32vdc to 24vdc

[Liquid Asset]

Hello,
I am new to the forum and my father and I will be closing on our new to us Hatteras this week. It is a 1982 50 convertible.

I was woundering if anyone here has converted their 32vdc electrical system on their hatteras to a 24vdc system. It seems that as time has gone on, there are a lot less 32vdc parts avalible for than in the past and we were considering a conversion. I guess a step down converter would be possible, but we were hoping to just get rid of all the batteries in the engine room too. there are 16 8vdc batteries and that takes up a lot of room. Any opinions and help would be appreciated.

Pat

 

[Nonchalant1]

Pat,

A number of boats have converted, but the battery banks sizes are there to handle the loads and amps required to run the boat. Whether or not you convert, you'll need to determine how you'll be operating the boat and how much you want to run the generator before reducing (or increasing) battery bank size.

For 24 volt service, you'll need 24 volt starters, alternators, lighting, heads, searchlight, etc. etc. and a possible upgrade of wiring since 24 volt power may need larger wires to run the same watts as the 32 volt service did. So, it's no small undertaking.

Doug Shuman
1978 53MY

 

[Liquid Asset]

I guess my main concern is the wiring. We do not take delivery unill July 1 and I am not sure if Hatteras has over sized the wire and it will be suficent for 24vdc, or if I would have to rewire the boat. The boat needs some things replaced and some of the parts we would like to upgrade and they are not avaliable in 24vdc.

What kind of amps can a stepdown converter handle? Could I run a windlass on one?

 

[Pascal]

early on, I also thought about converting from 32 to 24 but after i got boat i realized it really wasn't worth it. yes, some parts maybe a little harder to find but so far so good.

the only items i coudln't / didn't want to spend to much time searching for/paying way toomuch where the shower sumps. couldn't find 32v bilge pumps smaller than 2000 gph for that use. so i used basic 12v sumps. i already have a 12v battery/charger and fuse panel for the electronics so it was no big deal to wire the new sumps to that panel.

i think using 32v gives an added safety margin as wires and conenctions get older... on a complete electical refit, then yes, converting to 24v maybe worth it otherwise, i don't want to re invent the wheels.

even batteries are no problem, I use four 8v exide golf cart batteries per engine, works well, $320 a bank, small footprint.

 

[SKYCHENEY]

I too was concerned initially, but found 32v to be no real problem. You can find most items through SAMS Marine and those others that are 12v can be run off of a step-down transformer or a dedicated 12v battery bank. I would suggest using the boat for a while first and then decide.

I know a guy with a 1979 53 and he went with 12v to supply everything on his flybridge. Well, it wasn't long and he found that the old wiring could not supply enough amperage and he had to pull new wires from the 12v bank to the bridge.

 

[Liquid Asset]

Ok,so lets say that I need a new windlass. For lack of use of a stepdown converter, can a 32vdc to 24vdc converter handle the amperage of something like that. There is already a 32v to 12v converter on the bridge for the electronics, but my other concern is that it will be the weak link. If it dies, I have not electronics.

I have looked at them and they are expensive, but they are cheaper than doing a conversion. I guess that I need to use the boat, but we are buying it an know that somethings like the old drum style windlass will need replaced.

There is a 12v system on the boat to start the genny, but it was not designed to run electronics, one of the engines has a house set of batteries and that is what runs most things.

Should I use a stepdown converter and then create a 12v and 24v pannel in the boat as an addition?

Sorry for all the questions, but I am making some plans for the projects ahead.

 

[Pascal]

dont' assume the windlass needs replacement... if it's a galley maid like on so many older hatteras they are very solid. see the thread on that subject.

why do you mean by 12v system not designed to run electronics? if it has a battery and an alternator on the genset, you're fine... you could even runthe wires to the bridge so that you could easily switch to your genset battery in an emmergency.

my boat came with the 12v battery, 12v charger already installed. I like that setup better than having a converter.

 

[first230sl]

Everyone with an older Hatt has the 32/24/12 volt issue and we all solve it the best way we can.

Most things still are available in 32v (Pascal - even shower sumps - check this one out - I have one and it is great: http://www.lovettmarine.com/files/shower_sump.asp). But obviously the selection is much better in 12 and 24 volt systems.

There is nothing really wrong with a converter if you don't have many 12/24 V things to run.

Many owners, though (myself included) have opted to put in a 12V system *in addition* the the 32V system. It is much cheaper than converting your whole boat. In addition to my two 32V alternators and battery banks, I have a new-ish 12V alternator, charger, invertor and battery bank.

I have a few 24 V loads to power as well. The small loads I satisfy using a convertor.

A couple big 24V loads (aft deck winch and dingy davit) I run by taking a tap off three of the four 8V batteries that are in series. Not a perfect solution, but they are seldom used devices.

So - my point is that you can make due with a reliable system that will not require you to re-wire your entire boat and replace a lot of expensive things.

Take care - Murray

 

[Nonchalant1]

Pat,

For a windlass, I'd either look for a 32 volt one, or run a separate fused or circuit breakered run off the 3rd battery in a 4-battery bank. If you have 4 large 8 volt batteries in series to get 32 volts as most boats have, you can take 24 volt power directly from the major negative terminal connection on the first battery and the positive terminal of the 3rd battery. Since the windlass is a very high amp drawing consumer, but has infrequent use, you can calculate how big the wires need to be and it won't bother your bank's performance too much. Another option for davits and windlass is 120V A/C. You have plenty of A/C power from the genny and can start it whenever you want to run one of those items and the wiring can be much smaller gauge.

You can get reasonably high step-down converters, but that wastes a lot of power just to step it down. I have a 32V to 12V stepdown that handles 35 amps, for example.

Doug

 

[SKYCHENEY]

Good point about the 120v items. I have a salt-water washdown pump that is 120v. I don't use it much and it is no big deal to start the genset when I want to hose off my anchor.

Whatever you do, try to keep it simple and do it in a professional manner with all new wiring labeled and noted on your schematics. I ran away from a couple of Hatts that had a bunch of non-OEM wiring that was not labeled or even tied up very well.

And, as said before, if that windlass is a GalleyMaid or Ideal, you can have it rebuilt for less than you would pay for a new one. And probably have a heavier unit besides.

 

[Pascal]

murray

thks, that's what i took out.. i coudln't get them in 32v in a timely fashion and they were like 2 or 3 times the price... so i went cheap...

the last (one before last) issue of Passagemaker had an good article on powering windlasses and other systems with various voltage. it stated that tapping 3 out of 4 batteries could really shorten their life.

 

[Liquid Asset]

Ok,
So I am convinced that I do not need to make a conversion from 32vdc. Now, as I think about the things that will be gettind done to achive making due with the 32v I think about electronics. The boat has a 32v to 12v converter on the bridge for electronics. What are the reliability of these? My concer is that if it fails, I am screwed.

Next, the 12v system on the boat is for the genny. If I dont run the genny, then the 12v battery does not charge and I know that it will probably get charged most of the time, but I would hate to be out and have the genny stop working and then run my genny batter dead running electronics.

I guess that if the step down converter is reliable, which I am thinking it is since Hatteras installed it originally on the boat I could replace it with one that can handle the load of a lot of new electronics.


On another note, how safe is it to run 24vdc items off of the 32vdc bank? Will that damage the batteries in the series since you are bypassing the 4th battery?

Thanks for all the help.

 

[first230sl]

Ok,
On another note, how safe is it to run 24vdc items off of the 32vdc bank? Will that damage the batteries in the series since you are bypassing the 4th battery?
QUOTE]

Common sense (and passage maker) tells you that it is less than ideal because you are discharging 3 of the 4 batteries faster. When charging, the 4th battery will come up to full charge faster than the other three. So I imagine that the 4th battery is going to be overcharged - may lose water.

Having said that, I do exactly this for a couple large loads. I use them (the large loads) only rarely and I have not had a problem with shortened battery life.

If I was starting an electrical design for my boat from scratch, I would not design it this way. But as a *far* less expensive option than adding a 24 volt system (batteries, charger & alternator) my personal feeling is that it is perfectly reasonable for loads that are not used often.

Others may disagree.

Best regards - Murray

 

[Pascal]

Pat

i wouldn't run anything off the genset battery except in an emmergency. I like to keep that battery isolated from everything else.

32 to 12 converter must be reliable since you rarely see questions about them, that's a good sign indicating they rarely cause issues...

as i mentioend, i like the idea of having a 12v auxiliary battery with it's own charger. I get about 36 hours out of it, for the 2 shower sumps, CO detector, a few hours running with the electronics and teh Followme TV which i think must be the largest load. Granted, i must use a 12 charger to recharge that battery off the genset or shore but that's not a problem since even in winter i run the genset to recharge house and inverter batteries at night anyway .

if your converter is large enough, leave it alone maybe running wires to power things up from the genset battery in an emmergency. If you need more capacity, just add a a battery and charger...

 

[SKYCHENEY]

I have only 32v batteries(8v in series), no 12v batteries. My genset is a 32v and the only 12v items that I am powering is some of my electronics. I have several small step-down transformers. I believe it is 3 at the lower helm and 2 on the bridge. They are all original (1985) and I have not had a problem with any of them. If one did go out on me, I could always wire the selected device to one of the other transformers until I could get a replacement.

So, I think that the story on this is to have a backup. Make sure that you have more than one transformer and you will have peace of mind that you will not lose all of your electronics at once. And.....keep that hand held radio and a hand held GPS in the drawer as a last resort, just in case.

 

[Liquid Asset]

I think I have a good handle on this. As far as I can tell, the only thing that will have a 24v load is the Windlass. It really does not need replacing, but I need on with a gypsy. There is not always someone to stand at the helm and somone to go forward to handle the anchor, so I need the gypsy so that I can wire it to the helm.

I wounder what the load woudl be and if a step down transformer would handle it. Any Ideas?

I got the 12v thing solved in my head.

Thanks for all the help

 

[SKYCHENEY]

Your current windlass should be 32v. If you want to add a chain wildcat to it and it only has a capstan now, then you will need to pull it out and send it to GalleyMaid. I just did this with mine last winter. Call Rick @ GalleyMaid and he will walk you through it. Then, to add a helm switch is no problem. Rick will send you the wiring diagram.