Battery monitor

[cmedsailor]

I would like your opinion please. I have a NASA BM-1 battery monitor that after 6 years it seems that it’s time to replace as it has stopped working correctly (amp seem not to show correct). What I liked a lot on the BM-1 was the ability to see current amp in (charging) or out (discharging) as well as the cumulative. Amperes in were from the engine or my solar panel. I was zeroing the amp meter after removing the shore power with full batteries and then was easy to monitor what was going on since the BM-1 was doing all the mathematics. The cumulative figure was a good way to see the state of charge of my batteries.
Now I am considering two options. Either replace the BM-1 with a new one or buy a Balmar smartgauge. I understand that the Balmar is a nice piece of equipment that gives the state of your battery quite good but does not show any amperes, only voltage. I could live with this as long as I have an ampere meter somewhere to show me current amperes in or out (I am particularly interested to see that my solar panel is charging and how much).
What do you recommend? If I go with the Balmar smartgauge can you suggest any specific amp meter to use? I can find on ebay many cheap ones but cannot understand if these are OK to use.
Thanks

 

[robmcg]

I was shown a Victron BMV700 not that long ago which looked like the bees knees. I didn't buy one in the end (had a Nasa one instead) but that was more of a financial decision rather than a technical decision. I believe the Victron one will display everything you have described and apparently uses a very technical algorithm to more accurately measure % discharge rates. Google will give you the specs etc.

 

[alteredoutlook]

you could, of course, get the old one repaired - a cheaper option!

 

[cmedsailor]

you could, of course, get the old one repaired - a cheaper option!

I am afraid not for me as I don't live in the UK and will involve delivery costs. Otherwise 100% agree.

 

[Yngmar]

Talk to Nasa marine. They have a reputation for being extremely helpful, and are one of the few marine industry companies with reasonably priced spares.

I've repaired my BM-1 with a new shunt (£10 after a chat at the boat show - the small screws had corroded off) and soldering and re-crimping the wire ends which had gone green and high resistance (leaky stanchion dripped into the battery locker). Good as new now and still a nice piece of kit.

The Smartgauge gives you a percentage, but no amps, as it has no shunt and determines battery level by black magic (which works though). I've also fancied the Victron BMV already mentioned above, but since the Nasa part was so cheap by comparison, I went that route and am happy with the result.

A solar charge controller would normally have a separate monitor (e.g. Victron MPPT Control - matching looks with the BMV-700). This would show you how much juice your solar system is supplying.

 

[yotter]

I had a NASA BM1 on my last boat and it was great, the clear display was very good. I changed boat, the new boat had no battery monitor, so I went for the Victron BMV600S (now superseded by BMV700), this does everything the BM1 does bat has many more features, highly recommended and I believe a lot more accurate than the BM1. about £30 more expensive. YM did a review of battery monitors recently but omitted the Victron, I emailed then to highlight the omission, they did respond but I felt they should really have printed an apology and explanation for the oversight in the next months magazine. No connection, just a happy customer.
Angus

 

[dunedin]

Just fitted the Victron 702 (similar to the 700 but also monitors engine battery voltage).

Display is quite small and not the easiest to read, but seems to have the functionality needed

According to manual a Bluetooth add on is available to display on phone, but not found this

 

[Redfox226]

According to manual a Bluetooth add on is available to display on phone, but not found this

Try this: http://www.ebay.co.uk/itm/Victron-E...-Energy-dongle-FREE-EU-Delivery-/301579173692

 

[VicMallows]

I've had a BM-1 on the boat for around 10 years and it has been faultless (apart from the inline fuse which causes no end of trouble and should be replaced by a decent blade fuse).
For me, Voltage, Amps and cumulative Ahr are the only things of interest. I am not interested in someones percentage calculation of the battery capacity.

However perfectly good meters with the same function are available much cheaper. I have fitted one similar to this:

http://www.ebay.co.uk/itm/DC-0-120V...ery-Monitor-/171204313281?hash=item27dc9280c1

in the caravan and it does the job just as well (I paid £13 inc delivery auction-style from same seller). You do need to be competent at interpreting Chinese English If you manage to work out how, you can even calibrate it which is more than you can do with the BM-1!

 

[DipperToo]

Just fitted the Victron 702 (similar to the 700 but also monitors engine battery voltage).

Display is quite small and not the easiest to read, but seems to have the functionality needed

According to manual a Bluetooth add on is available to display on phone, but not found this

+1 - Once set up very accurate.

 

[VicS]

+1 - Once set up very accurate.

How do you determine the accuracy of such an instrument ?

 

[dunedin]

Try this: http://www.ebay.co.uk/itm/Victron-E...-Energy-dongle-FREE-EU-Delivery-/301579173692

Perfect thanks. Anybody using this with a BMV700/702 care to give view on whether this is worth adding?

 

[DipperToo]

How do you determine the accuracy of such an instrument ?

Put a known load onto the system for 4 hours and checked the values on the 702 (% remaining and amps used). Also monitored actual current drain displayed against variable (but known) loads.