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Caravan battery charging from wheelsViews : 3109 Replies : 21Users Viewing This Thread : |
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Apr 23rd, 2018, 20:59 | #11 | |
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14V x 160A = 2240 Watts or 2.24 kW A Volvo 185hp D5 engine is 136kW So the alternator running at full output is using 2.24/136 = 1.6% of the maximum engine power But the engine is not at maximum power all the time, at idle it uses around 4kW to 8kW, so at just above idle the alternator is easily around 20% of the engine load. Not insignficant at all And remember the downside of charging a caravan using a trailer-wheel driver generator: the energy to pull the caravan comes from the vehicle engine. You incurr losses through the vehicle transmission and drive system. So charging the caravan directly from the car alternator is the most efficient as you don't have the drive train losses being added into the equation. If the caravan battery is not charging to 100%, consider increasing the diameter of the charge wire coming from the trailer plug to the caravan battery. The larger the wire, the less voltage drop and thus more charge voltage available.
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Apr 24th, 2018, 10:14 | #12 |
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Thanks, some really informed replies there.
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Apr 25th, 2018, 13:19 | #13 |
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Charging a 12 v flooded cell battery to 100% of it's capacity takes a long time. From 50% capacity to 80% might take several hours. To get it to 100% might well take a further 6 or more hours. As someone said earlier volt drop in the cable from alternator to battery will have an impact but even with no drop it's still a lengthy process.
If anyone really wants to get their head around the issue can I suggest they look on a site such as www.canalworld.net you can go on as a guest. Use the search facility and you will find enough information to keep you reading until doomsday. Like most forums you will find a range of opinions but also many absolute facts Frank (Boatie) Narrowboat owner with a 700 ah battery bank. |
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Jun 29th, 2018, 22:09 | #14 |
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Start by saying I'm not a caravaner (so shoot me if you want I just browse here occasionally to broaden my mind), however I do drive an articulated truck with a big trailer.
Trucks do use a 24v system so dragging up elementary electrical formulae from my school days, twice the voltage means half the current which would be 1/4 of the power lost due to resistance, but with a 40ft long trailer we still get lots of power to the rear lights, I'd suspect that losses due to length of wire is minimal unless the builders have really cheaped out and used very thin wires. What I find is more often a problem with an artic is the quality of the connection of the plug/socket on the front of the trailer, often one can observe that with the taillights and fog lights on adding the hazard flashers will cause the other lights to pulsate due to the earth return not being able to carry all that current, usually on the truck that is down to damage and wear in the plug/socket, on a caravan I would also consider the possibility of corrosion in the plug/socket reducing the efficiency of the connection. Batteries on truck trailers are not so common but with more and more electical gizmos on the trailer they're not so rare either. The charging methods are perhaps a little behind caravans given that it's not so established. Early trailer batteries were often only charged when the side lights were turned on, in a crude sense it ensured the truck was up and running before putting extra load on the electrical systems but it did lead to one company I worked for having to make a ruling that sidelights were to be kept on at all times as over the summer the batteries for the security systems would go flat leaving the trailer 'insecure'. My present job involves some double decker trailers with a moving deck which is done by an electrical hydraulic system, these are generally powered from mains electric at the hub but use their onboard batteries at the outbase depots, usually there's no problem but if we need to we can take power directly from the tractor unit but that uses what we call an Anderson Lead which has wires like jumper cables and a chunky plug with large electrical contacts. As others have suggested the 80% charge figure may be more related to the way a battery charges combined with the level of sophistication of the systems in the car and caravan to manage when the battery is actually being charged. Bear in mind that on a car we don't tend to do a deep discharge of the battery very often, usually just enough to start the car, whereas with a caravan one would be discharging the battery all evening to have light, watch telly etc and then need to put back all that charge while driving.
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David V70 2.5 10v Torslanda Manual 98 Sreg Last edited by DaveNP; Jun 29th, 2018 at 22:15. |
Jul 7th, 2018, 07:39 | #15 |
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I simplify matters by booking electric hook up on the pitch.
Van comes home for washing/ loading before a trip so gets connected to fully charge battery before trip, electric hook up means battery full at end of stay, wash unload before return to storage means battery full when it goes in and I fortunately have facility to charge in storage occasionally. Landrover doesn't have S plug and no idea if volvo 13 pin has split charge facility as never tried to charge battery on the run. Paul. |
Aug 15th, 2018, 13:02 | #16 | |
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While in storage the solar panel maintains the leisure battery charge, even through winter, and ensures it is charged for next time I need to hitch up with motor mover, the van is too big and heavy to pull by hand and not enough space to get car to the front to hitch up, and the leisure battery keeps the alarm/tracker battery topped up. Many new caravans now come with solar panel charging as standard. |
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Aug 15th, 2018, 14:14 | #17 |
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It's a solution looking for a problem. My leisure battery holds a charge all winter and will still drive a motor-mover no problem. The only charging it gets is when it's hooked up to my car, or via electric hookup, or occasionally from a solar panel when there is no hookup. It simply doesn't need to be charged via the caravan itself. If you have a decent leisure battery charging from the van itself simply isn't required in my experience.
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Aug 15th, 2018, 17:08 | #18 | |
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I like to move the van during storage to help prevent pitting of the wheel bearings, just half a revolution makes a difference. Without a reffresher charge my van battery would not of lasted the winter. I have no solar panel and it's a case of self discharge over time, cold weather inefficiency combining to result in a van that will not move on the movers at the end of the winter. Paul. |
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Aug 15th, 2018, 17:35 | #19 | |
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Feb 17th, 2019, 10:56 | #20 | |
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I fitted the hitch to my 940 myself with twin 7pin plug electrics and there is charge to the van battery. Last edited by Ian21401; Feb 17th, 2019 at 11:45. Reason: Add text. |
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