Smart gauge - - charging update

[Grace and Favour]

Don't worry bigcol . . . . it DOES get easier being without a TV . .

 

before you know it, you'll be on the fourth bottle by 8 o'clock!

 

Just chill

[Theo]

If you have never got it beyond 81% SOC then I would expect that the SG has no way of knowing what full charge is.

 

I'd be inclined to moor temporarily at a place with mains power and leave the batteries on charge for a few days. The SG will then learn what full charge is. You should also go up to full charge on a regular basis.

This isn't the way that I understand the manual.

 

Alternatively, if you are currently using the batteries (i.e. regularly discharging and charging them) you may simply leave SmartGauge to synchronise itself. This will typically take 2 or 3 discharge and recharge cycles. SmartGauge can synchronise itself in one discharge and recharge cycle but in order to do so the discharge has to go below 75% (actual, not displayed) and the charge has to exceed 95% (actual, not displayed). Once either of the these conditions has been met, SmartGauge will synchronise itself and track the battery state of charge from that time onwards. Synchronisation is not an instant effect. It is gradual over a period of time.

So you don't have to take any special steps to calibrate SG. Just leave it to do its own thing and it will settle down to be accurate. What is more it will give you the %age SOC of your batteries in their current state so if it says 80% then that is 80% of the current battery capacity which will usually be less than what is printed on the side.

 

Gibbo is very insistant that the SG absolutely must be connected directly to the battery terminals. Connecting it anywhere else means that it will see voltages that are not the actual battery voltages and the poor thing will not know what is happening.

 

N

 

Edited to add that most of that has been said!

Edited April 26, 2014 by Theo

[George94]

The SG doesn't work like that.

 

So you know how it works, do you? The most closely guarded secret in the universe is out.

 

So tell me, how does it know what 100% is if it's never been there?

 

Not saying you're wrong, you usually aren't, but I am curious to know.

[bottle]

Algorithms....I guess.

 

Lots of research by Gibbo and also some fairy dust was involved.

[nicknorman]

So you know how it works, do you? The most closely guarded secret in the universe is out.

 

So tell me, how does it know what 100% is if it's never been there?

 

Not saying you're wrong, you usually aren't, but I am curious to know.

As we know (from a previous thread where we looked at the circuitry) it only measures voltage. It then does some clever things with the voltage its first and probably second time derivatives, to work out the state of charge during discharge.

 

However during charge, the voltage is primarily determined by the charging device. In the earlier stages of charge, the rate of increase of charge voltage can probably be used as a clue, but in the latter stages of charge -absorption phase - the voltage is pretty much constant. But lead acid batteries, large or small, regardless of the max current of the charger, take a certain (long) amount of time to go from say 80% SoC to 100%.

 

Therefore once the charge voltage has stabilised, it is just a matter of holding that for x hours and one can then presume that the batteries are 100% charged. It is a guess, but then as we know one can only asymptotically (that word again) approach 100% SoC so there is no real perfect 100% SoC and the SG just makes a reasonable guesstimate, which in my experience is close enough for government work.

 

So the charging algorithm is just a voltage time integral, certainly once a fairly high state of charge is reached.

 

There is probably a bit of "learning" associated with how the battery behaves after the charge to 100% is removed, but I think that would primarily affect the accuracy on discharge. There is also probably a good bit of charge learning to be done in the charge up to say 80% so the system can better calibrate the voltage time integral, but after say 80-90% the battery is only going to charge at a certain rate regardless, within reason, of the charge voltage. It is pretty much just a matter of time.

Edited April 26, 2014 by nicknorman

[bigcol]

We're still together.

Last night one hour of casualty only

This morning smart gauge reads

Voltage 12.3

Status 57%

Fridge and courtesy led lights on overnight

Webasto came on automatically at 5 o'clock

 

Col

[Phil Ambrose]

We're still together.

Last night one hour of casualty only

This morning smart gauge reads

Voltage 12.3

Status 57%

Fridge and courtesy led lights on overnight

Webasto came on automatically at 5 o'clock

 

Col

Now you're getting there, bet its all making sense now.

Phil

[bigcol]

Do most stationary boats out on the cut,(without solar) use a generator/engine daily?

 

Phil. It's sinking in, yes from me!

 

Col

Edited April 27, 2014 by bigcol

[nicknorman]

We have 4 new Trojan T105s = 450AH. Tied up around 5pm, satellite telly on 7-11, under gunnel LEDs on in saloon / dinette / galley plus small mains incandescent table lamp (dimmed) ie whole living area well lit. Went to bed around 11:30 pm. Electric blanket on low until 3 am (woke up too hot). Fridge on 24/7. Now 8:30 am and AH-counting gauge is on 80%, Smartgauge on 78%.

 

So total usage 20-22%.

 

So you still have some way to go to reduce your consumption, but in your case the batteries are no doubt not at their rated capacity so whilst you used 43% it is probably 43% of less than you think!

Edited April 27, 2014 by nicknorman

[Naughty Cal]

It sounds as if your batteries have lost some capacity if they have dropped that much with so few items on overnight!

 

We moored up where we are now at about midday yesterday. The batteries were almost 100% SOC when we moored up (we were out overnight on Friday but the hour or so cruise here topped them back up).

 

The batteries are now reading 12.6v. We have had the fridge on, lights on, diesel heating on for a few hours this morning and the usual water pump use etc.

 

Just a thought are you taking your readings with items still switched on? This will give a false reading.

[nicknorman]

Just a thought are you taking your readings with items still switched on? This will give a false reading.

That wouldn't affect the Smartgauge SoC reading.

[Naughty Cal]

Ah. Ok then maybe not!

[GUMPY]

We're still together.

Last night one hour of casualty only

This morning smart gauge reads

Voltage 12.3

Status 57%

Fridge and courtesy led lights on overnight

Webasto came on automatically at 5 o'clock

 

Col

that's good, get it back on charge for as long as you can, you will be surprised just how much charging is needed to get back to above 90%.

that's why so many people wreck their batteries by only charging an hour or so a day.

[WotEver]

 

The instructions do not say anything like that...

Sure they do.

 

As Theo pointed out, at the bottom of Page 2 and the top of page 3 the manual states "... you may simply leave SmartGauge to synchronise itself. This will typically take 2 or 3 discharge and recharge cycles." My bold, and the bit that appeared to be missing in your original description, is that you have to get the batteries pretty well fully charged a couple of times before SG can know what they 'look like' when they're fully charged. If you NEVER approach 100% SOC of your bank then SG will struggle to know the bank's capacity.

[johnmck]

 

When out and about, we like to get the smartguage to 100 percent every day. This requires a minimum of 4 hours cruising for us. We are not over power hungry, having LED lighting, a 12v fridge and freezer. If we wish to use 240v products like the washing machine, we pick a time when the route is lock free for the duration of the cycle, swith on the travel power, amd bob's your uncle!

 

Would engaging the travel power without any load assist in making battery charging any quicker?

[WotEver]

It is especially "better than an AH counter" for uses where you don't take the SoC regularly to 100%.

However, if you have NEVER taken the SoC close to 100% since SG has been connected then it will struggle. Plus, you will very quickly knacker your batteries. Also, as someone else pointed out, it may well be that the batteries, having received so much abuse, may well be below 50% of their original capacity by now, which means that SG cannot give accurate results.

Would engaging the travel power without any load assist in making battery charging any quicker?

Probably not, because the batteries will be in absorption for the longest part of the charge cycle. It's not more amps they need, just more time.

[bottle]

Good morning Col

 

Yes and even with solar the generator is still used sometimes.

 

In winter as a liveabaord on an all electric boat we run the generator about three hours a day, not in one session.

 

What I try to do is make sure that the batteries are at least at 95% SOC at 8 pm. I know roughly how long it will take (hours) to say get from 75% SOC to 95% SOC so start the charging (generator) accordingly. We also usually cook a meal during that time (electric cooking), two birds one stone.

 

We're still together.
Last night one hour of casualty only
This morning smart gauge reads
Voltage 12.3
Status 57%
Fridge and courtesy led lights on overnight
Webasto came on automatically at 5 o'clock

Col

 

So now charge them up to about 95%SOC keep an eye on them and recharge again this evening again to about 95 SOC, then once a week, fortnight or month (your choice) get them to a true 100%SOC.

 

Remember that the Smartgauge will not be totally accurate when the batteries are being charged so you may need to charge more even though the gauge is showing 100%.

 

If you have a three stage charger then when that goes into 'float' that is when the batteries are 100% but as mentioned it is only 100% of the batteries present capacity, not what it says on the label.

 

As Nick says consumption could be reduced but it is a balancing act, life style, consumption, battery life, charging costs.

 

One thing you could try is to turn off the fridge at night and then whilst you charge the batteries in the morning, turn it back on.

 

It will mean that the batteries remain at a higher SOC and not 'work' so hard therefore extending their life. (theory not all will agree )

[nicknorman]

... If you NEVER approach 100% SOC of your bank then SG will struggle to know the bank's capacity.

The SG has no idea what the bank's capacity is, nor does it care. The behaviour of a lead acid battery is pretty much the same regardless of the size, in the terms that the SG can understand ie its voltage profile.

 

However, if you have NEVER taken the SoC close to 100% since SG has been connected then it will struggle. Plus, you will very quickly knacker your batteries. Also, as someone else pointed out, it may well be that the batteries, having received so much abuse, may well be below 50% of their original capacity by now, which means that SG cannot give accurate results.

I wouldn't say it would struggle if the SoC never reaches 100%. Yes it will be less accurate, but to a degree dependant on how far removed the profile of the bank is from the "standard profile" programmed into the SG.

 

I think this "50% rule" is to be treated as rough guidance only, just like the other "50% rule" (max recommended depth of discharge). It is not the fact that the bank has reduced to 50% of its original capacity that is the issue - after all removing 1/2 the batteries from a healthy bank wouldn't stop the SG from working properly. It is more the underlying causes of the loss of capacity. If the degradation is such that the properties of the batteries are significantly changed away from a "standard profile" then of course the SG will struggle, but when our last set of batteries fell to 50% of their capacity I didn't notice any loss of accuracy of the SG.

[bottle]

Spuds

 

Another thought how far is the Smartgauge, cable legth, from the batterries?

 

I cannot be bothered to look but am sure that over a certain distance the cables have to be larger. (mm²)

[BargeeSpud]

Sure they do.

 

As Theo pointed out, at the bottom of Page 2 and the top of page 3 the manual states "... you may simply leave SmartGauge to synchronise itself. This will typically take 2 or 3 discharge and recharge cycles." My bold, and the bit that appeared to be missing in your original description, is that you have to get the batteries pretty well fully charged a couple of times before SG can know what they 'look like' when they're fully charged. If you NEVER approach 100% SOC of your bank then SG will struggle to know the bank's capacity.

 

With all due respect, what has that got to do with manually synchronising SG? Which is was what I took Theo to mean with his post.

 

Spuds

 

Another thought how far is the Smartgauge, cable legth, from the batterries?

 

I cannot be bothered to look but am sure that over a certain distance the cables have to be larger. (mm²)

 

Mine are less than 2m from the battery posts to the gauge & are at least the 1mm2(or larger) as per manual, although not sure of actual size, they look like 2mm to me.

[George94]

The SG has no idea what the bank's capacity is, nor does it care. The behaviour of a lead acid battery is pretty much the same regardless of the size, in the terms that the SG can understand ie its voltage profile.

 

 

I wouldn't say it would struggle if the SoC never reaches 100%. Yes it will be less accurate, but to a degree dependant on how far removed the profile of the bank is from the "standard profile" programmed into the SG.

 

I think this "50% rule" is to be treated as rough guidance only, just like the other "50% rule" (max recommended depth of discharge). It is not the fact that the bank has reduced to 50% of its original capacity that is the issue - after all removing 1/2 the batteries from a healthy bank wouldn't stop the SG from working properly. It is more the underlying causes of the loss of capacity. If the degradation is such that the properties of the batteries are significantly changed away from a "standard profile" then of course the SG will struggle, but when our last set of batteries fell to 50% of their capacity I didn't notice any loss of accuracy of the SG.

 

The SG doesn't have to know the capacity in Ampere hours, but it does need to know it in percentage terms. You were rather vague in your description of how the SG calculates this (inevitably, since you aren't the designer and the design is not published), and I find it difficult to understand how it can know what is 100% if the batteries have never been anywhere near that state. 81% was the highest apparently.

 

When SG talk about two or three complete cycles, I am sure that includes taking the batteries up to 100%.

[WotEver]

I think this "50% rule" is to be treated as rough guidance only...

I believe it was Gibbo himself that stated that SG would not give accurate results on a bank that had lost more than 50% of its capacity. How 'not accurate' that might be, I have no idea.

 

With all due respect, what has that got to do with manually synchronising SG?

Nothing whatsoever.

 

I posted asking if you had synchronised SG as per the instructions. The instructions offer two methods - manually, or wait for two discharge/recharge cycles.

 

You replied: "The instructions do not say anything like that, you can simply leave the unit to get on with it & it will synchronise itself.". I pointed out in post 64 that it won't, unless you discharge and recharge the bank a couple of times. You have repeatedly told us that you have not recharged to anywhere close to 100%.

 

Tony

 

The SG doesn't have to know the capacity in Ampere hours, but it does need to know it in percentage terms. You were rather vague in your description of how the SG calculates this (inevitably, since you aren't the designer and the design is not published), and I find it difficult to understand how it can know what is 100% if the batteries have never been anywhere near that state. 81% was the highest apparently.

 

When SG talk about two or three complete cycles, I am sure that includes taking the batteries up to 100%.

Absolutely so.

[George94]

It's a bit worrying when two of the three electronic gurus on the forum don't agree.

 

I think we need SmileyPete to come along and adjudicate.

 

In fairness, I am not sure NN had noted how far from 100% Spuds' batteries had been.

[WotEver]

The problem with all discussions regarding SG is that none of us truly know exactly how it works, and therefore we can only make educated guesses as to what will happen under a certain set of unusual circumstances.

 

I find it difficult to understand how SG can accurately learn the characteristics of a bank that has never been fully charged in all the time that SG has been connected. Gibbo wrote in the manual "discharge/recharge cycles". He stated that the discharge must be to at least 75% but he didn't state what the recharge must be to, so I am assuming he meant 100%. I could be wrong.

 

Tony

[bigcol]

Good morning Col

 

Yes and even with solar the generator is still used sometimes.

 

In winter as a liveabaord on an all electric boat we run the generator about three hours a day, not in one session.

 

What I try to do is make sure that the batteries are at least at 95% SOC at 8 pm. I know roughly how long it will take (hours) to say get from 75% SOC to 95% SOC so start the charging (generator) accordingly. We also usually cook a meal during that time (electric cooking), two birds one stone.

 

 

 

 

 

So now charge them up to about 95%SOC keep an eye on them and recharge again this evening again to about 95 SOC, then once a week, fortnight or month (your choice) get them to a true 100%SOC.

 

Remember that the Smartgauge will not be totally accurate when the batteries are being charged so you may need to charge more even though the gauge is showing 100%.

 

If you have a three stage charger then when that goes into 'float' that is when the batteries are 100% but as mentioned it is only 100% of the batteries present capacity, not what it says on the label.

 

As Nick says consumption could be reduced but it is a balancing act, life style, consumption, battery life, charging costs.

 

One thing you could try is to turn off the fridge at night and then whilst you charge the batteries in the morning, turn it back on.

 

It will mean that the batteries remain at a higher SOC and not 'work' so hard therefore extending their life. (theory not all will agree )

Morning to you Bottle

 

Thanks for that

 

I was a bit surprised at the loss this morning re stays percentage of charge from last night.

 

So will turn of fridge tonight, thanks for the info re charging everyday.

It's the first time out off the mooring after 3/4 years sat in our home mooring with shore power.

 

So yes been out for 3 weeks today, not far but enjoying being out on our own, getting use to steering, and getting to grasp with power, and how not to abuse power on the boat.

 

Engine on and reading 76% 14.3 volts

 

Stupid statement but I imagine If I turned of 12v from the control board,when we go to bed, the smart gauge will be at the same in the morning when 12v restored,

 

I will quickly add SG IS wired direct to battery lol

 

Col

Edited April 27, 2014 by bigcol