Welder for a battery charger

Date 02-14-2008 05:38

it does work, ive jump started heavy equipment that way, probably isnt the most cost effective way to just charge a battery though.

By MDG Custom Weld (***)

Date 02-14-2008 14:37

It does work, but it can be dangerous. The CV voltage is not the problem, it's the amps that you are pushing at the given voltage. If the battery has a weak cell that has a short, the high amps that you put into it will cause the battery to explode in a matter of minutes. I have used my welder to jump start things, but I would never leave it on there for more that 3-5 minutes to charge. I did have a dozer that was dead and the welder took about 2 minutes to blow up the battery. It was a mess!! I found out from the crew that they had been having problems with the dozer batteries for about a week, which leads me to believe that it had a shorted cell, and the welder caused it to blow.
Don't make a habit of it and think it will replace your battery charger, but in a pinch it works (just use caution!!).

By Wrench Tech (**)

Date 02-14-2008 19:38

Yes, I can see how a battery with a cell that has a short in it would allow the welder to push a huge amperage through it.

By rlitman (***)

Date 02-14-2008 15:02

Hummm, from what I remember about battery chargers, they're neither CC nor CV, but have properties of both.
Anyway, they all have overcurrent limitation (which your welder does not in a CV mode, since its merely limited by the capacity of the machine, which is almost certainly over the charging limit of your batteries, unless maybe they're from a forklift), to prevent charging at too high a current.
Charging at too high a current will cause hydrogen gas to be generated by lead-acid batteries, and permanent battery damage.
My guess is that you can get away with this for a number of seconds, and a machine with true CV properties might make a decent jump starter, but you would really need to baby sit this like a boiling pot on the stove, to charge safely.
Dead lead-acid batteries are best charged in three steps.
The first step charges the battery up to 80% in a CC mode, and is kept at this current rate, until the battery voltage reaches 14.4V.
So, if you knew the voltage the batteries started at (say 9 each), and set your machine to that, and hooked it up.
Then, with an ammmeter (really important to do this with any degree of safety), you could keep increasing the voltage until the ammeter read the max charging current to simulate CC.
Then the battery is charged to 98% in a CV mode, at 14.4V, while the current will slowly decline.
Your machine will probably not be able to finish the battery off in the float mode.

Now that I wrote this, I noticed this great article found on google:
http://www.batteryuniversity.com/partone-13.htm

By Wrench Tech (**)

Date 02-14-2008 20:00

Thanks for the reply. I realize that you'd have to be very careful about this. But lots of times in the field you run across circumstances where this could be a handy trick. I'm talking about a machine where the charging system has failed or the operator left something on overnight. And I can see that the absence of current limitation is a cause for some concern. I was pretty sure this would work if the batteries are just flat but otherwise healthy but I thought I'd throw the idea out here just in case there was something I hadn't thought of. You can't know everything and in this case the consequences of a miscalculation could be disastrous. I think, under the right circumstances, I might try this. Thanks for the link - it's a good one.

By rlitman (***)

Date 02-15-2008 12:43

Funny thing is that Miller actually made an engine welder with a battery charging feature. It was available in one model of the AEAD (unfortunately, not MY version).
If your machine makes 110V, the best thing to do is to hook up a battery charger to that.
Its probably a bad idea to disconnect your battery while your machine is running, and hook up to a dead battery.

BTW, peak charging currents will depend on the cell's construction. Deep cycle batteries, such as those in Dave's boat, can be charger faster than batteries designed to start an engine. The bubbling in batteries being overcharged or charged to rapidly, can be easily heard in a quiet environment. Its kind of a sizzling sound. In sealed and pressurized batteries, that hydrogen could even possibly be reabsorbed, but when it vents, the batteries will lose some capacity.

By Wrench Tech (**)

Date 02-15-2008 14:58

It goes without saying that you'd never hook you welder up to a battery if you had a battery charger with you. And I'd not try it in a boat. My ususal situation puts me in fairly remote locations with heavy equipment. They have large batteries (4d orm 8d) that are usually connected in series to 24 volts. Now if this system is down to 14 volts or so, the machine will not start, especially if its cold. If I connected this battery system to my welder in CV mode, with the voltage turned well below or at the 14 volts there will me no or very little current flow. We are assuming, of course, that the batteries are otherwise healthy - no shorted cells etc. Now, if I turn the voltage up to 18 or 20 volts we'll get some current flow but not much. The batteries are charging. After 5 minutes or so I turn the voltage up to 24 or slightly higher and charge it up some more. I should be able to get these batteries in good enough shape to start the machine. The machines charging system can then take over and finish the job. Two points... If I'm unfamiliar with the machine and/or the batteries I won't use this proceedure. And I will not crank the machine withe the welder connected.

Did I miss something?

This would be a lot quicker than using my pickup and charging up one battery at a time. If you've done this as many times as I have you'll know what a pain this is.

Thanks for the replies.

By rlitman (***)

Date 02-15-2008 15:16

Yeah. I would just get a clamp on ammeter, to keep on eye on current (unless your machine has a meter built in). It may be hard to hear the bubbling from charging too fast over your engine.
It sure sounds like a good way to make do with what you have.
Plus, if you keep an eye on the current, you can actually start the charging with a surprisingly high voltage, and save some time.
BTW, make sure that the batteries are vented well, so if you do overcharge and let off hydrogen, it doesn't collect in an enclosed space.

By DaveBoyer (*****)

Date 02-15-2008 05:26

In addition to keeping the voltage under controll amperage should be limited to 20% of the amp/hour rating of the batteries. I have a reasonably sophisticated charging system on My boat that bulk charges at 14.5 volts at a maximum 130 amps. This is the 20% point of the 6 golf cart batterys that make up a 12 volt bank. The batteries bubble and get warm when charged at this rate. Before these "smart" regulators came about many people just used a rheostat similar to the fine controll on a SA 200 to controll the alternator field, this took nearly constant attention to keep in the 14 1/2 volt range, and this was with alternators much less powerfull than a welder.

By Wrench Tech (**)

Date 02-15-2008 15:15

It's quite a charging system that'll put out 130 amps at 14.5 volts! You must have a huge set of batteries in that boat. How do you vent the battery compartment?

By nevadanick (**)

Date 02-16-2008 01:48

be careful if you work around modern heavy equipment and check your voltage with a dvom before hooking up, because if it was turned up too high, over 30v, you can possibly fry one of the ecm's.

By Wrench Tech (**)

Date 02-17-2008 16:23

28 volts maximum

By DaveBoyer (*****)

Date 02-16-2008 05:13

Wrench Tec: The bank is 6 golf cart batteries, the same number that is used in an electric golf cart, but I set it up for 12 volts instead of 36 volts. The batteries are tightly packed in a fiberglassed plywood box, due to hight limitations I just cover the box with a sheet of Formica held in place with tape. The bank is located under My bunk with no particular means of ventilation. This is not an ideal setup, as there should be space between the batteries for air circulation to get rid of the heat. The batteries have the usual vented caps, however there are caps with a catalist that re-combines the hydrogen and oxygen into water so You seldom have to top off the cells. The alternator is a Herr Powerline rated at 190 amps cold and 165 hot. I carried 2 spares, as they don't hold up well in the hot engine compartment of My boat. I drive that alternator with a 9" 2 groove pulley on the engine and a 2.7" on the alternator. The alternator will put out 135 amps at 1,000 engine RPM when cold, 130 amps at 1,100 at operating temperature. A better [and larger] alternator for this purpose is the Leese Nevill 200, but I would have to do some major rework to fit one in. I lived on this boat the better part of 12 years and seldom had shore power, I used a Heart Interface 1800 watt invertor for AC power to run everything from an electric cooker to a tablesaw. It will run any 1/2 HP motor and some 3/4 HP or any universal motor [like in an angle grinder] to 15 amps.

By Wrench Tech (**)

Date 02-17-2008 16:48

I can see why you need a battery setup like that if it's your primary electricity source. I guess you can get away with your battery compartment's lack of ventilation if you don't deep cycle the batteries. Otherwise it'd be hot and stinky where you sleep!

By 803056

Date 02-18-2008 00:22

It probably is hot and stinky! :)

with or without the batteries! :)

Sorry Dave, I couldn't stop myself! :)

Al

By DaveBoyer (*****)

Date 02-18-2008 05:55

I did cycle the batteries fairly deeply, but usually less than 1 time per day. On my '93 trip My mechanical refrigeration gave problems and I used a 115 volt system that tied into the same holding plates off the invertor. I was cycling the bank 100+ amp hours 2 times a day. As it was summer in the southern Bahamas with daytime air temps in the upper 90s and nightime air and sea water temps not much lower, sleeping above that battery bank was a *******. I made it a point to keep Me from getting too stinkey, the goal to be less so than the locals and most of the other boaters. Unless there is an internal problem with the batteries they won't give off much odor when charged at 14.5 volts, but the heavy cycling 2 times a day and the resulting heat buildup did seriously shorten the life of this battery bank, they were shot & got replaced when I got back to Anapolis in the fall. Going north in the fall was stupid, and passing friends headed south just rubbed it in.

By 803056

Date 02-18-2008 12:59

When I retire, I want to be just like you and have your life style!

Best regards - Al

By DaveBoyer (*****)

Date 02-19-2008 04:39

Al, I surely hope that You can, but don't wait 'till You are old. I walked away from a pretty good tool & die job [that I burned out on from too much overtime] when I was 32. I did My livaboard cruising untill I got cancer at 44, otherwise I would still be doing it. I am 48 now, and if I ever get this cancer under controll I will be on that boat again [provided I am able]. Those years I lived mostly on the boat I didn't work much, but I ate a lot of fish & coconuts. I am darn glad to have done it when I did, especially now that I might not make it to a conventional retirement age.

By 803056

Date 02-19-2008 12:08

Hello Dave;

You and Henry are two of my favorite people here at the forum. To hear that either of you are not feeling up to snuff always makes me feel bad, but it makes me appreciate my health all the more. Good health and simply feeling well is something most of us take for granted until it is too late. I suppose I'm one of those people that abuses my body until I do get a cold or some other minor ailment and feel like a wet dog left out on a cold night.

I'm among the few fortunate people that really enjoys his work. I have been fortunate to work with some of the best welders, engineers, and inspectors over the course of my career. They took the time and had the patients to mentor me and I listened to every word they said. Now, I have the good fortune to have a consulting business that allows me to do some travel, but I still work from my home the majority of the time. That allows me to spent time with my family (including 6 grandchildren).

The grandchildren are the light of my life. They are the source of endless hours of entertainment just watching them grow and discover life. The other day my daughter called me to tell me that my four year old grandson, Gavin, was watching the Discovery channel when they showed someone welding. He hollered, "Mommy, come watch the TV, they're welding. Grandpa welds, he welds everything, he's so cool!"

This little fellow is going to give my daughter and son-in-law a run for their money. Nothing scares him and he's convinced he can do anything. The other day my wife, "Gavin you're handsome all dressed up."

He replied, "No grandma, I'm awesome!"

You never know what they hear during your conversations with other adults. They hear and understand more than we expect them to.

I have to run, I have a client to meet.

Take care of yourself. I suppose everyone says it, but I mean it. Attitude is an important part of living life, and I believe both you and Henry have the right stuff to conquer any problems you face.

I hope I never have to retire. Slow down a little, maybe, but retire, only if my health fails and I have no choice in the matter. One of my clients is in his 70's and still works everyday. Not because he has to, he works because he enjoys his what he does. His reply to people that ask him why he still works is, "Who's working, I'm still playing. What am I going to do? Watch television or walk around a golf course hitting and then chasing a small white ball?"

Best regards - Al

By DaveBoyer (*****)

Date 02-20-2008 05:40

Al, I can understand that You like Your work situation, work is fine when You can do it ON YOUR OWN TERMS or pretty much so. When I started in the tool & die trade I could not imagine doing anything else, and I put all of Myself into it. Then I got into sailing. At some point after I got the big sailboat I had a conversation with a guy who had just completed His residency as a MD. We were talking about working to the exclusion of everything else, and decided that it was not really a good thing. By that time I was already planning to go cruising, and was continuing to work to get the money saved up to do so. Those last few years were hard, but I needed to work those 10 hour days and 7 day weeks to make the numbers work. I was no longer doing what I WANTED to do, but what I HAD to do. There were a bunch of Us at the plant who were "greedy grabbers", and worked all the hours We could get. I was talking to one of the guys in the apprenticeship program, who was older than Me and had pretty much plant seniority. He commented that Craig was probably the happiest guy in the shop, and He worked almoast no overtime at all. This was an acurate observation, Craig and His son were into racing outboard hydroplanes and making propellers, they had each won the Nationals in thier class, the son more than once. Craig made the props in His own shop, the son worked there full time when He was finished school. Craig retired as son as He got His 30 years in [still pretty young] and works in the prop shop every day with NO INTENTION to stop. Yes, work is great when You are doing what You love.
Thanks for Your encouragement about My health situation.