Mains charger problem ?

Let's try something different. Disconnect all of the batteries except one from the onboard circuits. With everything off and the mains charger off, note the current draw according to the battery monitor. Switch something on, such as fridge Eber, nav light etc and not the exact current draw of each item, on i's own.You can also note it with all of those on at the same time.

Now turn everything off, including the charger, and disconnect the last battery. Turn the charger back on. Turn each of the single loads on, one at a time, noting the current again. Finally, turn them all on, again noting the current.

Please post the current readings that you wrote down for all tests.
 
PaulRainbow said:
Let's try something different. Disconnect all of the batteries except one from the onboard circuits. With everything off and the mains charger off, note the current draw according to the battery monitor. Switch something on, such as fridge Eber, nav light etc and not the exact current draw of each item, on i's own.You can also note it with all of those on at the same time.

Now turn everything off, including the charger, and disconnect the last battery. Turn the charger back on. Turn each of the single loads on, one at a time, noting the current again. Finally, turn them all on, again noting the current.

Please post the current readings that you wrote down for all tests.
Click to expand...

If you do the above, with every current reading, note the voltage as well.
 
Hi

Now on board and have conducted some further tests
All tests measured on the battery monitor unless otherwise noted. I have compared the voltage on the battery monitor to the multi-meter and found that they were about 5mV apart each other.

Test 1 resting voltage
The resting voltage of each battery is 12.9. This is after being isolated (from each other and from the load) for a few days.

Test 2
Re-connect just 1 battery, lets call it B1
Measure voltage and current draw - 12.89V 0A
Turn on every light and measure voltage and current - 12.1V 8A
Add the fridge and measure voltage and current - 12.0V 12A

Test 3
Repeat test 2 with a different battery, i.e. remove the cable from B1 and connect it to the adjacent battery, let’s call it B2
The results were the same as for B1

Test 4
Switch on the charger with a single battery connected and apply the same load(s)
With no load, 14.3V, 1.4A
With all lights, 14.04V. 4.4A
With all lights + fridge, 13.92V. 3.7A
Measure the voltage at the charger with multi-meter (all lights and fridge still on) 14.08V
This test was conducted with only B1 connected and with only B2 connected, with the same results

Test 5
Repeat test 4 after an hour with charger on with B1
With no load, 14.3V, 1.03A
With all lights, 14.04, 0.67A
With all lights + fridge. 13.92V, 0.45A

Conclusions
At least 2 of the batteries are knackered ?
I’m dropping 150mV between charger and batteries, that can’t be helping. Cables are short. e.g 50cm. Could be incorrectly sized cables and/or poor connection ?
I’m not yet sure why test 4 does not give consistent results
Charger may be OK

Thanks for any feedback
Cheers

Julian
 
Working away so only on my phone at the minute but I'd be buying a couple of decent batteries to break in.

What size cables do you have? Tend to chuck standard 16mm Oceanflex on all my smallish (<40A) installs as a complete overkill but know it'll always be ok.
 
Last edited:
matthewriches said:
Surely nothing will work as there is no charger connected at that point?
Click to expand...

Charger connected, no batteries connected.

As i asked in post #21 "Now turn everything off, including the charger, and disconnect the last battery. Turn the charger back on. Turn each of the single loads on, one at a time, noting the current again. Finally, turn them all on, again noting the current."
 
Thanks for responses

Yes all figures in above tests are positive
All cables 25mm or larger

I will be back on board during next week and will conduct a test with charger on and no batteries connected. When I tried to set that up before I couldn’t measure the current as the battery monitor was not functioning when there was no battery connected, so will need to work out how I can do that.
Will report back

Cheers

Julian
 
julianmingham said:
Hi

Now on board and have conducted some further tests
All tests measured on the battery monitor unless otherwise noted. I have compared the voltage on the battery monitor to the multi-meter and found that they were about 5mV apart each other.

Test 1 resting voltage
The resting voltage of each battery is 12.9. This is after being isolated (from each other and from the load) for a few days.
>Fine.
Test 2
Re-connect just 1 battery, lets call it B1
Measure voltage and current draw - 12.89V 0A
Turn on every light and measure voltage and current - 12.1V 8A
Add the fridge and measure voltage and current - 12.0V 12A
> Pulling down to 12V suggests a discharge rate of around C/7 if the battery is fully charged and healthy 84Ah or so?

Test 3
Repeat test 2 with a different battery, i.e. remove the cable from B1 and connect it to the adjacent battery, let’s call it B2
The results were the same as for B1

Test 4
Switch on the charger with a single battery connected and apply the same load(s)
With no load, 14.3V, 1.4A
With all lights, 14.04V. 4.4A
With all lights + fridge, 13.92V. 3.7A
Measure the voltage at the charger with multi-meter (all lights and fridge still on) 14.08V
This test was conducted with only B1 connected and with only B2 connected, with the same results
> Not totally clear on this one. Is the 3.7A a charge or a discharge? If it's discharge it would have to be surface charge on a very quick reading.
Assuming it's a charge, the charger is doing something like 12A into the loads and 3.7A into the battery, seems good to me?

Test 5
Repeat test 4 after an hour with charger on with B1
With no load, 14.3V, 1.03A
With all lights, 14.04, 0.67A
With all lights + fridge. 13.92V, 0.45A
>As above, but the second battery is taking less charge. Possibly because it is less discharged?
Conclusions
At least 2 of the batteries are knackered ?
I’m dropping 150mV between charger and batteries, that can’t be helping. Cables are short. e.g 50cm. Could be incorrectly sized cables and/or poor connection ?
I’m not yet sure why test 4 does not give consistent results
Charger may be OK

Thanks for any feedback
Cheers

Julian
Click to expand...

My comments in bold, multiquoting gone bad. HTH.
If the charger is running fridge and lights and putting up to 3.7A into the batteries at the same time, it's not too bad.
The batteries do not seem to bad, maybe I would watch their voltage drop with a fixed load and compare against the graph here to get an idea of capacity:
https://electronics.stackexchange.c...he-self-discharge-rate-of-a-lead-acid-battery

Fridges can be deceivers as they cycle on and of. I tend to use high power resistors or old headlamp bulbs as a load.
HTH.
 
Hi,

Firstly the results of tests with the charger on and no batteries connected
No load. 13.45V
8A load. 13.04V
12A load. 12.88V
22A load. 12.54V

Notes:
a) these results suggest that the batteries may never get a full charge from the charger as the voltage drops off quickly as current increases ? Unless there could be another reason for the voltage drop off ?
b) these results were taken at the +ve post adjacent to the batteries, yet at 12A load there is approx. 140mV difference between the +ve post and the terminal at the charger. This can’t be helping ?

To lw395’s points:
To test 2: the batteries are 100Ah so it’s more like C/8
To test 4: yes, charge, so agree the charger seems OK on this test
To test 5: yes, seems like the difference would be because the battery was less discharged
I havn’t yet conducted the discharge test and compared against the graph

Cheers

Julian
 
But what are the currents, frinstance, if you apply a known 8a load, what does the battery monitor show ? How about with a 22a load ?

The point of my questions, from early on, was to establish exactly what items put what loads on the system, then see if the various loads were matched by the charger. Because, in post #1 you said "Switch the mains charger back on and increase the DC load to about 11A (Eberspacher, lights, fridge compressor). The domestic bank then measured 12.9V and the current was -3A." With only a 11a load you should not be seeing a negative current at the batteries.
 
If not carried out already do the basic test, turn charger off, turn on cabin lights, wait a few minutes and turn mains charger on, did lights get brighter ? If they got brighter you have some charger output, if they did not you have a charger issue.

Turn charger off. put a load on, lights /fridge for 10 minutes, turn charger on and note volts and amps for battery and charger terminals. You are checking battery charger cycle, so you should see the various phases, what time period do they take ?

Brian
 
Hi

Thanks for feedback
Firstly to the question about what currents, the loads mentioned were as measured on a meter that shows load amps.

Secondly to Brian’s suggestions
I repeated what is described as the basic test (turn charger off, turn cabin lights on, wait a few minutes, turn charger back on). When charger turned back on the lights did not get brighter.
Based on Brian’s 2nd test I then made the following test
Turn charger off
Put a load on (measured at 6Amps on load amps meter and validated on battery monitor)
Wait 10 minutes
Turn charger on
I then measured and recorded the voltage (both at the battery and at the charger) - measured with a multi-meter. I also measured and recorded the current - measured with the battery monitor. Both voltages and current recorded over a few hours, all with the same 6A load
1st column is time, 2nd is battery voltage, 3rd is charger voltage, 4th is current
1.20, 12.92, 13.07, +7.5A
1.30, 13.00, 13.14, +0.94A
1.40, 13.09, 13.16, +0.4
1.50, 13.09, 13.16, +0.3
2.00, 13.09, 13.16, +0.26
2.30, 13.10, 13.17. +0.2
3.00, 13.10, 13.16, +0.17
3.30, 13.09, 13.16, +0.15

Any thoughts ?
 
julianmingham said:
Hi

Thanks for feedback
Firstly to the question about what currents, the loads mentioned were as measured on a meter that shows load amps.

Secondly to Brian’s suggestions
I repeated what is described as the basic test (turn charger off, turn cabin lights on, wait a few minutes, turn charger back on). When charger turned back on the lights did not get brighter.
Based on Brian’s 2nd test I then made the following test
Turn charger off
Put a load on (measured at 6Amps on load amps meter and validated on battery monitor)
Wait 10 minutes
Turn charger on
I then measured and recorded the voltage (both at the battery and at the charger) - measured with a multi-meter. I also measured and recorded the current - measured with the battery monitor. Both voltages and current recorded over a few hours, all with the same 6A load
1st column is time, 2nd is battery voltage, 3rd is charger voltage, 4th is current
1.20, 12.92, 13.07, +7.5A
1.30, 13.00, 13.14, +0.94A
1.40, 13.09, 13.16, +0.4
1.50, 13.09, 13.16, +0.3
2.00, 13.09, 13.16, +0.26
2.30, 13.10, 13.17. +0.2
3.00, 13.10, 13.16, +0.17
3.30, 13.09, 13.16, +0.15

Any thoughts ?
Click to expand...

Sorry to say it looks like the charger, it look like it has lost a phase, possibly a diode that is killing voltage above battery , hence only 13.0 volt. I would buy a cheap charge, not switch mode, and check the batteries are charging up to 14 volt plus, then look at a new multi-stage unit.

Brian
 
halcyon said:
Sorry to say it looks like the charger, it look like it has lost a phase, possibly a diode that is killing voltage above battery , hence only 13.0 volt. I would buy a cheap charge, not switch mode, and check the batteries are charging up to 14 volt plus, then look at a new multi-stage unit.

Brian
Click to expand...

Brian, what do you think of the voltage/current characteristics in post #31, assuming charger was in float mode? Do they support your comment above? I haven't run my IVO charger without a battery on, I have no idea how stable it should be.

Also look at some of the figures in post #24 where the boost voltage appears to be coming in.

Have to say I am now pretty confused about the location of some of these measurements and the direction of some of the currents!
 
Last edited:
Plevier said:
Brian, what do you think of the voltage/current characteristics in post #31, assuming charger was in float mode? Do they support your comment above? I haven't run my IVO charger without a battery on, I have no idea how stable it should be.

Also look at some of the figures in post #24 where the boost voltage appears to be coming in.

Have to say I am now pretty confused about the location of some of these measurements and the direction of some of the currents!
Click to expand...

If they are floating down at 13.1/13.2 for long periods is not doing any good to the batteries, they need a high voltage charge periodically.

If worried discharge batteries to 12.3/12.4 with no charger on, then re-run test and look for voltage phases.

rian
 
halcyon said:
If they are floating down at 13.1/13.2 for long periods is not doing any good to the batteries, they need a high voltage charge periodically.


rian
Click to expand...

Yes agree that. I've already suggested OP should switch to the higher float setting (assuming his IVO charger has same controls as mine.)

I was querying the apparent inconsistency between earlier figures and these latest ones.
 
julianmingham said:
Hi

Thanks for feedback
Firstly to the question about what currents, the loads mentioned were as measured on a meter that shows load amps.

Secondly to Brian’s suggestions
I repeated what is described as the basic test (turn charger off, turn cabin lights on, wait a few minutes, turn charger back on). When charger turned back on the lights did not get brighter.
Based on Brian’s 2nd test I then made the following test
Turn charger off
Put a load on (measured at 6Amps on load amps meter and validated on battery monitor)
Wait 10 minutes
Turn charger on
I then measured and recorded the voltage (both at the battery and at the charger) - measured with a multi-meter. I also measured and recorded the current - measured with the battery monitor. Both voltages and current recorded over a few hours, all with the same 6A load
1st column is time, 2nd is battery voltage, 3rd is charger voltage, 4th is current
1.20, 12.92, 13.07, +7.5A
1.30, 13.00, 13.14, +0.94A
1.40, 13.09, 13.16, +0.4
1.50, 13.09, 13.16, +0.3
2.00, 13.09, 13.16, +0.26
2.30, 13.10, 13.17. +0.2
3.00, 13.10, 13.16, +0.17
3.30, 13.09, 13.16, +0.15

Any thoughts ?
Click to expand...

The mastervolt chargers often seem to have a low float voltage at 13.25V.
So I suspect yours is just a bit 'out of cal', not unexpected after 10 years.
But I would be slightly concerned that you are seeing a 70mV difference from battery to charger at 150mA, but 150mV at 7.5A
So, personally I'd be getting my scope out or at least measuring the AC component of the charging voltage.

The first measurement is not a float condition, that should be an absorption charge at more like 14.2V
Another thing I would be doing is trying the charger at (or at least near) its full rated load.
Load the battery with a bunch of car headlight bulbs or other plain old linear load, then see if the charger can balance that.

It looks like your charger is not working properly.
I don't know this model, but AIUI it's programmable?
Maybe a 'factory reset' might put it back somewhere sensible?
Didn't some of these chargers have a 'float voltage only' setting? A little switch or PCB jumper? Might explain the first reading.
 
Thanks for feedback
I’ve had a kind offer to test my charger on a test rig (from Harbour Marine Services at Southwold) so I’ll take them up on that and report back the results

Julian
 
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