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Old 11-08-2010, 10:31 AM   #1
Rob
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Ford Lehman Alternator Upgrade

Our boat is powered by a single Ford Lehman 120. The electrical system/alternator is a stock unit which I believe to be about 55 Amp, the tachometer signal is derived from the alternator. I would like to upgrade the alternator to a larger unit, say nearly double the output. I have heard that there is a "Balmore" unit that can be installed. What all is involved with upping the size of the alternator. Please keep in mind that I need to get the tach signal from the new alternator. The reason that I want to increase the alternator output is so that I can get a better charge on my house batteries and decrease the run time on the generator set.
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Old 11-08-2010, 10:49 AM   #2
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RE: Ford Lehman Alternator Upgrade

Call Bob or Brian Smith at American Diesel. They know more about Lehman engines than just about anyone and they can tell you what is required to put a larger alternator on the engine. I believe you need to double the belt and so will need a new pulley for the front of the engine. They also may recommend running a separate belt for the water pump as putting a lot of sideways pressure on the coolant pump of an FL120 is a good way to shorten the bearing life.

But talk to them--- they will be able to tell you the best way to do it and probably have all the parts you need.
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Old 11-08-2010, 10:51 AM   #3
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RE: Ford Lehman Alternator Upgrade

This upgrade is a relatively simple procedure and I believe any new alternator will be able to provide input to the tach. The only drawback is the bigger the alternator, the more is will take away from the engine's power (a few HP less to move the boat).
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Old 11-08-2010, 11:01 AM   #4
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RE: Ford Lehman Alternator Upgrade

Rob, Rather than replace the alternator, think about adding an external regulator which will allow you to control the charge. Even with a larger alternator you would want this if you plan to be away from the dock for long periods. Chuck
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Old 11-08-2010, 06:32 PM   #5
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RE: Ford Lehman Alternator Upgrade

Replace the regulator first as Chuck suggested.

A larger alternator without an external three stage smart regulator will simply run through the bulk charging quicker, won't take long, and then basically shut down. The smart reg. will keep the smaller alternator putting out far longer with a better recharge overall.

I went through this but I did replace the reg. first with an Ample Power reg. It wasn't untill we started staying out for weeks at a time that I finally changed the alternator to a 150A , derated to 110A, and the total pkg , reg. and larger alternator makes a huge difference.

Best of course is get both at the same time.
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Old 11-08-2010, 07:14 PM   #6
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RE: Ford Lehman Alternator Upgrade

If you do upgrade the alternator, look here* (I think this link originally came from FF):

http://www.saase.us/index.php

They have (for example) a brand new 12V 120A Delco unit for $129.00.* They carry Delco, Prestolite, Leece-Neville, and Bosch units for commercial busses and big rigs.

As to the marine-vs-vehicle debate,* an over-the-road truck alternator is exposed to 130+ degree heat, -20 degree cold, rain, salt spray, and dirt-dirt-dirt.* My engine room isn't the nicest place in the world, but it sure is a lot more pleasant than that.

The external regulator is mandatory for big alternators.* Not only does it give the appropriate charging cycle, but it also compensates for the voltage loss in the wire between the alternator and the battery - it is signficant at the high amperage.* An alternator *temperature sensor is an option on some of them - not a bad idea.
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Old 11-09-2010, 04:22 AM   #7
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Ford Lehman Alternator Upgrade

Hiya,
* Mr. Rob.* I think Mr. Fotoman is correct in that most any alternator will provide a "tach pulse".** Mr. Marin,*I don't think double belts are necessary until you get above 110 amps or so.* Also Mr. Marin, is there any mod' to re-route that belt around the gosh darned expansion tank hose so I don't have to drain coolant to change the belt?* I know about the spare belts around the hose trick.

-- Edited by RT Firefly on Tuesday 9th of November 2010 05:26:36 AM
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Old 11-09-2010, 05:23 AM   #8
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Ford Lehman Alternator Upgrade

Change the belts next time you flush and change the anti-freeze. I do this every three years. If you need an emergency belt, carry one of those universal orange ones, but I bet you'll* never need it if you follow the recommendation above.

One thing to be careful of when upgrading an alternator on a Lehman is the increased side pressure on the water pump bearing. If you just slap a bigger one on there without giving this some thought, you'll start burning up water pumps. Again, Bob or Brian Smith at American Diesel can help you out with this.

-- Edited by Keith on Tuesday 9th of November 2010 06:25:42 AM
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Old 11-09-2010, 08:26 AM   #9
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RE: Ford Lehman Alternator Upgrade

"is there any mod' to re-route that belt around the gosh darned expansion tank hose so I don't have to drain coolant to change the belt"

yes I agree this is a riduculous design.
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Old 11-09-2010, 10:54 AM   #10
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RE: Ford Lehman Alternator Upgrade

Quote:
RT Firefly wrote:Also Mr. Marin, is there any mod' to re-route that belt around the gosh darned expansion tank hose so I don't have to drain coolant to change the belt?* I know about the spare belts around the hose trick.
Not that I'm aware of.* While it's a relatively minor "fault" it's one of the many things that makes an FL120 an engine to be avoided in a boat if one has a choice, in my opinion.

Ford of England designed the base engine to be a truck engine so it was intended to be hooked up to a radiator, not a header tank.* When Lehman Bros. created the marinized version back in the 1960s the "hose through the belt loop" was the simplest and most obvious way to hook up the tank.

So the wire-tie-the-spare-belt to the engine is the only practical solution I've ever seen.
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Old 11-09-2010, 01:26 PM   #11
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RE: Ford Lehman Alternator Upgrade

Attached is a photo of a 'behind the belt' conversion for the coolant hose.* I don't know where I found the photo or who did the work.

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[img]download.spark?ID=824883&aBID=115492[/img]
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Old 11-09-2010, 02:40 PM   #12
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RE: Ford Lehman Alternator Upgrade

Hiya,
** Thanks Larry and welcome to the forum.
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Old 11-09-2010, 04:13 PM   #13
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Ford Lehman Alternator Upgrade

Balmar makes a drop in replacement for the stock alternator. The 100 amp version will run with just a single belt. Get the ARS5 or MC614 external regulator. We installed a Balmar 6-series 100 amp on each of our FL120's six years ago. Have the two regulators connected to a Centerfielder unit so they both feed our 1350AH battery bank. Works like a charm.

Give Balmar a call. They will be happy to chat with you and answer any questions you have. I have had a couple of issues to resolve over the years and they have always responded quickly.


Their web site is www.balmar.net but it looks like they are going through a much-needed redesign.


-- Edited by ktischler on Tuesday 9th of November 2010 05:14:07 PM

-- Edited by ktischler on Tuesday 9th of November 2010 05:28:53 PM
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Old 11-09-2010, 04:27 PM   #14
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RE: Ford Lehman Alternator Upgrade

There is a water pump available with the output in the 2 o'clock position, rather than the standard 5 o'clock outlet. This allows you to route the hose behind the alternator belt. They are often available on ebay. Kind of expensive way around the issue, but if you need a new water pump anyway, it is something to consider.

For now, I am happy to just tie wrap a spare belt in place. I only had to drain hot anitifreeze in a rolling boat once to know I was never going to do that again!


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Old 11-09-2010, 06:44 PM   #15
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RE: Ford Lehman Alternator Upgrade

I'd like to thank everyone for all of the great info. This is my first posting on trawlerforum, and I'm very pleased with the results. I beleive that I'm going to go the Balmore route as that is the setup that my friend on "Northstar" has on his Willard trawler, but I wanted to hear other boaters suggestions. Again, Thanks!
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Old 11-09-2010, 10:25 PM   #16
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Ford Lehman Alternator Upgrade

Robb,* we should chat before you make a final decision about a Balmar.* It's true that you can run a single belt up to about 100 amps, but the single pully Balmar I installed has a hard time putting out that kind of current for very long.* When an alternator gets hot, the output drops, sometimes a lot.* The Balmar likes to run well over 200 degrees, which is way too hot.* They sell a temp sensor that you bolt to the alternator, and it reduces the charging current to reduce the heat.* In the long term, the heat will destroy the alternator.* A large frame alternator will better disipate the heat, but there may not be room.* If I had to do it over again (and I'm sure I will since it runs so hot) I would use a different brand, probably Leece-Neville, and spend a lot less money.......Arctic Traveller

-- Edited by Arctic Traveller on Tuesday 9th of November 2010 11:26:57 PM
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Old 11-10-2010, 03:48 AM   #17
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RE: Ford Lehman Alternator Upgrade

I would use a different brand, probably Leece-Neville, and spend a lot less money.

Truck store "prestolite" label, large frame 135A about $135.00, but its not "marine" so should not be on a gasoline powered boat.

All of the more industrial alts will have a graph of output vs temp vs rpm on their web sites.

High output is silly , unless the batt bank is huge AND the unit is controlled by a 3 or 4 stage aftermarket V reg.

The auto/truck charge profile is for start batts , where frequently tiny amperage is used , and to power fans , blowers and lights.

1/2 if what is needed per hour is its charge profile . Use a few amps for start , no sweat BUT

50% down (say 50A on a 100A bank) and it will charge at about 25A +10A , 25 the batt needs plus 10a to push it in.

After an hour 12.5A plus 5a to push it in.

As noticed it takes a looong time to get to the 100% charged that the deep cycle need to not loose capacity.

A 3 or 4 stage V reg WITH TEMPERATURE sensing is needed if charge times are to be realistic.

A batt bank usually is happy with 20% of its 20 hour rate as max charge.

The advantage (if there is one of spiral AGM) is they can accept higher initial charge , if you can create it.
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Old 10-13-2016, 08:15 PM   #18
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Quote:
Originally Posted by jleonard View Post
"is there any mod' to re-route that belt around the gosh darned expansion tank hose so I don't have to drain coolant to change the belt"

yes I agree this is a riduculous design.
Here is a shot of my Lehman with a different layout that doesn't have that problem
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Old 10-14-2016, 08:39 AM   #19
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Quote:
Originally Posted by Marin View Post
Call Bob or Brian Smith at American Diesel. They know more about Lehman engines than just about anyone and they can tell you what is required to put a larger alternator on the engine. I believe you need to double the belt and so will need a new pulley for the front of the engine. They also may recommend running a separate belt for the water pump as putting a lot of sideways pressure on the coolant pump of an FL120 is a good way to shorten the bearing life.

But talk to them--- they will be able to tell you the best way to do it and probably have all the parts you need.
WHat he said!

talk to Brian
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Old 10-14-2016, 08:45 AM   #20
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Originally Posted by FF View Post
I would use a different brand, probably Leece-Neville, and spend a lot less money.
Yes, but be aware,Leece-Neville does make alternators which by looks and fit, seems exactly the same, but it weighs 1/2 as much

Basically, it's a car alternator. It's not made to produce high amps for long periods.

I bought one, it's my emergency spare, as it's footprint and connections are the same. But if I ever have to use it, I would have to run the gen to keep the batteries up and stop the alternator from destroying itself.
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