how big an alternator can you install? and what horn sounds the best?

[glbft1]

Hello all,

Was wondering how big an alternator can you install on a series 2a 109 without frying anything?( running winch and lights)
Also wanted to get a new horn wanted the European high tone horn just want a cool sound!
Thanks
Greg

[I Leak Oil]

If the truck has an ammeter get rid of it. Wire the alt. direct to the battery. Wire the accessories correctly and you won't have any problems running as high an amp alt. as you wish. Whether or not the stock belt setup will drive a super high amp alt. is a different story though.

[albersj51]

I'm running a 78 amp on my 2a with no problems. As stated, disable the ammeter to avoid pegging it and then angering the Lucas Smoke Monster.

[glbft1]

what is a ammeter? sorry still on the quest for all things rover:thumb-up:
Regards
Greg

[gudjeon]

An ammeter takes a measure of current of the charging system. Personally, I like installing a voltmeter instead. For onr thing, they are cheaper, and measure the state of voltage for your entire system, not just what the alternator is doing. So with this, you can see if it is actually keeping up to the electrical load of the devices. I run a largish Delco alternator and have no problems with it charging on running a single belt.

A larger alternator will not fry anything if the the rest of the system is up for it. A small output dynamo or small output alternator is just as capable of "frying" the electrical if anything goes wrong. A high output alternator can keep up with the draw of high demand (high amperage) devices like a winch and aux. lights. The idea is that you can have your stuff turned on like lights, heater, wipers, etc and still have enough capacity left over to charge the battery while driving.

Think of amperage of "heat" or power and Voltage as the pressure to push it through the wires.

[stomper]

This link was posted on another forum, about the differenced between an ammeter and a volt meter. I will give credit to the original poster, who is on this board too, Safeoneair.:thumb-up:
http://www.egauges.com/ATM_Tips.asp?TipPage=voltmeterammeter.htm

[Terrys]

Greg, an ammeter is a current measurement device. In automotive applications, they are used to measure the current drain from the battery, and Zero, indicates current drain from the battery is matched by current output from the generator. If it's reading positive, you are giving back to the battery more than you are draining from it. When it's reading negative, you're drawing more from the battery than the generator is puting back into the system. In older, generator applications, the zero center ammeter had a range greater than the generator, and was wired into the system between the battery, and all loads (Heavy Brown wire) Older Land Rovers had an ammeter range of about 30 amps, but you can replace it with a higher capacity ammeter, like -60 - 0 +60. They generally don't go higher than 80 amps without having to go to an external shunt. The general thought process is that a voltmeter (really just an ammeter) that reads up to 16 volts or so, gives more information. It doesn't really give you more information, it is just a better indicator of battery condition. An ammeter still tells you more easily to what extent you are loading down the system.
Technically, all voltmeters are ammeters, whose scale is in volts. They have a known, fixed internal meter resistance (like a small load), and because they are parallel to the loads, act like a current divider ( Ohms law E=I/R)

[glbft1]

I looked on my dash no ammeter at all, do hve a red light that comes on until i rev up the engine a little and it goes out then stays out... is it possible it never had one?
Thanks
Greg

[SafeAirOne]

is it possible it never had one?

VERY possible. Probable, in fact.



I will give credit to the original poster, who is on this board too, Safeoneair.:thumb-up:

He has a screen name very similar to mine! ;)

[SafeAirOne]

Oh...As for which horn sounds the best, it's pretty subjective, but I like this one (http://www.superiorhorns.com/media/upload/file/1001.wav).

[LR Max]

I have a 70...or 90??? amp alternator off of a Jag. Works well with my extra lights, winch, etc.

I have the hella horns. It sounds like one of the jeeps off of MASH.

[Nium]

I'm kinda partial to air horns. Like that you would see on a mac truck except a little smaller so it'll fit under the hood. Definitely not original to a Landy but one blast of that thing and anyone on a cell phone with the music blaring will definitely hear you coming. If your close enough you may even scare them off the road.

A down side to an ammeter that wasn't mentioned is that they have to be wired in series with the load being monitored. Which means an unfused line from the alternator through the firewall to the ammeter on the dash and back out to the solenoid. Kinda dangerous (IMHO) because of all the electricity flowing through it. If a fuse was put in line with the ammeter then the alternator would fry itself if the fuse blew. A self resetting circuit breaker could be used instead of a fuse but expensive and hard to find. Voltmeter definitely safer and less likely to cause a fire if the wire insulation gets knackered and grounds out.

Size of alternator...as big as you can fit in thar, but do you really need some monstrosity? What are your plans?

[siiirhd88]

I have a 140 amp standard size Delco on a Pangolin mount on my 109. The wife's 3.9 V8 109 has a similar 140 amp Delco for normal loads and a second big case 140 amp Delco for the winch battery and other accessories.

I run a single belt to each alternator, but it is recommended that anything over 100 amps should be driven by twin belts.

I have the standard barely audible horn on my 109. The wife's 109 has triple Fiaam (sp?) air horns, with the SIIA horn button closing the ground on a relay that powers the air compressor.

Bob
'02 Disco II SD
'80 SIII 109
'75 SIII 88 V8
'68 SIIA 109 V8

[glbft1]

I wanted to just run a winch extra lights one set and a cb the alt has double belts now will clean up and see what size, the PO had the generator switched out and a alt installed with a new brace pieces( aftermarket alt holder)
It has a optima yellow top battery the goal was maybe increase the alt to work the heaver draw..
Thanks everyone !!
Greg

[LR Max]

Yeah, do the AC Delco swap and when winching, keep your RPM's around 2k.

You won't have any problems.

When I do my once-a-month winch, I leave the truck off and winch in the entire 100~ish foot of rope. There is plenty of juice left in the battery (granted, it is a light load on the winch but still it is running for a while).

[greenmeanie]

If you have a 3 wire system you can run as big an alternator as you can imagine. It will only put out the amps on demand so as long as it is rated to meet your max load (Sit down and calculate this rather than guessing at teh biggest unit you can fit) you'll be just fine. Note that you usually have to run the engine at a minimum rpm for the alternator to be producing any output so, unless you are lucky, or have played with the pulleys to get the correct rpm, it won't be doing much at idle. A hand throttle helps here.

Of more importance to your original question is the gauge and condition of the wire in your charging system. Its been a long time since I looked at an original Rover wiring loom but IIRC the charge wire is 12AWG which should be good for about 25.5A. Someone can correct me on that. I would want a minimum of 10AWG (Preferably 8AWG) and probably double it up to the main load point if I was running a winch. I'd also install a Maxi fuse in the line to protect the truck if the alt control goes wrong.

[JimCT]

Output drops off dramatically as the case heats up, so do not be too hung up on output. That is why alternators for ambulances for example are large cases for cooling. Also if the fuse blows on the alt. output it fries the alt, sending it to full field.

[greenmeanie]

Output drops off dramatically as the case heats up, so do not be too hung up on output. That is why alternators for ambulances for example are large cases for cooling. Also if the fuse blows on the alt. output it fries the alt, sending it to full field.

Not that I know anything but case temperature may be what you look at but it is the resistance in the magnetic wire and to a small degree a loss of magnetism that affects output due to heat. The fan and the design of the casing to allow for airflow both over and through the unit are of more importance than casing size. The casing, after all, only conducts heat from the stator and does very little for the rotor.

You can only push so many amps through a given cross section of wire or obtain so much magnetic field from a given size of magnet unless you go with something fancy. Bigger units for a given rating merely have larger copper and magnets which gives them a greater margin when it comes to generating heat. Heat is energy loss so the bigger the unit for a given rating the more efficient it will be in broad terms. As you move to bigger units you also tend to see less PM alternators and more wound field units which, again allow for increases in efficiency and thermal resilience.

The fan and the design of the casing to allow for airflow both over and through the unit are of more importance than casing size. The casing, after all, only conducts heat from the stator magnets.

I'll admit I'm used to bigger units that include a thermal switch as an added protection against overload which you probably don't get on a cheapy automotive unit. If you install the correct fuse its failure point should be greater than the rated output of the generator but less than the wiring harness. If the fuse blows it is indicative that the alternator is already overloaded so you have a failure in your charge system. I'd rather slag the alternator than have it melt the harness with associated fire risk.

[JimCT]

All true, just wanted to make sure folks knew they need a nice buss fuse in the output and not a small inline automotive type

[amcordo]

I used this horn:
http://www.sherco-auto.com/Merchant2/merchant.mvc?Session_ID=fcbb9d09fb102abb61ddb6f56f 3e8a61&Screen=PROD&Product_Code=HN-1

It's very loud and it has a nice higher-pitched european sound to it. It seems right inside the rover.

[xsbowes]

Output drops off dramatically as the case heats up, so do not be too hung up on output.

you could install an alternator cooling system similar to what BMWs use. Quikcool for example.