Chartplotters Power Consumption Part 2

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mick

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I now see that Standard Horizon's CP180i has a power consumption figure of 520mA max @ 12v, while Garmin's Gpsmap 550 has a figure of 15 watts max at 13.8 VDC. mA?? Watts?? What does it all mean, oh my aching head? Why do they quote different units and how do you compare one with another? And please, no snide comments from intolerant experts. Kind replies only, please.
 
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I now see that Standard Horizon's CP180i has a power consumption figure of 520mA max @ 12v, while Garmin's Gpsmap 550 has a figure of 15 watts max at 13.8 VDC. mA?? Watts?? What does it all mean, oh my aching head? Why do they quote different units and how do you compare one with another? And please, no snide comments from intolerant experts. Kind replies only, please.

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Kind reply .... divide watts by volts and that gives you amps.

If Garmins cutting 15 watts - that's 1.25A ... not on my boat thank you !! I keep my Lowrance down to about 450 mA .... approx. 1/3rd of the Garmin quote - I can only assume that it must be a reasonable size machine and possibly running other stuff as well ?
 
If Garmins cutting 15 watts - that's 1.25A ... not on my boat thank you !!


So would that be an unacceptable drain on a battery while under sail? (Sorry about the 2-part reply.)
 
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If Garmins cutting 15 watts - that's 1.25A ... not on my boat thank you !!

So would that be an unacceptable drain on a battery while under sail? (Sorry about the 2-part reply.)

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On my boat yes. Lets take worst case scenario. Night time crossing baltic for me.

That's nav-lights at ~ 30W, small cabin light 10W, compass and other instrument lights at another 5W, autohelm at probably 30W, GPS / E-S / Log taking another possible 15W .... total navigation power of about 90W ... = 7.5A

Take average battery on a boat of say 100 A/hr - mine ! ... 50% is unuseable or you risk damage to the battery. So that leaves 50 A/hr useable. Divide 50 by 7.5A = 6.7 hrs

Starts to make you think ... where's all that power now ? Now change just the plotter to 1.25A from the previous 500mA ... time to use 50% of that battery is now down to 6 hrs. It may not sound a lot of reduction - but given that I can switch of other gear to conserve power - I don;t want to switch of GPS plotter - so would prefer that to be frugal. My Lowrance is at less than 750mA full on. That's nigh half the Garmin quoted !
 
Around half the power is probably used running the backlight on the screen at full brightness. Make sure the unit you buy has screen dimming. That will make a big difference. Probably most/all do these days, but worth checking.
 
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Been trying to find screen dimming on a raymarine c80 but it doiesnt seem to have it.

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Most sets will have a "Night View" and a "Daylight View" - that is the backlight variable.
 
I new there was agood reason I kept my old furuno gps 32 when I fitted my chart plotter (SH cp180). I use the furuno with a yeoman on passage such as crossing the channel and the plotter for closer to ports and for 'pilotage'. The nmea output from each is feed via a switch to the radio, repeater and autohelm. Having said that clearly the garmin is talking max power rather than an average figure given by standard horizon. Though I expect the current drain for the garmin must be high or another figure might have been given. ( Or am I being cynical)
 
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I new there was agood reason I kept my old furuno gps 32 when I fitted my chart plotter (SH cp180). I use the furuno with a yeoman on passage such as crossing the channel and the plotter for closer to ports and for 'pilotage'. The nmea output from each is feed via a switch to the radio, repeater and autohelm. Having said that clearly the garmin is talking max power rather than an average figure given by standard horizon.

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I agree about the Furuno 32 it is one of the few low power simple, non plotting, but with display gps units left with a power consumption of only 0.24A (about 3w ) (although Furuno do not specify backlight conditions for this figure.)
The standard horizon units do quote maximum consumption figures. The CP 180 is even better at 0.46A and they quote at 12v meaning the maximum consumption is only 5.5W, considerably less than the Garmin.
I would be very surprised if these figures were not accurate, but if you could measure the consumption of your units it would be great. All you need is a cheap multimeter, make sure nothing else is on and all charging is off (motor etc). disconnect a battery terminal and put the meter in series between the battery post and the battery terminal. (don't try to measure currents above 10A using this method).
Even easier and very useful (but less accurate) is a clamp on meter.
 
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