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Old 03-02-2014, 00:46   #16
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Re: battery discharge monitor question

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Originally Posted by Dockhead View Post
....I would think that a perfect battery monitor could be made by combining the Smartgauge approach with data about loads from a shunt....
I've had long discussions with the SmartGauge Owners about this - it would also give us an amps IN/OUT reading as well.

But they were very clear that they would never add a shunt to the SmartGauge for two reasons.

Reason number one:- it is not needed to improve the accuracy. Recently feedback from Enersys, who make Optima batteries, claimed it was much better than a shunt based Battery Monitor. They quoted an inaccuracy of 0.1% which seems unbelievable. If it was 50 times that value @ 5% I would be happy.

Reason number two:- the accuracy would probably be reduced in many cases because many installations are wrong, and the programming is wrong or just left at the default values.

Maine Sail has said that "perhaps 7 out of 10 I see installed by pro's and DIY's are wired incorrectly (shunt wiring) and 9.5 out of 10 are programmed incorrectly."
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Old 03-02-2014, 01:25   #17
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Re: battery discharge monitor question

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Originally Posted by sailinglegend View Post
I've had long discussions with the SmartGauge Owners about this - it would also give us an amps IN/OUT reading as well.

But they were very clear that they would never add a shunt to the SmartGauge for two reasons.

Reason number one:- it is not needed to improve the accuracy. Recently feedback from Enersys, who make Optima batteries, claimed it was much better than a shunt based Battery Monitor. They quoted an inaccuracy of 0.1% which seems unbelievable. If it was 50 times that value @ 5% I would be happy.

Reason number two:- the accuracy would probably be reduced in many cases because many installations are wrong, and the programming is wrong or just left at the default values.

Maine Sail has said that "perhaps 7 out of 10 I see installed by pro's and DIY's are wired incorrectly (shunt wiring) and 9.5 out of 10 are programmed incorrectly."
Wow, that's pretty hard to believe -- I don't think 0.1% is measureable even with very accurate SG, so how do they know?

But claims of great accuracy (and I agree with you -- +/- 5% would be "great accuracy", as far as I'm concerned) do correspond to lots of other data. As far as I know, the UK Ministry of Defense chose the Smartgauge for all their mobile battery bank monitoring -- another pretty strong endorsement.

I think there's nothing for it for me but to order one. They're only 150 quid over here at full list price.
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