Wire size wire for...4 Ice chrgrs-20 feet from 12v battery

What size wire would I need to run up to 4 Duratrax Ice Chargers about 20 feet away for a 12v car battery? Can a car battery handle charging 4 batteries at once?

[BrianG]

How much current will each charger require at ~12v? To get the required current, just multiply the max battery pack voltage X the charge current, then divide that by 12. Do this for all four chargers and add the currents together.

So, let's say you have four sets of 5s 8Ah Lipos. Each set of lipos will require 168W (4.2v X 5s X 8A) to charge. At 12v, that is 14A. For four of these, the current will be 56A total. Add 5% to account for charger losses to be safe for a total of 58.8A.

20 feet at 20A to 35A total, I'd go 8 gauge.
20 feet at 35A to 80A total, I'd go 4 gauge.

The easiest place to get this type of wire would be to go to a car stereo shop and get the wires there. You're gonna want a very good connection too, and don't forget some type of distribution block.

Thanks for helping me out. For my wild guess I was thinking maybe 12 gauge but, that is way to small. This may take a little more time. I was hoping to throw something together tonight. Somehow I'll figure something out.

I would say no to charging that many at the same time on just one 12v car battery. Only cause Ive tried it on a ( New) fairly beefy van battery and it didn't like it. Its fine for about 15mins then it just went under voltage.

I now use a 750w Jenny to juice up a power supply. and it only cost a little more than a new 12v car battery......just my 2 cent

[BrianG]

That is true! I just assumed the vehicle would be running so the Alternator will be helping out.

If you can get a power supply that can output a solid 14.4v (typical car voltage with vehicle running), it will pull less current for the same amount of power. From my example, 58.8A @ 12v would be the same power output as 49A at 14.4v.

I have power supplies for normal use but I was going to be at a remote location. Sand dunes to be exact. Me and my kids are pretty much all set. I was hoping to pit at the back of the vehicle with the chargers inside the vehicle to keep the yahoos from getting sand in my equipment with their quads. Maybe I'll try to stick to 1 or 2 chargers. Can I run the vehicle while charging with the Ice chargers? I assumed that would be too much voltage.

Just check the manual. Input voltage is from 11-15 volts so to answer my own question. Yes.

[BrianG]

Actually, I didn't mean "power supply" as in a "power supply unit", but rather a "supply of power". Sorry about the confusion! :)

Most, if not all, of these ~12v input chargers seem to have vehicle use in mind. That's why (among other reasons) they use the 11-15v range, so yes, they can be run in a vehicle, but you've already answered your question.

Oh! ok, I see what your saying now. At higher voltage your not pulling as much current. It all makes sense when you stop and think about it. I love learning about this stuff. At higher votage can you also go down on the gauge of wire you use? My guess is, only by a small amount.

[BrianG]

Originally Posted by Cartwheels

Oh! ok, I see what your saying now. At higher voltage your not pulling as much current. It all makes sense when you stop and think about it. I love learning about this stuff. At higher votage can you also go down on the gauge of wire you use? My guess is, only by a small amount.

Think of it as a power transfer. V x A = power. Higher voltage = less current for a given power. That's kinda the same idea behind using higher voltage on a BL motor with a higher amount of turns (lower KV/more resistance). Requires less current.

You could go down on the gauge, but the current is still high-ish, especially using 4 chargers. Now, if you only use two like you mentioned, you could go with 8 gauge. I really wouldn't go down any lower than that unless you are charging right by the battery. The two big factors in choosing a wire gauge is the wire length and current. Any wire has some resistance, generally expressed as ohms per foot (or milli-ohms per foot since it is relatively small). Longer wire=more resistance. Current through a resistance creates a voltage drop. Higher current=higher voltage drop on the wire itself. Higher voltage drop = less voltage at the charger.