Battery Monitors (again!)

[Dougal]

There's been a lot of threads about these, but I can't find out for certain if any of them support dual battery banks.
I'm guessing most people use dual batteries these days. Do any of you have monitors fitted, and do they provide useful information?

 

[Tranona]

Yes. NASA BM2 does (and sure other more sophisticated units do - read the specs), although not sure of the value if your second bank is just a simple engine start battery as this is usually fully charged. The value is in monitoring your consumption from the domestic bank as you get a constant readout of the amps you are drawing, or putting in plus a fairly reliable indication of state of charge of your battery. I have a BM1 just monitoring the domestic bank as the other two banks, engine start and bow thruster get very little use.

 

[VicS]

Yes. NASA BM2 does (and sure other more sophisticated units do - read the specs), although not sure of the value if your second bank is just a simple engine start battery as this is usually fully charged. The value is in monitoring your consumption from the domestic bank as you get a constant readout of the amps you are drawing, or putting in plus a fairly reliable indication of state of charge of your battery. I have a BM1 just monitoring the domestic bank as the other two banks, engine start and bow thruster get very little use.

Nasa BM1 and BM2 both fully monitor the domestic battery and give a simple voltage reading of the engine start battery. BM1 has max current reading of 100 amps, BM2 a max of 200 amps

There is also a compact version of the BM1 which does not have an ampere hour mode or measure the start battery volts.

There is now a "Blue tooth" version of the BM1. I dont know what that does but it sounds terrifying.

 

[dunedin]

Similarly the Victron BMV 702 includes monitoring of voltage only for a second battery - e.g. Crank battery.

The BMV 700 doesn't have this feature, so if going Victron route I would suggest the 702 is the better option (plus Bluetooth link extra if preferred)

 

[pcatterall]

There's been a lot of threads about these, but I can't find out for certain if any of them support dual battery banks.
I'm guessing most people use dual batteries these days. Do any of you have monitors fitted, and do they provide useful information?

I fitted a BM1 and it is great, a very useful tool. As others say it provides all details about the leisure bank and just voltage on the starter battery.
great kit! ( this despite my complaints about poor quality connections on the shunt and on the in line fuse.

 

[GHA]

Do any of you have monitors fitted, and do they provide useful information?

As well as a bep battery monitor which gives amps one bank/voltage on 2, I have a cheap ebay voltmeter wired direct to the battery terminals which probably gives more bang for the buck than a monitor. Really worthwhile addition and cheap enough to fit two or a 2 way switch. Surprising just how much voltage is lost along the way to the battery monitor when there's a heavy load.

Suns up

 

[duncan99210]

I have a NASA Compact BM1. Its hooked up to the domestic bank only, as this is the one I need to keep an eye on. The engine battery looks after itself, although I do have a simple volt meter hooked up to it so that I can check it's resting/charging voltage if the mood takes me. 15 minutes after the engine has started, the voltage at the engine battery shows it back to being as near to fully charged as makes no difference.

 

[macd]

To fully monitor a second bank of batteries (or any other point in the boat's electrics), the device needs a second shunt (from which amps is determined). Otherwise all it can read is volts across wherever it senses. If no second shunt can be fitted, monitoring is limited to volts.

My old Sterling could read from four or five shunts, not that I ever asked it to. As said, that's not a big deal with an engine battery.

 

[Poey50]

I've got a Smartguage which gives a readout of % charge remaining in the house bank and voltages on the house bank and separate engine battery. Very easy to fit and super-clever. It doesn't give amps in or out so I have a DC clamp meter for that.