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When to replace a starter battery


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Easy enough to get started and home with a flat starter battery - especially when you have a separate leisure battery to jump start it with.

I'm more worried about overworking the alternator through charging old inefficient batteries. Wouldn't be able to drive far with a duff alternator on a modern engine - everything is electric.

So I replace my batteries about every 4 years - for the sake of the alternator.

The alternator already has more work than it was intended for with the addition of leisure batteries to charge.

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"Returning to your original question, as (realistically) it will be difficult to test whether your around-5-years-old battery should be replaced now, you’ve got two choices - either pick a rigid ‘lifespan’ for a starter-battery (say the 5 years blaven mentions) and change it at that age even if the battery shows absolutely no signs of deterioration, or wait until the battery does show signs of deterioration and then replace it immediately".




I agree with Derek on the two options.

If it was me, I would leave the battery and listen to the Starter Motor turning speed at start-up. At the slightest sign of trouble, I would replace it, before any damage occurs.


A car Starter battery can have an 8 year life. So can a Motorhome Starter battery.

However if you have an 'after market' stereo that draws power from the Starter battery to maintain the Station, etc. memory, or has a Tracker or has an 'after market alarm' or is allowed to drop below around 12.5v on a regular basis or has constant Solar charging then you are less likely to get even 5 years.

If you have all 5 going on you should probably consider yourself lucky if you get 3 years.


The life of a Starter battery in a motorhome will be directly proportional to the work it does and how low the voltage is allowed to drop between each start.




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I don’t know if it’s worth mentioning but, although a battery’s ‘labelled’ guarantee-duration should be relevant when the battery has been bought as a replacement, this may well not be the case when the battery has been factory-fitted when the motorhome’s base-vehicle was built.


I recall a letter in a motorhome magazine complaining that a starter-battery carrying a label stating that it had (say) a 4-year guarantee had failed early and the battery’s manufacturer had refused to replace it.


The reason given was that the battery had been sold to the base-vehicle manufacturer (no doubt at a huge quantity-discount) and it was the base-vehicle manufacturer that thus ‘owned’ the battery’s guarantee, not the eventual purchaser of the completed motorhome.


If the base-vehicle manufacturer’s guarantee was shorter than that shown on the battery’s label it was the shorter period that applied, and any claim for replacement must be made using the base-vehicle's guarantee procedure not direct to the the battery’s manufacturer.



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aandncaravan - 2018-06-13 8:48 PM

............... or has constant Solar charging then you are less likely to get even 5 years ..............


Allan: I can see how an uncontrolled, stand alone solar charger for the starter battery could/would damage it but would that case apply to a solar charger that regulates a starter battery charge circuit as a secondary function of a leisure battery charging system?


You can probably guess, from that, I have such a system and also that I'm going to dig out the paperwork and see just what it supplies to the starter battery ............



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Maybe, depends on the solution.

But yes, if it a proper Motorhome regulator with a low 13.4v Float, the damage should be minimal.



The worst might be a fixed split, like 50/50, with the Habitation battery set up as AGM because the Starter may get the AGM's 14.8v charge.





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