# NASA BM1 or the BM2 battery monitor.



## Tezza (Nov 18, 2017)

I’m thinking of getting one of the above but not sure which . From what I have read the only difference I can see is that the BM1 has a 100amp shunt and the BM2 has a 200 amp shunt. Now I know I will never ever draw even a 100 amps but I do have the ctek duo with smart pass that should be putting in 120 amps at times . So ......do I need the BM 2 because of that , will I do damage if I have the BM1?
Does anybody else have one , if I could make do with the BM1 I would get the compact as it looks a bit tidier.
Cheers.


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## Admin (Nov 18, 2017)

For the extra £20 I would buy the 200 amp version, if not it won't be accurate over 100 amps.

Make sure you buy the compact one as the standard one is quite large.


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## Minisorella (Nov 18, 2017)

There's a BM2 compact as well Terry... I've just got one for mine.


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## Tezza (Nov 18, 2017)

That’s great , and is it all it should be? Are you happy with it?


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## hextal (Nov 18, 2017)

Drop Nasa Marine an email or give them a ring - I did when I was setting mine up about 5yrs back and they were a really helpful bunch.


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## mistericeman (Nov 18, 2017)

I went for the BM2 as we have a 3000w inverter ...i went for the standard one as the display is easier to read at a glance IMHO .

Not cheap BUT well worth it IF you want to keep an eye on your power supply .


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## Tezza (Nov 18, 2017)

Just looked around and seamark Gunn are doing them for £110.40 . So think they will be getting an order


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## sparrks (Nov 18, 2017)

Unless you have a large battery bank (>300Ah) that is run down to it's minimum then you won't be putting anything like a 120 A into the batteries and even then it would only be for a very short while.


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## Tezza (Nov 18, 2017)

Well I have 2x110 at the mo , but when they have died am going to get 3x110.


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## sparrks (Nov 18, 2017)

Tezza said:


> Well I have 2x110 at the mo , but when they have died am going I get 3x110.



Which ever one you get it should be a good bit of kit. I've had mine probably approaching ten years.


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## mistericeman (Nov 18, 2017)

Chainsaw Charlie said:


> Anything that's primarily aimed at the boating fraternity is generally far better quality than the caravan or motorhome suppliers produce .
> I looked for the advice I wanted when doing my batteries etc on boating forums as those boys don't often talk nonsense.



Sadly anything aimed at the boating community also attracts "Boat Tax " ....IE about double what it's actually worth lol .

Walking into a boating/chandlers place is tantamount to wearing a sign saying "charge me as much as you like "


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## mistericeman (Nov 18, 2017)

Chainsaw Charlie said:


> Yes I have had the pleasure of owning 2 holes in the water that you pour money into !:lol-049:




Lived on a narrow boat for 10 plus years .....inland waterway chandlers are a law unto themselves ...

I wouldnt swap my time on my narrow boat for time in the poshest hotel frankly ...especially in winter when all the marina navigators have gone home, nothing for company but the ducks on the cut 
Ohh and the red headed lass that lived in a house backing onto the moorings that thought narrow boats were Soooooooo romantic ;-)


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## Deleted member 62288 (Jan 28, 2018)

*NASA/Clipper BM-1*

I love these battery monitors, last week, I bought my third unit, to be fitted to the Hymer. I've previously fitted them to a touring caravan as well as my (now sold) Damon American RV.

The Hymer has a fairly simple battery monitor as factory fit, the DT 100 display gives me battery volts and charge/discharge rates.

The Elektoblok unit and the factory installed charging circuits all top out around 25A anyway so unless I by-pass the Elektroblok I will always be limited to 20-25A. Which could negate the additional PV panels potential output. 

If I continue to route all of the charging circuits through the Elektroblok, I can never get more out than this unit can manage - around 25A.

So no matter how many amps are coming down from the roof, or engine or EHU (or any combination) I will always be limited to 25A.

If I by-pass the Elektroblok  controller for solar charging, I figure that I will get the max from the engine when driving or EHU (max 25A) plus whatever the sunshine gives me into the mppt box directly to the LBs. The new configuration will allow me to extract more than 25A overall. 

eg driving or EHU will give me the default max of up to 25A plus a second circuit exclusively for the LBs from the mppt circuit which should deliver me another 15-25A directly to the battery.

I had 3x extra PV panels fitted last year in Portugal, this install included a Victron BMV-700 battery monitor and a Elektoblock charge controller that plugs into the usual Elektoblock unit. 

I will be removing the BMV-700 monitor and the EB charge controller and harness. These will become surplus.

I intend the replace these with a BM-1 monitor and a Victron mppt 40a controller wired directly to the LBs only, the existing circuits can already manage the EB. I don't intend to complicate things by trying to also charge the EB from the mppt controller.

The BM1 (100A version) is my personal choice. It gives me all of the info that I need to confidently understand the state of the LBs.

I also looked at the BM-2 (200A version) but I can never see a situation where I would ever have anything like 100A never mind 200A of charge current on a Hymer.

The only different I can see between the models is the capacity of the shunt, 100A vs 200A.

That said the BM-1 is my choice. The local marina sells these at around £90 (Inc VAT), well worth it for the confidence that they give me.

so my combined options would be :

Alternator gives me up to max 25A 
Solar gives me a separate 15-25A
EHU gives me 25A if connected


anyone see any flaws in my thinking ?

constructive inputs are very welcome.

james


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## maingate (Jan 28, 2018)

You don't say which EBL you have but the usual max charge they do is 18 amps. 16 to the Leisure batteries and a 2 amp float charge to the engine battery.


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## Deleted member 62288 (Jan 28, 2018)

maingate said:


> You don't say which EBL you have but the usual max charge they do is 18 amps. 16 to the Leisure batteries and a 2 amp float charge to the engine battery.



Thanks, I didn't check which model I have but whichever one, whether 18 or 25 amps still limits the overall max current in the charging circuits to that limit. 
which is why I would try to bypass the EBL for the solar circuit.

james


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## wildebus (Jan 28, 2018)

Curious to why you would remove a Victron BMV-700 you already have and buy a NASA Marine BM1?  What is your reasoning behind this?


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## Deleted member 62288 (Jan 28, 2018)

wildebus said:


> Curious to why you would remove a Victron BMV-700 you already have and buy a NASA Marine BM1?  What is your reasoning behind this?



Yes, the victron unit is small, I need my specs to read the display. Plus I have to learn how to step through the options to find what I am looking for, which in turn means that I have to learn & retain how to operate a new bit of kit. 
It (The Victron unit) has been installed for around a year during which I have looked at it a few times but I've had to dig out the manual to navigate through the options. Basically I find it counter intuitive.

The NASA units are big and easy to use and I am very familiar with them sans the booklet.

james


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## mistericeman (Jan 28, 2018)

wobblyjim said:


> Yes, the victron unit is small, I need my specs to read the display. Plus I have to learn how to step through the options to find what I am looking for, which in turn means that I have to learn & retain how to operate a new bit of kit.
> It (The Victron unit) has been installed for around a year during which I have looked at it a few times but I've had to dig out the manual to navigate through the options. Basically I find it counter intuitive.
> 
> The NASA units are big and easy to use and I am very familiar with them sans the booklet.
> ...



Couldn't have explained my preference any better.


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## wildebus (Jan 28, 2018)

wobblyjim said:


> Yes, the victron unit is small, I need my specs to read the display. Plus I have to learn how to step through the options to find what I am looking for, which in turn means that I have to learn & retain how to operate a new bit of kit.
> It (The Victron unit) has been installed for around a year during which I have looked at it a few times but I've had to dig out the manual to navigate through the options. Basically I find it counter intuitive.
> 
> The NASA units are big and easy to use and I am very familiar with them sans the booklet.
> ...


Fair Enough  Makes sense. The BM1 definately has a clearer display for reading.

I tend to use my phone to both setup and read the BMV Info (I have the BMV-712) when also checking the Solar (I have a Victron 100/30) the same way.


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## Deleted member 62288 (Jan 28, 2018)

wildebus said:


> Fair Enough  Makes sense. The BM1 definately has a clearer display for reading.
> 
> I tend to use my phone to both setup and read the BMV Info (I have the BMV-712) when also checking the Solar (I have a Victron 100/30) the same way.



The Victron range of kit is some of the best in the world. But their battery monitor is simply too complex for my needs.

I just bought a new washing machine, it has WiFi and an APP.  **** ! 
Not that I will ever enable it.


james


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## Admin (Jan 28, 2018)

I have a victron battery monitor but it is connected to my ColorControl so it is easier to read on there. If it was not then I would not use it either.




The NASA BM1/2 compact are great


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## wildebus (Jan 28, 2018)

Admin said:


> I have a victron battery monitor but it is connected to my ColorControl so it is easier to read on there. If it was not then I would not use it either.
> 
> View attachment 60860
> 
> ...


I like the Phone Apps for the Victron stuff and quite tempted to get the Venus GX unit - which is essentially the same as the Control Control GX without the display.


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## ScoTTyBEEE (Feb 1, 2018)

I bought one of these for £20. Does the same thing, maybe slightly less sophisticated but easily readable and accurate.

DC 0-120V 0-50A Voltage Current Capacity Power Charge Discharge Battery Monitor  | eBay


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## Tezza (Feb 1, 2018)

I had the Bm 2 fitted in the week  and at the time it all worked fine. Amps in and amps out .went to the van today and all it is showing is the 13.4 of the battery ( we drove 30 miles) any ideas why charging and drawing currant isn’t showing. It’s on 0A. Cheers.


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