How to track down a current drain

[smac999]

A bad alternator will draw around 6a backwards from the battery. And won’t be on the breakers. It’ll be warm if it is.

But you need to get in with the clamp meter to trace what’s doing it.

[danstanford]

Originally Posted by smac999

A bad alternator will draw around 6a backwards from the battery. And won’t be on the breakers. It’ll be warm if it is.

But you need to get in with the clamp meter to trace what’s doing it.

Is that when the engine is running only?

[Mickeyrouse]

Originally Posted by Madehn

do you have an inverter--.

Nope- - no inverter

[MWGDVC]

I have put an incandescent bulb (rated the same voltage as the circuit) in series with the battery negative circuit. It will glow if current is flowing. Keep disconnecting circuits until the lamp extinguishes, then reconnect that circuit and disconnect devices on that circuit to isolate the faulty device. I have found many faults using this method.

[goboatingnow]

Originally Posted by MWGDVC

I have put an incandescent bulb (rated the same voltage as the circuit) in series with the battery negative circuit. It will glow if current is flowing. Keep disconnecting circuits until the lamp extinguishes, then reconnect that circuit and disconnect devices on that circuit to isolate the faulty device. I have found many faults using this method.

Yes this is the same approach with a clamp meter. You have to go through the systems one by one.

[smac999]

Originally Posted by danstanford

Is that when the engine is running only?

No. Constant if connected to a battery.

If it’s connected to start battery it would be draining that battery instead.

[Kenpimentel]

I had a small drain of about 1A with everything turned off. I started looking for the problem with my clamp meter. As I leaned into the compartment, I rested my hand on a small black relay. It was warm. I tested the leads to the relay and there was my drain. The relay was installed by Beneteau to prevent people from using the windlass without the engine. I had already circumvented the relay at the windlass because it had become intermittent. Pulling the connector off the relay resolved my drain.

6 amps is a lot. That’s like 72 watts. In my digging around, I learned that my boat’s diesel heater is direct to the battery, so my battery switches didn’t affect it. It is intentional as you don’t want to shut down the heater inadvertently.

I also have a small FLIR device that attaches to my phone. Something like that should spot a 72 watt drain if the rest of the boat is “cold” (not sure where you’re based).

[coopec43]

I am very interested in this thread as I destroyed a starter battery a few month back.

I've just about completed the wiring on my yacht but now would like to run a meter over it to check that everything is going according to plan. What do you think of one of these meters? (Yes I'm sure it will be Chinese made )




Price-drop

Digital Clamp Meter AC/DC Voltage Resistance Frequency DM6266 - Batteries Incl.

$31.90


Digital Clamp Meter AC/DC Voltage Resistance Frequency DM6266 - Batteries Incl. DM6266 multifunction digital clamp meter Fully functional overload protection Measures AC current, AC voltage, DC voltage, resistance, frequency, Temperature Portable design, one-hand operation, easy to use Clamp with a double insulation protection, enhanced anti-jamming Non-contact measurement, to improve the measurement safety. Specifications: DC voltage: 1000V ± (0.8% + 2) AC voltage: 750V ± (1.2% + 4) AC current: 200A / 1000A ± (2.5% / 3.0% + 5) Resistance: 200Ω / 20kΩ ± (1.0% + 1) Continuity alarm Low voltage display Data Hold Input impedance: 10MΩ Sampling frequency: 3 times / s AC Frequency: (40-400) Hz Manual range Maximum display: 1999 Jaw opening: 50mm Power: 9V (6F22) Battery x 1 Colors: body - dark gray

https://www.lasoo.com.au/products/bo...s&gclsrc=aw.ds

[noelex 77]

Originally Posted by coopec43

I've just about completed the wiring on my yacht but now would like to run a meter over it to check that everything is going according to plan. What do you think of one of these meters? (Yes I'm sure it will be Chinese made )

The specifications suggest it will not measure DC current. This is the measurement you most need from a clamp on meter on a boat. Find another model.

[coopec43]

Originally Posted by noelex 77

The specifications suggest it will not measure DC current. This is the measurement you most need from a clamp on meter on a boat. Find another model.

Geez! I hadn't noticed that. I would be very surprised if it didn't detect DC current (but then I know nothing about clamp meters)

Thanks

[coopec43]

Originally Posted by noelex 77

The specifications suggest it will not measure DC current. This is the measurement you most need from a clamp on meter on a boat. Find another model.

I notice two other meters that won't handle DC current but it looks like this HT206D will. (I've got a lot of checking to do)

[noelex 77]

Originally Posted by coopec43

I would be very surprised if it didn't detect DC current (but then I know nothing about clamp meters)

Many are AC only.

[coopec43]

Originally Posted by noelex 77

Many are AC only.

That's what I am finding. Thanks.

[noelex 77]

Originally Posted by coopec43

I notice two other meters that won't handle DC current but it looks like this HT206D will. (I've got a lot of checking to do)

That model looks better.

You need to be careful, some will measure DC current, but only by the wire probes not via the clamp. However, the specifications for the HT206D indicate it will measure up to 600A DC, which is only possible via clamp, so it should be OK.

The other thing to look for is the smallest current value it will measure. Clamp meters become less accurate at very low current levels but it is still helpful to trace small currents when looking for parasitic loads.