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  #1  
Old August 2nd, 2009, 04:44 AM
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school me on increasing amps on alternator

I have a 2.8 Intl diesel with a bosche alternator. It is rated I believe at 60 amps. I would like north of 90 amps for my dual battery and electronics setup. since my alternator is also my vacuum pump, I need to keep it, but can I have it rewound to increase the output? if so, what are the pro's and con's and what is the max amps I can push through my harness before overloading it?
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  #2  
Old August 2nd, 2009, 06:42 AM
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Quote:
Originally Posted by Overlander
I have a 2.8 Intl diesel with a bosche alternator. It is rated I believe at 60 amps. I would like north of 90 amps for my dual battery and electronics setup. since my alternator is also my vacuum pump, I need to keep it, but can I have it rewound to increase the output? if so, what are the pro's and con's and what is the max amps I can push through my harness before overloading it?
On my friends 2.8 the plate where the vacuum pump would normally live on a 300Tdi is there, so if you remove it an look in, you may see the lobe on the camshaft where the vacuum pump is "powered" by.

If so, you could fit a 300Tdi pump then fit any kind of alternator that you can make fit in there.
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Old August 2nd, 2009, 12:12 PM
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Pretty sure thats a 90 amp alternator. I have been through this with a number of people/customers. You are better off to leave it alone. That alternator is superior to anything LR ever used. And you have an intercooler pipe clearance problem if you go with a larger alternator.

I have a large case 120amp Bosch I have built for engines that do not use the vacuum pump. If you want to install the factory pump or an electric vacuum pump I can have one made for you. It will just fit the area.

But as I said you will not overtax the alternator you have. Consider the amp draw used currently and weigh your options.
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  #4  
Old August 2nd, 2009, 12:15 PM
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Good to know that Bosch could be a possible spare for my Nippon Denso alt with vacuum pump that resides on my Daihatsu. Of course it's nice to have Japanese electronics and not worry about these things generally.
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Old August 2nd, 2009, 01:29 PM
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Quote:
Originally Posted by pendy
Pretty sure thats a 90 amp alternator. I have been through this with a number of people/customers. You are better off to leave it alone. That alternator is superior to anything LR ever used. And you have an intercooler pipe clearance problem if you go with a larger alternator.

I have a large case 120amp Bosch I have built for engines that do not use the vacuum pump. If you want to install the factory pump or an electric vacuum pump I can have one made for you. It will just fit the area.

But as I said you will not overtax the alternator you have. Consider the amp draw used currently and weigh your options.
Thanks for chiming in Pendy. I'm home on leave at end of August, and will double check, but I'm pretty sure it was 60-65 amp. Hopefully, I was reading it upside down!

Also good to know I have an option if needed, and that I can install a 300 tdi vacuum pump if I ever need a replacement.
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Old November 27th, 2011, 06:05 PM
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How can i identify which alternator I have on my 300tdi? There are no numbers or marks on it. it has a metal heat shield. My engine was installed in 04. I'm trying to figure out if I have the stock 65 amp or the 100. Do I need to upgrade it when installing dual batteries?
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Old November 27th, 2011, 07:44 PM
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You will be far better off buying larger batteries than buying a larger alternator, especially if you know how to hook them up with a smart alternator regulator and monitor. You want one battery to be constantly charged so you never need worry about starting the engine. This has been covered in many many posts.

Your 100 amp alternator on its best day with all aspects of the charging circuit in top condition will put out about 40 amps with the engine at full scream wide open throttle. The 65 amp one about 30-odd give or take a few.
You really don't get much in the way of alternator output with a low revving diesel, so you need a larger battery bank to keep the batteries from discharging dangerously.

Alternators are rated at their max RPM output, usually like 6500 rpm. Your diesel is never gonna get there.

What is the amp draw with everything (electrical) running? Add up all the watts and divide by 12.
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  #8  
Old November 27th, 2011, 08:34 PM
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Quote:
Originally Posted by o2batsea View Post
You really don't get much in the way of alternator output with a low revving diesel..
Are you on drugs? They install different pulleys on engines the rev lower so that the alternator still runs at the correct speed....
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Old November 27th, 2011, 08:59 PM
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Thanks, that's helpful. I have read all the posts on here related to dual batteries and 300tdi alternators and I didn't find any alternator recommendations when using dual battery set ups. My question was, is a 65 Amp alternator (assuming I have stock, I have yet to identify it) sufficient for two deep cycle batteries (870 CA, 55AH)? I guess in a roundabout way you have answered my question. I assume from what you're saying it'll be fine? I just want to make sure I won't constantly be driving around with under-charged batteries. Silly question, I know, I'm new to this.

Quote:
Originally Posted by o2batsea View Post
You will be far better off buying larger batteries than buying a larger alternator, especially if you know how to hook them up with a smart alternator regulator and monitor. You want one battery to be constantly charged so you never need worry about starting the engine. This has been covered in many many posts.

Your 100 amp alternator on its best day with all aspects of the charging circuit in top condition will put out about 40 amps with the engine at full scream wide open throttle. The 65 amp one about 30-odd give or take a few.
You really don't get much in the way of alternator output with a low revving diesel, so you need a larger battery bank to keep the batteries from discharging dangerously.

Alternators are rated at their max RPM output, usually like 6500 rpm. Your diesel is never gonna get there.

What is the amp draw with everything (electrical) running? Add up all the watts and divide by 12.
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Old November 27th, 2011, 09:13 PM
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Installation issues aside, how large a capacity alternator you need really depends on how much you drain your batteries and how quickly you need them recharged before the next drain. It also depends on how much reserve capacity your batteries have to handle loads that exceed the capacity of your alternator to supply.
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  #11  
Old November 28th, 2011, 06:05 AM
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Quote:
Originally Posted by Red90 View Post
Are you on drugs? They install different pulleys on engines the rev lower so that the alternator still runs at the correct speed....
The point is that the alternator will never get to its rated output RPM. Pulley ratio notwithstanding. Yes I am high on caffeine and sugar.

------ Follow up post added November 28th, 2011 06:31 AM ------

Quote:
Originally Posted by Manimal View Post
Thanks, that's helpful. I have read all the posts on here related to dual batteries and 300tdi alternators and I didn't find any alternator recommendations when using dual battery set ups. My question was, is a 65 Amp alternator (assuming I have stock, I have yet to identify it) sufficient for two deep cycle batteries (870 CA, 55AH)? I guess in a roundabout way you have answered my question. I assume from what you're saying it'll be fine? I just want to make sure I won't constantly be driving around with under-charged batteries. Silly question, I know, I'm new to this.
OK the reason for two batteries is to be sure that no matter how much you use one you keep the other fully charged and ready to start the engine. You want to be able to charge both, but keep them isolated from one another so that the lower one won't suck power from the fully charged one, leaving you flat.
You will need a split charging system.
One battery will be your dedicated start battery and the other will handle everything else...lighting, accessories, winch, reefer. It doesn't have to be a deep cycle battery. You don't use the "start" battery for anything but starting the engine.
You also need an emergency parallel switch just in case.
The 65 amp alternator will be able to charge the "house" battery and using a voltage sensing relay (VSR), bleed off excess charge current to the start battery. It will be plenty unless you are using high draw things like hair dryers, microwaves, and winching for long periods. Even if you do flatten the house battery, no worries, just start the engine and recharge the "bank".
If you do indeed use a lot of juice, consider keeping the two deep cycle batteries as a single bank and get a third start battery.
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  #12  
Old November 28th, 2011, 01:14 PM
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Originally Posted by o2batsea View Post
The point is that the alternator will never get to its rated output RPM. Pulley ratio notwithstanding. Yes I am high on caffeine and sugar.
But you seem to state that this is a diesel problem....... It would be WORSE on a gasoline engine as they normally run at a lower ratio to the maximum rpm....
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Old November 28th, 2011, 09:43 PM
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That's exactly where I'm headed. Thanks. This may be a stupid question. When you say that I shouldn't use the start battery for anything but starting, do you recommend moving all the house loads (everything that is drawing power through the stock fuse panel; lights, horn, signals, etc) over to the auxiliary battery as well? If the start battery truly is exclusively dedicated to starting then everything else should be on the other battery.

Quote:
OK the reason for two batteries is to be sure that no matter how much you use one you keep the other fully charged and ready to start the engine. You want to be able to charge both, but keep them isolated from one another so that the lower one won't suck power from the fully charged one, leaving you flat.
You will need a split charging system.
One battery will be your dedicated start battery and the other will handle everything else...lighting, accessories, winch, reefer. It doesn't have to be a deep cycle battery. You don't use the "start" battery for anything but starting the engine.
You also need an emergency parallel switch just in case.
The 65 amp alternator will be able to charge the "house" battery and using a voltage sensing relay (VSR), bleed off excess charge current to the start battery. It will be plenty unless you are using high draw things like hair dryers, microwaves, and winching for long periods. Even if you do flatten the house battery, no worries, just start the engine and recharge the "bank".
If you do indeed use a lot of juice, consider keeping the two deep cycle batteries as a single bank and get a third start battery.
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Old November 28th, 2011, 10:27 PM
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Quote:
Originally Posted by Manimal View Post
That's exactly where I'm headed. Thanks. This may be a stupid question. When you say that I shouldn't use the start battery for anything but starting, do you recommend moving all the house loads (everything that is drawing power through the stock fuse panel; lights, horn, signals, etc) over to the auxiliary battery as well? If the start battery truly is exclusively dedicated to starting then everything else should be on the other battery.
The idea of isolating batteries, which not everyone does, isn't to have one that's used only for starting. Your "stock" battery can continue for all normal vehicle needs.

Your secondary battery would be used for winching, auxiliary lights, high watt stereo, fridge, stuff like that. Things that would exceed your alternator's ability to supply without relying on battery power, or things you might power with the engine not running.
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Old November 28th, 2011, 11:06 PM
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It depends on your use. If you are interested in building a fail safe 12v system for off road use then you will definitely want two banks with a dedicated start battery.
If you simply wish to increase your reserve for occasional high demand, just parallel a second battery. Adding a second battery in parallel will more than double the life expectancy of both batteries.
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Old November 29th, 2011, 01:13 AM
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Thanks fellas for your conflicting, yet informative advice. My plan is to use all stock draws on the starter batteries and all frivolous accessories on the other. After much research and deliberation I have decided on the Blue Sea System ML series - Heavy Duty ACR (model 7622) as shown here: http://offroadpassport.com/forum/sho...0&postcount=39
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Old November 29th, 2011, 06:12 AM
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That's a good plan. I find that you cannot beat the prices and service from this guy
For the ACR, try Defender.com or go2marine.com
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Old November 29th, 2011, 09:16 AM
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Quote:
Originally Posted by Antichrist View Post
Your secondary battery would be used for winching, auxiliary lights, high watt stereo, fridge, stuff like that. Things that would exceed your alternator's ability to supply without relying on battery power, or things you might power with the engine not running.
Extra demand does not equate to the desire for isolation.

Running items with the engine off to protect the battery used for starting or protection from accidental discharge is a reason for isolation. If it is just extra load, they can be run without isolation.

I'm using one of these for isolation: http://www.powerstream.com/battery-isolator.htm Best price for a good automatic idolator I've found.
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Old November 29th, 2011, 10:10 AM
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With the ACR, you don't need a 1,2,BOTH, OFF switch. You do need a way to parallel the batteries. Easiest way is to simply have a cable on hand that you can install quickly across both POS terminals.
Also, don't use "marine" type battery connectors with wing nuts. Throw the wing nuts away and use hex nuts.
See the "electrickery" thread
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Old November 29th, 2011, 10:31 AM
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The ML series ACR's come with this particular switch (see photo). When set in the middle it is automatic but you can also force it to parallel and force it to isolate if need be. I already have an add-a-battery ACR and (gigantic) switch from BSS that I bought a long time ago but I decided to go with the HD ML series instead which has a 500 Amp capacity and a much smaller switch.

Thanks for the tips!

Quote:
Originally Posted by o2batsea
With the ACR, you don't need a 1,2,BOTH, OFF switch. You do need a way to parallel the batteries. Easiest way is to simply have a cable on hand that you can install quickly across both POS terminals.
Also, don't use "marine" type battery connectors with wing nuts. Throw the wing nuts away and use hex nuts.
See the "electrickery" thread
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