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About ericmark

  • Rank
    Over 500 posts
  • Birthday 10/03/1951

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  • Gender
  • Location
    North Wales
  • Interests
    Photography, Radio
  • Towcar
    Kia Sorento XS Year 2007
  • Caravan
    Elddis Odyssey 524 Year 2002

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  1. It depends on the car, if no stop/start then simple relay in the car will allow a little charging, if it has stop start then it needs an inverter to charge second battery. I found a split charging relay will on starting car charge the second battery at around 15 to 20 amp, but within 15 to 20 minutes it's dropped to 2 or 3 amp, so with a 110 amp/hour battery half charged you would need to be towing for 12 hours to do much good. Many boats have DC to DC inverters to charge the bow thruster battery so it may be possible to use that? Main thing is:- 1) Some thing to stop drawing that much from car that car will not start. 2) Stop power going from aux battery to prime mover battery when cranking. With a DC to DC inverter it will do that without the need for relays.
  2. I would say with the consumer unit in the bathroom the risk not doing it is less than the risk doing it. How they get away with a consumer unit in bathroom I don't know? The problem is it varies caravan to caravan, with mine, if plugged into mains with RCD and MCB on then battery is charging, it does not matter if master switch off or on, other caravan master switch must be on. One would think the battery isolator did just that, and isolated the battery, but no, all it does is isolate the motor mover. And having the radio receiver active on the motor mover will discharge the battery. Charging the battery with a Lidi 3.8 amp battery charger and you can safely leave it on charge for months, problem is any power cut and it does not auto restart, but with built in battery charger if can charge at around 30 amp, so if a cell fails on the battery you could get the hydrogen gas it produces ignite. In the drive OK you can smell it, in storage your not there. So you have a tracker etc, then you have to remove battery and take it home for charging, so much for the tracker. When I monitored charging a battery I was surprised how long it takes to fully charge, up to 98% quite quick, but that last little bit can take a week, so removing a battery to charge it and it is off the caravan for a week, I have an old car battery so batteries are swapped rather than simply removing it, but until I had an energy monitor I did not realise how long it took to fully charge. Radio is a problem, there is no twin supply, so if you remove power, radio on getting power back auto switches on in demo mode, so it has to be powered all the time to stop it auto switching on. However forget when swapping battery to turn radio off again, and radio is discharging the battery.
  3. Over simplified, modern smart chargers have different ways to ensure battery is fully charged. One can select a make of charger and detail what happens when, however as you move make to make the whole system changes.
  4. I have an energy monitor, so I tried charging some sulphated batteries while monitoring the input to charger, it sat there for 10 days doing as it seemed nothing, then as if a switch had been flicked over an hour it went to full charge rate for that charger, OK only 0.8 amp, it continued to charge for Ah/charge rate, then ramped down again, and the battery seemed to be fully charged. This was unexpected, did not expect after 10 days it would do anything, but repeated this with other batteries 3 times, 4th however failed, it seemed to be following same pattern then voltage dropped and in the end it went to skip site. When I bought the last caravan it had a fault, so I had to work out how it was wired, and I used a small 7 Ah battery to test with, I found there are from memory 5 relays, and it seems the ignition live works a relay so permanent live is connected to an output, can't remember of hand exactly which way around, however BS7671 says same supply should not be used to charge battery and run fridge, so relay gives one a second ignition supply from permanent live supply. However today things are changing, the problem of cars switching off the charger means the simple split charging no longer works, so the inverter charger is slowing getting more and more popular, this lifts the voltage from car and so charges the caravan battery a lot faster then ever before, however with a 10 amp version 110 Ah battery still needs 11 hours and we don't normally tow for that long. So I use a starting pack, a 150 watt inverter charges the pack at quite a low rate, but it's being charged every time I use the car, and also useful for pumping up push bike tyres. And if we have drained caravan battery too much, it will give us an extra 20 Ah. Not best idea, but already have it all so cost nothing.
  5. Are you sure actually turned off, with my caravan there was a large isolator in the battery box, great I thought turn that off, and battery disconnected from everything. Wrong. It seemed it only turned off supply to motor mover. There was also a master switch, however some one had bypassed this, so turning it off did nothing. I found the link and the reason for fitting it, a blown fuse. However once corrected then a problem with radio, if you loose the permanent supply to the radio it defaults to demo mode, so each time car ignition switched off/on the radio switches on in demo mode, so had to alter supply to radio, so now can't turn radio off, it does not drain the battery much, but still month is around the limit. OK two supplies to radio and it would work as designed, however getting the extra wire is not easy. So there is one simple method, remove the battery terminal, some time simple method is best.
  6. We did use old pans from kitchen that no longer work since we fitted an induction hob, but now use induction hob in caravan, so pans need magnetic base. The comment on handles makes a lot of sense, if handles remove, can also be used in oven, and since using gas in the main, easy to burn handles, although we take an induction hob with us, it depends on hook-up, so all pans need to work with gas, and since gas is so slow (compared with induction) thin light pans means faster reaction times, so really the pans used with induction not really any good with gas as too heavy. So with electric we have always used heavy pans, the old halogen hob was switching off/on and the heavy pan evened out the heat, with gas always light pans, using a wok on electric simply does not work, and light pans often means cheap pans.
  7. It would have been better to start a new thread than restart a 6 year old one. Tayna batteries say yes to fit in the caravan likely a very good charger, to use at home, I would use cheap Lidi, they have moved on in the 6 years since answers given, now Lidi also has a LCD voltage display.
  8. To charge a lead acid battery takes time, there are ways to speed it up, using stage chargers one can recharge a battery in around 8 hours, but with a float charge looking at 48 hours, that is from 10% charged state and we rarely discharge a battery that much, but the charge rate 10% to 80% is always faster than from 80% to 100% and unless you complete the charge cycle the capacity of the battery will drop week by week. It is considered you should charge a battery once a month, and with valve regulated glass mat this can be extended, in real terms likely every 2 months will keep battery from sulphating if you charge it for long enough. It really does not matter on size or how much you have discharged the battery, after use you should use a smart charger for 24 to 48 hours. The longer since last FULL charge the longer it needs to recharge. I had two VRLA batteries used to power a chair lift, they were left discharged for around 6 months, when I came to charge them, they sat taking no charge for a week, then as if some one had flicked a switch they recharged, so where a battery has been allowed to remain in a part charged state for some time it may take a week or two for it to take the charge. This is where the smart charger or voltage regulated charger comes into its own, as to leave a battery for two week on a non regulated charger could damage the battery. Anyway since we tend not to tow for 8 hours, and most caravans are not fitted with DC to DC stage battery chargers so without them looking more like 24 hours and no one should tow for 24 hours, then some way some how you need a mains supply to recharge the battery. As to if the last day of holiday you use a hook up, or if you power caravan once you get home, or if you remove the battery to take where it can be fully recharged, that's up to you. I use a cheap Lidi 3.8A charger, set at under 20 Ah it actually switches off once battery fully charged, and at over 20 Ah it reduces charge rate to a very small amount, so safe to connect battery and forget for week or two. The worry when charging a battery is a shorted cell, some battery chargers can over charge the remaining cells if one cell goes faulty, you get bad egg smell, so using caravans built in charger means regular visits just in case, but using the Lidi charger once the charge rate has dropped it alternates between 0.8, 0.1 and zero amps which will not gas a battery enough to cause danger. Oddly the C-tek charger will return to 3.8A so the cheap Lidi is better as connect and forget charger. Although the DC to DC charger will speed up the recharging, likely a solar panel is better value for money.
  9. Spec says. 8 Reversing light 9 Continuous power supply 10 Power supply controlled by ignition switch 11 Return for core No. 10 12 Coding for coupled trailer 13 Return for core No. 9 It does not say how this it to be arranged, and over the years it has changed, there is nothing to say there should be anything to stop power going from 13 pin socket to car, normally we fit blocking diodes or relays, the latter either voltage controlled or alternator controlled, and one would hope there is a fuse. But regulations don't say that. Early caravan Sprite Aerial never had a battery, there was one festoon bulb lamp near door to allow you to see to turn on gas lamp, and the pin was then pin 2 on the 7 pin plug latter called the N type, and that pin did air warning, reversing and rear guard fog warning as time went on. But be it a horse box or caravan it does not need to have a battery fitted in the trailer, so only when there is a battery in the trailer must you prevent reverse flow. I have never checked mine, suppose I should, but the voltage dependent relay was the standard method used for years, but with cars with auto stop start, then we have a problem, we don't want the power to fail where it works the anti-snake, so the voltage dependent relay could result in it dropping out, for me not a problem as I don't have an electric anti-snake, but now the device to stop back feed is in the caravan as well as the car, we are returning to the blocking diode in the car, the schottky diode has less of a volt drop, and the voltage at the caravan is no longer so important with the battery to battery inverter in the caravan raising the voltage to required level. However no one is saying the old caravans need up grading, so we now have a chance the systems car and caravan don't match. The car manufacturer could put a special relay which disconnects only when the starter is cranked, it does not need to be a schottky diode, I note with wife's car it has TSA, part of the Dynamic Stability Control (DSC), and it has minimum load of 6 watt for brake lights and indicators. It says Permanent battery feed, and Ignition feed have a 15 amp maximum, this assumes an official wiring system. There is nothing in the instructions that says how the car knows it's towing something, it clearly must know, as the indicator warning lamp detects trailer bulb failure, everything seems to have moved on, and we can no longer assume.
  10. I had it on my old caravan I was living in while working on the building of Sizewell 'B' power station, it worked well, however touring simply don't want the extra weight, with caravan static for over 2 years OK, but also had a caravan wrecked when an aqua role broke loose and rocked back and to between both sides of the caravan, so now always travel with them empty. 2 gallons of fresh water tipped out on the grass before leaving one can get away with, 7 gallons is a bit OTT. I also had a 16 volt transformer to work the fridge, at that time it was 12 volt or gas, there was no 230 volt option, but 16 volt was a little too much, so I used a spring as a resistor to drop it down a bit, in an adaptable box, which got warm of course, so I put it under the aqua role and it was enough to stop it freezing. I used an old under sink water heater with the element swapped for 1 kW instead of 3 kW, and swapped the thermostat for one with change over contacts, which feed a thermostat on the wall that in turn fed a socket which had a converted fan heater plugged in 1 kW or 500W instead of standard 1 kW or 2 kW, so when water needed heating it switched off the fan heater. The battery charger was not regulated, and would over charge the battery, so made a unit with head lamp bulb and a 2N3055 power transistor as the voltage went over 13.8 volt it would start switching on the bulb, so stopped over charging by putting a load on the charger, when bulb was glowing I knew battery was charged. They all worked, but today the fridge works direct on 230 volt, the battery charger is regulated, we have a 16A supply not 5A and the built in central heating has 500W, 1kW and 2kW options, so all the tricks no longer required, including the light spring and washer to hold the mantel down, did not stop them breaking but reduced how often, today not even got gas lights. I am thinking what it would have been like pumping the rubber dome in the floor so your wife could have a shower? I think see would be told don't be so lazy go to the shower block.
  11. Early climate control switched on the air conditioner which had one set output, and also the heater when it did not need full output, so yes those old units did take some power, however even with the old system, the drag caused by opening windows can affect MPG more than what the AC uses, and also had stones thrown up on the motorway that punched the radiator and caused a lot of damage to bodywork, had the window been open then they would have really hurt, car in front had driven onto French drain on centre reservation, so I want windows closed on motorways for safety. So if warm AC goes on, don't care what fuel it uses.
  12. With a float battery charger between 13.4 to 13.8 volt, with a stage charger it can go to 14.8 volt, With a stage charger it also measures amps, they vary in design, but normally volt drops 14.8 to 13.6 when the charge current drops to around 4 amp with a 110 Ah battery, if a battery cell goes faulty then the amps will not drop so the charger can still over charge with high (14.8 volt) volts with no fault on the charger. Some chargers have a switch float/stage if that's case switch to float and should not be over 13.8 volt.
  13. Years ago Standard Germany vehicle wiring white is negative and black is positive and the wires have numbers, 30 positive and 31 negative for example. British vehicles (are there any left) black was negative and unfused positive was brown, fused was purple, ignition non fused white and fused red. This is for negative earth vehicles. As for today, we have harmonised with Europe but only green/yellow and white are reserved for earth and combined earth/neutral and white has been used for extra low voltage for years so only colour which is really reserved is green/yellow. It does recommend colours for DC however they seem to be ignored. Even AC with split phase as used with site 110 volt supplies the colours should be line 1 brown and line 2 black and earth green/yellow, I have yet to see yellow flex with those colours, it seems blue is always used instead of black and I have failed to find a suppler for cable with correct colours on the cores.
  14. Standard idea with UPS was a coal bunker type lean to with batteries outside but the charger and rest of electronics inside, and it would power an office full of computers so they did not fail with power cut. However it was soon realised there were problems having one large unit, so the UPS was made smaller powering just one computer each, still using lead acid batteries, although much smaller, and although today likely being replaced with NiMh they have been used for years in doors with no problem. With the caravan battery the problem with exploding is due to over charging, and the 25 amp charger used in a caravan can when either charger goes wrong or a cell fails in a battery with the addition of a small spark explode as the rapid burning of the hydrogen gas expands the gas quicker than it can escape. However with some thing like the cheap Lidi 3.8 amp charger this is not really a problem, the charger has 7 stages, however most we are not interested with, so it starts at 3.8 amp, within around 15 minutes it will normally drop to 3 amp, and it can stay at 3 amp for a day, then it drops to 0.8 amp and once this stage is reached it will not auto return to higher charge rates, and at 0.8 amp it will not produce enough hydrogen gas to be a danger. Even at 3.8 amp the danger is low, but one would want an area with air movement. So once at 0.8 amp there are three stages that the battery will cycle between, as the voltage raises it will drop further to 0.1 amp, and if it again raises it will drop to zero, as the volts fall it will restart charging at 0.8 amp, and so it repeats the charging sequence. In real terms the battery sits at 12.8 to 12.9 volt, as soon as it starts to charge the voltage raises to 14.4 volt so it switches off again. So it auto maintains the battery. Other units may be slightly different, I am told the Ctek charger will return to full charge rate if there is a drain on the battery, but as long as you select a low output model there will not be a problem. The Lidi charger will auto switch off with a power cut, you have to press a button to restart it charging, the Ctek I am told does not need a button pressing, however the Ctek is not duel voltage so swings and roundabouts. With an open vented battery there is always some small danger, with VRLA you can send them through the post, does not matter if used upright, or on side or on end, never mind stored, but open vented can spill so some care is required. I for years used a plastic bread bin, it ensured no acid could leak onto floor. Kitchen likely best place to charge in doors as tumble drier, or cooker hood will likely ensure air changes, if you smell bad eggs, then likely the battery is faulty, however when I had one go faulty in caravan it sat over charging for a couple of weeks before I attended and smelt it, in the house you soon realise some thing has gone wrong. Clearly if you ignore the tell tail smell then there may be danger, however I as an auto electrician would not worry about charging a battery in the house using a small automatic charger. What I have realised after monitoring power used by a small charger, a typical battery will charge to 95% within a day or two, but unless 100% charged slowly the capacity will drop as the battery sulphates, and it can take 2 weeks to get that last 5% into the battery. So once my caravan goes into storage, the battery will be removed and it will go into house and be left on charge until next required.
  15. Some stop start systems use a computer to ensure every so often the battery is fully charged but does maintain the battery at below full charge so it can use regenerative braking technology. The way around this when using as a motor caravan is to have the second battery controlled with a DC to DC inverter so the vehicle start battery is independent to the domestic battery, and you can have a valve regulated lead acid for vehicle start but still use a flooded battery as the domestic. See https://sterling-power.com/products/battery-to-battery-charger-caravan as an example.
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