Which Battery Monitor?

[Cloudinspector]

Simple question really, should I go for something like a smartgauge or a plain and simple ammeter?

 

Answers in laymans speak please

[Titus]

I've just fit a BMV 600s , cost about £130 but very good, bought online from Onboard Energy

[Chris Pink]

The others do what a smartgauge can't

 

The smartguage does what you'd otherwise have to use knowledge and experience for.

 

It's not an either/or really. But if you wanted one I'd recommend any of the Victron / NASA type and a bit of research will tell you all your need to know.

 

If you get an ammeter (Ebay stylee) get a voltmeter too. And make sure it can be powered off the source your are measuring, not all can. Smiley Pete's usually up to speed on these.

 

Hang on a minute......

 

 

OOOOOOYYYYYY!

 

(he'll be along soon)

[Richard10002]

Simple question really, should I go for something like a smartgauge or a plain and simple ammeter?

 

Answers in laymans speak please

I fitted a NASA BM2 because I want to see amps, volts, and cumulative amp hours. I am not too concerned about State of Charge as I can judge that from the other info.

 

I considered a simple ammeter but that wouldn't give cumulative amp hours, which I want.

 

If you are not technically inclined a Smartguage is probably the best solution. People seem to swear by it with respect to State of Charge, and it seems to fair well when compared directly with other State of Charge measures.

 

IMHO a simple ammeter tells you little. Even a simple voltmeter enables you to deduce more.

[MtB]

I think first, you need to decide what you want to know about your batteries.

 

Then selecting the kit to tell you will probably become a lot easier.

 

 

MtB

 

 

Edited to make a sentence make sense!

Edited July 16, 2013 by Mike the Boilerman

[nicknorman]

Yes, basically 3 options:

 

1/ A voltage reading device with very clever algorithms to derive the state of charge regardless of the current load. The only device that does this is the Smartgauge as far as I am aware

 

2/ A current-reading, amphour counting device such as a Victron BMV or NASA as mentioned by Chris. These take into account such things as charge efficiency, peukert's forumla etc, so are "slightly clever"

 

3/ An accurate voltmeter and current meter. These are not clever at all, the cleverness has to come from the user in their interpretation

 

1 and 2 are a similar price. 3 is much cheaper

 

1 is the easiest to install and use, probably followed by 2 then 3

 

1 is the simplest to use - fit and forget. It gives state of charge as a percentage of actual capacity, not initial new battery capacity. Therefore its good for not over-discharging your batteries and telling you when they are fully charged, less good for letting you notice how your battery bank is deteriorating.

 

2 is more complicated to use, especially if you are not in the habit of fully recharging each day. It gives state of charge relative to the battery bank capacity you have set. So it doesn't automatically take account of the gradual deterioration of the bank and you could find yourself with flat batteries whilst the gauge thinks you are fine.

 

3 is not exactly complicated to use, but does require a lot of interpretation.

 

In my view, the best possible solution is a combination of 1 and 2 because it tells you your current actual state of charge whilst allowing you to keep track of the actual (as opposed to new) battery capacity.

Edited July 16, 2013 by nicknorman

[Chalky]

I fitted a NASA BM2 because I want to see amps, volts, and cumulative amp hours. I am not too concerned about State of Charge as I can judge that from the other info.

 

I considered a simple ammeter but that wouldn't give cumulative amp hours, which I want.

 

If you are not technically inclined a Smartguage is probably the best solution. People seem to swear by it with respect to State of Charge, and it seems to fair well when compared directly with other State of Charge measures.

 

IMHO a simple ammeter tells you little. Even a simple voltmeter enables you to deduce more.

 

I've got a NASA BM-1. Great for volts and amps however the State of Charge algorithm is very inaccurate. It tries to be clever however fails dismally. The volts and amps are enough to tell you what's going on - if you know how.

[churchward]

All I can say I decided to fit a Smartgauge a few years ago and feel no need to fit an ammeter. The Smartgauge tells me what I need to know.

 

Whether the same arrangement will be right for you is another matter.

[bizzard]

And all these electrical gauges, warning lights, bleepers, buzzers, monitors, and monitors monitoring the monitors ect don't work for nothing, all those little twitching gauge needles, warning lights, bleepers and buzzers ect are all contributing to the big battery drain and contributing to trying to flatten them. One big vicious circle.

[nicknorman]

And all these electrical gauges, warning lights, bleepers, buzzers, monitors, and monitors monitoring the monitors ect don't work for nothing, all those little twitching gauge needles, warning lights, bleepers and buzzers ect are all contributing to the big battery drain and contributing to trying to flatten them. One big vicious circle.

True, but they do look pretty!

[bizzard]

True, but they do look pretty!

So does my picture of Venus asleep.

[Cloudinspector]

I think first, you need to decide what you want to know about your batteries.

 

Then selecting the kit to tell you will probably become a lot easier.

 

 

MtB

 

 

Edited to make a sentence make sense!

A bit more info is in order I guess. Basically we spend 6 months out on the cut with 200w of solar and engine running to charge the batteries,, possibly a generator sometime in the future. I want to be able to look at a gauge which will simply tell me how discharged the batteries are in simple terms.

Something with a state of charge reading seems to fit the bill.

[WotEver]

Basically we spend 6 months out on the cut with 200w of solar and engine running to charge the batteries,, possibly a generator sometime in the future. I want to be able to look at a gauge which will simply tell me how discharged the batteries are in simple terms.

 

You've just described a Smartguage.

 

Tony

[churchward]

 

You've just described a Smartguage.

 

Tony

Yep I think he has.

 

If the OP wants the best gizmo that will show the most accurate SOC across a range of circumstances then the Smartgauge is the answer.

 

It is what I use mine for,

Edited July 16, 2013 by churchward

[mrsmelly]

I've just fit a BMV 600s , cost about £130 but very good, bought online from Onboard Energy

Thats what I use and if read and used with experience will tell you everything you need to know about batteries. A smartgauge is ok to use just as you would say use a petrol gauge so they have their use and could be good as a back up but as standalone there are many better bits of kit.

A simple ampmeter and volt meter if accurate will suffice.

 

Tim

[trackman]

I swear by the Smartgauge. It does what the OP says he needs, and only needs two simple connections. No shunts or other bits to confuse the non technical.

Mine also controls a Smartbank & relay split charge system as we've only one alternator. That system also splits the solar power from the solar regulator to ensure both banks get topped up from that source.

[blackrose]

And all these electrical gauges, warning lights, bleepers, buzzers, monitors, and monitors monitoring the monitors ect don't work for nothing, all those little twitching gauge needles, warning lights, bleepers and buzzers ect are all contributing to the big battery drain and contributing to trying to flatten them. One big vicious circle.

 

The battery monitors themselves have LED or LCD displays and draw virtually nothing.

 

I have a Smartgauge and a BEP 600 DC meter. The combination seems to cover most things.

[nicknorman]

The battery monitors themselves have LED or LCD displays and draw virtually nothing.

 

I have a Smartgauge and a BEP 600 DC meter. The combination seems to cover most things.

Well to be fair to Mr Biz, an LED display takes a non-trivial amount of current, however it times out and goes blank a couple of minutes after the last button press. An LCD display does take virtually nothing, that's why it remains on permanently.

[blackrose]

Well to be fair to Mr Biz, an LED display takes a non-trivial amount of current, however it times out and goes blank a couple of minutes after the last button press. An LCD display does take virtually nothing, that's why it remains on permanently.

 

In other words battery monitors don't really contribute to battery drain as Biz said.

[dmr]

Well to be fair to Mr Biz, an LED display takes a non-trivial amount of current, however it times out and goes blank a couple of minutes after the last button press. An LCD display does take virtually nothing, that's why it remains on permanently.

 

You can turn the brightness down on the Smartgage, and arrange that it does not go to sleep, and so its always on needing just a glance each time you walk past .... without even needing to press a button. This saves me having to lean over the engine.

 

Even with the display on the consumption is probably less than the self discharge of the battery. (I bet some padant will do the sums now and prove me wrong).

 

..............Dave

[bottle]

You can also set it to only come on when the voltage is above a set figure, your choice.

 

Mine sleeps unless the batteries are being charged.

 

ps. the Smartgauge will also do a lot of other things, if set up properly. ie. remote start a generator if the SOC/voltage gets to low

[Cloudinspector]

Sounds like a smartgauge fits the bill.

Thanks folks

[blackrose]

 

You can turn the brightness down on the Smartgage, and arrange that it does not go to sleep, and so its always on needing just a glance each time you walk past .... without even needing to press a button. This saves me having to lean over the engine.

 

I can see the benefit of being able to see a battery monitor from the helm in a wheelhouse for example, but failing that I'd rather have my battery monitors mounted inside the cabin. All my monitors are in one place - DC, AC and temp/humidity.

 

[mrsmelly]

As this topic keeps running I am wondering if the proposed new smartgauge has materialised yet? Where is Gibbo when you want him?

 

Tim

[MikeV]

I think I've found one flaw with SmartGauge - it doesn't cope well with small solar panels and little or no battery cycling. I've had a SG for about 4 years and used it as my primary gauge regarding state-of-charge when cruising. However I also have voltmeter, ammeter and amp-hour meter so can also judge state-of-charge from these other instruments.

 

I've not done much boating this year but have a 32W panel lying flat on the roof to keep the batteries topped up so when visiting the boat for a few days I don't particularly have to run the engine. I've noticed that if, say, I leave the boat with the amphour meter reading -25Ah and the SG SoC reading 90% and come back to the boat a few days later the amphour meter reads zero, which shows that at least 25Ah of energy has been returned to the batteries, but the SG still reads 90%. If I run the engine I can see from the charge amps that the batteries are more or less fully charged. The maximum I've seen from the solar panel at midday is 1.7 amps (full sun), so I'm guessing on a long summer's day it returns about 15Ah to the batteries per day.

 

I think the issue is, particularly at this time of year, that the batteries are being charged most of the time from the solar panel and I don't the the SG can measure SoC accurately during the charging process. I'm surprised however it doesn't correct itself based on the overnight voltage. I'm sure once I use the batteries over a normal discharge/charge cycle the SG will catch up.