up to 15.02v.

 

The batteries are at 18C which is 7C below 25C. 0.03v x7 = 0.21v + 14.8v = 15.01v, so I'm satisfied everything is working perfectly.

 

Thanks All for your input.

Edited July 14 by blackrose