Smartgauge percentages

[Phil.]

Is there a reason why the rate of discharge measured by smartgauge would vary if the electrical equipment usage is constant. I.E. On some occasions when going to bed the reading is say C 85 then in the morning it shows C 72. Then last night reading was C 50 and this morning it was C 49. In both instances the equipment drawing power during the night has been the same. I.E. Fridge, Inverter, and some gauge lights. Thanks.

[nicknorman]

Is there a reason why the rate of discharge measured by smartgauge would vary if the electrical equipment usage is constant. I.E. On some occasions when going to bed the reading is say C 85 then in the morning it shows C 72. Then last night reading was C 50 and this morning it was C 49. In both instances the equipment drawing power during the night has been the same. I.E. Fridge, Inverter, and some gauge lights. Thanks.

Obviously consumption from something like a fridge can vary due to whether the door was recently opened and the ambient temperature. But I suspect what you are seeing is more to do with the SG's behaviour during charge. In my experience it tends to lag behind until getting close to 100%, so for example if I start from 50% and stop at an indicated 70%, in reality it is nearer 80%. On discharge, the SG handles this by holding the reading (in this example, 70%) until the actual SoC passes the indicated value, whereupon it starts showing a decreasing reading again.

 

Had you recently partially charged you batteries, stopping with an indication of around 50%?

[Phil.]

I normally recharge when SG is in the high 60s or low 70s. Occasionally if we fancy an engine free day will allow it to go as low as 50 then recharge. Normally run engine until at least 90 and on every other recharge up to 100. Occasionally I allow engine to continue running for and hour or so after 100 is reached just to ensure really topped up.

[Jambo]

I don't suppose cold weather could cause it? It does affect battery capacity so would the Smartgauge be affected as well?

[smileypete]

I would give thanks it's not a BMV which can tell outright lies if not carefully and properly set up!

 

Would be interesting (to me anyway ) to compare what the voltages were to SG reading before retiring and first thing.

 

cheers, Pete.

~smpt~

[Richard10002]

It strikes me that there is no way of answering the question because the OP doesnt know how many amp hours have been used, nor the true capacity of the batteries.

 

This was the reason I chose the NASA BM2 over the Smartguage. A Smartguage that also measured Ah could be close to the ideal, but it would be expensive.

[Phil.]

I would give thanks it's not a BMV which can tell outright lies if not carefully and properly set up!

 

Would be interesting (to me anyway ) to compare what the voltages were to SG reading before retiring and first thing.

 

cheers, Pete.

~smpt~

I will have a look tonight and again in the morning and post the results. In both cases though they will not be resting voltages as some equipment is always on, not sure if that makes a difference.

[DaveC]

Just a thought .......

 

When the designer of the Smartgauge used to post on here nobody had a bad word to say about the SG. Now .....

 

 

 

Dave

[bottle]

It strikes me that there is no way of answering the question because the OP doesnt know how many amp hours have been used, nor the true capacity of the batteries.

 

This was the reason I chose the NASA BM2 over the Smartguage. A Smartguage that also measured Ah could be close to the ideal, but it would be expensive.

 

It exists and it is.

[Phil.]

I would give thanks it's not a BMV which can tell outright lies if not carefully and properly set up!

 

Would be interesting (to me anyway ) to compare what the voltages were to SG reading before retiring and first thing.

 

cheers, Pete.

~smpt~

So the start point yesterday afternoon 1300 hrs SG reading C60.

Ran engine til 1900 SG reading C100, this was achieved by 1730 but kept engine running as using lots of elec stuff.

At 2345 hrs SG reading was C96 voltage 1270

At 0600 hrs SG reading was C89 voltage 1250, fridge,couple of gauge lights and inverter on during night

At 0945 hrs SG reading was C82 voltage 1255, in addition to above usage now add 2 hours on Hurricane diesel heater.

Couple of things, not sure why SoC has dropped which you would expect but voltage has increased between 0600 hrs and 0945 hrs. This rate of decline seems fairly even, my point in the OP was sometimes the morning reading can be as low as mid 70s on SoC with difference in the usage.

Edited October 27, 2014 by Phil.

[Kae]

Just a thought .......

 

When the designer of the Smartgauge used to post on here nobody had a bad word to say about the SG. Now .....

 

 

 

Dave

 

That's not my recollection, in fact, there were some rather long and heated threads about exactly that!

[nicknorman]

So the start point yesterday afternoon 1300 hrs SG reading C60.

Ran engine til 1900 SG reading C100, this was achieved by 1730 but kept engine running as using lots of elec stuff.

At 2345 hrs SG reading was C96 voltage 1270

At 0600 hrs SG reading was C89 voltage 1250, fridge,couple of gauge lights and inverter on during night

At 0945 hrs SG reading was C82 voltage 1255, in addition to above usage now add 2 hours on Hurricane diesel heater.

Couple of things, not sure why SoC has dropped which you would expect but voltage has increased between 0600 hrs and 0945 hrs. This rate of decline seems fairly even, my point in the OP was sometimes the morning reading can be as low as mid 70s on SoC with difference in the usage.

That all looks reasonable to me. When you have loads on it affects the voltage reading, so the voltage is only really relevant if you have no loads on. Probably at 06:00 the fridge compressor was running at 09:45 it wasn't.

 

Don't forget the voltage only reads to the nearest 0.05v so you have to watch the display for a while to see if it jumps up or down 0.05 and interpolate in proportion to the time spent on each value. Really, it is better to use a digital multimeter if you want an accurate battery voltage measurement.

Edited October 27, 2014 by nicknorman

[Phil.]

Thanks Nick. On Friday I shall be on shorepower for the first time in a couple of months so I think I will give them a good long charge then equalise them and see how high the specific gravity will go.

[by'eck]

I think anyone with the potential to question the performance of a Smartgauge should be banned from buying one. They should be clearly marked - Only available to the electrically challenged

 

In making them available to the general public Gibbo shot himself in the foot

[Phil.]

Only[/i] available to the electrically challenged

Thats me.

[bottle]

And that is why he designed it, specifically for his other half, it worked and so he decided to sell it to the general public.

 

ps. It works on my boat, very well, as the other half can understand the state of the batteries.

[londonron]

i was on here searching for a meter. This may be it. i do have a question. My engine room is seperate as its a 70ft narrow boat. I am getting a sterling pro invertor with a 10m remote lead. How far away from the batteries can you put one of these for it to realistically work. I can mount it on the engine bulkhead 1m away but more meters would allow not to get off the sofa and walk into the bedroom to check it.

i do have a thick cable running down the boat so volt drop shouldnt be too much of an issue. 10m away would stick it next to the off switch for the invertor

Edited October 31, 2014 by londonron

[Theo]

Londonron.

 

It can be rather important not to have the low voltage leads to the inverter too long because the currents in them can be pretty huge. An inverter providing 1200W will be drawing a bit more than 100A (Current = Power/Voltage. Plus a bit because the iverter is not 100% efficient.

 

If you are using 25 square mm 12V cables then you will be wasting some 7W for every metre length so if the inverter is one metre further way than it needs to be then you will be wasting an extre 14W.

 

N

[nicknorman]

I could be wrong but I think londonron is asking about the installation of a Smartgauge, not an inverter. If so, the answer from the designer is that it is OK up to 10 metres away from the batteries:

 

http://www.canalworld.net/forums/index.php?showtopic=52784&p=990449

 

However bear in mind that the Smartgauge must be connected direct to the battery posts by its own dedicated wires. You cannot use wires that are also used for something else, so it must not be connected to some general purpose wires running down the boat. Since the Smartgauge works primarily by sensing voltage at the battery terminals, if there is any additional current in the connecting wires this will throw the Smartgauge off.

[Bod]

i was on here searching for a meter. This may be it. i do have a question. My engine room is seperate as its a 70ft narrow boat. I am getting a sterling pro invertor with a 10m remote lead. How far away from the batteries can you put one of these for it to realistically work. I can mount it on the engine bulkhead 1m away but more meters would allow not to get off the sofa and walk into the bedroom to check it.

i do have a thick cable running down the boat so volt drop shouldnt be too much of an issue. 10m away would stick it next to the off switch for the invertor

 

 

Can you get a longer remote lead?

The chances are that it will have standard connections, so unless you require a really long (50-100m) lead then there shouldn't be problems. But ask Sterling first!

 

Bod

[by'eck]

I could be wrong but I think londonron is asking about the installation of a Smartgauge, not an inverter. If so, the answer from the designer is that it is OK up to 10 metres away from the batteries:

That's how I read it.

 

Can you get a longer remote lead?

The chances are that it will have standard connections, so unless you require a really long (50-100m) lead then there shouldn't be problems. But ask Sterling first!

 

Bod

Ref above as it appears to be the Smartgauge that needs to match the existing inverters remote location.

[londonron]

what i need is a sensor at the battery with a display in the cabin so i can turn off the invertor. The invertor remote lead has a 10m lead so a display at 10m would be good. So i am at least past the bedroom and into the kitchen area when i use it

[nicknorman]

what i need is a sensor at the battery with a display in the cabin so i can turn off the invertor. The invertor remote lead has a 10m lead so a display at 10m would be good. So i am at least past the bedroom and into the kitchen area when i use it

So yes, you can mount a Smartgauge at 10 metres distance from the batteries. It must have its own dedicated 1mm^2 wiring direct onto the battery terminals.

Edited November 2, 2014 by nicknorman

[Theo]

Hi, Londonron

 

I think that I misunderstood your question.

 

I now believe that you are asking: "How long can the leads to the Smartguage be?"

 

To which the answer is. "As long as you like." It's a voltage sensing instrument and needs very thin leads which take virtually no current. But the leads must be connected directly to the battery posts.

 

N

 

PS NIck Norman beat me to it!

Edited November 2, 2014 by Theo

[londonron]

and it wont volt drop at 10m ? I thought any voltage will drop as you distance yourself. or is their a sensor at the battery itself?