Which Battery Monitor

Volts and current are key for me. The bm1 did admirably on the last one. Yesterday i finished fitting a Victron BMV - so simple to fit, it monitors volts on 2 banks (aux and engine) and it was so easy to fit (have Imentioned that before?).
 
sailinglegend420 said:
it's interesting that maybe 75% of battery monitor installations are wrong, many because extra equipment has been installed afterwards which has bypassed the shunt. This can't happen with the SmartGauge which goes directly to the service battery so a 1,2,both switch can't confuse it. This applies also to battery monitors which must go directly to the battery. Probably 90% of Battery Monitors are programmed incorrectly which is one of the reasons they become more and more inaccurate as the batteries age. With the SmartGauge it becomes more and more accurate as it learns the battery dynamics.

Most battery monitors, including SmartGauge, measure at least two battery voltages. With a SmartGauge also buy a digital amp meter to keep an eye on charging and discharge currents.
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Second all of that. I have a smartguage coupled to smartbank with a digital ammeter showing rate of charge/discharge. It is an excellent system and simply gives priority to the starting battery until it has reached a healthy level and then closes a relay to charge both. the ammeter is on the service battery only which tells me everything I need to know. I would add that I recently posted to congratulate Merlin who sell smartgauge on their outstanding after sales service replacing a shorted out smartbank that was out of warranty caused by my own stupidity at no cost to me. Can't say enough in praise of an excellent bit of kit from a very caring company.
 
MikeBz said:
it would always bug me that I just can't understand how it can possibly work from the amount of information it has.
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Yep, that was pretty much my initial opinion, but their website tries to explain without giving too much away. Still don't understand it. though.
 
sailinglegend420 said:
See this thread for all the answers. Also my own experience in the Med over the last 7 years would suggest that 100% of boats with battery monitors that I have spoken to are either wired incorrectly or programmed incorrectly.

http://www.ybw.com/forums/showthrea...on-House-batts-necessary&highlight=SmartGauge
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Fair enough, I can't be bothered to wade through the thread linked to but surely if they are able to confirm to you that their monitors are wired or programmed incorrectly why don't they rectify the problem? It's not that complicated, you just have to read the manual!
 
dslittle said:
As I said, I have a Smartgauge. I got it because (a) I am lazy and (b) I am easily confused by electrickery.

Whilst I have no doubt this works for you, and strongly believe in each to their own, I realy don't want to 'guess' an inaccurate number and then use that to determine the state of my battery bank. As has been said before the Smartgauge takes all of the guesswork out (if you believe/trust it - I personally do...)
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See my post number 6 on this thread where I think I said exactly what you are saying. Ideally, and for completeness, I would have a Smartguage aswell.
 
MikeBz said:
Reducing the capacity setting in the BM is only going to make the SoC % drop faster. It takes about 3Ah of consumption to drop it by 20%, so from that you could deduce that it thinks the total capacity is about 15Ah. With 3-5A being drawn and the voltage stable at 12.8V it's clear to me that the SoC must be pretty close to 100%.

Anyway I can't really complain (even though I am) as I was warned by plenty of threads on the subject and made my decision!
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I think I have said, in several threads, that the SOC on the NASA BM monitors is not good. Having owned one for a couple of years, I have found a way of making the SOC better... But it isn't ideal. Mine dropped tonight to 80% very soon after I stopped the engine, yet the batteries must have been pretty much at capacity.. But tomorrow morning, it will show about 60% or so, after using about 60 Ah. As I have also said a few times, ideally, I would have a Smartguage as well.

I understand that Merlin offer a Smartguage with an Amp Hour counter but, when I googled it, it seems to be about £600!! It will be cheaper to buy a separate Smartguage, which I might do when I feel a bit flusher :)
 
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Richard10002 said:
I think I have said, in several threads, that the SOC on the NASA BM monitors is not good. Having owned one for a couple of years, I have found a way of making the SOC better... But it isn't ideal. Mine dropped tonight to 80% very soon after I stopped the engine, yet the batteries must have been pretty much at capacity.. But tomorrow morning, it will show about 60% or so, after using about 60 Ah. As I have also said a few times, ideally, I would have a Smartguage as well.

I understand that Merlin offer a Smartguage with an Amp Hour counter but, when I googled it, it seems to be about £600!! It will be cheaper to buy a separate Smartguage, which I might do when I feel a bit flusher :)
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Disclaimer: I am not an electronics engineer. But: My belief is that all gauges have a tendancy to understate the % state of charge a bit, but this might be due to the nature of lead acid batteries that probably need an elevated voltage for a sustained time to reach a theoretical 100% charge. Frankly I use the % reading with only secondary interest. What is not in doubt is the reading of actual voltage given but even then you need to recognise that the reading is only going to give you an accurate SOC estimate when the batteries have been at rest for a while. It's also important to see how the voltage drops when under load and/or how many amps charge they are actually getting which is why you ideally need an ammeter as well. Amp hour counters are a bit OTT in my opinion and I certainly wouldn't pay £600 for one.
 
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