Sterling-NASA -Victron

[Glynn]

Which one of these would you recommend for keeping an eye on amps used and put back into battery bank from

Sterling PMP1

Victron BMV700

NASA BM2

 

[rusty69]

Nasa has a nice big display. 

Victron is a bit more classy imo. 

 All Three will do what you want 

[Robbo]

I’ve got the Simarine, it’s early days and doesn’t have logging yet (out soon) but is in active development and I would recommend.

[Tony Brooks]

8 hours ago, Glynn said:

Which one of these would you recommend for keeping an eye on amps used and put back into battery bank from

Sterling PMP1

Victron BMV700

NASA BM2

 

The term "amps used and put back into battery" worries me. If you mean amps in and out then fine but if you really mean "amp hours used and put back into battery then in most peoples hands such such meters are very keen on telling lies and helping you destroy your battery.

Ignore anything they show other than amps and volts. Amps in to indicate when to stop charging and rested volts to tell you when to start charging.

[mross]

If you have a large inverter, make sure the current shunt has enough capacity.  A 3kW inverter can draw 250A and some of those battery monitors can only record up to 200A.  The shunt can withstand short term overloads but the meter probably won't record them.

[nicknorman]

1 hour ago, Tony Brooks said:

The term "amps used and put back into battery" worries me. If you mean amps in and out then fine but if you really mean "amp hours used and put back into battery then in most peoples hands such such meters are very keen on telling lies and helping you destroy your battery.

Ignore anything they show other than amps and volts. Amps in to indicate when to stop charging and rested volts to tell you when to start charging.

 Don't think this is correct really. Whether the OP wants to know instantaneous amps in or out, or cumulative amp hours in and out, any of these gauges will do so accurately. What they won't do (and I think what you are thinking of) is show an accurate State of Charge. And of course what you do with the information about how many AH taken out or put back, is another matter.

 

i would want one that automatically calculates Charge Efficiency Factor, has an adjustable tail current, and a shunt that can easily cope with the maximum feasible current. And one that doesn't mis-apply Peukert.

On which point I note this in the BM2 manual, showing that unlike so many people on here, they do understand Peukert in relation to battery monitors (my bold):

If higher currents than the 20-hour rate are drawn from the battery, the available capacity is reduced. For example, if it is steadily discharged at 10 times the 20-hour rate (50 Amps from a 100Ahr battery), the available capacity falls to about half of the stated capacity. The battery will be flat after about 1 hour instead of the expected 2 hours. (However, if the battery is left to recover with the heavy load removed, most of its remaining capacity will return after perhaps 20 hours' resting or at a discharge rate close to the 20-hour rate.) The BM1/BM2 makes due allowance for these effects when estimating the battery's state of charge and the expected time to discharge the battery fully. 

[mrsmelly]

9 hours ago, Glynn said:

Which one of these would you recommend for keeping an eye on amps used and put back into battery bank from

Sterling PMP1

Victron BMV700

NASA BM2

 

Ive had the victron and the Nasa, I fitted Nasa again on this boat simply because it has a HOOOOOOGE readout so no need for reading specs oh and its waterproof so can be fitted outside if ya want to.

[Sea Dog]

1 hour ago, mross said:

If you have a large inverter, make sure the current shunt has enough capacity.  A 3kW inverter can draw 250A and some of those battery monitors can only record up to 200A.  The shunt can withstand short term overloads but the meter probably won't record them.

Precisely the reason I went with the Victron over the NASA. The Victron BMV shunt is a 500 amp version, whereas the NASA BM-2, which to be fair probably has the better display, is 200 amp.

OP, I've been happy with the Victron.  I'm content that the Ah out measurement is close enough for a quick indication of what's been used since last full charge (normally just overnight for me) but I don't take much notice the percentage charge figures either in agreement with the cautionary comments above. I use mine to monitor amps when charging and volts when discharging and I think, if you're at all technically minded, a search and read on that subject will pay dividends.

[Tony Brooks]

55 minutes ago, nicknorman said:

 Don't think this is correct really. Whether the OP wants to know instantaneous amps in or out, or cumulative amp hours in and out, any of these gauges will do so accurately. What they won't do (and I think what you are thinking of) is show an accurate State of Charge. And of course what you do with the information about how many AH taken out or put back, is another matter.

 

i would want one that automatically calculates Charge Efficiency Factor, has an adjustable tail current, and a shunt that can easily cope with the maximum feasible current. And one that doesn't mis-apply Peukert.

On which point I note this in the BM2 manual, showing that unlike so many people on here, they do understand Peukert in relation to battery monitors (my bold):

If higher currents than the 20-hour rate are drawn from the battery, the available capacity is reduced. For example, if it is steadily discharged at 10 times the 20-hour rate (50 Amps from a 100Ahr battery), the available capacity falls to about half of the stated capacity. The battery will be flat after about 1 hour instead of the expected 2 hours. (However, if the battery is left to recover with the heavy load removed, most of its remaining capacity will return after perhaps 20 hours' resting or at a discharge rate close to the 20-hour rate.) The BM1/BM2 makes due allowance for these effects when estimating the battery's state of charge and the expected time to discharge the battery fully. 

I agree amp hours out will be accurate but what real practical use is that to the average boater who has little understanding of batteries and no easy way of knowing the battery capacity at that time? As an example lets take a 110Ah battery that is a year or so old. It is mots likely that the capacity is rather less than 100Ah so lets say 90Ah because of sulphation but it could well be a lot lower. The boater knows from here and elsewhere that its not a good idea to discharge below 50% so discharges by 50 Ah, that is more than 50% of the capacity at that time. OK so over discharging by 5Ah is unlikely to produce a noticeable loss of cyclic life but next year it will be worse and so it goes on. It will be even worse if the batteries are not fully charged to start with.

Likewise I agree that the Ah in figure will accurately sow the amps flowing into the battery over time but what  it can not give is an accurate figure for how many of those amp hours have been converted to stored chemical energy. Simply relying on the Ah meter and charging until the AH in equalled the last Ah out reading will result in less than fully charged batteries.

In my view for all practical purposes such gauges in the hands of typical boaters a shown by so may battery posts here do in effect tell lies so to avoid the pitfalls ordinary boaters are best advised to only rely upon amps and volts for battery monitoring.

[OldGoat]

I'm a fan of Sterling kit generally, but his PMP1 is a bit pricey and not the best display. If you wanted to measure power at different points in your network, then it may be good value.

[Nightwatch]

We have the Victron 702. We get on with it okay.

[Richard10002]

I have a NASA BM2. I watch Amps and Volts, and assume they are accurate. Thus, when Amps drawn by the battery are low enough, I am reasonably sure that the batteries are pretty much as full as they are going to get. At this point I zero the cumulative Ah reading.

I watch AmpHours to see how much of the bank I have used, and I tend to assume that this is fairly accurate. Such that, if it says I have used 75Ah since my last fill up, The SOC is about 62.5%. I say "fairly", as the 490W solar bank will be producing some energy, which won't all be converted into stored energy.

I also watch Ah when charging to see how things are going, but I am very careful to not assume that the batteries are full when Cumulative Ah is zero. As above, I only accept that the batteries are full when Amps drawn is low enough.

It only has a 200A shunt and I have a 2500W inverter, but it is rare for me to draw more than 200A, and the amount of energy used when drawing more than 200A is minimal. It does not affect my charging policy, so doesn't really matter.

I can therefore recommend the NASA BM2.

 

[Tony Brooks]

5 minutes ago, Richard10002 said:

I have a NASA BM2. I watch Amps and Volts, and assume they are accurate. Thus, when Amps drawn by the battery are low enough, I am reasonably sure that the batteries are pretty much as full as they are going to get. At this point I zero the cumulative Ah reading.

I watch AmpHours to see how much of the bank I have used, and I tend to assume that this is fairly accurate. Such that, if it says I have used 75Ah since my last fill up, The SOC is about 62.5%. I say "fairly", as the 490W solar bank will be producing some energy, which won't all be converted into stored energy.

I also watch Ah when charging to see how things are going, but I am very careful to not assume that the batteries are full when Cumulative Ah is zero. As above, I only accept that the batteries are full when Amps drawn is low enough.

It only has a 200A shunt and I have a 2500W inverter, but it is rare for me to draw more than 200A, and the amount of energy used when drawing more than 200A is minimal. It does not affect my charging policy, so doesn't really matter.

I can therefore recommend the NASA BM2.

 

Your use is sensible and avoids the pitfalls. Remember that the 1 to 2% of bank capacity thing for assessing full charge is only reasonable at about 14.2 volts and above.

[nicknorman]

2 hours ago, Tony Brooks said:

I agree amp hours out will be accurate but what real practical use is that to the average boater who has little understanding of batteries and no easy way of knowing the battery capacity at that time? As an example lets take a 110Ah battery that is a year or so old. It is mots likely that the capacity is rather less than 100Ah so lets say 90Ah because of sulphation but it could well be a lot lower. The boater knows from here and elsewhere that its not a good idea to discharge below 50% so discharges by 50 Ah, that is more than 50% of the capacity at that time. OK so over discharging by 5Ah is unlikely to produce a noticeable loss of cyclic life but next year it will be worse and so it goes on. It will be even worse if the batteries are not fully charged to start with.

Likewise I agree that the Ah in figure will accurately sow the amps flowing into the battery over time but what  it can not give is an accurate figure for how many of those amp hours have been converted to stored chemical energy. Simply relying on the Ah meter and charging until the AH in equalled the last Ah out reading will result in less than fully charged batteries.

In my view for all practical purposes such gauges in the hands of typical boaters a shown by so may battery posts here do in effect tell lies so to avoid the pitfalls ordinary boaters are best advised to only rely upon amps and volts for battery monitoring.

Yes, knowing some figures is one thing, interpreting them correctly is quite another!

Just on the point I've put into bold, gauges such as the Victron and I think the NASA, do calculate the charge efficiency factor provided they are set up correctly with a low tail current and the batteries are fully charged after a discharge cycle such that the SoC reading automatically resets to 100%. My Mastershunt does this too and I find it a useful health check - the CEF is normally around 94% but I know if/when it starts dropping that the batteries are getting tired.

[Nightwatch]

Can damage be caused by charging at 15+ volts?

[cuthound]

12 minutes ago, Nightwatch said:

Can damage be caused by charging at 15+ volts?

Yes

Charging at 15 volts plus should only be done periodically as an equalisation charge, or as a temperature compensated absortion charge during really cold weather.

Charging at this temperature as a normal absorption chsrge will boil off electrolyte (for wet cells) and increase plate corrosion.

[Nightwatch]

How can this be avoided? 

[WotEver]

9 hours ago, Nightwatch said:

How can this be avoided? 

That question is more usually worded “How can this be achieved?”  

No charge source will routinely output 15V+ unless broken, so it isn’t something that needs to be actively avoided, simply routinely monitored. 

[Tony Brooks]

14 minutes ago, WotEver said:

That question is more usually worded “How can this be achieved?”  

No charge source will routinely output 15V+ unless broken, so it isn’t something that needs to be actively avoided, simply routinely monitored. 

Solar without controller and very well charged batteries?

Agreed though. Now we need to know exactly what is in the charging system because the most likely problem is a battery sensed system with a dodgy/disconnected sense wire. or on a conventional system a blown field diode.

What is the voltage reading bewteen B+ and D+ with the batteries charged and engine revving?

[Nightwatch]

Thanks Tony and Mr wotever.

As I mentioned in my recent thread. I'm a numpty with electrics. Are diodes accessible? Are they changeable? Is it a job for an electrician?

it doesn't always charge at 15+ volts when first charging. I very rarely use more than 80 ah before charging. I charge daily. When the used amp hrs are nearly zero, that is when the voltage rises. When the amp hrs used are zero I carryon charging until the charge amps are down to 7. and less. If I have the inverter on at this time the,excuse my terminology, input scale light hovers between yellow and red at the top of the scale. I gave a Sterling 3000w inverter. This was rewired by Dave Reynolds some three years ago when he carried out a rewire of the boat. (Engine and fuse panels etc.). 

 

[Glynn]

Thanks for all the replies.

What I am actually wanting though is to be able to see the amps being drawn and put back into the battery bank rather than show a state of charge or accumulated amps totted up/down.

Reading the Smartgauge write up, they do seem to have a point.

Is there any decent simple good digital amp meters available ?, or can the NASA, Sterling & Victron models be used this way ?

There are a lot of cheap prices amp meters with shunts on ebay, any good ? e.g. http://www.ebay.co.uk/itm/200V-200A-DC-Digital-LED-Amp-Volt-Combo-Meter-With-Shunt-for-HHO-EV-car-Solar-1-/161036443632?epid=1131939908&hash=item257e851ff0:g:s1MAAOSwnsZZgCfP

[Robbo]

12 minutes ago, Glynn said:

Thanks for all the replies.

What I am actually wanting though is to be able to see the amps being drawn and put back into the battery bank rather than show a state of charge or accumulated amps totted up/down.

So you don’t really want a battery monitor just a amp meter? 

If you want something a little more then take a look at the Simarine Pico.  It doesn’t have logging yet but should be a new firmware out soon.   You’ll be able to see historically how many amps in/out when it does.  Also supports multiple shunts as well as tank and temperature monitoring.

https://canalworld.net/forums/index.php?/topic/93060-nice-looking-battery-monitor/&do=findComment&comment=2041092

 

Edited October 2, 2017 by Robbo

[Tony Brooks]

Providing the ammeter ans shunt are sufficient for your current draw then any ammeter would do what you want as long as its accurate enough.

If you are prepared to do a bit of homework and gaining experience than any reasonable accurate digital voltmeter will also do what you want. Ammeter to tell you when to stop charging and voltmeter to show when you should/need to/ must start charging.

Any of the meters you list will give you voltage and amperage readings but just treat any other reading with more than a little scepticism until you learn how to set it up properly and fully understand the weaknesses.

[Glynn]

Thanks everyone, Ive ordered a Pico.

[Robbo]

11 hours ago, Glynn said:

Thanks everyone, Ive ordered a Pico.

Think you will like, it still feels like a early stage product, but the firmware is getting updated regularly.   I've not had it long to do a proper review yet and the stuff I want (logging/history) isn't out yet