Upgrading alternator on Lehman 135

Hi, I am in the process of upgrading my house batts to Agm super cycle total 940ah. I have twin 135’s in my DeFever 44 trawler. I want to upgrade the alternator on my starboard engine to dedicate to charging the house batts. Looking at the Balmar XT 250, should I add this as a second independent alternator and use twin v belts driving off the crankshaft alone, ( comes with complications and cost around install of brackets and tension bars and limited space) or go the easier route and replace the existing alternator and install a serpentine belt system.

Welcome thoughts and recommendations.

Thanks.

Graham.

I preferred to add a second alternator and keep the 2 systems independent as I only have one engine for propulsion. Below is an album with a series of pictures from the project.

https://www.trawlerforum.com/forums/members/1458-albums983.html

My preference for the alternator was a large frame 220 amp Leece Neville with an external regulator from Balmar.

Ted

Graham
You should be able to drive an externally regulated 110 amp 12 volt alternator off each engine with one belt and existing hanger. Assuming current setup has one alternator for engine starts and other for house batteries tie them together with a ACR or DC - DC charger. Leece Neville or Prestolite alternators are my favorites in this single belt amperage range.

For us normal cruisers with twins the above setup is simple and dependable. Any solar you hook up can easily be accommodated. One’s cruising style plays a big role in your onboard charging requirements.

I would go the serpentine route for a 250 amp alternator.

Grahambda said:

Hi, I am in the process of upgrading my house batts to Agm super cycle total 940ah. I have twin 135’s in my DeFever 44 trawler. I want to upgrade the alternator on my starboard engine to dedicate to charging the house batts. Looking at the Balmar XT 250, should I add this as a second independent alternator and use twin v belts driving off the crankshaft alone, ( comes with complications and cost around install of brackets and tension bars and limited space) or go the easier route and replace the existing alternator and install a serpentine belt system.



Welcome thoughts and recommendations.



Thanks.



Graham.

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Graham, on my DF44, I charge a FLA 920Ah bank using a single 100 amp Balmar on each engine controlled by a Balmar Centerfielder. When depleted to 50% SOC, it takes about 5.5 hours to get to full charge, the same amount of time when charged through shore power from 50% SOC. You do not need an XT 270. Do not be seduced by the seemingly faster charge acceptance rates of AGMs. It is an illusion. At one time, I had thought of adding the Balmar XT 270 and went so far as to adding double-belt pulleys. Then, after doing the Great Loop with my existing Balmars, I learned that it was all a waste, at least to me. The pulleys are still there on one engine. They look pretty.

I suggest you get in touch with Ian McLoud, another DF44 owner. He installed an AGM bank on his boat of about 1,300 AH, as I recall. You can find him through the DeFever Cruisers website.

You have a Lehman?

I would also suggest that you contact American Diesel to see if he has any advice.

https://americandieselcorp.com/

C lectric said:

You have a Lehman?

I would also suggest that you contact American Diesel to see if he has any advice.

https://americandieselcorp.com/

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With respect, why bother Brian with this question. This is a simple electrical question having nothing to do with the brand of engine. While I am at it, Graham, here is a picture of the reconfigured coolant hose I did on my FL120. Being unable to use the curved Balmar adjustable arm that I had, I instead used a turnbuckle which easily tensions the belt. I also included a picture on my now wholly unnecessary double belt on the other engine. Isn't it pretty?

I mentioned Brian because he likely is aware of questions like this and maybe he can recommend a kit.


Your reply and photos should help, a lot.

C lectric said:

I mentioned Brian because he likely is aware of questions like this and maybe he can recommend a kit.


Your reply and photos should help, a lot.

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Ah, yes, perhaps there is a kit. Thank you.

Yes, there was a kit available at one time, maybe still, that would change it to a serpentine belt. Don’t remember what the company was. Brian may know.

Comodave said:

Yes, there was a kit available at one time, maybe still, that would change it to a serpentine belt. Don’t remember what the company was. Brian may know.

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Changing to serpentine will require a new crankshaft pulley.

On a twin engine DeFever a number of single belt alternators are available that will quite easily provide the necessary charging amps for normal conditions. No need for a serpentine belt unless one has large draws or elects to do it for hobbyist and arguments sake.

With the multitude of choices for batteries, alternators, BMSes, inverter/chargers, gensets and solar panels simplicity and reliability often get overlooked. I often remember a good friend who cruised with two big dogs and had a very big chest freezer to store dog food for long journeys. His entire vessel's charging systems were dog and frozen fish dedicated.

My point, individual needs and comfort determine our respective vessel's electrical setups.

catalinajack said:

Changing to serpentine will require a new crankshaft pulley.

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I believe that the kit I saw had the adapter that slid over the existing pulley.

Comodave said:

I believe that the kit I saw had the adapter that slid over the existing pulley.

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Yes, there is, indeed. But it is still a new pulley.

catalinajack said:

Yes, there is, indeed. But it is still a new pulley.

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Well of course if you have a Vee belt pulley and go to a serpentine belt it will require a new pulley. My point was that the kit I saw had a new pulley that slid over the old one.

Comodave said:

Well of course if you have a Vee belt pulley and go to a serpentine belt it will require a new pulley. My point was that the kit I saw had a new pulley that slid over the old one.

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I recall looking at that kit when I had thoughts of replacing the Alt on the GB36, but dismissed the idea due to cost for 50% more amps. It did not make sense for my needs. But a larger house bank scenario, it does make sense.