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Old 03-11-2016, 08:33   #1
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Replacing analog panel meters.

Does anyone have experience with replacing analog panel meters with digital? My panel has analog meters for DC voltage and current, with selector switches next to each to choose the input to that meter. Is it worth replacing those meters with digital versions? The pros I see with digital is that the numbers are unambiguous compared to estimating the position of an analog needle, easily read without reading glasses (damn, I hate getting old), can be read at night without a flashlight, etc.

Blue Sea Systems sells digital meters that would appear to fit my panel. The voltmeter is probably a simple switch-out, but I'm concerned about the ammeter. The analog ammeter has a built-in shunt, whereas the digital requires an external one. Since I have the selector switch, that may complicate the wiring with an external shunt...

Or should I just leave the analog meters in place?

Thanks in advance!
-David
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Old 03-11-2016, 08:38   #2
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Re: Replacing analog panel meters.

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Originally Posted by Davidhoy View Post
Does anyone have experience with replacing analog panel meters with digital? My panel has analog meters for DC voltage and current, with selector switches next to each to choose the input to that meter. Is it worth replacing those meters with digital versions? The pros I see with digital is that the numbers are unambiguous compared to estimating the position of an analog needle, easily read without reading glasses (damn, I hate getting old), can be read at night without a flashlight, etc.

Blue Sea Systems sells digital meters that would appear to fit my panel. The voltmeter is probably a simple switch-out, but I'm concerned about the ammeter. The analog ammeter has a built-in shunt, whereas the digital requires an external one. Since I have the selector switch, that may complicate the wiring with an external shunt...

Or should I just leave the analog meters in place?

Thanks in advance!
-David
Other than the fact that the digital meters will draw some power themselves I don't really see any downfall. The power draw on the meters is probably negligible. I want to install digital meters on my boat when I redo all the electrical.
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Old 03-11-2016, 08:50   #3
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Re: Replacing analog panel meters.

Just to throw in another point of view: the advantage of analog meters in many applications is that you can tell at a glance if the needle is "pointing in the right direction" without actually having to take the time to read it. They're also beneficial when you want to easily follow a changing reading (hopefully not the case with your batteries ) - there's a reason digital speedometers never catch on in cars.
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Old 03-11-2016, 10:07   #4
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Re: Replacing analog panel meters.

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- there's a reason digital speedometers never catch on in cars.

Or in aircraft, even "glass" cockpits, emulate round gauges. This one we use.

A trick on aircraft with lots of round gauges was to turn them so that normal operation had all the pointers pointing straight up, then all you had to do was glance and see if any weren't straight up.
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Old 03-11-2016, 10:23   #5
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Re: Replacing analog panel meters.

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A trick on aircraft with lots of round gauges was to turn them so that normal operation had all the pointers pointing straight up, then all you had to do was glance and see if any weren't straight up.
An old NASCAR trick, at 200MPH you don't have much time to study the gauges.
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Old 03-11-2016, 10:27   #6
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Re: Replacing analog panel meters.

The problem is that on my analog voltmeter the a change in voltage from 12.7 to 12.3 volts is a very small movement of the needle, but a significant difference in battery charge level. On a digital meter this can be much more readily apparent. Similarly with a digital ammeter I think I could be much more precise in determining load by reading a number than looking at a needle.

Perhaps a little background on my question would help. I bought a boat back in July that was hit by lightning shortly after the purchase. A lot of the electric and electronic systems were subsequently replaced, and only now am I getting to actually use them. Everything seems to be working well, and over the weekend I did an overnight trip from Fort Myers Beach to Marathon. I was trying to estimate the battery load by reading the ammeter, and it looked like around 5 amps during daylight running with all the instruments, chart plotter, GPS, autopilot, etc. Load would increase a little when the AP kicked in, but nothing extreme. At night the load was up around 10 amps with the addition of the nav lights (some are LED, some are not yet upgraded to LED). Again nothing extreme, and overall very happy with the new system's performance, I only wish I had more precise numbers. I was thinking that digital meters (instead of the analog meters) might give me that...

-David
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Old 03-11-2016, 10:32   #7
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Re: Replacing analog panel meters.

Some digital meters put out a LOT of RF, causing significant interference with HF/SSB radio.

I have a Blue Sea Systems digital DC voltmeter which is extremely noisy, even when turned "off". Had to put a toggle switch in line with the sensor wires so it could be really turned off. Made a really big difference.

BTW I, too, often prefer analog meters because they can be read at a glance. I have several such meters on my panel for: charging current (DC ammeter), AC voltage, AC ammeter, etc.

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Old 03-11-2016, 10:46   #8
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Re: Replacing analog panel meters.

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Some digital meters put out a LOT of RF, causing significant interference with HF/SSB radio.

I have a Blue Sea Systems digital DC voltmeter which is extremely noisy, even when turned "off". Had to put a toggle switch in line with the sensor wires so it could be really turned off. Made a really big difference.

BTW I, too, often prefer analog meters because they can be read at a glance. I have several such meters on my panel for: charging current (DC ammeter), AC voltage, AC ammeter, etc.

Bill
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Good to know about the RF noise, as I was looking at the Blue Sea digital meters in particular. While I don't have an HF/SSB radio yet, I plan to install one in the next year or two as I get the boat (and myself) ready to go extended cruising.

-David
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Old 03-11-2016, 11:11   #9
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Re: Replacing analog panel meters.

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Good to know about the RF noise, as I was looking at the Blue Sea digital meters in particular. While I don't have an HF/SSB radio yet, I plan to install one in the next year or two as I get the boat (and myself) ready to go extended cruising.

-David
Yeah, it took me much longer than it should have to find the problem on my own boat (and I'm in the marine communications business, inter alia!). Finally, one day when hauled in a boatyard I decided to find the problem which had been plaguing me for years.

I had an S9 noise level, even with everything turned off AND with the big battery cables removed from all my batteries! Turned out it was a sensor wire for the BSS digital voltmeter. Removing that sense wire from the battery dropped the noise level to S1-2.....a huge difference. I couldn't believe it.

So, I installed a toggle switch in the meter itself which broke the connection from the sensor wires to the meter. That did it.

Remember, that anything with a "soft switch" rather than a mechanical switch has an activated circuit, even when "off". So, the push button off switch on the meter just killed the LED readout, but the meter circuitry was still activated and generating a lot of noise, especially in the 6-9mHz range.

I went on to test and catalog other things aboard, and found lots which generated RFI -- like on all modern boats -- but none stronger than about S5 on my boat.

I did a little writeup on this case, and would be happy to share it with anyone interested (it's a pdf file). Just email me: bill at wdsg dot com

Bill
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Old 03-11-2016, 11:37   #10
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Post Re: Replacing analog panel meters.

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Originally Posted by Davidhoy View Post
The problem is that on my analog voltmeter the a change in voltage from 12.7 to 12.3 volts is a very small movement of the needle, but a significant difference in battery charge level. On a digital meter this can be much more readily apparent. Similarly with a digital ammeter I think I could be much more precise in determining load by reading a number than looking at a needle.
The are accurate panel voltmeters on ebay for a few dollars, it's worth considering mounting one connected directly to the battery terminals where you can see it easily in addition to anything on the panel. Very useful tool.

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Old 03-11-2016, 12:25   #11
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Re: Replacing analog panel meters.

I would say keep the analogue meters for the "at a glance" reasons mentioned by others and install another digital meter to accurately track the voltage.

I have seen in the past and you may be able to find them still, limited range analogue voltmeters that will only display the range in question, they can also be of the non-linear display type where the display's movement varies with needle position giving you more resolution where you need it.

Your in the US I think so check out Mouse electronics etc.. you'll pay much less by buying from them rather than buying a BlueSea job or similar. You'll get the same or much better spec. for less money.
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Old 03-11-2016, 13:38   #12
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Re: Replacing analog panel meters.

Thanks Conachair for the info on getting small cheap voltmeters from Ebay. I've wanted that info in a couple places. For 8 bucks and easy connect I'll have it.

Dave
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Old 03-11-2016, 13:48   #13
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Re: Replacing analog panel meters.

Many if not most digital gauges are if anything less accurate than the analog ones, just cause they display to the hundredth of a volt, does not mean they are accurate.
For accuracy, I like my fluke, and my smart gauge has been pretty good, but the advice to measure the bank directly with a dedicated wire is I think good advice, there can be significant voltage loss, especially in old wires.
For monitoring your banks, a smart gauge may be a good investment, but you can get there with an accurate voltmeter, just requires a little thinking.
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Old 03-11-2016, 14:00   #14
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Re: Replacing analog panel meters.

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For monitoring your banks, a smart gauge may be a good investment, but you can get there with an accurate voltmeter, just requires a little thinking.
+1 for Smartgauge. Best bang for the buck in battery monitoring for simple installation and easy mounting. Monitors the battery voltage directly but is connected with a thin gauge wire so makes mounting it somewhere in sight easy. I have found them to be accurate enough in a few installations on working charter boats and live-aboards. Unlike some of the more expensive battery monitors they don't go out of sync with the bank.

Quite agree that EBay or similar is a good source of meters although I have had one very bad experience with one that issued more smoke than information which is why I suggested Mouser or another big name.
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Old 04-11-2016, 09:49   #15
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Re: Replacing analog panel meters.

FYI, Practical Sailor just did a review on battery monitors a month or two ago. -- Bass
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