24 volts?

[greenkarson]

im purchasing a aquair submersible 100w altenator its 24 volts.  am i commited to keep everything 24v? ie. batteries and inverter or is  there some way to make a 12 volt inverter work?  just wondering do to cost differance

[dnix71]

Two 12v batteries is 24v. You could just tap out one battery to run the inverter and switch batteries occasionally to even out the wear.

That said, a 24v inverter is more efficient because you are pulling 1/2 the current to get the same load.

http://www.radio-factory.com/truck-24v-300w-dc-12vac-220v-power-inverter-adapter-p-1182.html

I don't about their quality, but it's only $37 plus shipping. Any truck depot should carry something like it since semi's have 24v systems.

[ghurd]

One related to Woof's new poll.

I notice this is a 220VAC 50Hz inverter, with the price in $.

Small 24V 115V 60Hz inverters in the USA are hard to find, expensive, and junk. YMMY.

Wonder about "Output Wave FormFModified pure sine",

and

"Input 12V DCCThe Current consumption on the transformation<0.25A

Low-voltage shutoff:18.4~19.6".  

(uhh...  what?)

G-

[sk windpirate]

Hi

You could use a series paralelle switch.

Charge 24 and use 12 volts.

[wpowokal]

There is no way to tap half a bank with out causing all kinds of battery problems.

allan down under

[Opera House]

Your results may vary.  Reading info says it needs a regulator.  Stream conditions could change the output.

If you are going to spend that much on an alternator, It is certainly worth it to put a switching regulator on this to get the most power out by operating alternator at the optimum voltage and converting it down to 12V.  The higher alternator voltage is ideal for transmitting the power to its final use.  A 100W switching regulator is certainly in the realm of the novice to build out of an old computer power supply.

[random]

Your question is unclear, you don't say what your existing battery bank voltage is.

Assuming you don't have a battery bank and are setting up from scratch, I would highly recommend avoiding a 12v battery bank.  I went with 24v, others use 36v or 48v.  If you go above 50vDC it no longer qualifies as "low voltage DC" and the NEC requirements become enforceable (in the US).

If you have a 24v bank, you can get 12v from it by using a DC voltage converter.  I use a Samlex SDC-30 which is no longer available but they now offer a 60a continuous version in its place.  The nice thing is that I'll still be getting my 12v (actually 13.74v) nice and solid until the batteries are discharged far too far, until the 24v bank is down to around 16v.  It isn't something one wants to do, but it could come in handy during a blizzard or some other emergency situation.  If I had a 12v bank and was running DC loads directly connected, the DC voltage would vary with battery discharge and my 12v appliances would be attempting to use 11.8v or whatever.

Keep in mind that if you have a 24v battery bank you'd (traditionally) want to be able to charge it to about 29-31v which you cannot do if your generation equipment is putting out exactly 24v.

Probably the largest drawback of a 12v bank is that you need very large cables because for the same power level a 12v bank will be supplying twice the amps as a 24v bank would.

If you have 24vDC and need to use it to charge a 12v battery bank you could probably use a Samlex SDC-60 to convert it to 13.74 volts which would be a reasonable (though not optimal) charging voltage for a 12v bank, if its 60amps continuous ouput is adequate for charging purposes.  I'm sure they have other converters available if current above 60a is required, and I'd contact them and ask before purchasing.

Some solar controllers will accept various voltages and convert them downward as part of their charging process, but many state that they aren't intended for uses other than solar.  Other, non-solar, charge controllers exist I believe.

If you need more help posting some more information would be helpful.

[Lowhead]

Regarding the NEC comment above.  Since a 48V system is usually charged around 56 volts, would the NEC requirements apply or is that already factored in?

[dnix71]

Under 60 volts is "low voltage." So a 48 volt system fully charged should still be under the limit.

[dnix71]

His product is here:

http://www.boost-energy.com/ampair/products_product5.asp

It's intended to be towed behind a boat or tied to an oil platform or buoy.

[random]

I had to comply with NEC-2003 because that's what our county required.  It called below 50 volts "low voltage".  I assume they meant "50 volts nominal" but I discarded my copy of the NEC spec as a rite of exorcism after passing the inspection.  Since my system runs 24v nominal it never became an issue.

I see that another comment was posted saying "under 60 volts" is considered low voltage, but I don't know what version of what spec that came from.  NEC-2003 is old now but if you have local building codes (some counties don't) you will probably need to know what version of the NEC they are using unless you're hiring out the electrical work.