cagey
Well-Known Member
My BEP smart monitor has packed up, it is at least 15 years old, what is a modern replacement please. 3 banks 2house and 1 engine 12v .
Thanks
K
Thanks
K
Battery monitor
- Thread starter cagey
- Start date
Minchsailor
Well-Known Member
pvb
Well-Known Member
I also fitted a Pico battery monitor last winter. I chose it primarily because of its looks, and the versatility. The display is a lovely-looking bit of kit, with very stylish graphics, and makes a lot of other monitors look rather crude. My second choice would have been the Victron BMV-700, which works well, but does look a bit basic in comparison. I don't yet have enough experience of using the Pico to say how well it works, but initial impressions are very positive.
adamlang
Well-Known Member
Does anyone have any experience with the cheapo shunt battery monitors, like this. £45 for a 350A version. I've ordered one that I was going to test with a basic domestic (non-boat) Solar system, before maybe getting one for the boat.
Presumably the OP will need a different shunt for each bank, maybe individual displays too? That would add up pretty quickly at Victron prices.
Presumably the OP will need a different shunt for each bank, maybe individual displays too? That would add up pretty quickly at Victron prices.
Alan S
Well-Known Member
Why 2 house banks? Or do you mean 1 house bank consisting of 2 batteries in parallel?
Poey50
Well-Known Member
Have a look at the Balmar SG200. It amalgamates the Merlin Smartguage with an ammeter and other bits of cleverness. I have a Victron BMV712 which is good but the Balmar may have raised the bar.
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LadyInBed
Well-Known Member
peterf
Member
Yes, I fitted one of those 350A units.. What can I say, it just worked...
Caveats: It works by you configuring the unit with the amount of Amp/hrs in your system. You manually tell the unit when 100% is reached. It subtracts Amp/hr total as current flows out.
- I believe this approach is pretty standard.
The length of cable between the shunt and the meter is just a couple of meters. I assume that the interface is analog along this cable so extending it 'might' reduce the accuracy.
The shunt is very sturdy and looks engineered. The meter looks a little flimsy but does the job.
Would I recommend: Well yes, I believe the general benefit products like this is to help you get an intuitive feeling of the amount of power your vessel uses. I don't think you need a 'Live' display, rather you generally check it maybe once or twice a day..
For such a small amount of money, its a solution to a problem.. Just doesn't look great...
Caveats: It works by you configuring the unit with the amount of Amp/hrs in your system. You manually tell the unit when 100% is reached. It subtracts Amp/hr total as current flows out.
- I believe this approach is pretty standard.
The length of cable between the shunt and the meter is just a couple of meters. I assume that the interface is analog along this cable so extending it 'might' reduce the accuracy.
The shunt is very sturdy and looks engineered. The meter looks a little flimsy but does the job.
Would I recommend: Well yes, I believe the general benefit products like this is to help you get an intuitive feeling of the amount of power your vessel uses. I don't think you need a 'Live' display, rather you generally check it maybe once or twice a day..
For such a small amount of money, its a solution to a problem.. Just doesn't look great...
pvb
Well-Known Member
Proper battery monitors adjust the Ah reading to take account of the Peukert exponent, and also the charge efficiency factor. Cheap meters don't do this.
adamlang
Well-Known Member
Thanks. I've got one of those with a more basic shunt (without any circuitry). I've not used it a great deal and might have wired it up wrong, but I think it doesn't differentiate between amps going into, or amps coming out of the battery. Meaning it just counts amps and adds them up, which doesn't give any indication of the amps left in the battery at any one point. Apparently its possible to use two of these systems on each of the input and draw negatives, but that seems a bit of a pain.
adamlang
Well-Known Member
Would there be a way of testing whether a cheaper meter took this into account? Maybe just running a battery down to a set voltage at 5amp and then 10amps, and see if it does the maths? Presumably the monitors also take into account voltage?
I know they should be set up with the actual capacity of the battery rather than it's stated capacity, taking into account that you can only 'use' about half of the stated capacity without damaging it. Presumably, one could consider the typical draws on the battery and adjust what the monitor think is the capacity downwards to give a little leeway, and help to keep the battery healthy.
pvb
Well-Known Member
You'll find that cheap meters won't use Peukert or CEF. About the cheapest which uses Peukert in some way is the Nasa BM1 which is about £100. It doesn't allow you to set a specific Peukert exponent for whatever batteries you're using, you need a more sophisticated monitor for that.
As far as I can see, the cheap meter linked to by LadyInBed only measures current one way; in other words if you want to measure current in and current out you'll need two of them.
Graham_Wright
Well-Known Member
I fitted Nasa BM1, one each for three batteries. I like the big digits as I can see at a glance just what is what.
Nasa is British.
Nasa is British.
Aardee
Well-Known Member
+1 for the NASA monitor. Only fitted a couple of months ago but so far, so good.
Poey50
Well-Known Member
Disasters seem more often to be caused not by genuine ignorance but by false knowledge. Cheaper battery monitors are fine at giving information on voltage and balance of current in / out but what you pay the extra cost for is the level of accuracy of state of charge. Even the best and most expensive of them will struggle with this over repeated cycles if not returned to full charge so you have to know the limitations of the monitors and how to get the best out of them. The worst of them are for stage of charge what the Nordkyn Design site aptly calls "random number generators". If in ignorance of state of charge then you will be careful and give a wide margin of error, but if you have faith in your SOC reading - especially with a crude monitor - you could be in trouble. I wouldn't buy a NASA - Victron is not much more expensive and better, but even so, not fit-and-forget.
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peterf
Member
Yes, you are right.
Question:
Would it be fair to say that the Peukert exponent becomes significant at higher current draw ie > 30amp/hr? For those of us with fridge/autoHelm being the highest draw (<10amp/hr combined) than would you say that the likely effect effect of not having that feature should be low?
pcatterall
Well-Known Member
+1 for the nasa cheapo. We have a BM2 and it has been invaluable.
Clancy Moped
Well-Known Member
I couldn't fault my old SmartGauge Electronics - Homepage
pvb
Well-Known Member
Firstly, current is measured in amps, not amp/hr which is meaningless.
The Peukert effect works both ways; at higher currents the battery's effective capacity (Ah) is reduced, but equally at lower currents the battery's capacity is increased. It depends what you want from a battery monitor. If you just want to measure voltage and current, any cheap meter will do. If you want a fairly accurate measure of remaining battery capacity, you need to pay rather more (the Nasa monitor's state of charge display is often said to be hopeless). Spending almost twice as much as the Nasa BM1 on the Victron BMV-702 or the Mastervolt Battman brings a huge increase in accuracy and functionality.
Poey50
Well-Known Member
Yes, very good and easy to fit with no shunt. I have that and the Victron BMV712. But even with the Smartguage you need to know that it is more accurate on discharge than on charging.