Split relay not topping up engine battery in storage

Discussion in 'Tech/Mech General' started by magicsurfbus, Aug 1, 2013.

  1. magicsurfbus

    magicsurfbus Funster

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    When I store my MH I connect a temporary split relay circuit from the leisure battery to the engine battery to keep the engine battery topped up. This arrangement has worked fine in the past.

    Today when I picked it up, the leisure battery (linked to a solar panel) was full to the brim, with the charge controller light flashing to indicate full battery, and a battery voltage at one of the habitation area sockets of 13.6v in bright sunshine.

    However the engine battery was flat as a very flat thing. It took twenty minutes on jump leads from my car engine before it would start up.

    The split relay circuit is working - I've got the MH on EHU and I'm using the split relay to recharge the engine battery indirectly from the mains. I've checked the voltages, and the relay is clicking on and off as it should.

    Nothing was left on in storage to cause a battery drain, and with the current sunny weather you wouldn't have thought an engine battery would go flat so easily.

    The leisure battery is carbon fibre and is 5 years old, the engine battery is more recent.

    My personal theory is that the leisure battery may be getting on a bit and is getting too weak to pass enough surplus charge on to the engine battery to keep it alive. It's OK on EHU with 14v in the circuit, but maybe just standing with the solar panel on isn't enough any more?

    Any thoughts/observations most welcome. I realise my engine battery will be less efficient for having discharged and I plan to keep close tabs on it during the next trip out.
     
  2. haganap

    haganap Funster Life Member

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    If you have it like you write it, sounds very much like the Engine battery needs to go to the big engine battery place in the sky.... the Batttery is dead, long live the new battery:thumb:
     
  3. hilldweller

    hilldweller Funster Life Member

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    I wonder what voltage your "split relay" trips in at. 13.6 on the leisure battery sounds enough. Maybe this is the problem.
     
  4. rainbow chasers

    rainbow chasers Read Only Funster

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    Did you leave something on such as the stereo front on after market ones, or the very, very common one of turning off the headlights using the beam adjustment dial next to the headlight dial.

    I get lots of those after storage! Something such as this would create enough of a drain over the winter for the solar panel to struggle to keep up with. It would also explain why your relay seems to click over now, but didn't over the winter. It probably had - but the drain was greater than the charge, with winter charge rate being low.
     
  5. hilldweller

    hilldweller Funster Life Member

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    I have a headlight height dial but what is beam adjustment ? Never heard of that.

    Anyway, our lights go off with the ignition.
     
  6. rainbow chasers

    rainbow chasers Read Only Funster

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    Cheapskate!:Rofl1:

    On some of the upper models, you have two headlight dials identical to one another, right next to each other. The headlight switch is badly placed, being the inner of the two, and slightly out of sight. The beam adjustment dial is on the outer side, and what people naturally go for when turning off the lights

    They then get out, and not realise the sidelights/parking light is on (if they have knocked the indicator arm getting/putting steering lock on) On some budget models, the running lights are wired into live headlight feed, rather than ignition - meaning headlights go off with ignition - running lights stay on.

    Problem with storage is, there is so much to do when you are storing, the simple things like that do get forgotten as people are remembering to clear everything, disconnect gas, pump off, pull fuse,secure windows, taps on, fridge off, panel off, fridge door open etc etc.

    Another issue with the french bases, is water in the engine bay/design of battery location. 9 out of 10 have a loose live connection due to it's dodgy location and fear of frying themselves, so are left a little loose or hand tight. The water ingress when parked nose down can cause all sorts of short drains that are not apparent when dry. Oddest one I had this year was a damaged reverse light switch being shorted by water, which caused the reverse sensors to stay on (the reverse light was on ignition and the feed for the sensor isolated due to canbus)

    The common one is the light switch though!:thumb:
     
  7. cmcardle75

    cmcardle75 Read Only Funster

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    Clearly the split charge wasn't activating for the solar. Perhaps the solar gives 13.7V, but the EHU gives 14.4V and your split charge was set for 13.8V, so only activates for EHU.

    Check the battery voltage with a digital multimeter when on solar. If the leisure battery is showing 13.7V in bright sunshine, then the leisure battery is not affecting the engine battery charging, whether the leisure battery is knackered or not.

    Personally, I have a quick disconnect on my batteries and actually disconnect the engine battery. However, if I wanted instead to have it solar charge, I'd just connect a jump lead between the two positives. My batteries are adjacent, so this is easy for me.
     
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