Battery bank monitoring

I did a search in the Forums, and though we have a lot of info on batteries, placement of said, and charging systems, talk about keeping batteries healthy through monitoring charge state has been sparse. Thought I'd start the discussion and see if anyone has experience or plans to implement a battery monitoring system.

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I'm looking for more than a simple voltmeter, although this one is pretty swift as far as its design:

Martel digital voltmeter

However, looking at the spec sheet indicates that this units accuracy is +/- .2-.3V, which can be a significant amount of available charge in a 12V system where fully charged is 12.6V and 10.5V is flat-out dead.

At $35, it's not expensive, but I'd be tempted just to hack up my cheap voltage meter, wire it in, and mount it's faceplate instead of buying this product, because my voltage meter is more accurate...

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So, I've been looking around at different monitors. One which gets high marks from everyone I have seen write on the subject is the Link 10 (and 20 I would guess) battery bank monitors. The 10 retails around $200, the 20 seems to be about $50-100 more than that.

Link monitors

Lotta dough, that. But this thing will tell you way more than charge state. It will indicate how many amp hours remain in your battery, how long your battery will last at the current discharge rate, and a lot of other really neat info. Good stuff to know.

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Here is one of the same type, from across the pond. The only pricing I saw was £238.23 including VAT. Sounds like that is more than the Link 10.

Victron BMV-501

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In my web searching, I found another possible alternative - a trolling motor battery monitor. At about $250 though, it seems like it would be just as good to get a boat-interior-specific monitor.

CellTec MoniTroll

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Edit: After reading through the 30 page owners manual, it seems that this device is mostly for measuring loads on a battery, not for monitoring. Still, it is an interesting device with some possible marine applications, so I'll leave the link posted...

"Watt's Up" mini battery analyzer


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Anyone else have ideas, suggestions, contributions?

go for the link! It looks the most purpose built. Let us know what happens. Can you turn the meter off? So you don't slowly Drain the batteries while checking it?

Hi Anthony :)

I may get one, but it won't be soon - First I need the high thrust prop, and the spreader bases, and the LED nav lights, and some lumber for interior building, and the... well, you get the picture, a battery monitor is a ways down the road yet. ;)

As far as battery drain, the monitors use very small amounts of juice - milliamps - so they wouldn't impose much of a drain, not enough to worry about anyway. I imagine you could rig it into a circuit where you could shut it off. In fact, I probably would.

Merry Christmas! :)