Omega Owners Forum
Omega Help Area => Omega Electrical and Audio Help => Topic started by: 05omegav6 on 26 February 2014, 01:25:38
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Have a genuine pair of towbar wiring kits, one for trailer lights and one for caravanist things...
If I were to fit a battery box in the boot for several obscure reasons, could the caravan wiring be used to charge it?
I don't suppose it would be any different from charging a battery bank of a caravan if plugged in whilst engine running :-\
Want to fit trailer electrics anyways...
Also, how much ventilation, if any would the battery need? Would a vent hole straight into the boot suffice?
Thinking 18mm board for the box :-\
Would I be better off replacing current battery with summat like this...
http://www.halfords.com/webapp/wcs/stores/servlet/ProductMobileDisplay?zygonManPartNum=HSB019&zygonPrice=0&zygonId=12774105&zygonArticleNum=161078&zygonGenericCode=000000&catalogId=10151&storeId=10001&productId=734844&categoryId=165762&langId=-1 :-\
Reason for asking is that current battery goes flat if the headlights are left on for ten minutes, but otherwise behaves as expected. Contents of the boot are unlikely to be used without engine running, but if the battery is weak then I might be taking a chance, even if left idling via a runlock :-\
Car is currently fitted with 140amp Plod alternator and a Bosch Silver battery which is 3.5 years old, HSB 075 iirc,although I do have a brand new HSB 096 Yuasa battery provided by halfrods in exchange for another 3.5 year old Bosch equivalent ::) Always keep the receipts kids :-X
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12v Auto Batteries as a rule dont like being connected in Parallel for long periods if they are they really need to both the same type and rating and in similar (good) condition, otherwise the poorer of the two will start to discharge the good one.
Having said that Ive done something similar with a Mig TD Estate where I have to work out of the back on it, using Flood Lights and UPS Inverter running Tools and Lappy, soon become apparent that the only way this was going to work was to fit a second Battery and also fit a HD Isolation switch betwwen the two batteries, that way I always had the Main Battery for normal car use and start the thing should the second battery run low.
I found using this method worked well, and before setting off with the Engine running, I would flick the Isolation switch on and then charge the second battery whilst on the move.
Wiring wise I used semi heavy duty Positive red and Neutral black cable directly to each battery (about the same cable thickness as a set of cheap jump leads) via the Isolation switch on the Positive side as well as Earthing the second Battery locally.
On the Battery vent side I just sorced a BMW Boot Battery, actually the same size and Rating as the 065 Mig ones but has a small vent tube running down through the floor pan via a rubber grommet. :y
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I would be concerned about the resistance between front and rear if using the car's existing wiring. It doesn't take much voltage drop before your aux. battery isn't charging at all!
For that reason, I'd run your own wire back from the alternator B+ terminal and rate it as generously as you can. Fuse it at the front end with an appropriate value of fuse, of course.
Use a caravan charge relay or an ordinary relay triggered by the fuel pump feed, oil pressure switch, etc. to isolate the battery except when it's charging. :y
You might want to look into using an AGM battery to avoid spillage. Failing that, many wet lead acid batteries have a vent connection to which you can connect a hose, which can then lead outside the vehicle. If it's going to be boxed in at all, it needs to vent outside the vehicle, and using a hose avoids the corrosive fumes from rotting the boot.
Also, bear in mind that you might be better off with a battery designed for cyclic use if it's going to be used a great deal with the engine off - i.e. a leisure battery rather than a starting battery.
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I certainly agree with KW's comments regarding venting, or maybe use a gel-electrolyte type of battery?
Regarding charging, there are automatic devices to allow both batteries to be charged, but not to discharge both at the same time - i.e. just use the boot battery for auxiliaries, as caravanners do - using deep-cycle leisure batteries, as suggested.
Caravan shops will supply a unit which is basically two fat diodes in a box, and charge caravan prices!
Relays are an alternative, and you might find this link useful?
www.ybw.com/forums/showthread.php?307638-Split-charge-diodes-versus-split-charge-relays
If I've misunderstood your intended use, please come back to me and I'll try to help you more......
Ron.
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Thanks chaps :y
The engine will be running when the boot contents are in use, so I don't know if I would actually need a second battery or not :-\
The towbar wiring kits I have are:
93160931, which is a fused relay controlled trailer charging supply/separate power supply plus reversing lights (12S),
93165101, which is a trailer lighting kit (12N).
The instructions for the first thing are pretty clear with a couple of very ambiguous connections, namely Pin 86 on the relay (shown as connected to +15 next to a picture of a fuse box), and a spade connector on a red fly led in the boot area. Pin 85 goes to the starter motor (+50 is all that is shown next to a picture of the starter motor... surely that should be the alternator :-\), Pin 30 to the battery and Pin 87 to the towbar socket. So would presume that the black wire from Pin 86 goes to the switched ignition circuit...
The thinking being that the power board would be connected directly to its own local battery, with the yellow feed from the relay connecting to the positive terminal. There by keeping the engine battery nicely isolated from the extra one, whilst charging the second one when the engine is running :-\
The other slight issue is the fact that the trailer lighting wiring kit was supplied with the exact same instructions as the charging one >:(
Used to have a diode pack on the boat, which had a starter battery along with three domestic ones, so aware of the concept, but the system was fitted by the boatyard, so I never paid much attention to it beyond topping up the batteries :-[
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Actually.. What am I thinking? You need to fuse it at both ends, of course!
The problem with involving diodes is that they cause another 0.7V of voltage drop each, and that really limits the charging capability. You go from 14V at the alternator to 13.3 which isn't really enough.
I'd be happy to look over the bits you have and figure out what you can make out of them, if you like?
I guess this might be a good time to mention Curry, too? ::)
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Ah yes, the C word... posting elsewhere :y
Thanks for the offer, should have most of the gubbins fitted by then, and therefore a more accurate idea of power demands :y
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I have exactly this setup in mine - a 85AH Gel battery (to remove spill risk) secured in a battery box in the boot. I used the existing wiring to feed through a voltage sensitive relay so that the boot battery is connected when the engine is running but can't flatten the main battery.
Voltage drop is a little high with the in car wiring, but it does work - I get 13.8V with engine running, which is actually ideal for my Gel battery, but would be too low to fully charge a conventional open battery.
Steve
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Is your second battery wired independently of the main one :-\
What current demands are you putting through it :-\
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It feeds 3 standard cigarette lighter sockets in the boot, running a cool box, charging phones and occasionally an inverter. Normal load is around 4 - 5 amps Max (with the inverter) has been around 20 amps.
It then charger using the tow bar / caravan supply in the boot, but with a voltage sensitive relay installed so it can only be charged and the load in the boot can't flatten the main car battery.
Steve
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So you effectively have the tow bar power socket, and have tapped into the charging supply for the second battery :-\
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Thats it - in the tow bar socket there is a permanent live which I have used. That is why I need the VSR or it will just flatten the main car battery when the engine is off.
I can get a photo tonight and post here if that helps :-)
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Why not use the caravan charge supply :-\ or is the power from a trailer lighting connection :-\
Or have I missed summat...
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The supply I have connect to is for charging a caravan battery / running a fridge - however it relies on the caravan having a suitable VSR or other device to stop the main battery being drained.
There is no switched / ignition feed in the standard VX wiring (certainly not on my car anyway)
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The supply I have connect to is for charging a caravan battery / running a fridge - however it relies on the caravan having a suitable VSR or other device to stop the main battery being drained.
There is no switched / ignition feed in the standard VX wiring (certainly not on my car anyway)
Agreed, there is a permanent 12V, on a fairly thin wire, but nothing ignition switched.
For the 'van (in my case) I have put ignition SWITCHED relays in, near the existing battery, and run substantial wires through to the boot to connect to the 13 pin socket for the van, in your case to the "extra" battery. The advantage of this is all the fuses are very near the "battery" ends of the cable runs.
Be aware there are two types of control relays ... one is ignition switched the other is voltage sensitive (VSR). The switched units are more reliable and give less of a voltage drop, but do require the extra wiring of the ignition source feed. The VSR are easier to fit but can be prone to problems, the "switching" voltage seems to be unstable on many IME.
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There are a couple of downsides to using the existing permanent feed to the towing connector, IMHO:
1) I believe it was actually provided to power the trailer lights through a relay module in the OEM towing kit rather than for charging batteries, running fridges, etc.
2) The fuse is shared with other devices (e.g. seat & mirror adjustment on the same fuse and many other things on the same fusible link) on some cars, meaning if you blew the fuse it would cause a nuisance by disabling items in the car, and the extra loads might cause a bit more voltage drop, exacerbating the situation when charging batteries.
3) Whilst it's fused at 30A, it's 2.5mm2 wire. I wouldn't trust it at over 20A continuous current. Although, if a serious fault occurred, I'm sure the short term overload would blow a 30A fuse I'm not sure I'd say the same about a long term mild overloading of that wire. Load it to 29.5A for long periods of time, and my bet is that the wire would melt. In any case, the voltage drop would be higher than you'd want.
If you're going to use a voltage sensing relay, you need the bare minimum of voltage drop between it and the vehicle supply to prevent it dropping out erroneously. Best off to mount it up the front end of the car (but then you've got to run a dedicated wire down to the back end). ;)
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2) The fuse is shared with other devices (e.g. seat & mirror adjustment on the same fuse and many other things on the same fusible link) on some cars, ....
Not on my MFL car is doesn't. I fitted the fuse to power my caravan fridge/charging and everything that should work was working before hand.
My trailer lights are now actually fed via a module that's powered directly from the battery (using a fuse ;)) using an OEM kit but that's a completely different set up from the trailer lighting plug behind the rear boot trim
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2) The fuse is shared with other devices (e.g. seat & mirror adjustment on the same fuse and many other things on the same fusible link) on some cars, ....
Not on my MFL car is doesn't. I fitted the fuse to power my caravan fridge/charging and everything that should work was working before hand.
My trailer lights are now actually fed via a module that's powered directly from the battery (using a fuse ;)) using an OEM kit but that's a completely different set up from the trailer lighting plug behind the rear boot trim
That's why I said some cars (including the OP's). ;)
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For the sake of clarity, this is the GM part in question...
http://oemcats.com/oem-parts/93160931.html
http://www.ebay.co.uk/itm/VAUXHALL-TRAILER-COUPLING-ELECTRICS-KIT-12S-7-PIN-GENUINE-93160931-/221378263883
Which might well be what Andy has fitted :-\
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For the sake of clarity, this is the GM part in question...
http://oemcats.com/oem-parts/93160931.html
http://www.ebay.co.uk/itm/VAUXHALL-TRAILER-COUPLING-ELECTRICS-KIT-12S-7-PIN-GENUINE-93160931-/221378263883
Which might well be what Andy has fitted :-\
No, mine's a 13 pin ;)
I've still used the original 12 volt feed from the square socket on my car (I know the facelifts' are round ;))
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Kevin,
I think its an expectaion thing - it certainly does work very well for me, but I only have limited charging requirements - fairly small single battery in the boot that is never really flat. Totally agree with you that if you want to achieve fast charging of several hundred amp hours of battery in a caravan you are going to need some much thicker wire.
Not sure which the OP is after.
Steve
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Kevin,
I think its an expectaion thing - it certainly does work very well for me, but I only have limited charging requirements - fairly small single battery in the boot that is never really flat. Totally agree with you that if you want to achieve fast charging of several hundred amp hours of battery in a caravan you are going to need some much thicker wire.
Not sure which the OP is after.
Steve
An efficient way to get approximately 140-180 amps to the boot :y
Option 1. run a suitably sized cable from main battery to a distribution board in the boot.
Option 2. fit a battery in the boot with a short run to the distribution board, charging via the towbar wiring kit listed earlier.
Both options would employ a runlock for secure battery charging whilst on display...
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An efficient way to get approximately 140-180 amps to the boot :y
'kinell! are you putting another engine back there? :o
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I think you need a wet battery or 2 in the boot to do that, for long life you are looking to not flatten them below 50%. The cable to the front of the car would have to be 50mm or bigger to supply that and you would be flattening the car battery very quickly as the alternator is only going to put out 100 amps.
You will then need a bigger cable to the front the re-charge your setup as the current you would get down the installed cable would take too long to charge that sort of setup.
Just being nosey, what do you have in the boot that requires that kind of current?
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I think you put that more succinctly Kevin!
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Are you sure that you need such an enormous current feed to the boot battery? Granted you might need a heavy load from battery No. 2, but not to charge it, surely?
Ok, assuming that you really do, why not feed your alternator to each battery via a 200 Amp Schottky diode. "Schottky, because they have a low forward voltage drop of around 0.2 volt, "diode" because you want current to feed to each battery only and effectively have them isolated from each other - i.e. current cannot flow from either battery to the other. I wish I knew how to draw diagrams on here.....
The minimal voltage drop due to the diodes should not affect even today's clever regulators on the alternator and it is fully automatic - no need to remember to switch anything!
Ron.
P.S. Don't forget to use a grown-up cable to the boot battery if you really do need that heavy a current feed.
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I assume that is the current requirement based on the fuse ratings...
Front Blues 10A
Rear Blues 10A
Rear Reds 7A
Headlight flasher 15A + 3A
Taillight flasher 15A + 3A (though could drop to 10A as rear fogs draw less than main beam)
Siren Amp 10A
Siren control 10A
Take down/Alley lights 3A
Front Cruise lights 3A (cannot be used with front blues active)
Rear Cruise lights 3A (cannot be used with rear blues active)
That's 80A, plus video kit (?A), and could reroute the current ICE (50A) gubbins through it, as that is currently routed through the front seat feeds (suitably fused at connection) although if it ain't broke and all that... :-\
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If I drop the rear flasher down to 10A, leave the ICE as is and allow 20A for the video kit then that gives a total demand of 95A in the boot...
The lightbar power feed comes off the front battery, the boot is mostly switching current...
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Fuses are to protect the cables and prevent fire so the equipment should be actually using less than the fuse rating.
A bit of measuring required really.
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Yep, firstly, the fuse ratings will be pretty conservative, and secondly, you won't be loading every circuit to its' full rating at the same time.
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Ok, so panicking over nowt then :-\
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http://www.hallselectrical.co.uk/relay-voltage-sensitive-140-amp-12-volt-bx-1-0-727-33.html
i use one of these to charge a battery in the back of the van with 6mm wiring. does the job.