Batteries

[Fazandgil]

Can anyone advise on how to monitor leisure batteries to see how much power is in them, we did hear about a gauge that could be fitted but don't know where or anything about them

[Grace and Favour]

There are a few available, but many regard the Smartgauge (from Merlin) to be the most accurate, and certainly the easiest to fit.

Edited April 20, 2014 by Grace & Favour

[Fazandgil]

Thanks will have a look at them on the internet

[Phil Ambrose]

Or my favourite the Merlin Power Gauge Lite, not as simple to instal though

Phil

[Fazandgil]

Thanks Phil will also have a look on the internet at that one

Gill

[junior]

Another vote here for the Merlin SmartGuage. I couldn't comment on the ease of fitting as mine was fitted by someone else as part of a larger install, but it's a handy bit of kit!

[Fazandgil]

It's sounding good on the reviews I have read but so has the power gauge lite

[JDR]

The power is rated in Amp Hours, ie: a common size leisure battery is 110Ah. This will in theory be able to supply 1A for 110 hours BUT if you tried to power a high current device from the same battery it would run out of charge much quicker. In addition you don't want to run the battery or batteries below 50% of their rated capacity if you want them to last. Google "Smartgauge" and have a read of the tech pages. It will expksin charging, what size charger you need, the advantage of adding mote batteries (Peukert's law) and more useful stuff it is worth knowing.

[Alan de Enfield]

You can have simple cheap and inaccurate
You can have simple cheap and "OK" accuracy
You can have complicated, expensive and inaccurate
You can have complicated, expensive and accurate.

If you are fairly good at maintaining your batteries then it could be just a voltmeter you need - keep an eye on the voltage when it gets down to 12.2 volts either run the engine or put the batteries on charge.

A reasonable voltmeter kept 'in line' will give you an instant reading and will help to manage your batteries.

Every charge & discharge destroys your batteries to some degree, a big discharge (say down to 10 volts)
does major damage and has a huge effect on battery life. It has been identified that the best compromise between battery use and battery life is to keep the batteries charged above 50% (ie 12.2 volts)

[nicknorman]

The Smartgauge is in the second category mentioned by Alan, and as such I suggest it is the option best suited to the OP.

[Fazandgil]

Thanks all for replying I know more now than I did

[Theo]

Thanks all for replying I know more now than I did

That's what CWDF is all about!

 

I am moving this to the equipment section. It will be easier for others to find.

 

Nearly forgot: welcome to the forum.

 

Nick

[larryjc]

A quick vote for the NASA BM2 - not expensive (about £100 if you shop around) and it measures current as well as voltage so you can see how much your boat uses as well as how well your charging system is coping - great for doing a current audit. The State of Charge calculation is OK but you need to treat it with caution as it is very sensitive to the setting you give it for the capacity of you batteries.

[Theo]

A quick vote for the NASA BM2 - not expensive (about £100 if you shop around) and it measures current as well as voltage so you can see how much your boat uses as well as how well your charging system is coping - great for doing a current audit. The State of Charge calculation is OK but you need to treat it with caution as it is very sensitive to the setting you give it for the capacity of you batteries.

That's why you need Smartgauge. Within the limits of its accuracy the percentage reading is always the fraction of the actual capacity of the batteries. It takes account of their condition.

 

N

[larryjc]

That's why you need Smartgauge. Within the limits of its accuracy the percentage reading is always the fraction of the actual capacity of the batteries. It takes account of their condition.

 

N

Well I don't know the smartguage but I do know it doesn't measure current which is important when looking at how much power you use and generate. My BM2 is in sight when I am motoring so I can monitor my charging voltages and current flow. I can also see how my solar panels are performing. Frankly my percentage charge can be seen from the no load battery voltage to the accuracy I need and I tend to ignore the BM2 SOC percentage. That said I fiddled about with the input of battery capacity last year and got it quite accurate. That's also a useful thing - you can change the capacity and then monitor the SOC until it makes sense and then get a fair idea on how much the battery bank capacity has dropped. For example in my case I have 5 110 AH AGMs (previous owner fitted them) and they are 6 years old but are still at about 500 AH.

I guess all these gauges work differently and do differerent things, I had a BTM mastervolt on my last boat and hated it as it was so complicated. For me the NASA works as well as anything else and isn't expensive.

[Ex- Member]

Initially when first on the water with our solar and new batteries the SOC became a bit of a worry almost to a point of paranoia LOL, I could have well paid £100 +++ for a battery monitor around that time, fortunately I didn't.

 

Now having lived with the system for 8 months I can pretty much judge how the batteries are faring by looking at the original analogue needle gauge on the 12v panel.

 

We do have a fitted amp meter too and don't take too much notice of that either.

 

Just through a couple of months trial & error I reckon I can judge the batteries SOC as well as any gadget gadget. I do try not to let batteries go over 50% SOC, but in reality I'm not going to lose sleep over it, we went 4 days a couple of weeks ago with poor weather and hardly any input from solar, batteries would have been well below 50% SOC but I didn't need to burn expensive fuel to recharge them either, so I might lose a tiny fraction of battery life, but how much would the fuel cost and wear & tare on engine against a possible tiny amount of lost battery life.

 

Our analogue volt gauge has in the past read Empty but ample power on the boat, if I disconnect all loads from the batteries, within a couple of hours they're back up to 12.4/5v

 

I really don't think spending money on these type gadgets gains anything. Our MPPT controller also logs how many amps gleaned so some simple maths keeps us on top of things, learning how you use and judge your own energy use accordingly is much more interesting. Having not ever drained batteries to the point of setting of inverter alarms I reckon we're doing pretty well.

 

We do use a clamp meter a lot through the winter though for charging purposes, really useful for assessing amps input to better select appropriate charge methods.

[Alan de Enfield]

 

. I do try not to let batteries go over 50% SOC,

 

 

It may help if you occasionally let them

[smileypete]

If living aboard 'off grid' with more than minimal electrical needs, it helps to have some rudimentary knowledge at least of what the amps and volts mean, and how to avoid the common pitfalls.

 

cheers, Pete.

~smpt~

[Ex- Member]

 

It may help if you occasionally let them

 

Well I do wonder, after all the manufactures recommend over charging the batteries every month at 15.5v LOL

 

I really don't see it as a problem if happening occasionally.

[YamYam]

You could just save money and use the rule that if your battery lights dim when the water pump is being used they probably need a quick charge :-)

[nicknorman]

I have to say I think it is rather unhelpful to the OP, who (and I hope she will forgive me if I am wrong here) doesn't seem to have much knowledge of battery electrics, and probably not much interest in gaining such, when posters can't resist saying how clever they are to be able to know their battery state by performing complex differential calculus on the number of hydrogen atoms in their batteries (that they have personally counted), applying a factor acquired by oberving their tea leaves, and then running the whole thing through an analogue computer that uses seaweed as the ALU.

 

For someone whose hobby is not staring at their batteries all day, the Smartgauge is the obvious choice for a fit-and-forget solution to having a pretty good idea how the batteries are doing, at a glance, without needoing to have a degree in subatomic physics.

 

Clever:yes. Helpful:no

[Ex- Member]

I have to say I think it is rather unhelpful to the OP, who (and I hope she will forgive me if I am wrong here) doesn't seem to have much knowledge of battery electrics, and probably not much interest in gaining such, when posters can't resist saying how clever they are to be able to know their battery state by performing complex differential calculus on the number of hydrogen atoms in their batteries (that they have personally counted), applying a factor acquired by oberving their tea leaves, and then running the whole thing through an analogue computer that uses seaweed as the ALU.

 

For someone whose hobby is not staring at their batteries all day, the Smartgauge is the obvious choice for a fit-and-forget solution to having a pretty good idea how the batteries are doing, at a glance, without needoing to have a degree in subatomic physics.

 

Clever:yes. Helpful:no

 

Some might like to learn something

 

Clearly you've purchased one LOL

[Phil Ambrose]

Nick, you've nailed it.

Phil

[Ex- Member]

Nick, you've nailed it.

Phil

 

Not you too LOL

[nicknorman]

Nick, you've nailed it.

Phil

Do you mind, I'll have you know I screwed ours to the wall. Nailing is reserved for reattaching any rivets that might fall off.