-3A Loss According To Battery Monitor

  • Thread starter Thread starter Deleted member 36384
  • Start date Start date
D

Deleted member 36384

Guest
Hello,

I have an older BEP battery monitor that shows a constant -3A draw from my batteries with all breakers switched off. The 3A is not stable, occasionally it cycles down to -1.5A and then increases to -3A again. The cycle is quite quick, over a say 10 seconds but the period at -3A is longer about a few minutes.

The boat has 4 x Trojan T105s wired in series for 24V and a pair of lower cost 12V batteries wired in series for the starter motor. The BEP is only connected to the Trojan bank. I have an older BEP 24/12 converter for the 12V consumers.

When the Sterling Charger is on, the voltage on the charger is 29.4V but at the BEP it is a bit less, around 28V. The Sterling is connected to both battery banks. I also have an Air-X 400 wind powered generator fitted When it is windy with big gusts I used to see the BEP change from a current loss to a current gain, also the voltage increase in the gusts but now I do not see that. The Air-X is connected to a heat sink which is supposed to convert any excess voltage to heat, could this work backwards if it was damaged and draw current from the batteries if the components were faulty? It is an optional extra according to the Air-X manual (this could be a red herring).

The 24V circuit has two 24V sockets protected with a breaker and the BEP is wired through this breaker i.e. when the domestic battery isolator is switched on the BEP does not power up until I switch on the 24V circuit breaker. Before the rewire this was not the case and the 24/12 differentiation at circuit breakers did not exist, just at the 24/12 converter.

I also have 240V mains wiring, via a consumer unit with galvanic isolator installed.

The boat was partially rewired by a professional last winter and at this time of year he is very busy and I have not managed to get him to have look. As far as I am aware, there were no changes to the charging circuits or power supplies from the batteries, just a new switch board in a new position, new LED cabin lighting and new wires run to clean up the old circuits.

Any information would be useful but in particular I am interested in what checks I could do to try and trace the fault.

Thanks,

BlowingOldBoots
 
What you need is a clamp meter that measures DC AMPS. The standard ones from B&Q, screw fix, etc will not measure this range so you'll need to look on RS, eBay, etc if you don't have one. Or beg one from the marina workshop for 1/2 hour.

You can then clip on to anything to see what is going on. Also might be worth testing the output of your shunt to ensure it is within spec. Nothing wired before your breaker panel that is actually using juice?

Best advice would be to get your electrician when he is available to double check everything.
 
The first thing I would do is use my multimeter on the 10A setting and disconnect the battery banks one at a time and put the multimeter across the disconnected battery terminal. This will immediately show if there is any current drain and which battery bank it's coming from.

If there is a real current drain, I would then start pulling fuses/disconnecting things/switching breakers one by one until the drain stops and I have found the source.

Richard
 
RichardS said:
The first thing I would do is use my multimeter on the 10A setting and disconnect the battery banks one at a time and put the multimeter across the disconnected battery terminal. This will immediately show if there is any current drain and which battery bank it's coming from.
Click to expand...

I'll wager £50k that the drain is coming from the domestic bank Richard, and i'll give you 100/1 odds, up for it ?

If there is a real current drain, I would then start pulling fuses/disconnecting things/switching breakers one by one until the drain stops and I have found the source.

Richard
Click to expand...

Matthews clamp meter is quicker, but in the absence of one this would be a good choice.

On the subject of clamp meters, RS sell some decent enough multimeters with a built in DC clamp ammeter, well worth having onboard.
 
RichardS said:
The first thing I would do is use my multimeter on the 10A setting and disconnect the battery banks one at a time and put the multimeter across the disconnected battery terminal. This will immediately show if there is any current drain and which battery bank it's coming from.

If there is a real current drain, I would then start pulling fuses/disconnecting things/switching breakers one by one until the drain stops and I have found the source.

Richard
Click to expand...

I think I would start by diconnecting the shunt from the battery bank ( The shunt should be the only connection) and reconnecting via the multimeter. That will confirm. or other wise, the monitor reading.

If it is genuine then start hunting down the reason.

3 amps should be enough to make something warm, or dissolve a bit of under water metalwork, such as a sail drive, by electrolysis fairly quickly.
 
PaulRainbow said:
I'll wager £50k that the drain is coming from the domestic bank Richard, and i'll give you 100/1 odds, up for it ?
Click to expand...

I'd be mad to take the bet as the dice are already loaded against me by the OP's description of his system, although he didn't put in it himself so he might not be totally correct so if there was no drain from the house bank I'd still check the starters. ;)

Richard
 
RichardS said:
I'd be mad to take the bet as the dice are already loaded against me by the OP's description of his system, although he didn't put in it himself so he might not be totally correct so if there was no drain from the house bank I'd still check the starters. ;)

Richard
Click to expand...

He did say "The BEP is only connected to the Trojan bank", so 100/1 might not be great odds :)
 
I bought the clamp on meter (RS Pro ICMA1 ACDC Clamp Meter) as recommended and it arrived this morning. I have some queries which hopefully you can help: -

1. It shows about 0.18A on DC and 0.11A on AC, flickering +/- 0.02A. This is without it clamped around anything, just sitting on the kitchen table or if I am holding it. Is this normal?
2. I clamped it around the Kettle flex and the Coffee Maker flex (240V mains) and it showed no change to the background amp when the appliances were on and when I disconnected the plug. Is this because it is a twin core flex? Does the device only work on single cables?
3. Clamped around a single incomer feed to the house, where it enters the main fuse and on AC it showed 4.8A, on DC it just showed the background 0.18A and on Auto it detected the 4.8A.
4. If I use the zero function, the background amps go to zero and then rise again to 0.11A reading.

Maybe I have a magnetic personality (Aye right, short, fat ging'er). There are phones, laptops, wifi routers, iPads, all around the house, is this what is causing a background field that is being picked up by the clamp on meter? Also the flex thing, I just want to be sure that it is only supposed to work on a single wire.

I will be up to the boat on Friday night through to Saturday so will check the actual problem then.
 
BlowingOldBoots said:
I bought the clamp on meter (RS Pro ICMA1 ACDC Clamp Meter) as recommended and it arrived this morning. I have some queries which hopefully you can help: -

1. It shows about 0.18A on DC and 0.11A on AC, flickering +/- 0.02A. This is without it clamped around anything, just sitting on the kitchen table or if I am holding it. Is this normal?
2. I clamped it around the Kettle flex and the Coffee Maker flex (240V mains) and it showed no change to the background amp when the appliances were on and when I disconnected the plug. Is this because it is a twin core flex? Does the device only work on single cables?
3. Clamped around a single incomer feed to the house, where it enters the main fuse and on AC it showed 4.8A, on DC it just showed the background 0.18A and on Auto it detected the 4.8A.
4. If I use the zero function, the background amps go to zero and then rise again to 0.11A reading.

Maybe I have a magnetic personality (Aye right, short, fat ging'er). There are phones, laptops, wifi routers, iPads, all around the house, is this what is causing a background field that is being picked up by the clamp on meter? Also the flex thing, I just want to be sure that it is only supposed to work on a single wire.

I will be up to the boat on Friday night through to Saturday so will check the actual problem then.
Click to expand...

1. Cannot explain the background readings. Do you get the same well away from the hous/ other electrical installations

2. Will only work on single cables. With twin the magnetic fields of the two cancel each other out.

3. is 4.8 amps right for the amount of load you have on ?

4. ???
 
BlowingOldBoots said:
Maybe I have a magnetic personality (Aye right, short, fat ging'er). There are phones, laptops, wifi routers, iPads, all around the house, is this what is causing a background field that is being picked up by the clamp on meter? Also the flex thing, I just want to be sure that it is only supposed to work on a single wire.

I will be up to the boat on Friday night through to Saturday so will check the actual problem then.
Click to expand...

It measures magnetic field value around the cable and direction for polarity. In the case of your kettle, you have a pos and neutral cable, so they cancel each other and you get no amps, measure one cable you get amp reading.

Have you measured volt drop across the shunt ? if you the two cables to meter are not twisted pair, the two feed wires can pick up inductive voltages giving false readings.

Brian
 
Thanks Vic and Brian for the clarifications. No change out in the garden to the background readings, but I will test this on the way to the boat which passes through remote areas. The current value on the single mains is about right as daughter was drying hair and stuff, it is now down to 1.25A.
 
The background value is a bit of residual magnetic field from previous reading, there is a reset / zero button, pressing will zero meter prior to test, zero each time you check current.

Brian
 
Last edited:
At the end of a long day yesterday I did a basic check. Everything except house battery and the 24V socket breaker (which also powers the BEP) was off. The BEP was showing -1.0A, steady, battery banks 97% capacity, voltage 28.1V, Sterling charger unplugged from the mains.

Before I unplugged the Sterling Charger I checked the two red wires going to the starter and domestic banks and the single black wire coaming out the bottom of the charger. Sterling LED panel read 0.3A and the two red wires read the back ground figure of 0.01A but the single black wire read the 0.3A. Sterling was then unplugged from the mains.

All cables that I measured (all battery cables plus wind generator and everything else around the battery isolators) were 0.01A to 0.03A (which is the same as the back ground (I know that might not be the correct term). Each time with the device around the wire I used the zero function. I checked the black wires going into a BSP bus bar, the single black coaming out. I then went to the BEP battery monitor which has a thicker red wire a terminal 1, top and at terminals 7, 8, 9 respectively thin red, thin black and coaxial ground. With the BEP showing -1A terminal 1 wire sowed the background after zeroing, 0.01 - 0.02A. I could not get the device around any of the two thin wires, ground and snapped the thin red while trying to cut open the flex. I went home after that.

The next time up at the boat I will lift the cockpit locker sole and check the shunt wires. I must admit that a clamp on meter is a great tool but I am not that savvy electrically so I am missing the ability to interpret what the readings mean beyond there is a current value in the wire i.e. why do the two reds not add up to the Sterling black wire amp, or even if they even should do. The way I think about it the 0.3A from the sterling is going into a battery and being used up, so why does the black read 0.3A?
 
Last edited by a moderator:
BlowingOldBoots said:
At the end of a long day yesterday I did a basic check. Everything except house battery and the 24V socket breaker (which also powers the BEP) was off. The BEP was showing -1.0A, steady, battery banks 97% capacity, voltage 28.1V, Sterling charger unplugged from the mains.

Before I unplugged the Sterling Charger I checked the two red wires going to the starter and domestic banks and the single black wire coaming out the bottom of the charger. Sterling LED panel read 0.3A and the two red wires read the back ground figure of 0.01A but the single black wire read the 0.3A. Sterling was then unplugged from the mains.

All cables that I measured (all battery cables plus wind generator and everything else around the battery isolators) were 0.01A to 0.03A (which is the same as the back ground (I know that might not be the correct term). Each time with the device around the wire I used the zero function. I checked the black wires going into a BSP bus bar, the single black coaming out. I then went to the BEP battery monitor which has a thicker red wire a terminal 1, top and at terminals 7, 8, 9 respectively thin red, thin black and coaxial ground. With the BEP showing -1A terminal 1 wire sowed the background after zeroing, 0.01 - 0.02A. I could not get the device around any of the two thin wires, ground and snapped the thin red while trying to cut open the flex. I went home after that.

The next time up at the boat I will lift the cockpit locker sole and check the shunt wires. I must admit that a clamp on meter is a great tool but I am not that savvy electrically so I am missing the ability to interpret what the readings mean beyond there is a current value in the wire i.e. why do the two reds not add up to the Sterling black wire amp, or even if they even should do. The way I think about it the 0.3A from the sterling is going into a battery and being used up, so why does the black read 0.3A?
Click to expand...
You now appear to bectalkingabout an unexpected 1.0 amp reading on the battery monitor and an unexplained 0.3 amps flowing in the battery charger negative connection. You dont say if this current is still flowing when the charger is unplugged. It might be informative if you take a current reading on the whole power connection to the charger with it plugged in but with the power turned off. Also reading on any other earth connection the charger may have.
 
You must log in or register to reply here.

Share this page

Top