Nominal battery drain with all appliances turned OFF ?

[baz]

Subject: Nominal battery drain with all appliances turned OFF ?

I'm curious to know what my battery drain is with all my appliances turned OFF.

I know that there are various things that will draw battery power even with all major appliances being turned OFF, such as bilge pumps, Garmin units wanting to keep their internal memory/data preserved, Solar panels display, KISAE Inverter/Charger panel, and TV antenna. I assume these type units draw very little electrical demands.

The reason for wanting to know this is, that I do not connect to shore power for one or two weeks at a time, and only connect shore power for 24 hrs for each one or two weeks. I do this to reduce the erosion of my under water zincs by a factor of 4x compared to having shore power connected 100% of the time.

Note: I can power OFF the KISAE Inverter/Charger panel display if I wanted. It automatically will power up when connecting shore power.

Is there a way to measure what is the nominal battery drain with all appliances turned OFF ?

Thanks... 🙂

 

[Pilotnavigator]

Yes there is a way to determine the current draw with all devices turned off... you buy a DC clamp meter for about 100 to 200 dollars for a good one that is reliable. There are real cheap AC ones but you should all have a good DC meter on board.
Process. Turn off all devices, then at the house battery bank, turn on the meter and clamp the jaws around the red cable. The meter will show the current coming from the battery. You can use the meter to clamp the red lead from the solar charge controller and see the current your panel is producing at any given time of day.
Get one and you will not have to guess where your valuable current is going.

 

[BB marine]

The easiest way to test for "Parasitic Draw" a battery draw with all systems off. Use a digital VOA meter that has a capability of 10 amp setting. Confirm batteries are fully charged when testing 12.6 or higher. Remove the Negative battery lead from the battery. Attach the red VOA lead to the negative battery lead and the black VOA lead to the negative post of the battery. Read amp draw. It probably will not be much. 1 amp or less I would expect unless something is running.

Barry I understand your reason for not using shore power. Have you thought about a small charger that would be plugged into the dock shore power outlet using a 30 amp adapter. Use 12 or 10 ga extension cord with a ground fault. Connect the charger to the house bank and use it to keep the batteries maintained. With all systems off all battery switch's in the off position. A small smart charger would keep the batteries in full charge condition and the shore power use would be isolated from the boat.

https://no.co/brands , I'm not recommending this charger ( NOCO G3500) I'm just using it for an example. There are many on the market available.

 

[Pilotnavigator]

Just get a clamp meter. No need to disconnect cables, and when you find a current draw at the battery you are going to want to know where it is going. This is real fast with a clamp meter. Just clamp each line back form the battery it find which branch circuit is on. No need to disturb any wires, takes only a few minutes.

 

[Cessna172]

I have an amp gauge installed on my C28.
With everything shut off the gauge shows a draw between .5 and .7 amps. I believe the fluctuation (.5 to .7) is related to the Garmin autopilot as the reading change corresponds to the blinking light of the autopilot.

Gary

 

[baz]

I have an amp gauge installed on my C28.
With everything shut off the gauge shows a draw between .5 and .7 amps. I believe the fluctuation (.5 to .7) is related to the Garmin autopilot as the reading change corresponds to the blinking light of the autopilot.

Gary

Thanks.... that is a good piece of data. 🙂

I guess I could check the Kwh on my Shore Power pedestal and then connect the boat to shore power for a set period of time and then take another Kwh reading on the shore power pedestal to figure out what the boat's electrical use has been during the elapsed time.

So for a 7-day period, using your 0.7 amps as being the boat's draw I should see around 120 * 0.7 * 24 * 7 = 14.1 Kwh

I list below the Kwh I used per month for Apr, May, June, July, Aug, Sep, and Oct 2019. During these months I was not necessarily consistent in having my shore power disconnected from my boat for 6-days per week. However, it does indicate a measure of my use and for determining what my boat's electrical devices were drawing to arrive at an average amperage being drawn over these 7 months.

Apr - 38 Kwh
May - 33 KWh
June - 23 KWh
July - 27 KWh
Aug - 20 Kwh
Sep - 32 Kwh
Oct - 68 Kwh

I'm going to eliminate the Oct number as being anomalous and a month where I kept shore power connected for more time than for the previous months. Also, for many of the previous months I kept the cabin refrigerator at #2 setting.

Using the Apr - Sep Kwh use, the average monthly use is 28.8 Kwh. This translates to an average daily amperage draw equal to (28.8) / (120 * 24 * 7) = 1.4 amps.

This 1.4 amps (based on what Gary/Cessna172 has posted) gives me hope that I can easily determine/approximate my boat's shore power draw when I have all my electrical devices off and being connected to shore power, keeping in mind that some of the electrical draw will be used for charging the batteries given they had no charging for 6 days.

In conclusion I feel quite confident that Gary/Cessna172's 0.5 to 0.7 amps draw with all my electrical devices being OFF is a reasonable number for me to use.

Thank you Gary. 😀

 

[baz]

To get a close to realistic assessment for my boat's electrical demand with all known devises turned off I connected shore power at 12:24:36 yesterday and noted the shore power pedestal's Kwh at 16934. To day at 3:11:47 I captured the kWh again and it was 16939. Thus 5 Kwh had been used over a period of 26.786 hrs.

Thus (5000) / (120 * 26.786) is equal to 1.55 amp and this includes any demand for battery charging at the beginning of the shore power connection. This 'charging' use could be minimized by allowing the shore power to be connected for a longer time.

So with this test I'm going to assume when shore power is not connected my boat with all known devices turned off will be drawing 1.4 amp or some 190 watts (approx). On the face of it, this seems high to me! What devices collectively would be drawing 190 watts ? Is my method and arithmetic correct I wonder ?

 

[marcham]

The ac charge power is not a good assesment as there are losses. Both the charger and battery generate heat during charging which increases your perceived consumption. Your battery would also be recharging.

As mentioned above and with everything off, a simple multimeter can adequately measure dc current.

5000Wh / 26.8 hrs / 12V = 15.5A (dc) average current

Sent from my SM-T720 using Tapatalk

 

[Admiral S]

Is there any particular reason you are leaving the house battery switch on when leaving the boat?

By turning OFF the house battery switch the only draws would be the CO detectors and the bilge pumps.

This is always what I did when leaving the boat as there was no way to power down the garmin auto pilot and other various items.

 

[GZigmont]

So a question for all of you: I left my Marlow Hunter 40 sailboat plugged in at the dock all of the time and boat was in salt water. MH40 had a galvanic isolator, and I had zinc anodes on the sail drive and the bow thruster. I would replace the anodes every year as cheap insurance, but they were not even 50% corroded.

I plan on installing a galvanic isolator right away in the Spring, and of course making putting anodes on the shaft, thrusters, trim tabs, swim platform supports, and wherever else is required. Is there any reason why these Ranger Tugs are more susceptible to galvanic corrosion than the sailboat was?

 

[baz]

I'm guessing that every situation is different; such as salt vs. fresh water, one marina to the next (mine is 'hot', marina's shore power anomalies, and so on.

For me, my Marina is 'hot' and using a GI as I had on a previous Ranger Tug R25 Classic made no difference to the rate at which my underwater zincs eroded.... so I refrain from spending money on the same device again. I simply connect to shore power one per week for 24 hrs just to ensure the battery are topped up. This method has taken me from 3 month having 50% left on the zincs to close to 12 months with 50% remaining.

 

[GZigmont]

Wow! An isolation transformer may work a bit better in your case, Baz. Unfortunately, they are also more expensive. I keep our fridge full of adult beverages, butter, cheese, etc. I wouldn’t want to have to turn everything off all the time. I wish you had an easier time of it.