DC to DC Converter vs Alternator upgrade

[Daveonthebreeze]

Thanks Goathill..Appreciate the alternator cooling suggestion, paired with the DC to DC charger.

[guyrj33]

Dave
You need a bigger alternator to efficiently charge your 400+AH bank.
Get a setup with a good adjustable external voltage regulator. You’ll probably need to upgrade belt and pulleys too. Just go for the whole package it’s worth it.
John61ct
Your answers are always quick and typically contain at least one inaccurate statement, I’d like to suggest you read your posts out loud before hitting send. Perhaps then you’ll see the errors everyone else sees.

[Pizzazz]

Now that we have cleared the terminology, it would be great to compare the following three approaches in terms of cost and efficiency:

1) Charge through stock, cheap Hitachi alternator but pull the voltage sense wire higher than the battery voltage somehow, to make sure that you are charging faster.

2) Convert Hitachi regulator to external regulation (tricky and time consuming)

3) Use the DCDC charging method describe above.

I would appreciate comments about efficiency, cost and so on. Let’s face it we all know that the beat solution is a Balmer alternator plus external regulation. But it costs $1,500 at least vs. $75 for an 80A Hitachi alternator off Amazon.

SV Pizzazz

[evm1024]

Originally Posted by Daveonthebreeze

Hey all, thanks for the input... Good to see the distinction between a DC to DC Converter and a DC to DC Charger. Reading Sterlings marketing material on their charger, I was attracted by their claim:
"... The B2Bs have become extremely popular as they fast charge batteries as you cruise along without the need for complex wiring, touching your alternator, voiding the alternator’s warranty and tampering with the electronic control units (ECUs). You can provide the onboard batteries with a fast 4 stage charging profile with a very simple and speedy installation. All of the benefits of advanced charging without any of the draw backs. Simply connect the B2B between the battery being charged and the battery you wish to charge."

From your input, I'm concluding that I may get some improvement on both rate of charge and charge regulation, but am somewhat limited by the realities of the existing Hitachi alternator. The gold solution sounds like the Alternator upgrade, with an External Regulator. Be still my shuddering cheque book!!

BTW, great call out on Nigel Calder's book (or should I say sailors bible). My dog eared copy makes great winter reading up here in the frosty Great Lakes. Congrats to all who have actually read it in it's entirety "cover to cover"!!

Modern cars and trucks ECU are quite "clever" and ... I'm sure you know.

But we are talking about a very old school alternator and no ECU. Both noelex77 and dockhead gave great summaries of the pickle that you are in.

I ran a 55 amp Hitachi alternator in an older boat (with a 3HMF) and was able to pick up a larger Hitachi that fit right in. But...

... you are still in the same pickle and given the size on the batteries that you installed are likely to burn the alt up. The DC to DC "charger" will help prevent that but at the expense of limiting your charging current to the chargers rating.

I'm thinking that the "gold" solution is the only real solution. There are ways of getting around the high cost of (new) Balmar alternators and regulators.

I suppose that setting your goals are the first order. And then seeing what is needed to reach those goals.

In terms of getting a better deal you might look around to see if there is someone who is upgrading or has just got back from a long cruise and has a spare to sell.

For example I just sold a 150 amp HEHR alt (similar to a Balmar 91 series) on eBay for $150. The alt was fully rebuilt by PMX of PDX.

In any case getting a "smart" regulator with temp sensors for the alt (at least) will get you the charge performance that you will be happy with.

Regards

PS when I upgraded my alt on my yanmar I also put in larger batteries. The alt failed about 8 months later (about 1/2 mile from my home port at night) at the end of a cruise. The failure was at the B+ stud on the alt. It was running hot and baked the insulation allowing the stud to contact the case of the alt. Bigger batteries, bigger needs.

[oleman]

There are various types of DC-DC converters basically there are:
A. Bucking converters they take a higher input voltage and convert it to a lower output voltage. The output current can be higher or lower than the input current but wattage can not increase.
B. Boost converts they take a lower input voltage and create a higher output voltage. Output current will always be lower than input current.
C. Buck, Boost converts are designs that create a constant out voltage that can be lower or higher than the input voltage, these are primarily used on solar panels because of the widely varying output based on sun light availability. These are also used as battery to battery chargers allowing two batteries of the same chemistry to charge each other. So I can charge my 24 V bank from a 12V bank or the 12V bank from the 24V bank, in some cases with the same BB converter.



The rule here is that output power will always be less than input power, since there is no free lunch in physics.



E. Then there are DC to AC inverters:
These are basically boost DC to DC inverters with a frequency based stepped output to produce the correct frequency at what ever output voltage required. A true sine wave version just has more steps in the output conversion and sometimes better frequency and voltage regulation in the conversion process.


F. Another innovation is the brush less DC motor. Not a dc motor at all. It simply has a miniature DC to AC inverter built in, thus it is actually an AC motor.


None of the technology is new thinking the cost has just been reduced to make it practical for real people.



Thomas Edison would be proud today, his DC power distribution ideas are now in use.

[Stu Jackson]

Dave,


Welcome. As you get to know the folks here, you will begin to get a better feels for those who know their stuff and those who blow a lot of incomprehensible smoke.


Here's the REASON Hitachi alternators bite the dust. I've posted this at least 25 times on this forum, and copied it from a Maine Sail post. Not all OEM alternators are like this, and not all car alternators are like this either. Dockhead is, quite correctly, a proponent of larger school bus alternators, but he has a larger boat and engine that can accommodate such equipment. Most of those of us in the 30-42 foot range simply don't.


You might also want to search here on Small Engine Mode when it comes to using an external regulator. Maine Sail's website also has some very superb material on external regulators.


All the best.


************************


Hitachi/Yanmar Alternators: (by Maine Sail)

Some alternators though, such as those made by Hitachi and found on Yanmar diesels, are dumber than a pound of beetle poop. Actually, to the alternator, they are pretty smart but to your batteries and the speed of charging they are flat out stupid. Why?

Hitachi alts with dumb regulators, and some others, limit voltage but also reduce voltage based on alternator temperature. This is a self protective feature installed in the internal dumb regulator to prevent the alternator from cooking itself. Remember voltage is the pressure that allows more current to flow. So, if we reduce the absorption voltage, then we also reduce the current the alternator is supplying.. Any battery at any state of charge simply will not accept the same current at 13.4V that it did at 14.4V and as a result the alternator will run cooler. What do you suppose this does to your batteries over time.......?

The problem is that when cold you will get 14.3V to 14.4V out of the Hitachi but as the alternator heats up the dumb regulator begins to reduce the CV/voltage limit based on the alternators internal temperature. It is not uncommon to find a Hitachi alternator at 13.4V when hot. This is REALLY, REALLY DUMB....

If you have a dumb regulator, and notice the voltage dropping, it is likely a temp compensated dumb regulator. Get rid of it or plan to buy new batteries more often.

If you have a temp compensated alternator or a Hitachi alternator on a Yanmar you really are in dire need of external regulation if deep cycling a larger battery bank.

This is from:

http://forums.sbo.sailboatowners.com...d.php?t=125392

and these, too:

http://www.cruisersforum.com/forums/...on-125843.html


http://www.cruisersforum.com/forums/...or-142083.html

[bcboomer]

I don't know where the OP is but I bought an industrial 200 amp smallish frame alternator for $320 CAD. Cheaply converted to an external regulator by a local alternator repair shop.
Works well, pumps out 185 amps for at least an hour.
More money than the DC-DC but I think a better solution.

[Dockhead]

Originally Posted by john61ct

Yes, a smaller alt won't provide as much power as a bigger one.

But increasing the **quality** of that output by just converting to a good external VR (or adding a DCDC charger) may well be enough of an improvement for a low-demand setup.

If not, either could continue to be used in an upgraded HO alt setup when that's done later.

The mechanical / infrastructure work getting brackets, multi-vee belts, pulley ratios, fatter wiring etc right is an area most owners need to bring in a pro, and can easily cost more than all the electrical components put together.

It is not at all a question of big versus small. It is a question of designed task -- topping off a starting battery and carrying small car-type house loads, or generating bulk power. These are fundamentally different types of alternators. A 60 amp Hitachi alternator is not designed to produce 60 amps of power except for a few minutes at a time. Such an alternator is designed to be attached to a starting battery, not to a bank of deep cycle batteries.



Because of this intended use, car-type alternators do not have the cooling capacity or temperature resistant diodes, windings and other components needed for sustained high output use -- "high" meaning a large percentage of rated output, whatever it is, not necessarily big or small. If you try to use a car-type alternator, especially a Hitachi, at anything near its rated output, by regulating it to force it to do so, or using an A2B charger, you will melt it down or, if you have temperature sensors which are set at a level which the alternator will stand, you will get only a fraction of the rated power on a continuously basis.



School bus alternators are the gold standard. They are built from the ground up to put out their rated power 24/7 and in a high temperature engine room. It's much easier to design for high output when you are allowed to have a big thermal mass, large components, and you have space for dealing with a large volume of cooling air. But for those who can't fit school bus alternators, there are small-case alternators which are designed for bulk power production; that is probably what the OP needs to look at.


"When ever possible, when charging large Ah banks, it is best to try and fit a large frame alternator designed specifically for a heavy duty applications. Small case alternators, even “high performance” models, despite what many folks think, are not constant duty rated, not even the Balmar AT or XT series. If your bulk charging will be longer than about 30 minutes even a Balmar AT or XT will need to be current limited, via the external regulator, to make it last."
https://marinehowto.com/automotive-a...cle-batteries/

The Balmar AT/XT is a good choice for a high (or higher) output small case alternator:


XT-Series and AT-Series Alternators | Balmar


There alternators can operate at a higher percentage of their rated power on a continuous basis because high temperature components are installed and cooling is improved. Some of the get the diodes out of the alternator case and mount them externally.



Besides Balmar, there are other variants; Mark Grasser also makes higher output small case alternators: https://markgrasser.com/?page_id=1425; also OceanPlanet: https://oceanplanetenergy.com/high-o...rs/alternator/.


As to regulation, I like the Balmar regulator which allows you to specifically derate the alternator ("belt saver"), which will really help extend the life of a small case alternator used for bulk power production, and will save belts, too. There are other good ones, but as far as I can tell the Balmar has the widest range of controls.



I do not particularly see the point of A2B chargers, and Charles Sterling himself says that their main virtue is being easier to install than a good external regulator.

[Q Xopa]

Originally Posted by Pizzazz

Now that we have cleared the terminology, it would be great to compare the following three approaches in terms of cost and efficiency:

1) Charge through stock, cheap Hitachi alternator but pull the voltage sense wire higher than the battery voltage somehow, to make sure that you are charging faster.

2) Convert Hitachi regulator to external regulation (tricky and time consuming)

3) Use the DCDC charging method describe above.

I would appreciate comments about efficiency, cost and so on. Let’s face it we all know that the beat solution is a Balmer alternator plus external regulation. But it costs $1,500 at least vs. $75 for an 80A Hitachi alternator off Amazon.

SV Pizzazz

Balmar are certainly good, but not the only choice. Mark Gasser and others also have good alternators and regulators.

The other suggestion, if you are DIY inclined, is to make your own. Actually there are people always available to help if you look. I appreciate not everyone feels capable or want to invest the time. I did mine for considerably less if you don't count your time.

As Dockhead is fond of suggesting, a 'school bus' alternator is a good start. I used 28si's, which is s large case 200A.

A contributor here has a thread you can search for converting to external regulators.

Mounts, pullies and wiring information can also be found with some searches. All more doable than most people realise, once you find out about it.

The other advantage with this approach is you will know everything about it and can fix it later when it has an issue.

As others have said not the easiest solution, but IMHO well worth it.

[Dockhead]

Originally Posted by Pizzazz

Now that we have cleared the terminology, it would be great to compare the following three approaches in terms of cost and efficiency:

1) Charge through stock, cheap Hitachi alternator but pull the voltage sense wire higher than the battery voltage somehow, to make sure that you are charging faster.

2) Convert Hitachi regulator to external regulation (tricky and time consuming)

3) Use the DCDC charging method describe above.

I would appreciate comments about efficiency, cost and so on. Let’s face it we all know that the beat solution is a Balmer alternator plus external regulation. But it costs $1,500 at least vs. $75 for an 80A Hitachi alternator off Amazon.

SV Pizzazz

If you are going to stick with the stock alternator, then you need good external regulation to get the maximum possible output out of it while not frying it. A2B charger will also do this, but the Balmar regulator allows you to not only turn down the alternator when it gets hot, but also to specifically derate the alternator, which you will want to do as part of the program. Figure you might get 50% of rated output out of it once it's hot, plus or minus, more if you're lucky. If that is enough power for you then there is nothing wrong with that approach.


Hooking up an external regulator is not a big deal. Hour or two max of fiddling with the alternator off the motor; some soldering may be required. External regulator also has a much smaller physical footprint than an A2B charger so depending on circumstances in your engine room, this may also influence ease of installation.


If cost is an issue then there are some ways to save money on a better alternator. The Balmar small frame ones are regularly seen on EBay at a good price. Actual large frame school bus alternators are cheap -- mine cost £500, probably $500, because they are standard automotive parts, not custom jobs. But the issue there is space -- not everyone can physically accomodate one on the engine -- and pulley setup, which has to be changed from stock, and this can be somewhat involved. But you might want to at least check to see if this is somehow possible -- definitely best bang for buck.

[rom]

Originally Posted by Dockhead

If you are going to stick with the stock alternator, then you need good external regulation to get the maximum possible output out of it while not frying it. A2B charger will also do this, but the Balmar regulator allows you to not only turn down the alternator when it gets hot, but also to specifically derate the alternator, which you will want to do as part of the program. Figure you might get 50% of rated output out of it once it's hot, plus or minus, more if you're lucky. If that is enough power for you then there is nothing wrong with that approach.

Sorry but you sound a bit like the other expert here. The OP has the "dumb" hitachi (I never understood what makes it dumb), which will work fine stock behind an A2B. I can't tell for other alternators but I suppose the Hitachi is not the only one with a self protection algorithm in the VR. I modified my hitachi 80A for use with an automotive 20EUR external VR, I got 70+A for long period at cruising speed. I read similar reports on forums. I have switched both engines to 28SI recently because the Hitachi was old and not powerful enough anyway for a 1000Ah battery.

If cost is an issue then there are some ways to save money on a better alternator. The Balmar small frame ones are regularly seen on EBay at a good price. Actual large frame school bus alternators are cheap -- mine cost £500, probably $500, because they are standard automotive parts, not custom jobs. But the issue there is space -- not everyone can physically accomodate one on the engine -- and pulley setup, which has to be changed from stock, and this can be somewhat involved. But you might want to at least check to see if this is somehow possible -- definitely best bang for buck.

Seriously, "save money" and "balmar" is the same sentence ? When you can buy a brand new 200A Delco 28SI for about 200 EUR.Please also note that having an alternator with a clean three stages charging profile is not always a necessity. I live pretty well with the internal VR because the solar system finishes the job properly.

[Dockhead]

Originally Posted by rom

Sorry but you sound a bit like the other expert here. The OP has the "dumb" hitachi (I never understood what makes it dumb), which will work fine stock behind an A2B.

I agree, and never said anything different. EITHER external regulation OR A2B charger will solve this problem.

Originally Posted by rom

I can't tell for other alternators but I suppose the Hitachi is not the only one with a self protection algorithm in the VR. I modified my hitachi 80A for use with an automotive 20EUR external VR, I got 70+A for long period at cruising speed. I read similar reports on forums. I have switched both engines to 28SI recently because the Hitachi was old and not powerful enough anyway for a 1000Ah battery.

That's a useful data point which contradicts a lot of other data I have seen, including MaineSail's. Maybe it's a different alternator? Incidentally I have this very alternator on my main engine, but never tried to get any power out of it because it's sole job is topping off the starter battery.

Originally Posted by rom

Seriously, "save money" and "balmar" is the same sentence ? When you can buy a brand new 200A Delco 28SI for about 200 EUR.

The Delco 28si is a proper school bus alternator, like what I recommended. I've never seen one, and looking through the brochure it seems to be quite a bit smaller than the equivalent Leece-Neville. Maybe a brilliant solution. As I said, school bus alternators are by far the best bang for the buck, the right solution to this provided you can make one fit.



One more pitch: Producing bulk power from a car-type alternator is like trying to haul freight with a Volkswagen Beetle. It can be done to some extent with modifictions, but it's an uphill battle, and really good solutions (Balmar) get expensive while still not being all that good. Better and cheaper to simply use a truck, which was designed from the beginning for the purpose, i.e., a school bus alternator, if you possibly can.

Originally Posted by rom

Please also note that having an alternator with a clean three stages charging profile is not always a necessity. I live pretty well with the internal VR because the solar system finishes the job properly.

Yes, I have been living "temporarily" with disconnected external regulator for almost two years now. With school bus alternators with no thermal protection, this works fine as long as you're not expecting to get a finishing charge on the batteries in a moderate amount of time.



However, nothing good will happen trying to run a Hitachi alternator that way. See MaineSail's article above. You do need either A2B or external regulation to get anything like useful power out of one of those.