Seem to be using more power than I thought

[Bewildered]

Oh dear looks like Maplin have stopped doing them. Do you know someone that you could have one delivered to from eBay? Eghttp://www.ebay.co.uk/itm/New-UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-CE-DC-AC-Volt-Amp-Meter-Tester-/141806606167?hash=item2104551757:g:8dIAAOSwhcJWJg0n

Just put an order in for this, being sent from Birmingham to West London to be brought to me somewhere near Wolverhampton next Sunday; bugger my carbon footprint

[Tony Brooks]

 

I think we should draw a distinction between a DC multimeter and a DC clamp meter. The latter is of FAR more use as breaking the conductor is not necessary.

 

well spotted. I meant to write 200 amps +, that has to be a clamp meter at the prices mentioned.

[nicknorman]

Jolly good. One tip about using these meters to measure currents: they use a Hall effect sensor which has a bit of a temperature coefficient, the upshot being that the zero accuracy isn't too good. However you can use the Relative function to zero the reading just before you insert the cable to be measured.

 

Of course if you are measuring 80A or whatever, 1/2A of zero error doesn't really matter.

Edited August 28, 2016 by nicknorman

[Chewbacka]

Completely agree about the clamp meter, I also have a UT203. If you have blade fuses and you want a bit more accuracy for fault finding then one of these plug in current meters is good. (make sure you get the correct size blades)

 

http://www.ebay.co.uk/itm/Automotive-Current-Tester-Circuit-Meter-Standard-Blade-Fuse-Car-Vehicle-/161933135036?hash=item25b3f78cbc:g:~wUAAOSwJcZWhACO

 

You need to take the battery out when in storage, otherwise it will be flat when you come to use it - Sadly I learnt this the hard way........

[Richard10002]

Smartguage is not accurate when charging. Mine gets to 100% when the batteries are still drawing 20A or so. It takes another couple of hours at 15v charging to get anywhere near the 4A or so when I can call them fully charged.

 

So you are not charging them fully, on a regular basis, and it doesn't take long to knacker a set of batteries with this regime.

 

In addition, if you think they are full, when they are only 80% full, and after watching TV for 5 hours, the SG says 75%, you have actually only used 5% or about 35Ah, thus an average of 7A over the 5 hours.

 

Smartguage is good, but not the panacea that some might think.

 

The manual tells us that it isn't accurate when charging.

[WotEver]

Smartguage is may not be accurate when charging.

 

The manual tells us that it isn't may not be accurate when charging.

I've corrected your post for you.

 

SG may be up to a maximum of 10% out when charging. It will resynch as soon as you start to discharge the batteries again

 

Tony

[MtB]

I've corrected your post for you.

 

SG may be up to a maximum of 10% out when charging.

 

<snip>

 

 

Yes, when the SG says 100% your batteries could easily have been charged to 110%.

 

Nice K&A Dundas bitter, this...

[Bewildered]

Smartguage is not accurate when charging. Mine gets to 100% when the batteries are still drawing 20A or so. It takes another couple of hours at 15v charging to get anywhere near the 4A or so when I can call them fully charged.

So you are not charging them fully, on a regular basis, and it doesn't take long to knacker a set of batteries with this regime.

In addition, if you think they are full, when they are only 80% full, and after watching TV for 5 hours, the SG says 75%, you have actually only used 5% or about 35Ah, thus an average of 7A over the 5 hours.

Smartguage is good, but not the panacea that some might think.

The manual tells us that it isn't accurate when charging.

This is something I have been wondering about. Today I charged the batteries using the engine alternator and the sterling 230v alternator via the battery charger until the smartguage read 95% I then swiched over to the petrol genny and battery charger only.

3/4 to an hour later it reached 100% and the charger switched to float mode. The genny had a full tank and I left it running for 4 hours or so.

Left batteries to settle for half an hour, the smartguage reads leisure batteries at 12.80 to 12.85 volt (flicking in between) and the starter is sitting at 12.90 volts. Usually after settling the leisure bank drops of to about 12.4 or 5 and the starter to 12.6

So it seems I have managed to get more charge into them. I try to monitor them tonight and charge in the same way tomorrow, unless I run out of petrol

[WotEver]

Fit an ammeter (they're very cheap from China these days) and you'll save the cost in not wasting fuel within a month.

 

As an added bonus your batteries will last longer.

 

Tony

[Alan de Enfield]

This is something I have been wondering about. Today I charged the batteries using the engine alternator and the sterling 230v alternator via the battery charger until the smartguage read 95% I then swiched over to the petrol genny and battery charger only.

3/4 to an hour later it reached 100% and the charger switched to float mode. The genny had a full tank and I left it running for 4 hours or so.

Left batteries to settle for half an hour, the smartguage reads leisure batteries at 12.80 to 12.85 volt (flicking in between) and the starter is sitting at 12.90 volts. Usually after settling the leisure bank drops of to about 12.4 or 5 and the starter to 12.6

So it seems I have managed to get more charge into them. I try to monitor them tonight and charge in the same way tomorrow, unless I run out of petrol

 

It is important to remember that a fully charged 12v FLA battery is fully charged at 12.8 volts. That reading should be taken after being allowed to stand for a few hours with no charge or discharge.

At 12.5 volts you are only getting to 80% charge.

At 12.4 volts you are only a tad over 70% charge

 

That may be the answer to your woes - maintain your batteries, and charge them for a minimum of 4 hours per day and 8 hours per day at weekends.

 

 

Edit to add :

using a generator to get the last 5%-10% in is an extremely inefficient and expensive way of doing it, these days most people rely on Solar to quietly 'drip feed' those last few % in.

A 100 watt panel can make a huge difference (and all for the price of a few cans of petrol).

Edited August 28, 2016 by Alan de Enfield

[WotEver]

 

Yes, when the SG says 100% your batteries could easily have been charged to 110%.

'TIs true.

 

An ammeter is the simplest cheap way of determining when to stop charging.

[Arthur Brown]

Smartgauge is good, but a full set of volt and amp meters is better when properly interpreted. Diesel is good for fast charging, solar is best for the end of a charge cycle and for float charging.

[WotEver]

Smartgauge is good, but a full set of volt and amp meters is better when properly interpreted.

And therein lies the rub.

 

SG and ammeter needs no interpretation whatsoever.

 

Tony

[Alan de Enfield]

Smartgauge is good, but a full set of volt and amp meters is better when properly interpreted. Diesel is good for fast charging, solar is best for the end of a charge cycle and for float charging.

 

And to determine when your battery is full - the best Method is to use an SG* meter, no interpretation, no ambiguity its a yes or no method.

However you need access to the batteries and removable caps - sealed batteries are 'the spawn if the Devil", you cannot test them and you cannot top them up.

 

 

 

* SG = Specific Gravity

[Bewildered]

Just ordered a NASA BM2 from Amazon.

Looked at the spec for the BM1, it is for battery banks of upto 600ah; as I have potentially 690ah I thought I best get the BM2.

So once fitted I will have a Smartguage, a NASA BM2 and the MT50 for the Tracer solar controller all monitoring the batteries.

I'm going the get repetitive strain syndrome in my index finger from all the button pushing

[WotEver]

Once you have the BM2 installed you'll be looking to see the charging current reduce to somewhere between 7A and 14A, or until it hasn't reduced over a period of around 30 minutes. At that stage your 690Ah bank is approximately fully charged.

 

Tony

[Justme]

If your trying to test any AC equipment then the best option is a plug in meter.

 

They can be left on for a period of time & then you will see the total used energy over the period of time chosen (1 hour, 1 day 1 week ect)

 

This is far more use than a single instantaneous reading especially on items that have a duty cycle like fridges.

[Greylady2]

I spoke to someone who upped their battery bank thinking it was a good idea, turned out their new batterys did not last either, apparently they were never getting a full charge.

 

I guess anything we take from the batterys has to be replaced daily (by engine running or solar panels)

[dccruiser]

Personally i use a smartguage in conjunction with a bmv702 along with a digital voltmeter just for good measure! The smartguage according to battery volts is extremely accurate a couple of hours after charging has stopped, the bvm is excellent to see whats going in and out of the batteries ... before i fitted this i just used a volt and amp meter to manage my charging regime which was obviously a far cheaper option.

 

with the batteries rested a good multimeter or accurate digital voltmeter will give a very good idea of the state of charge of your batteries.. i dont have it to hand but there is a table relating to %. s.o.c @ battery volts on an old thread that i had a copy of on my old panel as a reference before i upgraded.... using this method will at least give an immediate indication whether the problem is undercharging or a system fault.

 

Rick

 

Found one giving volts and specific gravity

 

STATE OF CHARGE

Open circuit voltage, or specific gravity per cell

Edited September 1, 2016 by dccruiser

[Bewildered]

 

I think I may have enough battery monitoring equipment now.

 

While fitting the BM2 I found an old shunt that was not connected to the batteries. It did however have a couple of small wires attached. On my control panel there is an analog ammeter that has never worked since I've had the boat. When I get time I will do a continuity test on these wires to see if they are from this meter.

 

Question, is there any reason why I can't wire the old analog ammeter across the shunt for the BM2?

 

Edit to say, I like to lay on my side whilst reading the meters

Edited September 5, 2016 by Bewildered

[nicknorman]

image.jpeg

I think I may have enough battery monitoring equipment now.

While fitting the BM2 I found an old shunt that was not connected to the batteries. It did however have a couple of small wires attached. On my control panel there is an analog ammeter that has never worked since I've had the boat. When I get time I will do a continuity test on these wires to see if they are from this meter.

Question, is there any reason why I can't wire the old analog ammeter across the shunt for the BM2?

Edit to say, I like to lay on my side whilst reading the meters

The resistance of the shunt has to match the ammeter. There is no guarantee that it would. Also if you put another device across the shunt (the ammeter) it might affect the accuracy of the BM2 especially if it is a fairly low resistance device like a mechanical ammeter. But anyway the BM2 gives you amps so why would you need another ammeter? Edited September 5, 2016 by nicknorman

[Bewildered]

The resistance of the shunt has to match the ammeter. There is no guarantee that it would. Also if you put another device across the shunt (the ammeter) it might affect the accuracy of the BM2 especially if it is a fairly low resistance device like a mechanical ammeter. But anyway the BM2 gives you amps so why would you need another ammeter?

I wasn't sure how delicate the measurements of the BM2 were, hence the question.

I don't need another ammeter, it just happens to be there on the instrument panel and I thought it might be a good idea to be able to read it whilst at the helm

[nicknorman]

I wasn't sure how delicate the measurements of the BM2 were, hence the question.

I don't need another ammeter, it just happens to be there on the instrument panel and I thought it might be a good idea to be able to read it whilst at the helm

Perhaps the answer is to try it. With the BM2 reading something non-zero try putting the ammeter across the shunt and see if the reading changes, and if the readings of the ammeter and BM2 match.

[Bewildered]

Perhaps the answer is to try it. With the BM2 reading something non-zero try putting the ammeter across the shunt and see if the reading changes, and if the readings of the ammeter and BM2 match.

I may well try that, but I will first wait to see if anyone comes up with a reason for not trying it; don't want to risk a brand new BM2

[Richard10002]

I may well try that, but I will first wait to see if anyone comes up with a reason for not trying it; don't want to risk a brand new BM2

And therein lies the reason

 

I am wondering why you want to do this other than, "because it's there".

 

Why not get the BM2 and Smartguage working, see what's going on with your batteries, and don't risk blowing things up?