Swapping alternator

[mauricio_28]

In preparation for adding various and sundry electrics, I'd like to swap the alternator for a unit that provides higher current. I was thinking of looking for a replacement unit in stores that sell parts for Nissan heavy trucks. But then I thought that alternators must be engine-specific since their size and geometry must mesh in perfectly with the engine belt. Is this correct?

Btw, the rig is a d40 Nissan Navara.

 

[rambrush]

Alternators don't have to be vehicle speciic, you can mount a huge leece Neville bus alternator in there if you have room and can fabricate sturdy mounting brackets.
The problem though is modern vehicle wiring can only handle the amp draw that was intended. in other words they are making the wires smaller and will fry and barbeque if to much amps are pulled on them.
Dual batteries might be the best option.

 

[whatcharterboat]

The problem though is modern vehicle wiring can only handle the amp draw that was intended

Quite right. At work we sometimes have to fit larger alternators or more commonly we get the OEM alternators rewound so that they can deliver a lot more current, but you should definitely upsize the main charge wire (from the alternator to the battery) accordingly and feed the heavy auxiliary loads from the battery and not your main fuse panel.

The main reason we would do this is to handle the extra loads of audio equipment, spotlights, etc. although the biggest load we normally have to cater for is a second air/con unit which can pull serious amps continuously. Fitting a dual battery won't help at all in this situation, so if you do the math and your loads exceed what your alternator is capable of dishing out , get a bigger one or you will be continuously punishing your battery (even if there is 2 of them).

Regards John.

 

[roscoFJ73]

In preparation for adding various and sundry electrics, I'd like to swap the alternator for a unit that provides higher current. I was thinking of looking for a replacement unit in stores that sell parts for Nissan heavy trucks. But then I thought that alternators must be engine-specific since their size and geometry must mesh in perfectly with the engine belt. Is this correct?

Btw, the rig is a d40 Nissan Navara.

Correct about the belt alignment but they are not always engine specific. You may find the same alt on a golf course lawn mower .

If you have a local alternator/starter motor,AC comp specialist nearby ,they usually sell universal alternators that can be easily fitted to most vehicles.
Someimes,the guts of a more powerful alternator can be shoehorned into your existing alternator casing.
They also have a standard method of measuring the various mounting points.
Then they can look through books for a similar size.

Some alternators come in identical left and right hand versions for various markets/models
One may have a higher output and the internals can be swapped.

There used to be some good online resources to search but they seem to be drying up.
Sometimes a search under well known electrical brands like Denso or Bosch will lead somewhere.

 

[madizell]

Alternators produce current on demand. If all you do is replace the alternator with a higher rated unit, you don't have to alter the wiring because the alternator won't produce more than the system demands. it is all the secondary add-ons that increase demand and require heavier wiring, but having done that, you are now back to the question of whether you should upgrade your primary wiring. You are likely to have a small gauge charging wire with a fusible link built in. The primary wire should be rated for the full system, and the fusible link should still be used to protect the system in the even of a major problem, so the link has to be sized correctly as well.

On the other hand, it isn't that big a deal. If you overload the original primary charging wire, you will simply smoke the fusible link, and then you will know it is time to upgrade a bit. The first time I did this was during an extended winch recovery. The alternator went off-line and that was it. I replaced the charging wire and everything was fine.

 

[b1gsleep]

A few more questions

So If I were to upgrade my alternator with a higher capacity one could I just use a larger charging wire to the battery or would I need to run a fusing link like the stock wiring does?
I've heard somewhere else that you could easily over-charge the battery by simply putting a bigger alternator in, this is why double batteries become more necessary.
Also, is there a way to throw a larger stator in a alternator like you would in a motorcycle? Or maybe a smaller pulley to spin it faster?
Sorry for all the newb questions

 

[whatcharterboat]

So If I were to upgrade my alternator with a higher capacity one could I just use a larger charging wire to the battery or would I need to run a fusing link like the stock wiring does?

I'm quite paranoid about fusing everything as close as possible to the battery (or power source, or main circuit breaker, etc) and if for no other reason than to protect the wiring.

I've heard somewhere else that you could easily over-charge the battery by simply putting a bigger alternator in, this is why double batteries become more necessary.

Doesn't sound completely right to me. As madizell said "Alternators produce current on demand" and when your loads increase the alternator should supply current to match the loads without actually increasing the current into the battery itself. Did that make sense??? However sure, the battery capacity should probably be looked at also if the overall system is being upsized.

Also, is there a way to throw a larger stator in an alternator like you would in a motorcycle? Or maybe a smaller pulley to spin it faster?
Sorry for all the newb questions

Don't be sorry . These are really good brain teasing questions. As I said before, we get our alternators rewound to increase the current output and while I could easily say yeah it'll be right just do this or that I would really like to get a more "official" perspective. One of my best friends teaches Auto Electrics at Trade School and I hope to catch up with him on Sunday. Hopefully he'll provide some clearer "words of wisdom" for us.

So will get back to this next week. John

 

[rambrush]

Alternators are like a dumb device As long as they are a turning they produce power. It is the job of the regulator to manage the cash flow.
Yes you can put a smaller pulley to spin it up but again the regulator is going to control things.

Now the Toyota Sequoia has a optional 150amp unit that has been used on other applications. It was mentioned awhile back over on tundrasolutions forums.
Rewinding is possible but not always cost effective.

 

[eugene]

I've found that there are only a few makers of alternators and then only a dozen or so configs from each maker. So while it sould like a lot they are really somewhat standarized. Think like a wheel, you have diameter and width and hub size and number of bolts and bolt pattern. Alternators are similar, you have a few different choices of number of mounts, location of mounts, etc. If you can find a place that does rebuild them they can look up the specs and find one that matches closest.

What I did on my truck was added a second battery and isolator. I removed the factory charge wire from the alterator and connected to one battery terminal of the isolator then the other side of the isolator goes to the second battery and all my additions go to it. The new charge wire from alternator to isolator is sized large enough to handle the load of both.

 

[madizell]

Regarding the use of a charging wire without a fuse, yes it can be done. I have been doing it on my race Jeep for years simply because I sometimes put a lot of strain on the system due to extreme winching, and don't want to fool with a fusible link. The fusible link is to protect the entire electrical and wiring system from an alternator failure should the voltage regulator fail. An unregulated alternator can make a lot of power, and at the least, your battery would not last long. I prefer to carry the risk.

If my old CJ-5 ever had a fuse in the charging wire, I don't know about it, but not something I deliberately did. I just left it as I found it. I assume all of the other vehicles I have are all link protected from the factory.

Perhaps there is a resettable circuit protector available that would do the job. Not something I have looked into. I would just say that if you have a relatively stock vehicle and don't run a winch full out a lot, I would use a fusible link in the system and run it that way until it proves to be a problem.

 

[eugene]

Easier said than done. I was going to add a fusible link in my secondary battery circuit and between the alternator and isolator. I couldn't find ones that large anywhere. e-mailed a few places selling fusible links and no one could get one. Best solution I can see is some of the large mega fuses.

 

[ntsqd]

An advantage of a smaller drive pulley is that the alternator will "turn on" and continue to produce power at a lower engine speed. A disadvantage is that if the engine is rev'd high you could exceed the max stator speed of the alternator.

A Mega Fuse is exactly what we used on MISF's Scout II. I can not recall ever seeing a fuse of any sort between an alternator and a battery. I have seen fusible links on the output stud of an alternator, but those feed power to various circuits in the vehicle, not to the battery.

I personally dislike fusible links. They are cheap, but I'd rather have a breaker.
Up to 150 amps here: http://order.waytekwire.com/products/M37/140/200/300/1
If that is not enough, one can put multiple breakers or fuses in parallel. Sort of cumbersome, but it solves the problem.

 

[Backwoods Rambler]

You are likely to have a small gauge charging wire with a fusible link built in.

What are you considering small here? What guage? If I'm upgrading from a 90a output to a 120a output is that a big enough difference to be concerned?

 

[IslandRidge]

bigger is better with alternators

Just go for a 200amp alternator.

You will need it with lights, winch, radios, GPS, stereo, etc..

I bought one from these guys.. http://www.alterstart.biz/ they do a lot of selling on ebay... have very high rating, I am happy with 2 years of service on my Jeep with no problems.. they also have a "load" of info on this site..

here is there ebay store. http://stores.ebay.com/Alterstart

 

[wistacoma]

If your interested in an upgrade you should try these guys. They took my stock 70 amp alternator from my 2004 Tacoma and rewired it to 120 amps ($120). After two years the alternator bearings started making noise and I sent it back to them. They replaced bearings and voltage regulator and charged me a whopping $24 of which $13 was shipping. One day turn around from when they received it. Customer service at its very best!

Boyle Future Technology
12325 Locksley Lane, Auburn, CA 95602

phone: (530) 888-6290