AMP HOURS

[Halfpint 19]

New to motorhoming and trying to get my head round the battery ie volts/amp hours. Came home from week away and then plugged into mains to get the Amp hours up again for the weekend. Nothing at all switched on taking power, but the amp hours showing on control panel are still slightly dropping instead of increasing. Its gone from 40 to 38. There is mains power getting through as i can work the microwave. Any idea what i am doing wrong?

 

[Richard n Ann]

What make and model control panel is it?

 

[Spriddler]

Perhaps the microwave is not drawing power from the 240v mains but from the hab battery via the inverter (if that's the sort of set up you have).
More detail of your leccy/battery system and info needed as said by Richard n Ann

 

[TheBig1]

charger turned off or fuse gone?

 

[Halfpint 19]

What make and model control panel is it?

Thank you for your quick reply. It is a EC480 and we do not have an inverter.

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[Halfpint 19]

Thank you for your quick reply. It is a EC480 and we do not have an inverter.Autosleeper.

 

[pappajohn]

What is the VOLTAGE on the control panel?
If its charging it will be between 13.6v and around 14v.
If its not charging it will be 12.6v or less.

 

[Halfpint 19]

What is the VOLTAGE on the control panel?
If its charging it will be between 13.6v and around 14v.
If its not charging it will be 12.6v or less.

Yes it is showing 13.8v

 

[two]

Welcome.
How are you determining the Ah?

 

[Bessy765]

don’t forget as you charge the battery the amps going in will reduce as the state of charge increases

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[autorouter]

Nothing at all switched on taking power, but the amp hours showing on control panel are still slightly dropping instead of increasing. Its gone from 40 to 38.

You are right, that drop in Ah reading, plus the voltage of 13.8V, does not add up. You could start with measuring the voltage at the actual battery terminals. The panel voltage might be wrong if there's a bad connection somewhere.

Do you have a multimeter? Any cheap one is OK for this. If the battery voltage is 12.0V to 12.6V, it's not being charged. If it's 13.0V or more then something is charging it. Probably a fuse or a bad connection, assuming the switches are set right.

 

[Halfpint 19]

You are right, that drop in Ah reading, plus the voltage of 13.8V, does not add up. You could start with measuring the voltage at the actual battery terminals. The panel voltage might be wrong if there's a bad connection somewhere.

Do you have a multimeter? Any cheap one is OK for this. If the battery voltage is 12.0V to 12.6V, it's not being charged. If it's 13.0V or more then something is charging it. Probably a fuse or a bad connection, assuming the switches are set right.

Thank you for your reply. We have 2 batteries wired. (See photo) The voltage at each battery using a mutimeter is 12.9 on one of them and 12.89 on the other. This afternoon the display for the leisure battery on the control panel shows 13.1 and the AH is still dropping very gradually. We have checked all fuses and are ok. We also have solar panels and the indicators for both batteries are showing full. The solar panels are wired directly to the battery and not via the control panel. ( separate panel for solar panels.) Any further advice would be appreciated.

Thanks

 

[Halfpint 19]

Welcome.
How are you determining the Ah?

Only by the control panel itself.

 

[autorouter]

Because your solar is wired direct to the batteries, the control panel cannot account for the charge the solar is putting into the batteries. The State Of Charge (SOC) indicator (Ah) will not be accurate. I'm not surprised it is going down even though the solar is topping up the batteries. It will be even more pronounced if there's no mains charging, which I presume does go through the panel.

Depending on the exact panel make and model, there might be a way to route the solar through it so the measurement is accurate. An alternative is fitting a battery monitor. Usually this requires fitting a shunt resistor by the negative terminal. Popular ones are Victron BMV, SmartShunt and NASA BM-1 or BM-2. Or you could just live with the inaccuracy, it's no big deal.

 

[Altinatom]

Eureka!
Newbie with similar problem is delighted to find super useful info which probably explains what has been driving him mad ever since he bought the MH a few weeks ago
Top advice
Top Forum

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[two]

Only by the control panel itself.

I'm not familiar with your control panel but doubt that you have a true "Amp counter".
It may be an assumed Ah capacity, based on the voltage of your leisure battery, which is cheap and easy to achieve. Even so, that's better than nothing.
A true Amp counter will have a heavy shunt close to the -ve of your battery.

 

[Lenny HB]

I'm not familiar with your control panel but doubt that you have a true "Amp counter".
It may be an assumed Ah capacity, based on the voltage of your leisure battery, which is cheap and easy to achieve. Even so, that's better than nothing.
A true Amp counter will have a heavy shunt close to the -ve of your battery.

Elektroblocks and CBE distribution units have shunts built in.

 

[autorouter]

I'm not familiar with your control panel but doubt that you have a true "Amp counter".
It may be an assumed Ah capacity, based on the voltage of your leisure battery, which is cheap and easy to achieve. Even so, that's better than nothing.
A true Amp counter will have a heavy shunt close to the -ve of your battery

In many systems that have a fuse/distribution box and a display panel, there is a shunt (technically a sense resistor) located in the distribution box. Schaudt Electroblocks, Sargent and CBE have them. They are in the positive battery feed. A shunt can be anywhere in the circuit loop, positive or negative side. There is a chip in the panel that takes data from the shunt and does all the counting.