Smartguage and Solar

[pearley]

It has been suggested that solar can confuse the Smartguage.

 

Can someone explain how so, if it is true.

[nicknorman]

Although lots of folk have disputed that point!

 

Perhaps, with a small solar panel, such that the battery voltage is barely charging, say 13v, it might get a bit confused as to whether it is in charging mode or not. But if you have a large bank, anecdotal evidence is that it works fine.

[Grace and Favour]

We have not experienced any confusion in our Smartgauge, and have had Solar (960w) running through an Outlook controller for a couple of years now.

[Justme]

We too have a SG & solar.

 

Have not noticed any issues.

 

1200 watts solar & huge battery bank

[trackman]

We have only 136W and again the SG works fine.

[pearley]

I also believe what my SG says, it is just that other forums dispute.

 

Besides my domestic alternator I have 240w of so!ar charging through a Tracer MPPT controller and, being gas free, have a 7kva generator which charges through a Victron multiplus. So if my SG reads 100% at 6.30pm and then we run the generator for an hour by which time the charger has switched to float, I reckon the batteries are fully charged. If they still read 100% at 10pm, long after solar could have any effect then I assume the reading to be correct.

 

But, I can always be proved wrong but time is too short to get the hydrometer out and start checking specific gravities.

[bottle]

As above but remember that it states in the manual that the Smartgauge can be up to 10% inaccurate when the batteries are being charged by whatever means.

 

My italics are not in the manual but still apply.

 

example in my situation,

 

Smartgauge reads 77% when retiring and all equipment, including inverter are switched off, arise in the morning and the Smartgauge reads 77%. Result.

[Detling]

I have no problem with my smartgauge and Mttp controller setup, However i think if you use a pwm solar controller they regulate the charge by 'chopping' the output voltage from the solar panel into small pulses to avoid overcharging the batteries, these pulses can have the voltage of the solar panel maximum volts (usually about 17-18 volts). Smartgauge will see these pulses as an overvoltage error and show that error.

 

I sometimes get this error when I am plugged into a shore supply via my combi inverter, When I start a motor load on the 240v (drill, angle grinder etc.) the spikes the inverter gets causes the battery voltage to spike and cause the smartgauge to display an overvoltage error. Just press any button and it goes away. I would only worry if you can't get the error to go away.

[Chalky]

Problem is more likely to occur with amp counting battery meters. The constant trickle charge can cause errors to build up in the SOC calculation and cause them to go out of sync. From what Gibbo said a while ago smartgauge works in a different way so won't suffer from this.

[smileypete]

It was in this topic back in 2012 that its accuracy with solar was questioned:

 

http://www.canalworld.net/forums/index.php?showtopic=45375

 

cheers, Pete.

~smpt~

Edited April 20, 2014 by smileypete

[by'eck]

Problem is more likely to occur with amp counting battery meters. The constant trickle charge can cause errors to build up in the SOC calculation and cause them to go out of sync. From what Gibbo said a while ago smartgauge works in a different way so won't suffer from this.

 

A constant trickle or float charge will surely eventually take a shunt based monitor to 100% SOC, after which any further charge current will be ignored by the SOC counter. Effectively this will re-sync the SOC counter.

[George94]

Problem is, there is no easy way to know whether the SG is right or not. When it says 100%, we believe it - because we want to! But what if it's actually 95%? Or what if it was actually 100% when it said 96%?

[nicknorman]

Problem is, there is no easy way to know whether the SG is right or not. When it says 100%, we believe it - because we want to! But what if it's actually 95%? Or what if it was actually 100% when it said 96%?

Well there is if you have an alternative means such as observing the charge tail current as I do. This allows confidence to be gained in the accuracy of the reading. As I have said before, it is not very accurate mid-charge but seems to be for the last 5-10%.

 

Anyway, what is 100% charged?

 

And even if it is 5% out at 100% (which in my experience it isn't) you are still far better informed about the state of charge than you would be with no instrumentation. No one is saying it is perfectly accurate, but neither does it need to be.

[George94]

Well there is if you have an alternative means such as observing the charge tail current as I do. This allows confidence to be gained in the accuracy of the reading. As I have said before, it is not very accurate mid-charge but seems to be for the last 5-10%.

 

Anyway, what is 100% charged?

 

And even if it is 5% out at 100% (which in my experience it isn't) you are still far better informed about the state of charge than you would be with no instrumentation. No one is saying it is perfectly accurate, but neither does it need to be.

 

I agree.

 

I have a Smartgauge and have a clamp ammeter on order. That will enable me to confirm whether my Smargauge is (reasonably) accurate or not.

[Jim_UK]

Expert in depth review & analysis of Smart Gauge.

 

Short version, beats everything else for accuracy and simplicity in showing voltages and State of Charge (for 1 or 2 banks).

 

It is so accurate, it measures it's own miniscule consumption and takes that into account too.

Edited April 24, 2014 by Jim_UK

[nicknorman]

Expert in depth review & analysis of Smart Gauge.

 

Short version, beats everything else for accuracy and simplicity in showing voltages and State of Charge (for 1 or 2 banks).

 

It is so accurate, it measures it's own miniscule consumption and takes that into account too.

 

Thanks for that link, I hadn't seen it before. It concurs with my own view which is that the SG is remarkably accurate during discharge, less so during charge but still pretty reasonable approaching fully charged. And as suggested in the article, I think this is because during charge it is really only "seeing" the characteristics of the charger and so it can only guess the SoC by looking at the charge voltage . time integral. It certainly doesn't do any "impedance testing" as there simply isn't the circuitry to support it, nor would if be feasible without much more prescriptive wiring and fusing.

[Jim_UK]

The author of that article, RC Collins, makes his living from stuff like that.

 

He says in this excellent article on 'How to install a Battery Monitor' (read them all!) that he thinks about 90% of all Battery Monitoring installations he sees are wrong. The primary reason why many of the Current Counters are inaccurate. I guess that is good business for him putting them all right!

 

Regardless of whether they have been professionally installed or done by the owner as a DIY job... they are a bit counter-intuitive as to how they actually are best & correctly installed and calibrated, so read this article and take 5 mins to check your own installation.

 

This no doubt explains why so many gripes about battery monitoring solutions.

Edited April 24, 2014 by Jim_UK