Alternator upgrade questions

[Benjamin85]

I have a Perkins 4.236 with the standard ac dealco single foot 65 amp alternator. I have two lead acid flooded cell battery banks (excluding the house battery) that totals roughly 800 ah. All batteries and charging sources are connected to what looks like an isolator and only charges the battery banks that need it (so I’ve been told and so the Victron battery meters show). We do not have the cash on hand to upgrade to a lithium battery system yet but do need a larger alternator. My question is is it worth it to upgrade to a serpentine kit now and get a larger alternator or get a dual foot alternator (the fly wheel has a dual belt configuration to run another belt). Also because we eventually want to upgrade our lead acid battery bank with lithium (about 4 years from now) we don’t want to undersize an alternator to much but we also don’t want to get to large an alternator and cook the lead acid battery banks. I welcome any advice that can be provided.

On a side note: redundancy is planned and we will instal solar as well as wind within the next two years as well. Just currently our batteries do not charge sufficiently while the engine is running.

[sailormed]

If you have an internally regulated alternator installed now, my first step would be to to install a good external regulator. Take a model that can regulate also a bigger alternator if you find you need one later down the road. Just the external regulator will improve alternator output a lot.

[Compass790]

I reckon you should size the alternator or dual alternators to suit your projected Lion setup & then get a programmable external regulator to control its output to suit your current lead acid setup. Modern ones can be programmed to suit differing battery types or max output AFAIK.
At a rough guess you could have a 200 amp alternator for yr present battery bank. I'd rather have 2 alternators for redundancy but up to you



We did a DIY setup to depower our alternator but it sounds like an off the shelf option will suit you better. You can set the load on the engine/alternator on a dial with our setup but you'd have to check on off the shelf ones how they do it



Others will chime in with brand recommendations.
Hope thats some help

[Stu Jackson]

Originally Posted by Benjamin85

>>>>>>>>>>>
>>>>>>>>>>>>>>>
...but we also don’t want to get to large an alternator and cook the lead acid battery banks. I welcome any advice that can be provided.

>>>>>>>>>>>

You can't. Why? Because the only thing that will cook batteries is too high a voltage.


Unless your charger, alternator or solar/wind system is pumping out an incorrect voltage for you bank you will not over charge. (Maine Sail)


An external regulator will give you a lot more flexibility in setting the correct voltage compared to an internal regulator. Internal regulators do not always have a voltage adjustment and you never know what you're getting (i.e., what voltage they are set for) when you buy one.

[tkeithlu]

Take a good look at a Balmar alternator and programmable voltage regulator. First choose the right alternator for the future - running it at max output to charge a large battery bank will burn it up. Then add the regulator, and program it for the cycle you need for your bank. It can be re-programmed (tedious, but not difficult) for any future batteries you choose.

https://balmar.net/alternators/

Then go find the best price....

[tkeithlu]

Let me expand on Stu's post.

A voltage regulator turns the alternator on and off, in thecaseof modern solid state regulators many times a second. The alternator slows down the amperage as the battery nears full charge. Notice that alternators have fans. That's because they get hot, and run wide open (little alternator, big empty battery) they overheat and burn up.

That's the basic picture. Then, a programmable regulator can do all kinds of fancy stuff giving your size and type of battery just the set of volts/amps/time it needs for good health. It's just like a sophisticated battery charger.

You've been using an ordinary Delco, possibly with an internal regulator, a single wire. Whther it is single wire or not, that's a pretty crude charging cycle, suitable to a 1950's car starting battery. I use one for my main engine and one for my genset, because all those batteries do is start the diesels and then recycle to full. I would not use something that crude on the house bank, which is too big and discharges too far in overnight use.

[Compass790]

Originally Posted by Stu Jackson

You can't. Why? Because the only thing that will cook batteries is too high a voltage.


Unless your charger, alternator or solar/wind system is pumping out an incorrect voltage for you bank you will not over charge. (Maine Sail)


An external regulator will give you a lot more flexibility in setting the correct voltage compared to an internal regulator. Internal regulators do not always have a voltage adjustment and you never know what you're getting (i.e., what voltage they are set for) when you buy one.

Yes good point about what batteries will accept determines alternator output. I'd forgotten that though I'd read mainesails article.

Important point for the OP so just as well you chimed in.
Most alternator voltage regulators I see advertised on fleabay or alislow do tell you the voltage setpoint BTW.

[goboatingnow]

Originally Posted by tkeithlu

Let me expand on Stu's post.

A voltage regulator turns the alternator on and off, in thecaseof modern solid state regulators many times a second. The alternator slows down the amperage as the battery nears full charge. Notice that alternators have fans. That's because they get hot, and run wide open (little alternator, big empty battery) they overheat and burn up.

That's the basic picture. Then, a programmable regulator can do all kinds of fancy stuff giving your size and type of battery just the set of volts/amps/time it needs for good health. It's just like a sophisticated battery charger.

You've been using an ordinary Delco, possibly with an internal regulator, a single wire. Whther it is single wire or not, that's a pretty crude charging cycle, suitable to a 1950's car starting battery. I use one for my main engine and one for my genset, because all those batteries do is start the diesels and then recycle to full. I would not use something that crude on the house bank, which is too big and discharges too far in overnight use.

Modern semiconductor regulators , in all modern alternators, use negative feedback to control the voltage , only the load determines the current based on ohms law . If the alternator wishes to restrict maximum current , it does this by lowering the voltage until ( hopefully ) the current falls. It can’t control current directly.

Negative feedback is a continuous analog process there is no process switching the alternator on or off.

In an alternator the current is controlled to the field coils and as a result control the stator voltage.