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Hi

On my p38 with all my electrical accessories turned on when towing my caravan (with its lights and fridge) and travelling for extended periods
I find that my Alternator is not keeping my batteries charged especially so when it is a hot day

for example this January crossing the Nullarbor each day I travelled over 1000Kms per day where I hit a heat wave (peak temperature 53 degrees Celsius)
result being fridges, car air-con and electric fans run non-stop and two flat battery's

rough calculations of electrical load confirm I need more Amps

So I would like to fit a second alternator I am thinking below power steering pump (Bosch/Thor engine)
basically in place of pully where ACE pump would go

has anyone done this/seen this?
is there another rover V8 bracket that I could use? such as from P76, MG etc

failing this I am thinking that i could remove the pully setup (where that ACE pump would go)
and make up some sort of bracket my self

also before anyone redirects thread...
1) I have tested my existing alternator and its is good, I even swapped it out with my brand new spare and same results on long trips
2) I have research upgrading alternator but as far as I can tell there are no large capacity
alternators which will fit, besides many are water cooled which if they fitted would be another problem

regards Peter
 

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I'm not going to redirect you from your vision of fitting a second alternator, but...
You say you've done a rough calculation of load. Have you actually used a decent clamping ammeter to measure the load? What kind of current do you need to supply to the various components?
Have you replaced your main charging cables and fittings (and earths) with 25mm2 (or greater) cables?
Have you replaced the standard accessory supply cables with a high power distribution system, using a fused busbar, to include high power connectors to your caravan and large x=section cables?
The reason I ask is that 14v DC will get a large voltage drop (or power consumption, if you like) through small cables at high power.
It is possible to get alternators re-wound to deliver a greater output- you'll have to research to find someone in Aus who does it, but I'm sure they exist over there
 

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Gotta go with OB on this one.
The stock Alt should be good for about 100 amps continuous, although in those temps it may de-rate, but not by much.
You are losing a significant bit of power somewhere. Probably to high resistance connections and undersized stock wiring.

You need to be sure all connections are SPOTLESSLY clean, and properly tight.
In your case, you absolutely need to upgrade all the heavy cabling, and install the high current distribution system with Anderson connectors wherever things come together.
Also VERY important, is to run both B+ and B- cables aft to the Caravan. DO NOT rely on the Chassis as a negative conductor.Also, add an extra heavy duty cable from the alternator case to the Batt neg terminal.
Having done all this, you will be in a much better position to test things.
DO get a decent DC clamp on meter and check Alt output, Batt current in and load current.

Just bunging in another alternator will be costly and if the aforementioned is not done, you will be in the same place, probably worse.
Be aware also that you can damage a battery by trying to shove too much current into it too quickly, especially if it is heat soaked (50+C qualifies)........You get thermal runaway, and the batteries will just fail outright......If you are lucky.....if unlucky, they will melt, explode and/ or catch fire.
I have personally witnessed this, and it is not pretty.

love the Nullabor. Just did a 20k Km drive round Oz in the 85 Classic.....Nullabor was one of the most pleasant bits, aside from Esperance and areas South.....
Good luck!
 

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The stock Alt should be good for about 100 amps continuous, although in those temps it may de-rate, but not by much.
Not to hijack the thread but is that continuous rating 2/3 of the 150A nominal output of the Thor alternators Bolt?
 

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what about installing a second battery in the caravan?, the second units gets piggy back charging from the vehicle and less overload of the truck.
a further option is a small auxiliary generator on the caravan.

I used to have a 30 footer with all american amenities, electric heater, twin roof a/c, shower, dish washer, propane gas and heat including electric brakes and it was pulled with a 95 classic LWB.

the break away brake safety had its own battery, then the caravan had it's own power supply battery plus the generator and shore power.
when connected to the vehicle, it charged the batteries of the caravan and when disconnected it would run on battery power,
then to maintain the power of if you needed or wanted to run more amenities you had the choice of generator or shore connectors.

basically a self contained mobile home.
 

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when towing a caravan the p38 alternator charges all batteries including those in caravan (and breakaway)
as well as powering caravan fridge and lights.

as mentioned I have calculated the load in AMPS
lets consider how much AMPS both p38 AirCon fans pull on full speed I believe 17 amps each
32 amp thermo FAN
17 amps caravan fridge
8 amps electric water pump (for p38 engine)
4 amps engel

Although this is close to 100 AMPs and although its under 150 amps
AMPS are still required for running the p38 just look at engine bay relays and fuses for a hint of requirements

Then there is also lights and charging battery (6 amps for caravan lights)
batteries will almost always require charging e.g. to reinstate after crank and moving from each idle at lights

IMO my current draw is to high
modern alternators such as the Bosch 150AMP as used in the p38 Thor do derate output both at idle and with heat
as evidenced by both my p38 crank battery and second battery going flat

could this please be back on thread can anyone offer words of wisdom on mounting 2nd alternator

regards Peter
 

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Must admit, I was surprised at your current figures, so I went out and measured my UK 1998 GEMS 4.6.
Air-Con is disabled because I'm waiting for new condenser, but here's the basic measurements. All were varying slightly, but I was staggered at the results.

Alternator = 52-54A
Battery to Fusebox = 40-42A
Battery Ground = 12A

Plus another 10A when EAS pump kicks in.
Condenser Fans on bench = 16A each

But back to your original question, I suspect you will need to create your own 2nd alternator bracket, plus add double pulley somewhere & find a suitable belt.

or maybe sort out the viscous fan & original water pump to save 40A on water system ?
 

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Looks like you have 61 amps over a stock vehicle drain so no surprise that its not keeping up.

Have you thought about putting a solar panel on the roof of the van? The one I have on my sail boat runs the fridge on a good day and its worth installing to keep the van battery fully charged when its parked up. A lot cheaper than installing another alternator. You could install an ammeter so you can shed load if the alternator is not keeping up. The fridge should have a microprocessor in the circuit so that it shuts off if the voltage drops too much so that it doesn't flatten the battery. There should be diodes in the circuit so that the car can't drain the trailer battery.

Maybe have a look at the wiring diagram for the van?

Another cheapie option is to get a voltmeter that plugs into the cigarette lighter and keep an eye on that.
 

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Since you say plural "batteries" are you saying you already have a dual battery system in the P38 and a third deep cycle RV battery in the trailer? If so, you should have a standard battery for big draw instant power engine starting, basics like lighting, safety system and root get you down the road items. Radio, RSE, kids iPads etc are pushing it. A secondary battery should be a heavy duty deep cycle battery to cushion the voltage requirement in the cabin for various plugins in the P38 for long term slower voltage use of accessories.

If this is the set up you have you and are still having issues you can have your alternator up rated via a custom rebuild. Magnetti Marelii were upgradeable to 170 or 180 amps and the later Bosch to 200-210 amps with no physical belt changes or programming changes in the BeCM trigger line. If you don't have dual battery in the P38 nor you will never be able to maintain the short cycle in your Rover and also maintain the deep cycle battery in the trailer. Two fast draw / standard batteries in the towing rig don't hold voltage well or long with lots of accessories running.

As noted above your trailer electricals should always shut down if voltage drops too far. This has been true of most RVs since the mid to late 70's here in the States. Most of my families travels were in aone ton monster GMC with the above dual battery set up and wired charging to the deep cycle in the trailer. Now we added to the electrical load as either mum and the cockers were in the trailer with lights on, watching TV and playing cards etc or I was in the trailer with the stereo going sacked out on the master bed with the cockers. A second deep cycle battery in our trailer solved the very few issues we had with the draw from the factory GMC alternator.

Deep cycle batteries charge slowly and drain slowly. They are the ultimate voltage buffer and it takes alot of effort to completely darin them. The voltage fluctuation is very much buffered. The amperage feed to the trailer has very little to do in the equation. A decent dual battery charging spliter will always charge the main car battery as primary and then switch over to cap off the deep cycle second while providing a constant wired feed to the trailer socket. Where it goes in the trailer depends on what set up you have for charged usage in the traveling cottage behind you. :thumb:
 

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yes I have multiple Batteries including deep cycle. Generators, AC chargers and solar panels are all useful once stopped but no good when driving long distances (stopping only for fuel)

while driving the fix is not solar panels which do not offer high AMPs nor is the fix switching items off such as electric engine cooling which was implemented to keep engine below 95c on a 48-53c day while towing uphill with head wind nor would I forgo A/C to keep me cool on the hot days and not having fridges going well this is plain stupid and of course having charged batteries once we stop is required for both using the caravan and restarting the car.

I am aware of custom alternator upgrades but typically these only offer small increases around 50amps but do not negate the fact that alternators only produce peak power at certain rpm and the custom alternator still derates with heat to around the same LOW amps as a standard alternator furthermore upgrade of existing alternator serves to make it run hotter which makes it derate more often

big rigs almost always run dual alternators as to boats with large battery banks (House Battery) these often have the alternators in parallel via controller to determine when both alternators are needed

dual alternators have also been used for years on Ambulances and fire engines. IMO duel alternator is the best way to provide more frequent high amps and at $350AU for another 150amp alternator reasonably cheap.
 

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Apologies for ruffling your feathers. Was just trying to clarify due to lack of details on your current setup. I only brought up my line of experience because it is proven to work, require no electrical upgrades and is user friendly. Upgraded alternators are a real world option, but if you don't want to go down that road with your current set up... nothing else simple exists.

There is NO bolt on option for second alternators. Even commercial chassis P38 variants for police, ambulance and delivery options manage their electrical taxing with only additional deep cycle batteries and power switching charger stations. ANYTHING you do is going to require custom fabrication, wiring, regulators and mountings. While we are at it I reread your diatribe. Big rigs do NOT run dual alternators they have one massive high output alternator to feed multiple batteries. I work on Peterbuilts and Kenworths for various buddies. I have never seen a semi, dump tuck etc in the commercial diesel end of things with 2 alternators. Same with any ambulances that are commercial chassis ford 350 or 450 diesels... or the rare Dodge commercial chassis. Lighting and electrical use is supplied by additional batteries and/or a generator while on site. You are barking up the wrong tree with your examples for converting your P38. It;s time to admit your rig simply does meet your needs as you are willing to outfit it and find a commercial vehicle to pull your trailer.
 

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just thinking out off the box , would it be possible to rig up an power supply that runs of the wheel of the trailer, so when you tow it it self charges. all said and done all you have to do is spin the alternator?
 

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Discussion Starter #13
upgraded alternator on p38 perhaps not an option as one is stuck with keeping to the same physical size as standard
and the largest I have found which will fit is 200 AMPS

200 amps is not enough if I want to run lights and wipers as well as existing load
also a single 200 AMP alternator below 2000rpm and/or with heat derates similar to a 150AMP
the only way to offer higher AMPS at low rpm and when hot is addtional alternator, there is plenty of information on the internet about this

I certainly can't speak for big-rigs and emergency vehicles overseas but have personally seen dual alternators on big-rigs in Perth AU and I have personally viewed dual alternators in fire engines in New Zealand standard fitment or not I can not say

My internet searches I have found results for emergency vehicles overseas with dual alternators

I have also found mention of US Ford and US GMC trucks (perhaps not considered big-rig) with dual alternators which appear to be standard fitment

there are also plenty of sites providing kits (some state OEM) for various cars including ford 250,350,450 etc (but not Rover)

So I would suggest dual alternator is normal is certain circles

with regards to the rover V8 there was from what I can tell a UK convoy van which in ambulance format had two alternators

also I am aware of other vehicles with the rover v8 as standard fitment with the alternator in the position I speak of
so I believe my query do any of these variants have alternator brackets which will fit is completely valid

furthermore IMO with suitable bracket there is room for a second alternator in this position on the p38
 

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That bracket would fit straight onto a GEMS but might need a bit of modding on a Thor. I'd be inclined to go with mad as suggestion of an alternator driven from a trailer wheel though.
 

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That bracket looks ideal, but wonder if there's enough space by the battery ?? Also will require special serpentine belt.

Maybe hang a generator off the back of the trailer ? . . . :D . . (yes silly beers comment)
 

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I was looking at my '99 Bosch last night and I thought this location (to the left of the original alternator from the front) looked like the best option. But you would have to re-locate the battery or possible remove the excess plastic behind the battery. Also would need to re-route the heater hose and possibly oil cooler lines. I can't see how you would do it from a trailer wheel. Considering that the spindles are stationary on a trailer, you don't have spinning shaft to drive from. Driving something from the actual wheel sounds like a problem and the alternator itself would have to mounted to the axle so it would move with the wheel. Sounds sketchy and prone to issues.
 
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