Replace alternator with higher amperage

[Chris]

Right, so it is wired as I thought. I hadn't considered the short circuit bit during start up - which is why I haven't connected a wire! So, the charging cable to the system is done with decent but not huge cable as it's only carrying charging currents. But the return cable to the driver's battery is much thicker, not because of the parallel charging currents under normal running, but because of the series link and big whoomph on starting to provide current to the starter system. When it isn't doing that, it is simply over spec for what it's doing. If I can put it like that. So any additional current carrying cable must mirror the original path, if we go that way.

I have stuck an extra earth in from the alternator though. That bit didn't confuse me.

Chris

 

[wobbly]

Going back to the very first post by Rob.

If the higher spec car has a larger alternator, why not check the part number for the alt to battery cable and see if its different to the part num of the one on your car.

If so, could do with upgrading, if not then manufacturer happy with the spec then no need to worry.

Bit late I know......

Pete

 

[Rob]

I later found out that the loom is the same on all petrols for that car so no problem fitting the larger alternator.

 

[tokaido]

Hi guys,

Thank you chris and rob, i've replaced my 80amp alternator to 110amp and its working superbly. Its all because from your discussion and opinion. Only one thing should do: we must add another thick cable/wire from the alternator direct to the battery to let the current flows smoothly due to prevent current 'traffic jam' to the oem cable. Am i right?

 

[Chris]

Well if you read my post at the top of the page I have already answered that. I have put an extra earth in but not an extra supply cable. I'm not sure it's necessary. I may upgrade the thinner section at some point but it's rare you will be pulling full current in any case. Unless you have huge loads on there, it will only be supplying the same amperage as the small original. Unless you are doing a massive winch exercise or something, the unit isn't going to ramp the amps.

 

[tokaido]

Hmm... there are many more i must learn....ok, its better if i just follow your advise. Fortunately, I already have the spare earth cable in the store... the good one from Sun Auto; Hot Inazma from japan. Thanks again Chris.

 

[tokaido]

Hmm... there are many more i must learn....ok, its better if i just follow your advise. Fortunately, I already have the spare earth cable in the store... the good one from Sun Auto; Hot Inazma japanese made. Thanks again Chris.

 

[Chris]

You're welcome. I may still run a second cable in there, but not convinced it's necessary. I have wondered if I could run a second cable from the alternator but to the spilt charge instead. I'd remove the link to the main battery and chargethe rear one directly. Well, it's just a thought in my head not a plan. When running the rear winch hard, I'd like the alternator to be sending everything it can, to the rear. Hmm, maybe a second alternator!

C

 

[Nuclear Chicken]

No point upgrading the alternator without the supporting infrastructure. Fire waiting to happen it you melt a cable. 100A+ is a lot of current.

Sent from my Galaxy Note

 

[Chris]

Sorry but that's simply an unqualified comment. Unless you know the capacity of the original cable then how can you say that it needs upgrading? This is no thin wire, the cable that comes from the alternator is pretty thick. Given the thickness of a winch motor cable and the cond of current they carry plus the wiring that comes with a split charge system, I'd say that there was little danger of setting melting the original. Sorry, but there it is. I have winched a great deal on this vehicle and having felt the charge cable it wasn't even warm.

I agree completely that a cable needs to the correct rating, but this isn't guess work. Look at what jump leads are rated at in terms of continuous current. The alternator lead is as thick as those at least. As for times when the vehicle is actually pulling 100 amps, it's not that often either.

Let's not frighten people without facts.

 

[Nuclear Chicken]

Definitely not unqualified! It's not a given that the original cable will handle the additional current. lt takes very little to start a fire with the low impedances and very high current found in batteries and alternators.


Sent from my Galaxy Note

 

[Chris]

I did say I agreed entirely that high current, too small a wire is an issue. You're dead right. Remember I lost my first 80 in an electrical fire. But you can't simply can't say it's necessary to upgrade a wire when you don't know what the capacity of the wire is. No, it's not a given that it's good enough. But it's not a given that it isn't either. Hence me saying that to have to upgrade it was unqualified. It is necessary to see if it needs to be upgraded. So far my findings have been that under high output conditions running two winches and three batteries, the cable hasn't even got warm. Mine is a 120 amp alternator too, not a 100.

It's right to be cautious but let's establish some facts first.

 

[Chris Green90]

All very interesting stuff here chaps. I have just had to replace my alternator as Lincomb sand didn't do it any favours (looks like it was on it way out anyhow). I replaced it with a 205a Load Boss one from a chap up in Scotland. The one I bought looks like it was designed for the 1KZ-T engine not the TE I have in the Dirty Gal so it mounts on the passenger side of the engine as opposd to the drivers side. It was only 75 quid though and TBH I did not realise it would not fit until it arrived. Figuring it would cost me £25 inc the post I had already paid to send it back plus another £50 to get a standard one from elsewhere I decided to strip it and the old one down and swap the new gubbins into the old housing. In the paperwork it explicitly tells you to replace the existing charge cable and put in a larger fuse. Nothing said about the ground cable though. well seen as though I had some winch wire handy I did so.

It seems a good piece of kit. Not been able to test it with any major load but bloody hell do the windows go up and down quick. I can scan of photo or something the data sheet if anyone is interested (showing the lab testing but IIRC it produces about 110A on tickover. and the full 205 at 2500 rpm. That IMHumbleO has got to give winching a good old helping hand.

P.S. Keyboard Breathalyzer not working

 

[Chris]

I'm the wrong person to explain these things, but a 100 amp alternator doesn't just produce 100 amps. it is CAPABLE of producing 100 amps. Until then it like driving a Fiesta against a Pagani Zonda. At 70 mph they are both doing 70 mph. No difference. But the Zonda is capable of more. But only if you require it to. If you have a 10, 000 amp alternator but only ever ask 60 amps of it - that's all it will do. It's an 'on demand' device. There is little that is driven directly from the alternator. Most power comes from the battery and the alternator puts the power back into the battery as it's used. Having a bigger alternator means it can do that faster. I appreciate your windows might be much faster, but that may and I stress MAY (cos I isn't a scientist, is it) be more indicative of your battery.

Delighted to be corrected, but you could fit a monster alternator and it never get anywhere near what it can do because you cannot create the demand. A standard 80 amp unit should be capable of replenishing the battery with you lights, heater, demister, CD on etc. That may well entail full load. I have a bigger unit because of the rear battery and my tendency to use the rear winch a lot. I need that capacity replacing fast. But there's no alternator that can supply a winch at full pull. ie if you removed the battery, would the alternator run the winch load? Nah. It needs the battery as a buffer. So, again as an amateur, I think it's unlikely on a standard motor, or at least in standard driving, that your alternator produces anything more than the old one did when it was working properly. Raising the revs doesn't necessarily raise the output. More volts yes between 12 to 14.4 but not necessarily more amps. Producing 110 on tick over I presume is with some sort of load. If there isn't any, it doesn't produce any current?

Someone with a science brain please confirm or debunk the theory here. Anyhoo, glad it's working for yah, buddy.

Chris

 

[tokaido]

Yes, I agree also with chiken nucklear opinion, precautions are important, but as chris said: It's right to be cautious but in the same time let's not frighten people without facts. My wife's car just only 1.3L engine but the alternator is 90amp, while my car 1.8L turbo engine but the alternator is only 70amp. We can see the power differences from these two car. I asked the baterry shop recently: i wanna buy the battery that can stand 100amp alternator. But they said to me: you can use any kind of the automotive battery as long as the alternator supply 12v with adding additional wire/cable (as chris said).

What i understand here: Caution is important, safety first; but with fact and always ask someone if you dont know.

 

[tokaido]

If you have a 10, 000 amp alternator but only ever ask 60 amps of it - that's all it will do. It's an 'on demand' device.

Chris

You are truly damn right chris. My brain starts to think many things to do with my machine.

 

[fridayman]

Can anyone tell me how much current the alternator is delivering when my batteries are being charged when they are linked, my starter is already full ie [email protected], but my 105a leisure battery us down to 12v or 50%?

 

[Chris Green90]

I'm the wrong person to explain these things, but a 100 amp alternator doesn't just produce 100 amps. it is CAPABLE of producing 100 amps. Until then it like driving a Fiesta against a Pagani Zonda. At 70 mph they are both doing 70 mph. No difference. But the Zonda is capable of more. But only if you require it to. If you have a 10, 000 amp alternator but only ever ask 60 amps of it - that's all it will do. It's an 'on demand' device. There is little that is driven directly from the alternator. Most power comes from the battery and the alternator puts the power back into the battery as it's used. Having a bigger alternator means it can do that faster. I appreciate your windows might be much faster, but that may and I stress MAY (cos I isn't a scientist, is it) be more indicative of your battery.

Delighted to be corrected, but you could fit a monster alternator and it never get anywhere near what it can do because you cannot create the demand. A standard 80 amp unit should be capable of replenishing the battery with you lights, heater, demister, CD on etc. That may well entail full load. I have a bigger unit because of the rear battery and my tendency to use the rear winch a lot. I need that capacity replacing fast. But there's no alternator that can supply a winch at full pull. ie if you removed the battery, would the alternator run the winch load? Nah. It needs the battery as a buffer. So, again as an amateur, I think it's unlikely on a standard motor, or at least in standard driving, that your alternator produces anything more than the old one did when it was working properly. Raising the revs doesn't necessarily raise the output. More volts yes between 12 to 14.4 but not necessarily more amps. Producing 110 on tick over I presume is with some sort of load. If there isn't any, it doesn't produce any current?

Someone with a science brain please confirm or debunk the theory here. Anyhoo, glad it's working for yah, buddy.

Chris

I appreciate what you are saying here Chris. The main reason I got this one was that it was Cheep. I understand that the alternator will only produce the power that is required but figure that it must be better to have something that is only running at 20% capacity than running something full tilt all the time. I upgraded the wiring because it said to do so and I had some in the shed. also the existing cable didn't seem very thick at all, about 4mm. again I can't see it being a problem going thicker and it seemed to me to be a sort of cheep/free insurance policy.

 

[Chris]

Can't argue that buddy. Bigger is unlikely to be a problem. Now as to whether 70 amps running full chat or 70 amps with ease is different - I have to declare my ignorance. I simply don't know. I have no idea of the relationship of output on an alternator V the strain placed upon it. 4 mm sounds very thin to me and it maybe that you have seen an improvement because of that. I think that where the instructions say it's necessary to upgrade is because they assume you are doing so in line with increased demand. If I put a bigger unit on my Missus' car, I wouldn't upgrade the wiring as there's no additional load potential.

Chris

 

[Rob]

When the battery is flat and your running the winch then you will most certainly be maxing out any alternator.

Taking your Fiesta and Zonda analogy further Chris, it would be like fitting the Zonda with the same tyres as the Fiesta (assume they fit) and then disconnecting the speedo on both cars. Although the Fiesta tyres should be good for 120 mph and you will notice if you are breaking the speed limit with enough reserve to ensure your tyres will not fail, you be mad to fit the Fiesta tyres to to Zonda in case you do go well above 120 mph. In the Fiesta it's not an issue as even though you have no idea how fast you are going due to lack of a speedo, you do not need to worry about the tyres. The tyres is the charging cable and the lack of speedo demonstrates the fact the you have no idea how much current is actually being drawn from the alternator.

My recommendation is always use wiring that will be able to handle the maximum possible current that can be produced or drawn. So if you use an alternator that is can produce x amps then ensure the charging cable is rated to carry at least x amps. If you wish to reduce the wiring diameter then fuse it accordingly. I'm sure we have discussed this in great detail earlier in the thread.