24v or 48v and what gauge of wires?

[AKR]

ok, i'm getting tired of searching everywhere and not finding the answer, so i'm gonna ask. is there any reason to choose 24v over 48v or vice versa? what gauge of electrical wire do each of these use? thanks, Reuben

[drdongle]

The higher the voltage the smaller the wire you need to distribute it around, also the the lower the amps, which means smaller fuses ( which some times means lower prices). It can also mean being able to locate your genny farther from the point of use.

[wpowokal]

Reuben, while you don't say what for one assumes you mean "the whole system"

So heres my opnion, I would choose 48v If I was starting over, why......

Basically less amps everywhere, which means less I sq R losses.

Smaller diamiter cables = cost saving.

48V inverters will have a larger surge  capability.

So lets look at this, if you have enough sola panels they don't care if they are wired for 24 or 48V.

If you are making a say duel rotor, you just wind the coils to suit.

Batteries well they are batteries and you buy and connect them to suit. Take a rating of say 1500 a/h, now it's 1500 a/h every which way and probally not much if any difference in price.

The down side there may be less equipment to choose from for 48v systems than 24, but if you intend to buy quality I don't believe thats a problem.

Generally the higher voltage is at the top end of the current market and most of the junk ops sorry budget equipment is in 12 and 24V range.

Realy depends what you are doing, and as to cable size, well cables for what? or did I miss a post somewhere.

allan down under

[Volvo farmer]

One thing that hasn't been mentioned yet...

Everyone I've talked to says that multiple parallel strings of batteries are a no-no. The ultimate battery setup is one series string but two parallel strings are acceptable. So at 48V, you can build a single series string at twice the Ahr rating of a 24v string with common 6v lead acid batteries.

I went 24V and am going to use eight L16s in two parallel strings. If I want to increase the Ahr rating of my batteries, I have to start looking at the more expensive two- and four-volt cells.

[Bruce S]

Volvo;

   We experienced this type of problem while trying to decide how to design the battery setup for the e-trike.

We needed 36Vdc with 17Ahr ratting for each hour of riding. The motor is a 36Vac 600 watt unit.

I built 2 different sets.

The battery sets I get for free are NiCd's already assembled as 19.2Vdc/1300mAh.

The first set was a parallel set that took the 19.2Vdc banks ran them up to the needed Amp rating and then connected to the second bank for the voltage .We have a regulator that also us to run the 40Vdc so there's less loss.

The second bank built is a mix of series/parallel that first takes the voltages up to 40Vdc then is connected in parallel for the Amps, each bank being 40Vdc @1300mAh.

What we found, is that it's the recharging that is the issue. We ran the very same charger for both banks for consistency.

The first bank had middle battery destruction before the second week was up.

The second set and up to now fourth set are still running and charging doesn't seem to be an issue anymore.

This is a very high quality 3-step charger, not one off the wally-world shelf so I'm sure it wasn't the charger's fault

In another post someone sent a link to a new type of e-meter. We've just ordered two early this week so we can have re-time data of the health of the batteries.

Will post once we have them installed and some decent data.

Cheers!

Bruce S

[nothing to lose]

"The second bank built is a mix of series/parallel that first takes the voltages up to 40Vdc then is connected in parallel for the Amps, each bank being 40Vdc @1300mAh."

So I should wire up 4 sets as 80Vdc first, then wire up 4 sets of 80V to encrease the amps. And this should charge better with less battery damage then.

 Got a plan for those batteries and I have PM DC motors, but they're well over 100V ones.

[Experimental]

   Hi Reuben,

   If I understand, you are asking about magnet wire, to wind your coils with -- if this is so, Hugh Piggott, used 150 turns of 18 gage in a 24 volt mill, and 290 turns of 21 gage for 48 volt..

   If you want to make life easier on yourself however -- I suggest clicking on the Otherpower name above (our benefactor) and buy Hughs book, for twenty bucks !!

   Nearly, if not all , your questions are answered in his book and it is well worth the price -- I don,t know why I waited so long to buy it myself !!

   I do believe the 24 volt model, might be a better choice, as inverters and such (I believe) are more readily available -- but that is just MY opinion....          

    Wishing you , much luck,  Bill H.......

[SparWeb]

I have a reliable (and accepted by the FAA!) source of wire sizing and selection information:  Advisory Circular 43.13-1B, Chapter 11 describes acceptable methods for selecting and installing wiring in aircraft.  It's pretty easy to read, and there are examples to follow.  It has charts for 28V and 115V systems, what to do with a 48V system is obvious once you understand what to do with 28V.  You can download it in PDF form from the FAA website, under "Advisory Circulars".

There, you can have a propeller, tail, and wiring like an airplane.  Now all you need is a seat up on that tower and you can start making vroom-vroom noises. :^))

[AKR]

ok, sorry i wasn't clear, everyone. i see i have people off on the wrong track. i meant the wire runs to receptacles and such. i have a bunch of 12-2 scraps i'd like to use. it sounds like 48v would be the best set up. fortunately, they have a 48v version of the inverter i'm looking at (tripp lite). again, sorry for the confusion! Reuben

[jmk]

 Ispent a long time looking for a reasonable 48 volt inverter. I thought I had found an sw Xantrex model for $1,700.00. They said they had just sold the last one. I wound up getting the sw4024 for the same price. Otherwise I would have had to pay around $2500.00.