nasa battery monitor
- Thread starter Cactus Sailing
- Start date
Elbows
Well-Known Member
Thanks, VicS and Scubadoo, sounds like it should be fine.
50mV at 100A means the shunt is only dissipating 5W which sounds reasonable for continuous operation. A spot of Googling of car starter motor current draw and some extrapoguesstimating suggests that 250A would be a generous estimate of current draw when starting a small 2 cylinder diesel such as mine, so that would be 12.5W at the shunt. The shunt is a chunky lump of brass with considerable thermal mass and a fairly large surface area so I suspect it would take quite a long time for 12.5W to heat it up to enough to cause problems. The link cable Nasa provides is pretty weedy though so I think I'll replace it with something more substantial.
doug748
Well-Known Member
I have had one for about 3 years, excellent bit of kit.
My understanding is that it will start the engine, through the smaller shunt, with no problem but would not measure the momentary, high draw, accurately. This is the gist of what NASA told me, so I bought the BM-1 with the standard shunt.
I do start my 20hp engine on the house battery, when it suits and, indeed, it has caused no problems that I have seen.
GrahamM376
Well-Known Member
Another happy user. Have had one on each domestic bank for maybe 8 years or so. Excellent to see at a glance what's going in or out of the batteries and voltage. The bar graph is perhaps the weakest point but OK as a rough indicator. Can start 1800cc diesel through 100 amp shunts when necessary.
Cactus Sailing
Well-Known Member
thats a large iron sail compared to my baby penta d1-20 although my alternator is 115A if i recall correctly
the difference is about £20 so ill opt for 200A anyway i think.
pvb
Well-Known Member
Not sure where to start really, the basic Victron BMV-700 is way more sophisticated than the Nasa BM-1. Just a few differences include:-
* The Victron is supplied with a robust 500A shunt, rather than the Nasa's 100A shunt. The Victron shunt has a simple plug-in connection for the sensing wire, and the supplied wire is 10 metres long, versus 5 metres for the Nasa.
* The Victron will cope with larger battery banks - 9999Ah versus 600Ah.
* As well as voltage, current, amp-hours and time remaining, the Victron has a Power reading in W. The Nasa doesn't.
* The Victron's backlight can be adjusted in 10 steps, the Nasa's is on or off.
* The Victron measures to an accuracy of +/- 0.1% for state-of-charge, +/- 0.3% for voltage and +/- 0.4% for current, whereas the Nasa's accuracy is .... actually, Nasa don't state the accuracy.
* The Victron has audible alarms for lots of user-configurable things like high voltage, low voltage, low state-of-charge, etc. The Nasa has no alarms.
* The Victron has a relay output which can be used to disconnect the batteries in the event of low state-of-charge, low voltage, etc, all user-configurable. The Nasa doesn't.
* The Victron can be hooked up to an optional Bluetooth transmitter so that you can view data on a smartphone. The Nasa doesn't.
* The Victron logs historical data, which you can access and view. The Nasa doesn't.
* The Victron automatically resets the Ah counter to zero when the batteries are fully charged. The Nasa doesn't.
* The Victron has adjustable settings for the Charge Efficiency Factor and for the Peukert Exponent, to allow for optimum accuracy. The Nasa has fixed settings.
* The Victron has a 5 year warranty, the Nasa warranty is only 1 year.
I'd also say that the Victron is a better-looking unit; it's a subjective assessment but I always think that Nasa's graphics are very crude and clunky.
The Victron is about £125, versus around £90 for the Nasa.
pvb
Well-Known Member
That's a great-looking monitor, isn't it? I could be tempted by that.
cpedw
Well-Known Member
It's a bit odd to combine it with a barograph. I can't see the connection but then my phone mysteriously has a barograph too.
Derek
pvb
Well-Known Member
Oh, we all have prejudices, even you. The BM-1 is one of the few Nasa products which seems to be well-liked, possibly because it has no moving parts. But when you look at what's available for a few quid more, it's difficult to claim that the BM-1 is good value.
Trundlebug
Well-Known Member
Interesting comparison, thanks for posting.
But out of that list I can think of only one that's worth having, that being the historical data log.
And maybe one other, the adjustable parameters.
And a few that I don't see as advantages, in fact they're the opposite. E.g. the auto resetting when the battery is fully charged. I want to reset it when I want it reset, not when it thinks it's appropriate.
The rest are just irrelevant, or superfluous to my circumstances. 500A shunt? 100A is fine thanks. 5 yr guarantee? I've had my BM1 for longer than that and it's been faultless.
Relays, alarms, bluetooth etc no use to me. I mean, unless you have a superyacht where it's a 10 minute walk to the instruments then bluetooth is no advantage - and if you had a superyacht the range of bluetooth would be too short anyway! Just a gimmick IMO. Just look at the display on the instrument itself FFS.
Backlight adjustment - not required, the single setting on the NASA has never been a problem. It's red anyway so brightness control not an issue.
Clearly each to their own and for some the differences would be well worth having.
But not for me, they're just showroom appeal.
Heckler
Well-Known Member
Have the BM1. Love it, the SOC a bit hit and miss. Also shows engine start battery volts since Ive wired it up!
The shunt handles the start of my MD22 when I forget to switch the engine battery on!
Would buy again.
Stu
Heckler
Well-Known Member
My 18 year old Navtex still going strong, my BM1 now 6ish years old, still going strong, My wind on the previous boat broke the wind cups, did the mod that was in PBO, ie knock out the remains of the old spindle, drill a few mm bigger and fit a thicker spindle and drill the cup to suit. That sorted it.
A good price for a good product.
Tranona
Well-Known Member
But it is a bit like having an all sing and dancing washing machine with multiple programmes which you never use or a Mac with huge capacity - which you will never need. I read your list of the things Victron can supposedly do - but who needs them? no point in buying something that has a load of features that are not relevant to you or not valued.
Read what owners say - essentially "does what I want and is reliable" - and many repeat purchasers.
pvb
Well-Known Member
I guess it depends on what you value. I'd value the audible alarm feature. I like being able to vary the backlighting on instruments. I appreciate well-engineered products, and reckon the Victron would be more accurate than the BM-1. And I like the fact that the manufacturer has enough confidence in the product to offer a 5 year warranty. If it were twice the price of the Nasa, I'd still rate the Victron, but in view of its competitive price I do think it's excellent value.
And owners also say the Nasa's state-of-charge display is a joke!
Tranona
Well-Known Member
Yes, but the fact that they are otherwise happy with it and in many cases are repeat buyers suggest that the feature is of little importance to them so its lack of accuracy is probably irrelevant.
Never felt the need for varying the back lighting. How often have your alarms sounded, or told you something you did not already know?
Is "accuracy" apart from the level of charge really that much better? and how useful is the greater accuracy?
Given that there are no reports here so far of any premature failures and several of long term ownership well over 5 years, not sure that a 5 year warranty has much value.
It is not really a question of money. As you say if these benefits were really of value then they might be worth paying for, but seems from this small sample here few consider them worth having. BTW all my instrument heads are square, so a round one would be rather odd!
pvb
Well-Known Member
We'll just have to agree to differ in our opinions then.
MountainGoat
Well-Known Member
NMEA2K. For me that's the Victron's killer feature.
I don't have to go downstairs and peer at the battery monitor and throw up, nor do I need to dedicate space on the binnacle to it. It's just a preset page on the i70s. "Been sailing a while, we left the fridge on, how's the battery doing?" *press a button* "Oh, it's still got 60% in, that's fine." *press button again, i70s goes back to displaying AIS*.
pvb
Well-Known Member
ghostlymoron
Well-Known Member
There's always doom sayers when it comes to NASA products. I've always found them good value for a basic, no frills product. Reports on the BM1/2 are mostly very positive. Some owners seem to be watching them all the time. SOC generally thought not very accurate but I wonder if it's a parameter that's not capable of satisfactory calculation.
The Smartgauge is well thought of as well, easier to install but no one seems to understand how it works.
The Smartgauge is well thought of as well, easier to install but no one seems to understand how it works.
pvb
Well-Known Member
It can be accurately calculated. I think the problem with the Nasa monitor is that it doesn't automatically zero the Ah counter when the batteries are fully charged, unlike better monitors. If the Ah counter gets out of sync, the SOC won't be accurate.