How many amps and volts from a GU4 TD42 alternator?

Submitted: Thursday, Mar 29, 2012 at 11:32
ThreadID: 92867 Views:8091 Replies:3 FollowUps:4
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Does anyone know what amps and volts a standard alternator would churn out on a Nissan GU4 TD42 Patrol, built September 2006?

A friend of mine wants to charge 2 batteries and a 39l Engel in the car, and another battery and a 3-way fridge in the caravan while travelling. (He'll use solar panels for the Engel, and gas for the 3-way when camped. I'm helping him to upgrade the wiring to minimise voltage losses (to 9.3 sq.mm cable), but I'm concerned that the alternator might not have enough capacity to handle the load when travelling.

Thanks,

GOM
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Reply By: Member - Bentaxle - Thursday, Mar 29, 2012 at 12:58

Thursday, Mar 29, 2012 at 12:58
GOM He shouldn't have any problems, I've a 3L TD GU Patrol that has a stock standard alternator which is running a dual battery system and on trips is also powering an 80L Engel and an extra battery in the Camper Trailer and a 3way fridge.
Mike
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Follow Up By: GOM - Thursday, Mar 29, 2012 at 19:52

Thursday, Mar 29, 2012 at 19:52
Thanks Bentaxle

He's heading off on a 5-month trip, so that gives me some comfort.

Cheers,

GOM
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Reply By: Member - Tezza Qld - Thursday, Mar 29, 2012 at 14:19

Thursday, Mar 29, 2012 at 14:19
Hi

No problems running fridges or charging batteries with the 4.2 alternator

Whilst driving my battery gauges are around 14.4 volts and last time I checked the output it was around 30 amps at over 800 rpm

I found that if I had to recharge when camped 800 rpm is the most efficient revs

My only suggestion if running a agm as a second battery under the bonnet is change the start battery and the aux battery around so that the agm is away from the turbo and heat source.

Cheers Teza
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Reply By: Member -Dodger - Thursday, Mar 29, 2012 at 16:31

Thursday, Mar 29, 2012 at 16:31
I have a GU 4.2td Patrol with the setup you mentioned and the alternator has been handling this load for 12 years ok.
The alternator should be a 100ah job so no probs.
To give you an idea of what it has been running.
Under bonnet = 1 aux and 1 cranking battery both 100ah.
Caravan = 1 battery charged by a dc to dc charger max 20ah and one 3 way fridge drawing 12amps continually when on 12v.

Whatever the pundits say this has worked well for 12 years.



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I used to have a handle on life, but it broke.

Cheers Dodg.

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Follow Up By: GOM - Thursday, Mar 29, 2012 at 19:58

Thursday, Mar 29, 2012 at 19:58
So Dodger,

Does this mean you've had to go to a DC-DC charger at the caravan to get any decent charge at the caravan battery? I was hoping he would get away with charging the caravan battery from the alternator while travelling.
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Follow Up By: Member -Dodger - Friday, Mar 30, 2012 at 11:22

Friday, Mar 30, 2012 at 11:22
I went to the DC to DC charger because it charges the van battery correctly via it's inbuilt 3 stage charging.
It also compensates for any loss of voltage in the cable from tug to van battery.
Because the fridge is a heavy draw in its own rite there van be a voltage drop when it is on and the van battery is a little low.
I have found consistently that the battery when low will come up to a fully charged state in around 4 hrs driving time. With the fridge in operation on 12v.
Having said this the 12v lead from van to both battery and fridge is heavy duty 6mm cable, via an Anderson Plug.
This way I can camp up to four days without power (provided fridge is on gas) or solar input if it is overcast then drive for one day and the van battery is again up to full charge. However as I have portable folding solar I make a point of putting it out when camped
Our traveling is done like this, 2hrs then morning tea another 2 hrs then lunch then 2 more hours and camp. We always run the fridge on gas when stopped for any break greater than 10 minutes.
This has worked well over the years.
The other backup is a genset mainly for air con and is very seldom used.
But is still started once a month because if you don't use it you lose it theory.

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I used to have a handle on life, but it broke.

Cheers Dodg.

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Follow Up By: GOM - Friday, Mar 30, 2012 at 13:57

Friday, Mar 30, 2012 at 13:57
Thanks for the detailed response Dodger. Our current plan is to see what the voltage will be like at the caravan battery, with the engine at fast idle. If it seems too low then we'll have a look at a DC-DC charger (perhaps the Ctek D250S DUAL, which would also allow for the solar panels to be hooked up to the caravan at times).

"if you don't use it you lose it". Hmm, I might get a t-shirt made up with that on it.

Cheers,

GOM
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