High Output Alternator options

[thrower78]

Hi All,
My standard 65A alternator in the 300tdi fender has died.
With the new gear going on the vehicle I am going to need a higher output alternator. Easiest option is that the local landie guy has a 100A disco one, I am wondering if I should go bigger or will 100A do?

I will have the following gear.
12,000lb winch
approximately 240Ah worth of batteries + starting / winching battery run through a redarc bms
Hid spotlights, led bar
Stereo with 2x400watt digital amps

Will a 100A alternator keep up with the recharging and power delivery needs? Or should I try and go with something closer to 150A to factor in a bit of redundancy?
Will I need to upgrade wiring between alternator and starter with an increase in constant power delivery?

Thanks Andrew

[phibbzy]

IMO its the constant use items that need to be considered. The winch will draw much more than what a alternator is capable of providing and will always draw from the battery anyway - but its intermittent use. LED bars use a nominal amount but Halogen spotties will draw a bit.

I run a 65AMP currently which powers what you listed plus fridge and various other items without issue - a bit of dimming on the spots when winching at night is about it.

Whatever you can get your hands on around the 100 amp mark will serve you well.

[thrower78]

Thanks mate that sounds good. Yeah I know that you will never keep up with the winch.
100A is easy for me to get hold of. I was just wondering about getting good charge into the batteries but I guess the Bms will only draw a certain amount regardless of the size of the alternator. Am I right in assuming that?

[Reads90]

I have always put in the disco 100amp alternator in my defenders when I have to replace the standard one.

Gives it all a bit more

[PAT303]

I have a Transit model on mine,bolts straight up for $250. Pat

[thrower78]

Is that out of a Ford transit pat? What amperage is that one?

[Sirocco]

Dont forget to consider uprating the charge cable between the alternator and the battery as you are nearly doubling its available capacity. Last thing you want is a bottleneck... or a fire!

Did you do the cable as well Reads? or not find it necessary?

G

[PAT303]

Is that out of a Ford transit pat? What amperage is that one?

Yeh mate,straight fit,amps,dunno,keeps both batteries charged and the fridge working. Pat

[rick130]

Or the Disco one (as Ali already suggested) bolts straight in, 100amps, may have to swap pulleys, depending on age of the Tdi.
About the same money from Karcraft as Pat paid for the Transit version.

[PAT303]

If your changing models make sure the drive belt is not too tight,I have a feeling that different model alternators maybe causing alot of the bearing issue's with the Tdi,if you can't slip the belt on with the tensioner backed off the belt is too tight. Pat

[BilboBoggles]

And also don't forget that the pulley size determines how fast it spins, the larger the pulley the slower it spins. Mainly an issue at idle, some alternators will not be spinning fast enough to charge much if at all if the pulley is too big.

The most important thing that differentiates alternators is their idle output. All well and good having a high current alternator, but if it's not charging at idle - and you are winching you are screwed. Some high output alternators have very poor low speed currents.. (Or maybe it was just the ones I happened to buy in the past to upgrade a 65A alternator to 120A. Those were a major dissapointment - damned noisey and worse than the factory 65A at idle)

Have a look at this PDF for some current curves vs RPM - http://www.dieselusa.com/productinfo/Bosch%20longhaul%20alternators%20160a%20to%20200a. pdf

[thrower78]

Anyone know what the 100amp disco one does at idle? Pointless me putting in something that only puts out decent power at high revs

[weeds]

Anyone know what the 100amp disco one does at idle? Pointless me putting in something that only puts out decent power at high revs

RE: pulley size, you can choose to run with the disco pulley which comes with the alternator which is what I did or put your defender pulley onto the disco alternator

[scottvdw]

I run 2x100A disco altenators on my 300TDI.
Not because I feel I need a max of 200A but for multiple redundancy.
The altenator in the standard position charges the start battery, the second altenator sits up next to the A/C pump (coverted to an air pump...) on a custom bracket and feeds my auxilary battery on a completely isolated system (except they have a common 0V)
If one of my altenators fails, I can change the system to a very conventional dual battery system with a 13mm spanner in about 5 min.
Of course I also have a large isolator switch between the batteries so the two systems can be joined for jump starting a flat starter battery.
The Auxilary battery also charges from 2x 100W solar panels hard mounted on the roof bars......

Early and late 300TDI defenders have different size pulleys (and a different length serpentine belt) - I think Disco 100A altenators have the same pulley as late 300TDI Defender altenators...?

Scott

[rick130]

Anyone know what the 100amp disco one does at idle? Pointless me putting in something that only puts out decent power at high revs


God, don't sweat it, it'll be fine, these aren't race engines.

The Deefer had a pulley size change in about '96 from large to small pulley too, just like the Disco.
The new Disco one I bought had the 'wrong' pulley for my 11/98 version so I just swapped the pulleys as;
a)I didn't have a long belt
b)I can see an advantage in a higher speed alternator for off road winching stuff too.

[2stroke]

I too have the Disco 100A alternator. My 130 is '95 so I used the belt and the smaller pulley that came with the alt. Couldn't see the sense in putting in a bigger alternator and running it slower than necessary.

[Michael2]

The D1 100amp alternator isn't just higher output, it's better quality with a sealed rear bearing.

I've got one of these and my next consideration would be a regulator from Sterling Power Products Australia (http://www.sterlingpower.com.au/)

They do a unit for $200 that acts as regulator and a 12V to 12V smart charger and charges batteries faster and to full capacity. I recently had what I thought was a dodgy reg on my alternator and inquired about bypassing the internal reg and using one of these - that would work fine, would require a solder though. In the end I had a loose wire, but this unit would give me some built in redundancy and better battery recovery after camping and running fridge and lights.

[PAT303]

I run 2x100A disco altenators on my 300TDI.
Not because I feel I need a max of 200A but for multiple redundancy.
The altenator in the standard position charges the start battery, the second altenator sits up next to the A/C pump (coverted to an air pump...) on a custom bracket and feeds my auxilary battery on a completely isolated system (except they have a common 0V)
If one of my altenators fails, I can change the system to a very conventional dual battery system with a 13mm spanner in about 5 min.
Of course I also have a large isolator switch between the batteries so the two systems can be joined for jump starting a flat starter battery.
The Auxilary battery also charges from 2x 100W solar panels hard mounted on the roof bars......

Early and late 300TDI defenders have different size pulleys (and a different length serpentine belt) - I think Disco 100A altenators have the same pulley as late 300TDI Defender altenators...?

Scott

I'd guess those alternators are costing you 10 or more HP at the wheels. :p. Pat

[bee utey]

I'd guess those alternators are costing you 10 or more HP at the wheels. :p. Pat
Why? I've spun up alternators with a power drill and they only draw power when they're doing some actual charging. The rest of the time they just freewheel.

[thrower78]

Disco alternator was an option until my local independent Landie place wanted 500 bucks for one. What a joke. Have to find a non genuine one or something else

[rick130]

Ring Karcraft and BMI.