Vlad The Impaler
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- Apr 22, 2012
- 1,633
- 2,227
- Funster No
- 20,691
- MH
- Coachbuilt
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- Since 2012 but longer in my dreams
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Sorry have i missed something here?
Unless I'm very much mistaken, the battery gauge is a volt meter not a battery capacity meter, so how do you know what capacity the battery has left in it.
When just taken off charge the meter should read nearly 13 volts and when on load it would properly drop to around 12.5v, a battery in good condition and a large capacity may not drop off for a while, the battery would be considered flat at around 10.5v, but its very difficult to judge what capacity is in a battery from just looking at a volt meter.
I also thought that the electrical systems in motorhomes wont allow the fridge to work off the leisure battery only, in the 2 motorhomes I've had when travelling you select the vehicle battery, once the engine is running and over 13v a relay kicks in and powers the fridge so as not to flatten the leisure battery, but maybe not all manufacturers make them the same way.
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.Batteries showed full before leaving,after all that driving Surley they should be full now?
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Just drove from Rutland to Loch Lomond driving approx 7hrs,had fridge on 12v DVD on socket in cab 7hrs.Just parked up checked battery level and it's showing three quarters full.Batteries showed full before leaving,after all that driving Surley they should be full now? What's going on?
Not so!
An open circuit voltage of 12V is 50% discharged and effectively flat (for a standard leisure battery). You shouldn't discharge these battery types below 50% discharge.
Just because your electrical panel switches off at 10.5V doesn't mean it's OK to discharge your battery that low.
You will damage the battery!
I'll just add that, with everything switched off, a voltage check of a battery is a reliable assessment of remaining capacity.
For more accuracy, you need to get your hydrometer out!
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The symptoms suggest that the battery is failing. A hot battery is a sign that one or more of its cells have failed. I suggest you do not recharge it again but get it checked / replaced pronto as charging a failing battery can cause it to gas. That may be the source of the acrid smell and one of the gases given off is likely to be hydrogen (no smell) which, as I'm sure you know, is highly explosive. I suggest you disconnect the negative terminal from the battery post and tape it securely away from the battery then get to a supplier for a new one.
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Hi Jonandshell
The company I work for used to make electric vehicles which ranged from small tugs mostly used at airports to the Tractor unit on an articulated lorry, we have also made electric fire engines and i remember them making some odd ball forklift trucks.
today we don't make anything and have gone into the mobility industry 100% although they had been involved with the NHS since 1954 when we were asked to repair electric Invalid Cars.
before I started working for Ross (34 years ago) I used to design and build electronic speed controllers, battery chargers and battery test equipment for the model industry.
and finally i have a bit of a battery fetish, i think you can tell that
the one thing I have never understood is why do MH manufacturers skimp on the battery side, if they fitted decent Monobloc (traction) batteries the benefits are tremendous as you have found.
I have to agree.I was trying to keep the reply short and had made some assumptions.
I had thought from previous posts that the MH had new batteries fitted and I had assumed that they were SVLA otherwise I would of recomended a hydrometer, as for 12v being concidered flat you would need to check the technical spec of the battery.
However I do understand why you have quoted 12v as being flat, as a rule 11v is normally considered the end of its useful life, I hadn't thought of the systems in the MH when I wrote the above.
If the battery is made to the UK ISO spec 80% discharge is considered flat while if its made to the US ISO spec 60% discharge is considered flat, a lot of cheaper battery manufacturers tend to use the US spec as the batteries are cheaper to make.
The reason I quoted 10.5v was simply at this point of discharge it is concidered an average maxium depth of discharge under load to achieve the full capacity of a battery without damaging the battery.
We test thousands of batteries every year with very good test equipment, which normally discharges the batteries at 20a to 25a down to 9.51v the equipment will display the state of the battery and when finished produce a print out of the results if required.
I think I've bored everyone now.
The most important thing is when you get home always put your battery on charge (in the morning will do) and never leave it in a semi discharged state for a long period also make sure you have not left anything on.
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Is it worth trying to get a sticky sorted out so that the battery geeks (Jon and Pigwam) can put some salient points together, and any advice on what type of batteries to buy, as this subject comes up all the time, and people still for some unknown reason pay a shed load of money to motorhome dealers for crap 110ah batteries when you can get a traction 135ah battery for similar prices.
[HI]But for godsake dont get these two together at a show[/HI], or I am sure they would a powerpoint presentation together, running through a laptop and projector powered through a complicated battery setup with sterling battery to battery charger, dioides and split charger relays