My neighbour has a 3 yr old motorhome. It has had a reoccurring problem, with a flat battery (new alternator and new battery has not fixed the issue) The starter battery even after a long 3-4hr drive will be flat if you immediately try and start a few moments after stopping. However, if you go away (not connecting the vehicle to anything) and come back after an hour it will start as if the battery had never had an issue. My basic thoughts are, is it the leisure battery that has transferred power to the motor battery or is there a ECU issue that could be failing.
Technical Battery Dead then 1 hr NOT
- Thread starter stevej999
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Technical Battery Dead then 1 hr NOT
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Could be a bad connection getting hot when running losing contact then
ok again when it cools, check earth strap, battery connections and starter
connections, clean and tight.
ok again when it cools, check earth strap, battery connections and starter
connections, clean and tight.
Matt Quinn
Member
If the auxiliary (leisure) battery is connected in such a way that it can 'backfeed' the starter battery; there is a fundamental wiring problem. It should be isolated with the engine off and only capable of being fed, when the engine is running. - Possible but unlikely, assuming this is a factory-built motorhome and not somebody's lash-up. By "flat" - do you mean the vehicle is 'stone dead' (i.e. no dash lights etc) when the key's turned to the 'on' (not start) position when hot? - Or the engine simply fails to turn over or turns over only slowly?
I'd tend to agree with Ralph in respect of an intermittent bad connection impacted by heat.
It's possible for a 'dodgy' connection to read OK offload but for the connection to collapse under load i.e. when current is drawn. - Starter current is very high; and its vital that both the 'send' (+) and 'return' (-, 'earth', 'ground' chassis - whatever you want to call it) paths are fully capable. So this could be as 'simple' as a 'bad earth' or a length of cable that has developed an internal break/high resistance.
Given the age and value (not to mention the electrical complexity that goes with that) of the vehicle - is this perhaps one that needs professional analysis with the 'full bhuna' scan tools. - Who 'prescribed' and fitted the new alternator? How did they measure how well it was supplying current to the batteries? Or were new parts just thrown at the problem in hope?
I'd tend to agree with Ralph in respect of an intermittent bad connection impacted by heat.
It's possible for a 'dodgy' connection to read OK offload but for the connection to collapse under load i.e. when current is drawn. - Starter current is very high; and its vital that both the 'send' (+) and 'return' (-, 'earth', 'ground' chassis - whatever you want to call it) paths are fully capable. So this could be as 'simple' as a 'bad earth' or a length of cable that has developed an internal break/high resistance.
Given the age and value (not to mention the electrical complexity that goes with that) of the vehicle - is this perhaps one that needs professional analysis with the 'full bhuna' scan tools. - Who 'prescribed' and fitted the new alternator? How did they measure how well it was supplying current to the batteries? Or were new parts just thrown at the problem in hope?
Cornish Ian
Member
I‘ve recently had ride on mower with a similar hot start issue. Started fine when cold but when it was hot it would only turn the engine slowly. Leave for an hour to cool and it would start.
After checking everything including starter brushes the only thing left was the starter armature / windings. New starter and all was well. Mine was an unusual fault but they happen so my point is it’s always best to systematically check the system rather than just throw parts at it.
