Do I Need New Batteries, Please?

[HKF]

Hi On my new-to-me MoHo, both of my batteries were showing the top end of 2/3 charge. Today, I had the water heater on for about 20 minutes and the hab battery dropped by one 'point'. I have solar panels and it's been really sunny here for days. Is this normal or do I need new batteries, please? Thank you

 

[Spriddler]

Before going of on a diagnostic red herring chase, do you have a 12v to 240v inverter because your water heater won't run on the 12v hab battery or the solar panels unless you have an inverter.
Is the m/h connected to a 240v main supply (EHU)?

 

[pappajohn]

The only thing connecting 12v to the water heater is the control circuit board and that will use practically nothing.
You need to use a multimeter on the battery terminals to get a true voltage.
The cab/starter battery won't be affected by anything 12v in the hab area but should be showing full charge.... I suspect the guages are inaccurate... Nothing new there then.

 

[HKF]

Before going of on a diagnostic red herring chase, do you have a 12v to 240v inverter because your water heater won't run on the 12v hab battery or the solar panels unless you have an inverter.
Is the m/h connected to a 240v main supply (EHU)?

Sentence 1 I have no idea
Sentence 2 No

 

[HKF]

The only thing connecting 12v to the water heater is the control circuit board and that will use practically nothing.
You need to use a multimeter on the battery terminals to get a true voltage.
The cab/starter battery won't be affected by anything 12v in the hab area but should be showing full charge.... I suspect the guages are inaccurate... Nothing new there then.

Thank you! After reading this very slowly, three times, I understand you However, even if the guages are faulty by not showing a full charge, would you still expect the battery to drop by 1 after 20 minutes of water heating? Or are you saying the guages are not doing anything correctly? If so, can I do anything about that, please? Thank you for your help

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[autorouter]

do you have a 12v to 240v inverter because your water heater won't run on the 12v hab battery or the solar panels unless you have an inverter.

Unless it's a gas-powered water heater with a 12V control circuit board.

 

[HKF]

Unless it's a gas-powered water heater with a 12V control circuit board.

I didn't have the gas connected

 

[Lenny HB]

I think your water heater is a Truma Combi so it will draw some current for the control electronics and the flue fan.
Any load on a battery will drop the voltage the heavier the load the higher the volt drop.
Those type of meter are just a guide I wouldn't worry about. If they drop a lot we can talk you through how to check your batteries.

 

[HKF]

I think your water heater is a Truma Combi so it will draw some current for the control electronics and the flue fan.
Any load on a battery will drop the voltage the heavier the load the higher the volt drop.
Those type of meter are just a guide I wouldn't worry about. If they drop a lot we can talk you through how to check your batteries.

GREAT!!! Thank you so much. Really appreciate your help!

 

[autorouter]

The gauges are probably showing voltage, in steps of coloured lights. Even if it was an accurate voltmeter, it would be a bit misleading.

A battery not being charged will have a voltage from 12.8V (fully charged) down to about 12.0V (the lower limit for normal use). If it's being charged, its voltage will be raised to anything up to 14.8V by the charger.

A very discharged battery could show 13.5V as it's being charged, and a very full battery could show 13.5V as the charger stops charging and switches to float mode. So you can see that simply measuring the voltage of a battery while it's charging doesn't give you much information. If it's LEDs and not a proper number, then it's even more vague. So that scale R - 1/3 - 2/3 - 3/3 is just decoration.

To answer the question, I'd want to do further tests and see how the batteries hold up in normal use, before getting too worried.

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[HKF]

The gauges are probably showing voltage, in steps of coloured lights. Even if it was an accurate voltmeter, it would be a bit misleading.

A battery not being charged will have a voltage from 12.8V (fully charged) down to about 12.0V (the lower limit for normal use). If it's being charged, its voltage will be raised to anything up to 14.8V by the charger.

A very discharged battery could show 13.5V as it's being charged, and a very full battery could show 13.5V as the charger stops charging and switches to float mode. So you can see that simply measuring the voltage of a battery while it's charging doesn't give you much information. If it's LEDs and not a proper number, then it's even more vague. So that scale R - 1/3 - 2/3 - 3/3 is just decoration.

To answer the question, I'd want to do further tests and see how the batteries hold up in normal use, before getting too worried.

Thank you so much for your easy to understand reply I'm learning something every day