Battery monitor upgrade

petedg

petedg

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I'm thinking of upgrading the battery monitor which is a simple needle dial type with a voltage readout. Was considering the NASA BM1, although I find it quite expensive but it does have a number of functions. Any other recommendations? Are they typically a simple drop in replacement?
Thanks in advance for your answers/suggestions.
 
petedg said:
I'm thinking of upgrading the battery monitor which is a simple needle dial type with a voltage readout. Was considering the NASA BM1, although I find it quite expensive but it does have a number of functions. Any other recommendations? Are they typically a simple drop in replacement?
Thanks in advance for your answers/suggestions.
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If you have, or are thinking of getting, solar panels, I would suggest having a look at one of these setups

1349970546_43472300.png


which give you a PWM solar panel controller (single or dual battery) plus remote display for surprisingly little (£73.99 from Photonic Universe, whose picture I used and of wom I am only a happy customer).

It's really just a voltmeter for the battery, and though there are empty ... full indicators they are easily fooled by discharges and tend to under-read if you're supplying anything. But what the heck, unless you are a battery condition fetishist (NTTAWWT) it tells you all you need to know about the battery as well as telling you know how many amps are going in, and how many amp-hours have gone in, from the solar panel.

http://www.photonicuniverse.com/en/...harge-controller-with-a-remote-LCD-meter.html
 
The NASA BM1 is very popular and considered cheap for the functions it provides. It's not a simple drop in though and requires a shunt for accurate measuring of current. There are lots of other battery monitors around - some are easier to install than others and they all claim to tell you, to the last second, how long till your lights go out. A claim that I treat with some suspicion. PBO mag did a review of these devices a little while ago which would be a good starting point for your research before buying.
I've got one of these which someone told me 'is better than nothing'!
 
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I used a cheap Chinese volt/ ammeter for years and having the current was invaluable. Recently broke it and I am on my 3rd replacement and still got issues either beacause woefully inn accurate or cannot show - current.

Probably going to buy a bm1.
 
BM1 is certainly cheap, and perfectly adequate for the simple systems aboard most leisure use yachts, it will give you a halfway decent indication of your power reserves if set up correctly.
 
For me the choice was between a Smartguage, and a BM2, (200A version of the NASA BM 1). I plumped for the BM2 because I wanted to see instantaneous Amps and cumulative Amp hours, as well as voltage. The percentage State of Charge is a bit of a stab in the dark, even if your guess at actual capacity is close.

The Smartguage gives its apparently accurate state of charge percentage, but tells you nothing about Amps - and its more expensive.

I tried some cheaper options, but it was the old adage of "buy cheap, buy twice".
 
Just fitted a Smartgauge, plenty of posts about it so won't repeat here. Certainly easy to fit (no shunt, two wires) and gives me a percentage reading which is the only thing I'm really interested in. Obviously two weeks aren't enough to tell how accurate it's going to be when the battery ages etc. So far I haven't read anything bad about them other than price, good enough for me.
 
A couple of thoughts (mostly obvious, sorry).
The capacity estimation of my BM1 (which came with the boat) is useless because not everything goes via the shunt. Stuff has been added over the years which shouldn't be a problem with a new installation, but many people probably *don't* have a single cable to a bus bar from their battery earth but instead have miscellaneous devices attached to different earth terminals on different batteries in the house bank. Fitting a battery monitor is an excellent time to rationalise but might involve more work than just installing the battery monitor. Re-wiring is near the top of my to do list at which point I'll be better able to comment on the "capacity" estimation of the BM1 :-)
The BM1's max current rating is 100amps which is fine for most things but a big inverter might exceed that. If you're in that position the more expensive BM2 as mentioned by Richard10002 might be worth a thought. My boat came with the 1500W windlass wired to the house bank (which I keep intending to change but haven't got round to).
Personally I find the ability to measure current rather than just state of charge to be invaluable. Greatly simplifies working out what is "costing" you and what you're really getting from solar/wind in order to prioritise sorting out electrical self-sufficiency.
 
I have an unused NASA BM2 in Brighton if you're interested. I bought it to install on our boat, but managed to get the old monitor working in the end.
 
BM2

jamiepyoung said:
I have an unused NASA BM2 in Brighton if you're interested. I bought it to install on our boat, but managed to get the old monitor working in the end.
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Thanks for the offer but at the moment I'm leaning towards Smart Gauge due to ease of fitting. However, when I'm back on the boat in October I want to check the electrical system configuration once more.
 
petedg said:
Thanks for the offer but at the moment I'm leaning towards Smart Gauge due to ease of fitting. However, when I'm back on the boat in October I want to check the electrical system configuration once more.
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Don't be worried about fitting a BM1 or BM2, they're not complicated and the ammeter giving constant current in/out, is the best feature. The shunt is in practice just an extension of the domestic neg terminal - one end of the shunt goes to the battery terminal, all negs then connect to the other end of the shunt.
 
Richard10002 said:
For me the choice was between a Smartguage, and a BM2, (200A version of the NASA BM 1). I plumped for the BM2 because I wanted to see instantaneous Amps and cumulative Amp hours, as well as voltage. The percentage State of Charge is a bit of a stab in the dark, even if your guess at actual capacity is close.

The Smartguage gives its apparently accurate state of charge percentage, but tells you nothing about Amps - and its more expensive.

I tried some cheaper options, but it was the old adage of "buy cheap, buy twice".
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I regard the essential readings off a monitor are the Amps and Voltages. I find the %charge rather irrelevant as the voltage really is the state of charge (rested). Besides, a monitor system with out amps input and output showing tells you absolutely nothing about what is happening. I want to know what the fridge is using and I want to know what the alternator is charging at- - so I would find the smartgauge useless to me.

The BM1 is very clear and simple to use - and I found it very simple to fit.
 
Chris_Robb said:
I regard the essential readings off a monitor are the Amps and Voltages. I find the %charge rather irrelevant as the voltage really is the state of charge (rested).
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Disagree. The amp hours figure is the number I most frequently monitor and with a correctly configured amp hour capacity the percentage figure is just the amp hours consumed from a different perspective.

Voltage is the figure I look at least because with variable demand and charging I would have to knock off all circuits and rest the battery before getting a valid reading.

Amps are useful for developing a picture of the demand different devices place on the battery.

The Link-10 battery monitor used to be the respected if pricey option when this subject was raised 6 used ago. That is what I have.
 
Chris_Robb said:
......Besides, a monitor system with out amps input and output showing tells you absolutely nothing about what is happening. I want to know what the fridge is using and I want to know what the alternator is charging at- - so I would find the smartgauge useless to me.....
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I agree that you need a digital meter to monitor the amps in/out to keep a close eye on how the systems are working, and continuing to work!!!

BUT a Battery Monitor that doesn't work accurately as the batteries age is a waste of time, which is why the man at Link got fed up with calls complaint about their accuracy that he developed the SmartGauge. It has proven to be much more accurate than a shunt bases monitor, >95% accuracy, and it gets more accurate as the batteries age as it "learns" the battery bank. I have a BEP which won't track the Ah capacity no matter how I change all the parameters, and I have a SmartGauge that I'm sure is accurate as it compares well with the battery voltage when the batteries are "off load". Off load should really mean ldisconnected and left for at least 4 hours, which is totally impractical on a boat.

if you buy a SmartGauge buy a digital Ah count meter as well.
 
Seems to me that you can easily determine the % full of the battery but you don't know the ultimate Ahr capacity so you don't know when your lights are going out.
 
sailinglegend420 said:
BUT a Battery Monitor that doesn't work accurately as the batteries age is a waste of time.
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Disagree. In the real world I very rarely look at the percentage, but every morning look at the amps used overnight, a very rough idea of how healthy the batteries are can be achieved by checking the voltage, very rough indeed but enough to give you a heads up that it might be time for a capacity test. Getting a full charge back in as often as possible is vital, it's not difficult to watch amps in at absorption voltage to get a good idea of that, and charging seems to be an area where the smartgauge accuracy suffers a bit so you would probably want to be keeping an eye on amps/volts anyway. The smartgauge does seem very accurate and would be another nice gadget to have but not anywhere near the top of the list for battery maintenance on a full time cruising boat, IMHO amp counting and an accurate voltmeter direct to the battery are much more useful.
For a boat plugged in regularly a smartgauge could well be the best way forward, especially for those non liveaboard who aren't so obsessed with electrons :)
 
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GHA said:
Disagree. In the real world I very rarely look at the percentage, but every morning look at the amps used overnight, a very rough idea of how healthy the batteries are can be achieved by checking the voltage, very rough indeed but enough to give you a heads up that it might be time for a capacity test. Getting a full charge back in as often as possible is vital, it's not difficult to watch amps in at absorption voltage to get a good idea of that. The smartgauge does seem very accurate and would be another nice gadget to have but not anywhere near the top of the list for battery maintenance on a full time cruising boat, IMHO amp counting and an accurate voltmeter direct to the battery are much more useful.
For a boat plugged in regularly a smartgauge could well be the best way forward, especially for those non liveaboard who aren't so obsessed with electrons :)
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I agree with you. When a battery bank is getting old its fairly obvious that although you are charging well, somehow your voltages in the morning (before the sun adds to them) are unexplainably low. This can also happen with cheap new batteries which are just badly made and should be avoided - you gets what you pay for - Numax springs t mind here and perhaps all the other labels which that cheap battery spawns.

I was staggered, when I chucked my 1 year old 4 x 110a/h numax set for E-nex, by the high voltages maintained overnight and even after 4 days of rain in harbour. The difference was so obvious, that I don't understand what an accurate % charge meter will bring to the party.
 
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