# question for nasa bm1 owners



## monkeyboy72 (Oct 8, 2012)

Hi, just reading the instructions before installing tomorrow, can you confirm in the engineering settings it asks for battery capacity, if for example I had one 110ah battery then I would enter this value but as I have three 110ah batteries linked together would I enter the value as 330, thanks


----------



## Techno100 (May 8, 2010)

yes you can enter up to 600


----------



## vicdicdoc (May 14, 2005)

yep, enter 330 & then select the temperature (winter I set mine to 10 &summer to 20


----------



## andyandsue (Sep 7, 2008)

*prezzy*

mines in my stocking .hung under the chimney so ill have to get back to you on boxing day

andrew


----------



## Techno100 (May 8, 2010)

Potential owners out there?
best deal I can find
http://www.ebay.co.uk/itm/140872372897?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649


----------



## Pudsey_Bear (Sep 25, 2008)

Techno100 said:


> Potential owners out there?
> best deal I can find
> http://www.ebay.co.uk/itm/140872372897?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649


Dumb question perhaps, but if you have a Solar regulator controller, why would you need one of these :?: :?:


----------



## Techno100 (May 8, 2010)

It actually calculates how long your battery capacity will last at any given rate of discharge (load) besides all else

http://jgtech.com/pdf/BM1.pdf


----------



## andyandsue (Sep 7, 2008)

*why?*

i dont have a solar reg

The meter seems a good piece of gear to me ( i am an industrial/commercial electrician ). The display is LCD and therefore low power. a large well thought out default display which shows you what u need to know 
1 battery voltage taken from the terminals
2 current flow direction....charge /discharge
3 amount of current flow

the other setting are useful including an easy to set bat temp which for us skiers is useful as my battery set often touches freezing!!!!

the UK designer has a background in marine instrument design so it should be tough and reliable

thought has been given to clear wiring diagrams and a calibrated wiring loom using known resistance wiring and a well calibrated shunt

im hoping it will act as the centre point/first point of call for all van energy queries as it will show all current use and all charging currents at all time..during driving/future solar use and hook up

when i do fit a solar reg it will installed in the cupboard as they tend to have somewhat ugly wiring terminals and smallish ,non too clear displays...although some have remote displays but in not too sure if they are mppt standard

andrew


----------



## eddievanbitz (May 1, 2005)

They do work very poorly when solar panels are fitted. 

Unless there is a discharge larger than the charge from the solar panel the Nasa unit will not update, this can seem to be zero when the solar regulator is down to a quiescent input.

Once the sun goes down the unit will update and you go from 100% to 80 odd percent in seconds which tends to upset people :lol:

Eddie


----------



## wakk44 (Jun 15, 2006)

I too have found the % SOC display to be inaccurate and don't take much notice of it-an approximate guide only.As Eddie says an overall discharge has to be applied for the unit to update.

The most important thing for me is the current display which I have found to be accurate.It's useful for calculating the current consumption of individual appliances and worth installing for this feature alone.

It will indicate the charge from the alternator/on board charger and solar panels in real time.It is accurate with the solar panels and will fluctuate when a cloud obscures the sun.

A very good accessory for wild campers who are mindful of their electrical consumption. :wink:


----------



## eddievanbitz (May 1, 2005)

We now only supply the Victron unit which has a 500amp shunt so can accurately handle the use of inverters. 

There is the ability to have the two shunt unit to monitor the engine battery independently which can be useful on modern motorhomes. 

More expensive but accurate.

I have a NASA on one of our vehicles and I still think that they were good value for money and wouldn't dream of changing it for the Victron, but if it went wrong I wouldn't dream of fitting another Nasa (if that makes sense lol)

Eddie


----------



## andyandsue (Sep 7, 2008)

*thanks*

Yes Eddie i kinda expect it to be all over the place when getting irregular charge amounts and periods......my heart usually sinks when someone ask me to "have a quick look" at why their pride of superdooper batteries is nearly empty but the computer says 75%!

Like Wakki im fitting primarily as a volt/current gauge with emphasis on its assumed reliability and accuracy

later will follow a decent MPPT controller for a couple of 100w panels..any suggestions fellas? ive followed a few threads on here and assume ill have to get a decent model with a torriodal tranny inside

shame there isnt anyone importing into UK a few of the good quality MPPT controllers at a reasonable price...looks like ill have to gamble getting one through customs by post without being pulled for duty


----------



## wakk44 (Jun 15, 2006)

eddievanbitz said:


> .......... a 500amp shunt so can accurately handle the use of inverters........................


I don't know what size shunt is on the BM1 unit but it handles my 2000 watt inverter ok.Most discharge I have ever had is 75 A/H from the toaster,luckily I like my toast lightly done. :wink:


----------



## andyandsue (Sep 7, 2008)

*toaster!!!*

a toaster via an invertor....luv it

heres me moaning like bugger if the MEM plugs a a12v hair dryer in

i think the BM1 has a 100A shunt whilst the new BM2 has a 200a shunt and an extra monitoring function for the engine battery


----------



## eddievanbitz (May 1, 2005)

wakk44 said:


> eddievanbitz said:
> 
> 
> > .......... a 500amp shunt so can accurately handle the use of inverters........................
> ...


I think (from memory) that the shunt on the BM1 is 100amp

Eddie


----------



## RichardD (Sep 14, 2009)

Hi Eddie,

Just looked at the Victron 602 info and the display looks fairly limited compared to the BM1. Looks like you have to toggle through the various measurements. Is that correct? 

The option of the second battery appeals to me as I get paranoid about whether the van will start after several days on a pitch and very little road time in between.

Will attaching the 602 directly to the engine battery stop the main ECU from going into sleep mode?

What are the other benefits that you see?

Richard


----------



## eddievanbitz (May 1, 2005)

RichardD said:


> Hi Eddie,
> 
> Just looked at the Victron 602 info and the display looks fairly limited compared to the BM1. Looks like you have to toggle through the various measurements. Is that correct?
> 
> ...


Hi Richard, yes you have to select the display that you want, but this is due to a highly customisable format. On my Gulf Stream I really only use the TTC (Time to go) or the SOC (State of charge) as that gives me the information I need.

I am running 2 x 130w panels, 100amp four stage charger/inverter 2500w pure sine wave inverter a built in 6 Kw generator and a lot of 130amp batteries so I am not normally interested in the discharge rate, to me the recharge is of more interest.

Running anything through a shunt will not effect it's operation, so no it would not anything going into sleep mode.
Your Rapido is fitted with a device similar to our Battery Master so you should not suffer with flat engine batteries (unless you have a stereo wired so it can be used without the ignition or shut off switch or have a dodgy battery)

Cheers

Eddie


----------



## mike800966 (May 1, 2005)

*Nasa BM1 Unit false readings*

Interesting posts. I fitted one of these about 3 years ago, all seemed well until the starter battery died in Portugal. 
The van has a Calira unit with a "battery master" type connection and I think the leisure battery tried to support the starter, I did connect 240 to try to get some life back into the starter battery as we were out in the hills. It seemed a good idea at the time!

Since then and despite replacing the shunt the BM1 displays about 0.4 discharge until I press the display light button in which case it will change to typically a 0.6 charge!! The error is not constant but typically about 0.8amp. Turn off the panel light and it slips back to a discharge! Because the errror is not constant I cannot just balance it out in the "eng settings"

Thanks Eddie for the comment on the solar panel.

I just mentally adjust the display as I can't understand why its showing this discharge, with the solar panel or mains connected I would not have expected to see a discharge with everything turned off. I have checked with the AVO and there is no discharge on the battery at this time, so it is just a false reading

Anyone got any ideas apart from replacing the rather expensive unit?

Mike


----------



## Pudsey_Bear (Sep 25, 2008)

Techno100 said:


> It actually calculates how long your battery capacity will last at any given rate of discharge (load) besides all else
> 
> http://jgtech.com/pdf/BM1.pdf


Thanks Andy.


----------



## RichardD (Sep 14, 2009)

Hi Eddie,

I've been looking at the BMV 602 datasheets in more detail, particularly the wiring diagram.

For 2 batteries it only shows one shunt, which is going to make the installation quite difficult due to where the current batteries are positioned.

Can you use 2 shunts on the one monitor?

Richard


----------



## Pudsey_Bear (Sep 25, 2008)

RichardD said:


> Hi Eddie,
> 
> I've been looking at the BMV 602 datasheets in more detail, particularly the wiring diagram.
> 
> ...


Did you look at the PDF Andy posted, it does say you can use 2 batteries, not sure if that helps you Richard.


----------



## eddievanbitz (May 1, 2005)

Hi the 600 is a single shunt and the 602 is a dual shunt.

Up to a point you can use as many batteries as you want so long as they are correctly coupled up. 

I have 6 x 135Ah :lol: 

Eddie


----------



## dpsuk999 (Mar 25, 2012)

eddievanbitz said:


> Hi the 600 is a single shunt and the 602 is a dual shunt.
> 
> Up to a point you can use as many batteries as you want so long as they are correctly coupled up.
> 
> ...


Hi, I've also got a BM1 but never really took much notice of it until this thread which has caused me now to question a couple of things.

I have 2 x 110ah batteries and the BM1 shows voltage at 13.1v i.e fully charged and no amp discharge (nothing connected) I then connected a mini dehumidifier rated at 70w which equates to 5.83 amps per hour but my BM1 shows a discharge of around 2.7 amps. Is this because I have 2 batteries connected (2.7 x 2 equals 5.4 amps)? I came to this conclusion because on my solar regulator it displays for example a 1 amp charge to the batteries but on my BM1 it only shows 0.5 amp charge so again 0.5 x w equals 1 amp)

I have 2 bus bars, one positive and one negative so the positive of both batteries goes to the positive bus bar which every positive connection is screwed to it and then the same with the negative. But I think it may be wired wrong as the shunt is between the negative from battery one only, battery 2 negative is straight to the negative bus bar, then all the vans negative connections are screwed to this.

2 questions :-

Should the negative of battery 2 go to the negative post of battery 1 then through the shunt to the negative bus bar. Well this then correct the display to show correct amounts of charge and discharge?

Would it be better to wire it up so battery 2 negative to battery 1 negative post, then through shunt to negative bus bar and same with positive, battery 2 positive to battery 1 positive post, then just one wire going from battery 1 to the positive bus bar?

Thanks


----------



## eddievanbitz (May 1, 2005)

dpsuk999 said:


> 2 questions :- Should the negative of battery 2 go to the negative post of battery 1 then through the shunt to the negative bus bar. Well this then correct the display to show correct amounts of charge and discharge?


Yes so long as nothing else at all is connected to the neg side of either battery.



dpsuk999 said:


> Would it be better to wire it up so battery 2 negative to battery 1 negative post, then through shunt to negative bus bar and same with positive, battery 2 positive to battery 1 positive post, then just one wire going from battery 1 to the positive bus bar?
> 
> Thanks


I don't understand why you need the positive shunt. Are you sure that it is connected to anything?

Eddie


----------



## dpsuk999 (Mar 25, 2012)

eddievanbitz said:


> dpsuk999 said:
> 
> 
> > 2 questions :- Should the negative of battery 2 go to the negative post of battery 1 then through the shunt to the negative bus bar. Well this then correct the display to show correct amounts of charge and discharge?
> ...


Hi Eddie, there is no shunt on the positive side, just a bus bar which I find easier than having loads of wires going to a battery terminal.

So because battery 2 negative is connected to the negative bus bar (all van negatives connected to this) and not going to battery 1 negative (and thus though the shunt) is why my BM1 never reads accurately and is always out by about half ?


----------



## eddievanbitz (May 1, 2005)

dpsuk999 said:


> eddievanbitz said:
> 
> 
> > dpsuk999 said:
> ...


That would do it :wink:


----------



## ceejayt (Nov 25, 2005)

Just had one of these fitted and have blogged about it here.
Very pleased with it and also with the excellent work by RoadPro in making such a neat job of it.


----------



## Techno100 (May 8, 2010)

I always shop around 
http://www.ebay.co.uk/itm/NASA-BM1C...TU%2BUA%2BFICS&otn=21&pmod=281046161857&ps=54

http://compare.ebay.co.uk/like/2810...ixedPriceItemTypes&var=sbar&adtype=pla&crdt=0


----------



## Techno100 (May 8, 2010)

dpsuk999 said:


> Hi Eddie, there is no shunt on the positive side, just a bus bar which I find easier than having loads of wires going to a battery terminal.


I bought this bus bar fuse box so just one cable off the battery 
http://www.ebay.co.uk/itm/170781860687?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649


----------



## RoadProAndy (May 23, 2005)

Techno100 said:


> I always shop around
> 
> "A cynic is a man who knows the price of everything and the value of nothing" [Oscar Wilde]


----------



## Techno100 (May 8, 2010)

Techno100 said:


> I always shop around





RoadProAndy said:


> "A cynic is a man who knows the price of everything and the value of nothing" [Oscar Wilde]


He was never strapped for cash :wink:

EDIT and died in the century before the last one so did not have Google :lol: or splitting hairs 1900 A.D.


----------

