Alternator options for 24v vs 48v?

[Sabre602]

Hello all,
Later this year I will be ditching my golf cart batteries and converting to lithium (LiFePO4) technology. I will install a new shore power charger, solar panels & controller, and alternator. My Lehman diesel currently has an ordinary 12 volt alternator that charges the two lead acid starting batteries; this will stay as it is for the time being. It also has a large-frame 12 volt alternator that charges the house bank, which consists of six GCBs.

I would like to install the lithium batteries in a 48 volt configuration. I am familiar with the AC charging, solar and the inverter side of this arrangement, but the alternator side of things is all new to me. I know that some setups will use two 24v alternators to achieve the 48v. It's going to come down to the cost of the upgrade; I'll keep it at 24v if the alternator cost of the 48v system is prohibitive.

I would like to hear some informed opinions talking about the options, pros & cons of 24 vs 48 volt alternators to address the high current capabilities of the lithium house bank.

 

[twistedtree]

I really wanted to go to 48V on my boat, but ultimately gave up. As you have found, the alternator is the missing link. I couldn't find one that wasn't a one-off contraption of some sort. In the Prestolite/Leece-Neville catalogs I found at least one 48V alternator and though I had nailed it, but when I called them I learned that it had been discontinued, along with all of their other 48V alternators.


It's a shame because I think it would make for a much better system, especially as power levels go up. And a 48V alternator would produce a lot less waste heat for the same power output.


The other challenge is to deal with the few high power 12V loads that will remain, like a windlass and thruster. What were you thinking for those?


If you find a production, or semi production 48V alternator, let me know. It's probably too late to change by system at this point, but you never know.

 

[Sabre602]

I really wanted to go to 48V on my boat, but ultimately gave up. As you have found, the alternator is the missing link. I couldn't find one that wasn't a one-off contraption of some sort. In the Prestolite/Leece-Neville catalogs I found at least one 48V alternator and though I had nailed it, but when I called them I learned that it had been discontinued, along with all of their other 48V alternators.


It's a shame because I think it would make for a much better system, especially as power levels go up. And a 48V alternator would produce a lot less waste heat for the same power output.


The other challenge is to deal with the few high power 12V loads that will remain, like a windlass and thruster. What were you thinking for those?


If you find a production, or semi production 48V alternator, let me know. It's probably too late to change by system at this point, but you never know.

Thanks for the response; this aligns with my preliminary research. Did you end up with 24 volt or remain at 12? I have no thruster, but the anchor winch is, indeed, a high-current load. It's wired to the starting bank rather than the house bank.

 

[mcarthur]

There are some good 48V alternators - I'm looking at Rapid Power here in Oz. They wind a 48V which Safiery use too - 4-5kW. I plan to use a Balmar MC620-48 as the external regulator instead of internal. My two engines can each handle upto 6kW from the PTO.

You may have to keep a separate 12V or 24V starter battery as the DC-DC convertors (48->12) may not give a high enough momentary current.

Use one or more DC-DC converters (like Victron Orion) for the remaining 12V items, and a Victron Multiplus or something like it for any 120/240V.

We'll be using the 48V bank for electric propulsion .

 

[Portage_Bay]

A question. Why not 32 V? Quite a few of the very old work boats I worked on a very long time ago had 32 V systems. I have no idea why it was common but it was. A quick google search turns up 32 v alternators.

 

[Ted]

32 volt equipment is getting harder to source

 

[Ski in NC]

32V system really runs about 37V. Might take just a bit of tweaking of the regulator to get to 48V. Some machines might handle it, some might not.

 

[Sabre602]

Looking at solar controllers, shore chargers, inverters, DC/DC converters, regulators, alternators, etc., I would like to stick with a standard voltage, i.e. 48/56, 24/28, 12/14.

I'll go with 24 if I have to, but the advantages of 48 are numerous. There are increasing numbers of systems, both home solar and vehicle-based, that are using the higher voltages for these reasons.

I just don't have the funding to plonk a 48 volt Balmar alternator in there.

 

[Insequent]

Yes, Balmar make 48V alternators. I can see 60A and 100A at one of my local suppliers although only the latter is in stock. For sure, 'not inexpensive', but readily available. In a new build I'd use a 48V house bank for the inverter and a modest 12V bank for electronics. Keep as much as possible AC.

Windlass and thrusters don't use very many Ah at all, and a bank with high CCA up in the bow is ideal. I would install 24V models, with an AC powered charger as the bank would only need to be topped up every couple of weeks. Inefficiencies in that charging route are bugger all in the overall scheme of things. If a 90% SOC for that bank worried you then just allocate one of your solar panels to it.

 

[Mako]

48V components are very common in the telecom industry. One issue I found was the average of $1000 higher price for a 48 versus a 24 of same capacity.

OP you may wish to ping Lepke for information on his 48V setup.

Should have read are, instead of aren't... Done..!

 

[FF]

"I just don't have the funding to plonk a 48 volt Balmar alternator in there."

24V is very common with OTR trucks and many buses,

The DN 50 is very common and can be had rebuilt with no core charge, work fine with 3 stage regulators and will produce 220A to over 400A.

BUT they are both huge and heavy , as are most things that last almost forever.

IF you can mount it it will be the Last alt. you will buy !!!