Smartgauge vs solar panels

[Col_T]

I'm thinking of installing some battery monitoring kit - something like a BM-1 and a Smartgauge. However, I have seen threads from a few years ago saying that Smartgauge doesn't work very well where solar is installed, and we have.

 

So, is this still a problem or something that has been resolved?

[Tony Brooks]

Probably posted by someone who did not read the manual. from what I can gather the Smartgauge is not particularly accurate during charging so with solar charging for long days it won't give a very true percentage of charge but once its dark and you use a bit of electricity it should be fine. However as you are talking about a BM1 that should accurately measure amps and volts use the amps to decide when the batteries are all but fully charged and learn to use rested volts to infer the state of charge. Ah out will be accurate but elapse ignore % charged and time to discharge unless you really understand the BM1's short comings ad get t set up properly - for most boaters both are unlikely to be possible. Rested volts will tell you much the same as a Smartguage.

[Kendorr]

I've got a smartguage connected, added a 100W solar last year. I sometimes get E3 showing, which is saying that the voltage was too high, doesn't appear to adversely affect anything though. 

[GUMPY]

If you have solar Smartgauge will lie to you during daylight hours. A couple of hours after sunset it will tell the truth provided you have made some use of your batteries. 

[Detling]

If you have a decent amount of solar (500 watts+)  you batteries are likely to be full by miday in summer, unless you are a power hog, so although the Smartgauge is not that smart when charging and reads 100% early, the important reading at bed time and when you get up will be good.  I have both Smartgauge and a BMV which tells me the Amphours used, which I find more useful, but since they are counted via a fiddle factor, and measuring tiny 1 amp type loads is not that accurate. When charging I don't rely on the amphour counter but rely on the volts and amps. 14.3+ volts and 4 amps is full (5 x 120 Ah batteries). 

In winter the smartgauge is more useful because if by 4 pm, after the solar is gone and it tells me I only have 70 ish percent, I know I need an evening boost., since I use about 15-20% most evenings and overnight. I usually have the engine on in the morning moving or not.

[Scholar Gypsy]

2 hours ago, Kendorr said:

I've got a smartguage connected, added a 100W solar last year. I sometimes get E3 showing, which is saying that the voltage was too high, doesn't appear to adversely affect anything though. 

Me too, I installed solar a couple of years ago, seems to work OK with my smartgauge. I normally get the E03 code when I first arrive on the boat and start cruising. Much less frequent after the boat has been in use for a couple of days and the fridge has been running etc.

[Richard10002]

1 hour ago, Scholar Gypsy said:

Me too, I installed solar a couple of years ago, seems to work OK with my smartgauge. I normally get the E03 code when I first arrive on the boat and start cruising. Much less frequent after the boat has been in use for a couple of days and the fridge has been running etc.

When I first got a Smartgauge I got a few error codes. Pretty sure I was able to stop them from reporting.

 

I have a NASA BM2 and subsequently got a Smartgauge, for my Lead Acid battery bank.

 

I recently fitted a Lithium bank and added a Victron BMV 712 to monitor it.

 

If I had my time again, I would have bought a Victron in the first place, and never had anything to do with The NASA and the Smartgauge. The NASA was/is OK, but the Victron is so much better.

[DandV]

The BMV 712 is a really useful bit of kit but the the percentage charge function should be used with extreme caution. 

When charging watching the charging amps decay and the voltage gives some idea of the success of that particular charging cycle.

The comparitive rested voltages without load first thing in the morning, and then the voltage depression under the same comparitive load, say the fridge starting and then running, or on cranking the Ebersplutter up give an indication of battery well being.

You do need gain experience of watching these unloaded and loaded battery voltages and charging voltages before and after running the engine and the duration of engine, shore power, and solar inputs, My experience of the BMV 712 was both on our narrow boat, and in an off grid house reliant on solar with occasional assistance from a generator. The indicated percentage charge became hopelessly optimistic as the battery condition faded. Probably could have continually reset it to guessed lower battery capacities.

[WotEver]

7 hours ago, DandV said:

Probably could have continually reset it to guessed lower battery capacities.

That’s where a SmartGauge is really useful. From 100% full, discharge a number of Ah, compare the used charge to the indicated SoC from Smartgauge and you can calculate a pretty accurate capacity for the bank. 

[Detling]

8 minutes ago, WotEver said:

That’s where a SmartGauge is really useful. From 100% full, discharge a number of Ah, compare the used charge to the indicated SoC from Smartgauge and you can calculate a pretty accurate capacity for the bank. 

Yes do that a couple times a year very useful. If boat use is intermittent, when you get to boat the solar will have the batteries at 100%. The first 3 or 4 days out the Smartgauge will be wrong, one day very low, one day very high and then better. After 4 days it seems to have recalibrated itself, I think long periods of no change makes it sleepy.

[DandV]

10 minutes ago, WotEver said:

That’s where a SmartGauge is really useful. From 100% full, discharge a number of Ah, compare the used charge to the indicated SoC from Smartgauge and you can calculate a pretty accurate capacity for the bank. 

Calculate? I just wanted to push buttons. For the holiday cottage 

 I bought the BMV 712 in the same order as the Victron combi.

And the other one I bought complete with a narrowboat!

[WotEver]

37 minutes ago, DandV said:

Calculate? I just wanted to push buttons.

It’s not a very difficult calculation...
 

”I’ve used 200Ah, my SoC is down to 60%, so 50Ah is 10%, and I therefore have 500Ah capacity.”

[Tony Brooks]

1 hour ago, DandV said:

Calculate? I just wanted to push buttons. For the holiday cottage 

 I bought the BMV 712 in the same order as the Victron combi.

And the other one I bought complete with a narrowboat!

 

I can't speak for a holiday cottage but can't see it would be any different from a boat but the bit in red is what allows the vendors to sell equipment that is known to be unreliable in the majority of boaters' hands and that gives them great encouragement to destroy batteries.

 

I don't see how one can avoid some form of calculation if you are trying to optimise battery life but its only very basic arithmetic, thus:-

 

1. As near to dam it fully charged is when the charging current has dropped to about 1% to 2% of battery capacity at around 14.4v and stabilised for an hour or so. You need to do a calculation to know what 1% to 2% of battery capacity is. You also need to do comparisons to see when the current has stopped falling for an hour.

 

2. From fully charged batteries you use them over night with the BVM/whatever zeroed and set to Ah. Next morning you take Ah out reading and the state of charge from either a Smartguage or rested voltage. So 35Ah used, state of charge 60%. You have used 40% of the battery capacity and drawn 35 Ah from the bank. So 35/40 = 0.875 and therefore bank capacity is 0.875 x 100 = 87.5 Ah

 

You can now enter that 87.5Ah capacity into the BVM and for a (very) short time be more confident in the % discharged reading etc.

Edited April 6, 2020 by Tony Brooks
Because I got my simple arithmatic wrong (100-60=40, not 30)

[WotEver]

12 minutes ago, Tony Brooks said:

but its only very basic arithmetic

Indeed. But if he’d rather believe the lies that his button presses tell him then that’s great news for the battery manufacturers. 

[Tony Brooks]

1 minute ago, WotEver said:

Indeed. But if he’d rather believe the lies that his button presses tell him then that’s great news for the battery manufacturers. 

I just had a thought, could his post have been in jest?

[DandV]

18 minutes ago, Tony Brooks said:

 

I can't speak for a holiday cottage but can't see it would be any different from a boat but the bit in red is what allows the vendors to sell equipment that is known to be unreliable in the majority of boaters' hands and that gives them great encouragement to destroy batteries.

 

I don't see how one can avoid some form of calculation if you are trying to optimise battery life but its only very basic arithmetic, thus:-

 

1. As near to dam it fully charged is when the charging current has dropped to about 1% to 2% of battery capacity at around 14.4v and stabilised for an hour or so. You need to do a calculation to know what 1% to 2% of battery capacity is. You also need to do comparisons to see when the current has stopped falling for an hour.

 

2. From fully charged batteries you use them over night with the BVM/whatever zeroed and set to Ah. Next morning you take Ah out reading and the state of charge from either a Smartguage or rested voltage. So 35Ah used, state of charge 60%. You have used 30% of the battery capacity and drawn 35 Ah from the bank. So 35/30 = 1.67 and therefore bank capacity is 1.67 x 100 = 167 Ah.

 

You can now enter that 167Ah capacity into the BVM and for a (very) short time be more confident in the % discharged reading etc.

I was more or less doing this, and fully agree with your last sentence. Interpreting the meter readings was much better then waiting to the lights went out, or shortening the life of appliances by depriving them of volts. I suspect that low input voltage, but still above shutdown voltage would stress the Inverter with consequent life reduction. I don't know as the 12 yr old  boat combi was still working when we sold, and the 14yr old holiday house combi is still working.

The real problem was the house was family owned and two generations using it, 

"But the gauge said 70% and the lights went out"

Solved that, sold my half share to my sister, but still have the use of it if her family are not.

Edited April 6, 2020 by DandV

[Tony Brooks]

8 minutes ago, WotEver said:

Indeed. But if he’d rather believe the lies that his button presses tell him then that’s great news for the battery manufacturers. 

and I got my example wrong - now corrected.

[MtB]

16 minutes ago, DandV said:

"But the gauge said 70% and the lights went out"

 

This is one of the areas where the Smartgauge is so misleading. It is marketed as a "Fuel Gauge For Batteries", when it so obviously is not once you read the instructions after buying it.

 

 Trading Standards ought to get involved with this.  

 

 

[Tony Brooks]

2 minutes ago, Mike the Boilerman said:

 

This is one of the areas where the Smartgauge is so misleading. It is marketed as a "Fuel Gauge For Batteries", when it so obviously is not once you read the instructions after buying it.

 

 Trading Standards ought to get involved with this.  

 

 

 

I think he was referring to 70% on the BVM, not a smart gauge. I think the Ah counitng gauges also need Trading Standards looking into them. I think they are more misleading than a Smartguage for most people (as long as the SG is properly calibrated that is).

[GUMPY]

It acts as a fuel gauge for batteries provided you are not charging at the time you read it.

Are car fuel gauges accurate whilst filling the tank? One car I had would read 3/4 full after brimming the tank, 20 minutes later after driving away it would read full

 

[Bod]

46 minutes ago, Tony Brooks said:

 

I can't speak for a holiday cottage but can't see it would be any different from a boat but the bit in red is what allows the vendors to sell equipment that is known to be unreliable in the majority of boaters' hands and that gives them great encouragement to destroy batteries.

 

I don't see how one can avoid some form of calculation if you are trying to optimise battery life but its only very basic arithmetic, thus:-

 

1. As near to dam it fully charged is when the charging current has dropped to about 1% to 2% of battery capacity at around 14.4v and stabilised for an hour or so. You need to do a calculation to know what 1% to 2% of battery capacity is. You also need to do comparisons to see when the current has stopped falling for an hour.

 

2. From fully charged batteries you use them over night with the BVM/whatever zeroed and set to Ah. Next morning you take Ah out reading and the state of charge from either a Smartguage or rested voltage. So 35Ah used, state of charge 60%. You have used 40% of the battery capacity and drawn 35 Ah from the bank. So 35/40 = 0.875 and therefore bank capacity is 0.875 x 100 = 87.5 Ah

 

You can now enter that 167Ah capacity into the BVM and for a (very) short time be more confident in the % discharged reading etc.

Trying understand the maths, where does the 167 Ah come from?

 

Bod.

[MtB]

5 minutes ago, Loddon said:

It acts as a fuel gauge for batteries provided you are not charging at the time you read it.

 

Not such a snappy advertising slogan though is it?

 

Are you saying you think its ok to mislead customers with "Fuel Gauge for Batteries" then?

 

Nobody buys a buys a car because they want a fuel gauge. I bought Smartgauges because I wanted "fuel gauges for my batteries". I didn't get what the slogan told me I was buying.

 

 

[Tony Brooks]

Just now, Bod said:

Trying understand the maths, where does the 167 Ah come from?

 

Bod.

from the initial mistake and the an incomplete edit, now corrected. made myself look a right prune - twice!

[GUMPY]

23 minutes ago, Mike the Boilerman said:

 

Not such a snappy advertising slogan though is it?

 

Are you saying you think its ok to mislead customers with "Fuel Gauge for Batteries" then?

 

Nobody buys a buys a car because they want a fuel gauge. I bought Smartgauges because I wanted "fuel gauges for my batteries". I didn't get what the slogan told me I was buying.

 

 

When it was designed there was almost no solar so no problem, as with everything you need to understand its limitations.

Is there anything better available ?

[WotEver]

1 hour ago, Tony Brooks said:

I just had a thought, could his post have been in jest?

I don’t believe so. 
 

I see Mike has jumped in with his usual observations.