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Twin alternator Set up


Mo Murphy

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What set ups are you twin alternator users using?

I like the idea of the redundancy of twin alternators, having spare in case of failure and the ability to recharge the aux battery with its own alternator when the fridge or the winch has flattened it.

I have a split charge at the moment running a numax starter battery and a numax deep cycle aux. This set up is adequate but nothing more.

With the current installation of power hungry air con proceeding well, and the power demands of winter driving with lights, heater, wipers and heated screens, mirrors and seats and a winch to power as well, the hour of improvement is at hand.

I'm considering a 100 amp alternator (as big as my v belt 200 Tdi can deal with I'm told) for the starter battery to run all the cars systems including the air con alongside a 70 amp for the aux battery to run the winch, fridge, compressor and various assorted power sockets.

What sort of twin alternator set up are you using and what would you recommend for my purposes ?

Cheers

Mo

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I run Twin 65amp alts on the 110 and that's plenty..... Batteries only accept about 8amps to charge them.

The 110 has a winch, lots of lights, big radio and will be getting alot more over time. I dont see a need to fit anything bigger.

Can you post some pics please Dave?

Now I have a spare (due to the old one dying :( ) complete cchange of plan as no airco now and with modern and high quality 12V compressor the OBA can have greater flexibility, just leaves a spare slot for the alt to fit.

Will be watching with interest.

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I just use an Aux feed from the 110s standard wiring into the 24volt warning light, 5 watt bulb in there and out to the alternator, couldn't be simpler if you tried. I will fit an isolator between the battery positives when I have money to spend on one.. I'll be starting the Bracket soon by the way.

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Hi Mo I've got the gwyn lewis twin alt setup on my 110 200tdi. My engine already had the 3 belt crank pulley on it. I've got 2 standard alternators (60/65 amp?) One as standard and the other is connected to my leisure batt for fridge etc. I have it wired to the spare 24v light on the dash. Wiring it in - google 'twin alternator wiring' and look for images you will probably find the gwyn lewis instruction drawing (basic drawing with coloured lines). Its along the lines of big wire from alt to aux batt, 12v from aux batt to one side of dash bulb, other side of dash bulb to the other alt terminal, but with a relay switching that wire that is triggered by the ignition - otherwise the dash light stays on I think. I've got some jump lead clamps and wire offcuts that I'll make into a short jump lead I can use to link the battery positives for jump starting if I drain my starting battery. Also, buying halfords jumpleads and cutting the clamps off is a surprisingly cheap way to get hold of cable quickly vs buying it by the metre at e.g. maplins or motor factors. The gwyn lewis kit isn't cheap but it might be a good place to start looking if you could fabricate your own. Hope some of that is useful. Guy

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I used a Glyn Lewis bracket on my V8 for a second alternator which charged a pair of Optiima yellow tops which powered my winches.

These were were completely seperate from the vehicle 12v supply (because of volt drop etc when winching hard), but what i did do is power the 12 excite winding to the 2nd alternator of the vehicle supply via switch, this enabled the winch alternator to just spin on its bearings and not take any load of the engine when it wasnt required, it worked a treat, there was no point in charging away when just driving around or whatever, and you could certainly hear the engine note change when it was activated.

Another money saving idea.....

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I use Glyn Lewis bracket on my V8 for a second alternator to connect to just a single (very large battery) with a second warning light bulb for the second alternator.
Only one alternator actually charges the battery at any one time due to the low charge current that a battery will accept, but it kicks in when the winches pull large currents.

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Depending on what fridge you are running have you thought of mounting a solar panel on the roof? This way batteries will be kept topped up when parked up and fridge is left on or if the vehicle not being used for a while. 100W solar panel and a good solar charge regulator can be had for about £200.

Jon

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