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You do not say where you are reading the 12V, or how the battery is being charged i.e. mains, or from alternator when engine running. Perhaps even from a solar panel.


I will make the assumption that you are reading on the CBE control panel, and charging from mains.


If the starter battery is U/S it will not start the engine. 12.0V is generally considered to be a flat battery.


The decimal parts of the reading are important when dealing with batteries, as a fully charged battery will only read about 12.8V, with charger switched off, and left to settle for several hours.


Based on the assumptions made above, I suspect that the CBE control panel has not been calibrated correctly, and may be giving a false low reading. See CBE handbook. I would not condem the battery on the sole evidence of CBE panel voltage reading.


When on mains charge from the CBE battery charger, the starter battery should will eventually read 13.0V, as you have read in the handbook.


To confirm that your battery is serviceable, will it start the engine after being left off charge for several hours? If it does start the engine normally, then the battery is probably OK.


I note that your Tio dates from 2012, so the battery is probably original, and about six years old. I changed the battery on our 2006 Tio 2.8 JTD at eleven years old as a precaution, but it was still OK.


Hope that the above helps,



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A meter (multi meter etc) is the best way of checking the battery.  
A so called 12 volt battery is made up of 6 cells each producing almost 2.2 volts, realistically just over 2.1 volts 12hrs after a charge.  This makes a rested 12 volt battery around 12.7v
As said if it was charged at 12v the battery would only get to 12v and engine wouldn't start, however rather than get into an argument I would get it checked at halfords or a local trusted garage.
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The starter-battery of a 2012 IHM “Tio” will be housed beneath a large removable ‘hatch' in the footwell in front of the cab passenger-seat. How straightforward it would be to access that battery would depend on whether what covers the footwell floor is easily removable, and there are caveats if the battery itself is to be replaced.




I hesitate to ask this, but why are you enquiring about this issue when you admit to having limited expertise in battery-related matters and it’s your husband who seems to be adamant that the starter-battery is knackered?


Alanb has asked several technical questions and (assuming that your husband is the motorhome electrical guru in your partnership) your husband would appear to be the right person to respond.

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Behind every successful woman is an astonished woman - and all our wives have encountered good reason to doubt their husband's infalibility,including on MH issues. It doesn't make sense, if you doubt your husband, to ask lots of other husbands, just because they contribute to a forum.


Batteries are not expensive and if you have reason to doubt their continuing reliability it is best to replace them before they fail completely rather than when they suddenly let you down while touring.


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I agree with Stuart,


The resting voltage of a battery is not 12.7v or 12.8v as stated above.

The resting voltage of a battery will depend on it's technology and acid strength, which 15 years ago was pretty much the same across the board.


Some of the best wet acid batteries, like the Varta LFD90, have a resting voltage close to 13.v (around 12.98v at 20 degrees), some of the worst, like the Banner Energy Bull are nearer 12.6v.

See chart from Yuasa below.

Shirley, you can see from the chart there is a world of difference between a high technology or typical VRLA battery, that is fully charged at 13.0v and dead at 12.0v?


The Varta's Powerframe construction means it is resistant to the internal Plate corrosion that occurs when the Acid strength is high, whereas the Antimony technology of the Banner makes it very prone to corrosion so Acid strength (and thereby voltage) is lower. The Powerframe technology means that an LFD90/Bosch L5 can manage a higher acid strength and voltage, gaining all the benefits that go with that higher voltge, small though it might seem to be.



So if your husband is aware there is a budget Starter battery under the floor, the low end of the 12v range might be acceptable to let the battery discharge so low.

However if there is a high quality OEM battery, or modern technology battery, installed then a voltage of the low 12's would indicate quite a discharged battery.


As Stuart says, if your battery is 6+ years old and low voltage it might be worth replacing it before the next use. When a battery gets tired it can skew attempts at accurate diagnostics. You may have a charging issue, you may not, but if you start from a good known point you have a better chance of reducing any ultimate costs. Especially as the battery is likely to be in it's twilight years anyway.




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On the other hand heres a direct quote from Varta  https://batteryworld.varta-automotive.com/en-gb/battery-test-results-interpret

Test and assessment of conventional wet batteries

Testing a starter battery only takes a short time. With this common type of battery, simply the determination of the open-circuit voltage provides adequately reliable information about the state of the battery, as with conventional starter batteries, only a powerful cold start current is decisive for full functionality.

Most starter batteries are now maintenance-free. With maintenance-free batteries, there are usually no filler plugs, so that there is no possibility of measurement with a hydrometer. However, the charge can also be measured with a voltmeter or a Multimeter. A fully charged starter battery has a voltage of 12.8 Volt. If the open-circuit voltage drops below 12.4 Volt, the battery needs to be recharged.

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Yes that is a quote for a old Starter wet battery from Yuasa that are generally low technology Calcium based units.

It won't apply to their AGM starter batteries which are VRLA's which they list in the column, as 13.0v


Only recently have Yuasa started rolling out decent technology flooded batteries, like the Motorhome Dual Purpose Leisure/Starter L36-Enhanced Flooded Battery.

Which incidentally sits just above their old YU-Micron range for voltage, but not as high as AGM or Bosch/Varta powerframe.



See photo below of a pair of Varta LFD's bought by the customer a while before and sent to us ready to fit the following week.

The photo was taken after the batteries had rested for a while, I think 2 weeks, but during mild conditions, I think ambient of about 29 degrees, so near ideal conditions.


And yes the voltmeter is verified accurate.


I am sure you will find lots of old data and evidence, even battery charts that make no mention whatever that different technology batteries from different manufacturers have different voltages.


What also isn't understand is that the batteries now have different acid specific gravities as well, so all those old charts won't always apply to a decent battery these days.



I am pleased to say the situation is getting even better. The likes of Yuasa and Banner have been caught napping by the Varta/Bosch technology advances but are starting to wake up after losing lots of sales. They both went off down a narrow alley in pursuit of AGM technology as the holy grail, but are now realising it wasn't, so are desperately trying to catch up.

Hence Yuasa's reinvestment in Flooded technology.

So next year will see a wave of advanced batteries onto the market from Banner especially.






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S, Suggest he takes it to someone who knows about the CBE chargers unique charging characteristics, they are like no other MH charger we know of, literally unique in the way they work.


The new CBE CB5xx -3 range is even quirkier.




Paul, your text on "Testing a Starter Battery" says it is specifically related to 'Conventional Batteries", which were superseded by far better batteries over 5 years ago.

Ford introduced high technology Silver Starter batteries some time before that, but the text is also inapplicable to a motorhome in another way.

Your text states,

"as with conventional starter batteries, only a powerful cold start current is decisive for full functionality".


That is only true of the average Car Starter battery that gets used every day, just as important for a motorhome is the batteries self discharge rate.

Absolutely no point in a fully charged battery passing a 600amp delivery test if it Self Discharges inside 2 weeks?


Capacity and how well it hangs on to that capacity is more important than outright current delivery for a motorhomes Starter battery that can sit idle for 3 weeks.

Obviously a Leisure Deep cycling battery that also starts a big engine would be the ideal - Something like a Varta LFD90?



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Replacement of a Ducato X250’s starter-battery was discussed in this 2017 forum thread




The original starter-battery of a 2012 Ducato (on which Shirley’s “Tio” is based) will almost certainly have been a 95Ah (or 110Ah) Italian-made FIAMM ‘wet acid’ battery and - beneath the hatch in the cab passenger-seat footwell - the installation will resemble the attached photo.


The FIAMM battery is ‘maintainable’ in that its cell-caps can be unscrewed and the electrolyte-level checked and topped up if necessary. Checking all 6 cell-caps involves disconnecting the battery to gain access to the caps and accessing the battery itself involves removing the hatch-cover. Whether either of those procedures has been performed on Shirley’s motorhome since 2012 is anybody’s guess...


My experience of ‘in situ’ battery testing is that it can be very basic. If the vehicle can be started by the owner and driven to where its battery is to be checked, there’s a fair likelihood that the battery being below par won’t be immediately apparent. And if the starter-battery is diagnosed as needing replacement, there’s the question of which replacement battery will be offered to the vehicle owner. If the vehicle owner is unsure whether or not the battery should be replaced and/or lacks the knowledge to decide whether what is being offered should be accepted (and at what asking-price) the checking exercise will be something of a minefield.


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