Two more electrical questions

By hewybo
Jun 25, 2006
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  1. Afriend is trying to loan her late spouse's motorized scooter to another ailing friend. Funds are short. The on-board trickle-charger won't bring the batteries back up, as they have been sitting for some time. These are two sealed, lead-acid 12V batteries. Will I splode 'em if I hook up my automotive (2 amp) trickle charger to them?

    Second- bought a little wire/flux welder. Needs a 20 amp circuit. Biggest in my house (except out of the 220 for the dryer) is 15 amp. what happens if I just plug in a 20 am breaker in place of the 15A that's on the circuit I will be using?

    Just tryin to be fire-safe. Tee-hee. :suspiciou :hotbounce
  2. Rik

    Rik Banned Posts: 3,814

    First question - Don't connect sealed led acids to a 2amp charger, it will definitely do damage. I personally have a top of the range intelligent radio controlled car charger that i use for such things, but even that wont "wake" a totally flat lead acid.

    Second question - The best thing to do would be to get a professional in to check your wiring. If you don't, you may be risking burning out your wiring or even worse, a fire.
  3. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,689   +395

    I dunno about it screwing up your batteries. I use some sealed lead batteries at work, and I've hooked them up to car chargers before, hell I even took one that was dead and gave it 10 amps (didn't fix it though). But I think 2 amp should be fine. Espically if they are the kind that can be used to push people around.

    Not sure about your welder, might want to see if any of your buddies know someone that could look at it, that way you may be able to get by without callign someone that will charge you.
  4. hewybo

    hewybo TS Maniac Topic Starter Posts: 435

    Yeah, that's why I'm here

    I checked 'em with a multimeter, and one's got around 10V, the other at 11. I couldn't think how a 2amp trickle could kill 'em. Doesn't generate that much heat. At any rate, I'm gonna try it, as she assumes she has to buy new anyway.

    On the welder- I used a rented one a couple years back, didn't hurt/kick out anything, but don't recall the amp draw it had. Don't have any real friends in Vegas- not sure they make 'em here. That's why I picked on you guys. Since this is my Mom's house, didn't wanna take chances. I'm just gonna fire it up through the 15 amp GFCI that it's on, won't do anything but kick the breaker.

    Thanks for the replies, guys. (SNGX- looks like the new dept. head hung on to ya, huh? Excellent judge of character, I say!)

    H :knock:
  5. KingCody

    KingCody TS Evangelist Posts: 992   +8

    haha :D

    anyways, there should be no harm in hooking a 2A trickle charger up to the battery. I wouldn't recommend leaving it unattended for long periods of time, but it certainly won't explode the second you hook it up. lead acid batteries will actually expand if they are overcharging (they physically bulge out on the sides and it starts to become round). if you see that start, then by all means disconnect it! personally I have used a cheesy wal-mart charger on 2A and 10A settings to charge up small sealed 12v L/A batteries (the ones used in emergency backup lighting), and it never did any harm at all. bottom line it should be fine, but i don't recommend leaving it unattended.

    as far as the outlet is concerned... you may be fine with the 15A breaker thats in there now. don't just slap a 20A in there because the wires may not be thick enough to handle the extra current. if the 15A breaker is not enough then you can buy a "slow-blow" 15A circuit breaker. electrical devices draw alot of current when they start up, but they draw less quicky afterwards. a slow-blow breaker will allow the welder to draw more than 15A for a couple seconds before it blows. this will handle the spike from the start up.

    cheers :)
  6. hewybo

    hewybo TS Maniac Topic Starter Posts: 435

    See what happens

    Thanks, King- been too busy to even plug it in, but if it kicks the switch, I'll try the slow-blow business. Oh well, might see a little welder on eBay soon. Life's a *****, but we all get dead, anyway. :dead:
  7. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,689   +395

    Now I'm not electrical genius, but, I would think that if you want to give it a go - you should be able to wire 2 120V things together without getting 240V (right?) then you could toss in a 30A breaker, because that way each one would only be carrying up to its 15A and be ok.

    We might want to wait for someone a little more electrical smart than us to comment on this, it would work with dc, and I think you can do it with AC as well, just not positive.
  8. hewybo

    hewybo TS Maniac Topic Starter Posts: 435


    wouldn'that be basically the same as just putting a 30A breaker in place of the 15? I mean it's still a 120V feed in and out. I don't know- that's why I'm asking. :suspiciou :confused: :confused:
  9. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,689   +395

    well, as long as they aren't using the same wiring I think it would work. sort of like taking 2 wires to do the job of one.

    Like if room1 has 15A breaker and room2 has 15 amp breaker. Different lines are going to each room. If you could use the wiring before it gets split into those rooms (or combine those 2) that should be able to carry more than 15A I would think. But I'm no electrician either, so I wouldn't try it without someone smarter than us telling you its ok.

    Actually, now that I think about it some more, I think you could just add a 30A breaker but not inplace of a 15. The big line comes into your house and you know its got to be bigger than 15A max so if you can add a 30A off of that it should be fine.
  10. KingCody

    KingCody TS Evangelist Posts: 992   +8

    that would not work...

    on homes with older wiring, they have 100A input (newer homes or re-wired homes will have a 200A input), with household AC if something needs more power than 20A, you don't increase the current, you increase the voltage to 220v-240v. this doubles the wattage without the need for thicker wires.

    a 30A breaker is actually two 15A breakers with the physical toggle attached (so that you cannot open or close them independantly), they work to create a single 30A (15A+15A) circuit via 230V

    one thing you have to understand is that even though there is 100A (or 200A) coming into the house at the main breaker, each individual breaker's feed is from the same source. connecting two of them in parallel does not magically create a 30A circuit, it just creates a parallel wired 15A circuit (in other words anything above 15A will still blow the breakers, in fact it will blow both of them)

    if the welder has a standard 110v household plug, then it should function on a 20A circuit without tripping the breaker, if it needed more than it would have a 220v plug instead.

    i know i'm not the best when it comes to explanations, but I hope i made it clear enough. :)
  11. hewybo

    hewybo TS Maniac Topic Starter Posts: 435

    That was my original question

    It's taken me a week and a half to get back, but- King Cody- that was what I was getting at- the welder does have a regular three-prong, 115-120V plug, but the breaker to my little shop is a 15A GFCI. There are no breakers above 15A, except the dryer circuit, which is 20A on a circuit wired for 220V. The AC is 220, but wired separately from the main box.

    Ultimately, I guess, it's just a matter of tryin the dang thing, and see what happens. Been too freakin busy (and HOT) here in Vegas to even think about it. I sincerely appreciate everyone's input, and will bump this after the grand experiment. (or not, if you happen to see a cloud of smoke rising from the Vegas valley)

    Thanks again- :hotbounce
  12. KingCody

    KingCody TS Evangelist Posts: 992   +8

    *** I am not an electrician, I am just giving you general information. do not attempt to change any wiring in your home without first consulting a licensed electrician ***

    with that being said...

    yeah just try it out... if it works, then great!! if it doesn't work than the breaker will just trip... big deal.

    if it does trip the breaker then:

    1. check the wire guage. generally you can run up to 15amps on a 14AWG wire, and up to 20amps on a 12AWG wire. if the wiring is 12AWG, then it should be safe to put a 20A breaker in place of the 15A.

    2. if you buy another breaker, don't get a thermal breaker. thermal breakers will trip with less current when hot, and more current when cold. and since you live in vegas, i would imagine it gets quite hot over there (i've never actually been there myself).

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