Losing amps

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navrep

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My boat has developed a 1.9amp draw which is to say the least a little draining.

With all fuses off this still shows, does this indicate that is has to be pre fuses? I think it does - or I guess could be amongst the fuse panel.

What is my best/easiest option for checking draw through certain cables?

Any obvious places to start looking?

When I left her last I took all cables off batteries.

There are 3 batteries onboard, 2 x domestic, 1 x engine start.

When left all attached all drop voltage when away from boat.

I have to admit to still not having quite figured out all the wiring - I made a diagram but there are a few ??? on it.

thanks in advance
 
A clamp on multimeter is the best diagnostic tool for this sort of problem. It will enable you to check which wire is carrying the current without the need to disconect anything.

They are not expensive, just make sure the one you buy/borrow can read DC amps.
 
navrep said:
My boat has developed a 1.9amp draw which is to say the least a little draining.

With all fuses off this still shows, does this indicate that is has to be pre fuses? I think it does - or I guess could be amongst the fuse panel.

What is my best/easiest option for checking draw through certain cables?

Any obvious places to start looking?

When I left her last I took all cables off batteries.

There are 3 batteries onboard, 2 x domestic, 1 x engine start.

When left all attached all drop voltage when away from boat.

I have to admit to still not having quite figured out all the wiring - I made a diagram but there are a few ??? on it.

thanks in advance
Click to expand...

How and whereabouts are you measuring the 1.9 amps ?

If the house and engine batteries are not paralleled and both loose power when left connected I think I would focus some attention on the charging system but systematic testing, using a clamp meter if possible, is the way to proceed.
 
Unless you have already done so, I would check this current draw by turning everything off and then disconnecting one of the terminals on each battery bank and then connecting a multimeter, on the correct 10A or whatever setting, between the cable and the bare terminal and seeing if there really is a continuous draw.

Richard
 
With all switchable services off this might leave essential supplies still connected.

This is means there should be an open circuit between the battery terminals. Here's what I would do (I assume the battery tops are clean and dry) ...

1 Disconnect +VE at each battery one at a time. Check voltage between the battery post and terminal lug just removed. This should be 0 volts.

2 Assuming you find a voltage above 0 on at least one, note which. Then disconnect all three and repeat the check at 1. If the voltage has gone away then you have a duff battery and one is simple discharging into the other. If the voltage remains then you have an external leakage.

3 Remove all the distribution fuses and or turn off all switchable MCBs, trips or breakers. Is the Volts drop at 1 still present. If no then reconnect each service one at a time until the fault returns, this will identify the service causing the issue.

4 If the voltage remains now start tracing all essential services and find a way of breaking the supply circuit to each until you find the culprit.

I would start with any circuits connecting to bilge pump float switches.
 
noelex said:
A clamp on multimeter is the best diagnostic tool for this sort of problem. It will enable you to check which wire is carrying the current without the need to disconect anything.

They are not expensive, just make sure the one you buy/borrow can read DC amps.
Click to expand...

Completely agree with this :encouragement:
 
On my Moody 44 I had a 0.5A current flowing when everything was turned off. Turned out the Navtex was wired directly to the batteries and its' on/off button didnt actually turn it off completely. I wired a switch into the circuit nearby, and all was well.

I can't recall how I discovered it, unless somebody here suggested it, (like I'm doing now :) ).
 
I have had a couple of UNI-T multimeters from Maplins for several years - one in my workshop and one on the boat. They seem OK and reliable enough.

Shame this clamp on doesn't include temperature probe measurement, but otherwise seems OK. If you want top end then Fluke will likely be ~5 times this price.
 
navrep said:
I don't believe that one can read below 2 amps DC.
Click to expand...

It is an issue with DC clamp meters, they are not in their element reading small currents. You have to be careful with zero-ing and check everything carefully.
But how are you aware of your rogue 1.9A?
where does this number come from?
 
lw395 said:
It is an issue with DC clamp meters, they are not in their element reading small currents. You have to be careful with zero-ing and check everything carefully.
But how are you aware of your rogue 1.9A?
where does this number come from?
Click to expand...

BEP DC current meter - and as the voltahe drops measured with a volt meter on the batteries when I was away for a couple of days I am inclined to believe it.
 
Richard10002 said:
On my Moody 44 I had a 0.5A current flowing when everything was turned off. Turned out the Navtex was wired directly to the batteries and its' on/off button didnt actually turn it off completely. I wired a switch into the circuit nearby, and all was well.

I can't recall how I discovered it, unless somebody here suggested it, (like I'm doing now :) ).
Click to expand...

That's about 10 times what a navtext receiver should be consuming when it's on let alone off. Needs further investigation.
 
navrep said:
BEP DC current meter - and as the voltahe drops measured with a volt meter on the batteries when I was away for a couple of days I am inclined to believe it.
Click to expand...

So, you have the means to measure the current, which makes a lot of the discussion redundant.
If you pull fuses and the current doesn't change, then what remains must be the culprit.
But, first you should consider the self-discharge or charging current of the batteries.
If you can disconnect each battery in turn, assuming you have several in a bank, then see if the current changes, or measure the current in/out of each battery.
 
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