12 volt battery charger repair. 

After watching most of the Videos on Car Battery Rechargers, this is the only one out there that is 100% a sure thing! Thankyou!

Making use of the ru-vid.comUgkxcJ22tnHH9l1vjdIdEIG27iOG55P7LXI8 reconditioning plan, I just saved 2 auto batteries from being completely junked. The guides were very simple to follow. I wish I would have found this years ago! You may use the guide to recondition any battery type

Bypassed the short stop and found it is not the problem. Not getting much voltage out of the transformer from what I can see. Not worth messing around with it any longer. It will cost more to fix it then to just replace the complete unit with a new battery charger. Still now I have a bag of diodes I may never use but I needed to take that chance that it might of been a diode. Still I have them in case they do go in other chargers down the road. Thanks for your help here.

Didn't see you remove diodes from holder. VERY important to install diode in correct direction. Looks like red mark is for the cathode.

No need to be sorry. I appreciated your help. The way I look at it is you win some and lose some. Fixed many items other people would of thrown away over the years. Just didn't work out with this item. I am only out 10 bucks and still have a bag of 50 amp button diodes I may eventually use or someone else may need. I will hold on to this charger anyway as it still has good cables that I may need down the road and who knows I may find out about another fix.

Thank you so much for this video. I just bought a new "smart" charger and the thing is a POS. But I still have my old Craftsman 2/10/50 that needs repair, now I know how.

Just placed an order with Skycraft. Ordered a dozen in case I need them down the road as I have other chargers probably using the same diode I believe. If not cheap insurance I guess. Shipping varied from $1.95 to $5.50. Took the First Class Mail at a $1.95. Want to thank you for your video and help in this matter. Will let you know how I made out later next week if the parts arrive by then.

I just ordered the diodes on Ebay. I think mine is an older model. The diode casing is riveted directly to the large heat sink. It seems you have to drill the rivets out and re-rivet it back on the heat sink. I think what I will do, is just drill a hole in the heat sink, rotate the diode casing to the hole and pop out the diode. Hopefully it works... Thanks for the video.

Same charger same problem, worked fine until I accidentally shorted out the out wires for about 5-10secs, then got a burning smell and the extra loud buzzing. Pulled it apart, it has 2 button diodes, so I believe this is full wave rectification, any way one diode measured short circuit (use your diode setting on your meter to test), which means it's toast, the other one was fine. I cannot find 50A button diodes so I going to use 25A ones as they seem the most common type, $9 for 12 including shipping. I'm thinking on the 6/10A model charger 25A will be fine, and that the only reason it may have had 50A ones is that they can have a common part across 2 models. The transformer measured good. As a side note, it is quite common to let diodes blow as a safety device, using them like a type of fuse, if you get my drift, they also do this for reverse polarity protection on electronics as well, Thank you for posting the video, it got me started on the repair.

Skycraft Parts and surplus had them for 65 per diode, I checked EVERYWHERE including radioshack which dont have them, and a few high end electronic business around, your better off to just buy them online like i did, and its worth the wait if thats the problem with it, just MAKE sure you install them exactly how they come out,

Cool, I had to go out an buy a new charger. I tried cracking mine open but they built it so you couldn't get into it. Nice save, should last you a long time.

Had thoughts of that box possibly being bad also. It is called a Short Stop as written on it.. Also reads that it is a 12 Volt 20 amp stop. I forgot to mention to you earlier the transformer on my charger is not making a loud hum. It is very quiet but it is bussing similiar to yours after you disconnected the bad diodes. Anyway it is a cheap fix replacing the diodes out first. Hopefully they will be in the mail later today Thursday or by the weekend. Tracking said possibly today.

Hi there, think the black lump is called the rectifier, the diodes can be tested with an ohm meter they should only conduct one way if there alright, also you can do it with multimeter on diode setting...think about 0.7 volt drop one way only, believe the other bit is prob called a current trip....from Fred in England.

yep bridge rectifier failure, it probably wont happen again, they dont really wear out, you just had a bad one, you can buy a bridge rectifier in a block, no need for separate diodes, and you can buy one with a higher amp rating than the old one, bolt that to a heatsink, and you wont have any issues again, just 4 connections, 2 for the ac side and 2 more pos + neg out

Yeah this thing lasts forever. I’ve had set to 2 amps trickle charging a car in the garage for close to 10 years. Didn’t realize the rectifier circuit is so basic though. Can’t be the cleanest 12V power source that’s for sure.

Thanks for the great info.I also have (2) 200 amp schumacher chargers bad.Next to do .

Thanks! I hope it lasts me under normal use at leaft 5 years,had a electronic Automatic battery charger with Desulfation mode, it took a crap after a year! but it had so many electronics in and transistors and etc, that i could not figure that one out, So i bought this manual one, anything else usually costs you big money to get it worked on and you still wont know how long it might last you afterwards,

Got the diodes in the mail today. A little smaller then the originals in my charger. Tried 2 of them out but it did not fix the problem. Funny thing I had to try the diodes both ways since they are not exactly like the others. Don't really know which way to put them in for sure. Either way I mount them the charger lights up 2 bulbs on the front of the charger without plugging the unit in the wall no matter which way they are mounted. Plug unit in wall but get a negative read out. I am stumped.

I saw the listing for 65 cents each also by a online vendor a little bit earlier. Didn't get a chance to check it out further as far as shipping goes. Was hoping to see if my local Radio Shack or other electronics store in my area carried them and at what cost first. Will try Monday. Wasn't about to buy another Harbor Freight Battery Charger. Did a little research on the HF Charger in question and can't believe all the complaints from so may other owners of the same battery charger dying out.

Problem is I am not getting a reading at the Black and Red Alligator clips. I believe everything is good from the transformer to the Black Alligator Clip as I tested it that far. This same black wire goes to the Short Stop which is working fine as I took voltage right to it. The problem from what I can see is where the positive coming from the Transformer goes to the circuit board. Somewhere from the board to the Red Alligator Clip wire there is no electric as I believe there is a bad component

Wel mine doesnt have a circuit boad on it anywhere, pretty much hard wiring and switch, and a short stop with a heat sink and diodes, Your might be a Automatic charger, mine is a manual, so if your is automatic, thats why you have s circuit board, i stayed away from those just because the last one i had gave me a problem after a year, i figure a manual charger would been best, so far it is, just cant be touching clamps for any reason so i learned, lol..

Not to confuse anyone there are 2 switches on my 03418 Harbor Freight Charger. Look at the charger online to see what I am talking about. The first switch to the left of the front panel is what I believe is defective. Tried cleaning it drenching it with Alcohol and a swab but didn't help. May take the board with me to an electronics store to see if the switch is available. If not too expensive I will replace it. Otherwise the same HF charger on sale sells for $34.99 although I won't buy another

Blkctthwt well the circuit breaker on the charger would not allow any coltage what so ever, if you hear it buzzing loud, its more likely the rectifying diodes, on that model you have, they are threaded 50 amp diodes, you can get them online, the job of the rectifying diode is to take the ac voltage and create DC voltage, you have one of them that is at fault or faulty, you will get that when both are not working, there is a video on here that shows a chager like yours the guy is replacing those rectifying diodes in a big charger just like yours, they both have to work or you will get a voltage varience like that, if both were no good, you would not get any coltage at all, one broke would produce a problem as you state, Good luck !

On the start/boost side I can still select a 2amp,10amp 12 Volt charge or even a 10amp 6 volt charge manually now. Only spent $3.95 for the replacement switch so I don't have a lot of money in this charge other then my spare time messing with it. As I said before these chargers can be purchased pretty cheaply and parts are not available from the Manufacturer. It was still worth it for me to give it a shot and look inside. Sometimes you win and sometimes you lose is what it all comes down to. lol

Thanks for the video. However I did Check all these things. And nothing. For anybody that's watching this, simply check the end terminal connections on the clamps. I found that one of my wires was pulled out... Go figure.. so I soldered mine on and its working fine now..

Ended up pulling the circuit board out last night to check the backside. Have to say someone did some crappy factory soldering and Harbor Freight doesn't carry parts for their chargers. Wouldn't buy another HF Charger ever again being they only come with a 90 day warrenty. I also own a Sears Die Hard Charger. Comes with a 3 year warranty and seems to be made better. Going to check the resistors on the board and see if I could test other components on the board with some Net Help before I giveup

sounds right to me, sounds like your charger is a automatic type, and something on the cicuirt board burned up, mine doesnt have that, but its manual. There could be a smaller and different Diode on that board, Diodes are only to allow current to flow in one direction, rectifying diodes i think turn the AC to DC current if im not mistaken

Well there is a Ring on the one end of the diode to tell you the polarity, they should be put in the same as the originals, withoutreally seeing the charger apart its hard to say , only thing you need to check that does and can go bad also is the SHORT STOP or circuit breaker, you need to check for voltage BEFORE the short stop and AFTER the diodes, if there is not voltage, there is something else that could be electronic in that charger, that i am not un aware of, could ALSO be the meter bad

Good deal, i got 10, incase i ran into the same problem the transformer usually dont go bad that fast, they are pretty simple, always best to have a few extra, just place them where you dont loose them, easy to get lost, lol.

I believe, its working, When i tested mine on 2 amp i had 10.2 volts and on 10 amp i had 12.7 volts i believe your charger is working,, not sure why strange, i believe the You should check voltage where both diodes mount, check them as one, not seperate at this point, you may get different readings from just checking one a time, but your getting power out through them non the less.

I couldn't find any 50A button diodes, searched ebay, none. So got the 25A MR3025, and they work fine in the Schumacher SE 86-2. These lower amperage ones my not work well in higher amperage chargers.

I have the same one. Thanks. I found the 25 amp at Skycraft parts. Still looking for the 50amp.

Damn diodes man! look at it, its brand new! not a scratch on it! for now on anythime i see a charger not working, im getting it to fix it, lol,. hey man i hope this might help, thanks for stoppin by always good to see ya man.

Thanks for the video, I determined I do have a burnt out diode. Now that I know that, i find no replacement Diodes anywhere? guess I'm just expected to throw it away? I see this video is from a while ago, but any recollection where you found the Diodes?

Shorted diodes, I used to work at Auto Zone and we got returns of so many BCs with bad diodes. Good for me cuz I took em home and put HD diodes in there.

Well im the same way, keep it you may figure it out later, never know, or need parts? Take care and be careful of any of those alligator clips touching at all, i found out the hard way it only takes one too many times

Mine were also smaller then originals, but works great,

nice. mine has this exact problem. however i will dish out for a new unit because im incompetent in this area. still gave a like

Ok I believe I found the problem this Sunday morning. As I mentioned there was some bad soldering. Took my soldering iron out and cleaned and resoldered what looked bad. Actually there was a loose joint on the board. I am now getting juice at the red and black alligator cables. Problem is I believe I have a bad switch on the board. The switch serves 2 purposes. Left position is charging, right position is engine start/boost. Charger works only on the start/boost side.See next post.

forgot to mention there is a Circuit breaker also that the battery leads attach to, that could also be bad, its the lil metal or plastic like box the leads go to, or through,

Couldn't walk away from it just yet. Now I don't believe there is anything wrong with my Transformer. Took my multi-tester and took a voltage reading coming right out of the negative side of the diodes going to the transformer and from the positive point at the plate the diodes are mounted to. Getting a 12.8 Volt to a 13 reading in the 10amp selection on the switch depending on what diode I touch, 10.6 -11 volts at the 2amp position and 7.8 to 8 volts at the 2 amp 6 volt battery position

Still waiting on the diodes to arrive. Will surely let everyone know how I made out.I finally found my multimeter this morning to checked voltage coming out of the Battery Charger and got a Zero reading. My charger has settings for 10 amp 6 volt manuel , 2 amp 10 amp 12 volt auto and 55amp engine start boost, No reading on any of the settings. I do remember crossing the negative and positive cables on a battery just before the unit died about a year ago. Hopefully I just blew out the diodes.

Well done and thank you good sir.

Well I remember my alligator clips touched just for a second, then i remember my charger made a loud Buzzing like humm like when its under a heavy load when it was not hooked to anything, when checked my voltage and i had 2 volts, i took diodes out and the loud buzzing stopped, so i knew i had a problem with those. i looked up the patent number, found the description and part numbers, then looked and found some online,otherwise id have to buy a new one, or send it back and pay.

Thanks for the video. I'm wondering where you are measuring the output for the meter.

i have the same one and sounds just like that but it charges fine. i use the 6 amp for my 12 volt battery for my cruiser and it work fine.

How would you bypass selector switch and wire it straight for 12v 6 amp

good job wall :) i got a charger doing the same thing .

Dónde se consiguen los diodos para remplazar

No reading on it must mean you have Noth diodes burned up, i had one bad on mine, and had a very low voltage on all settings, Im pretty sure its the diodes, damn shame these are not more available, think of how many battery chargers get tossed because of a 70 cent piece,mine was few months old, if i did not do the patent search i would not have figured it out, let me know if yours gets fixed from replacing them,

Heck you did most of the work for me. After reading you already checked Radio Shack and other local electronic places I took the easy way out buying them online as you suggested.

Using my Multi-Testor at the Alligator Clip black and red cables at the (Select Setting Switch) 12 volt setting of 10 amp it reads 12.4 DCV, 2amp setting 10.2 DCV. At the 6 volt 10 amp setting it reads 7.5 DCV. At the 55 Amp Boost it reads 14.90 DCV. This is all on the right side of the (Select Function Switch) reading Engine Start/Boost. When I switch it to the left side which reads Charging Only there is no electricity to the Red and Black Cables making me believe the one switch is bad.

Well i wish you luck in the journey into that, sorry i could not be any better help, i bought this Shumacher charger because they been aorund for a long long time, figure most chargers are basically the same, but who knows, i was goin to buy the HF charger but ended up buying this for more money, let me know if you find out what it is, im curious.

I have my grandfather's old Sears 2/10/50 charger. It's worked fine for the 8 years I've had it, but today it sparked inside of it when I plugged it into the wall, and now it doesn't show any amps on the meter.

How do youcheck the diodes? Front to back.bad they read shorted?

Great Video, it was very helpfull for me.

You need to give more detail on how to replace the diodes

I now believe there is something wrong with a component on the circuit board because I can't get any reading beyond where the wires coming from the Transformer go to the circuit board to the meter.

that is a pretty cheap half wave rectifier with 2 diodes i think in your vid, id upgrade it to a better bridge recitifier , and add one of a more amp capacity, maybe double what your charger says on the front, then you wont blow it if you accidentally short the wires, it seems your rectifier was shorting out the transformer, its rare they short out, they usually just fail to work

Yep, diode issue!

sure a lot of junk out there life time warranty may last a month if your lucky

I believe I have the same problem with my battery charger from Harbor Freight. Would of brought it back but it only came with a 90 day guarantee. Anyway have it apart but I am having a hard time finding replacement diodes out there. Came up with a link to Ebay of which 20 were sold but it seems no one has them on Ebay anymore and my google search did no good to find them. Any idea where else to look?

Do you know if it's possible to modify Schumacher battery chargers to operate on 220 volts? (e.g.: do the input transformers have unused taps for 220 volts?) My friends brought a Schumacher SE-5121A and XCS15 to Bolivia, not realizing there would be only 220 volts instead of 110. Is there any possibility someone could modify either of these chargers in the field to work on 220 volts?

quisiera que por favor me puede ayudar con el cargador Schumacher se-82-6 lo tengo desarmado y no se como conectar y si se puede explicar en español. muchas gracias

COOL, but i recall a diode allows current in only one direction, from physics class, so what is their purpose in this arrangement, do you know by chance?

Where did you get these diodes and what kind are they? I need them for mine. Thanks

Replaced the function switch, Wrong once again. Spent the morning probing the board and applying everything I know about electronics having 1 year of Electric Shop in High School many years ago. What I do know helped plenty over the years but not now. Somewhere in the circuit board there is a problem. I do have power as mentioned on one side of the function switch, the engine start/boost side but not on the charging side. It should still charge a battery up manually though even with a bad board.

I have similar charger made by penske that has bad diodes. they look exactly the same as the button diodes you have but i can't figure out how to remove them. it looks like they are press fitted in place very tightly. how did you remove yours, and would you be willing to sell two?

saludos desde Veracruz México por favor quiero saber las conexiones del selector de voltaje del cargador para baterías marca schumacher mod SE-82-6 por su atención muchas gracias

Do the diodes have an orientation to them, does it matter which way they go in?

Is it 2 25amp diodes or 2 50 amp diodes?

Will do.

thank you

I have an Autocraft 2/12/75 amp charger and I am not getting anything through to the hookup clamps. You can even touch them together and there is no spark. What do you think the problem is? It is only less than 2 years old and used less than 6 times. Thanks

I have the same charger

Well im not sure then, i know the diodes were not much money and 70 % of the time its those that go bad, if yours is anything close to the one i have, it cannot be something hard to find, there not much to go wrong, gotta be something simple, unless transformer is no good, you will use those diodes maybe in good time, think of it this way someone else might need them, you can still sell them, if need be, Sorry i could not assist you any better in your repair,

my schumacher charger does not make that sound , but the voltage only reaches 10 volts, and then sometimes after it has been on for say 5 minutes it drops out to zero???

I have a P6001414 Invacare power chair and its 24v battery has suddenly stopped charging. The flashing lights on the top of the control stick only show two red lights flashing when the battery is supposed to be charging (instead of two red,two amber and two green). I have tried chugging overnight but have had no success. Does anybody have any ideas?

I'm assuming you replaced diodes, you didn't say.

there is a place that sells online you can message your email to me i can send you the link i cannot post it on here it will not let me, shows them to be 65 cents each.

Too bad you could not look up a schematic for a "like" battery charger, and wire it for manual operation.

Where do you read the Voltage?

Sorry, that should be "charging" instead of "chugging"

Where did you buy the diodes?

Busted unit

Poor video bad camera more shots of out side of charger than inside.

The problem with the charger is the same problem we face with about everything people own today. It can be equipment, tools that operate on electric, gas and manual power. This is the same problem we all have 99% of the time. 𝐛𝐞𝐜𝐚𝐮𝐬𝐞 𝐞𝐯𝐞𝐫𝐲𝐭𝐡𝐢𝐧𝐠 𝐢𝐬 𝐦𝐚𝐝𝐞 𝐢𝐧 𝐂𝐇𝐈𝐍𝐀!!!!!!! It's all junk, no quality and made by forced slave labor and the thought consumers have thinking it's less expensive is incorrect. Less expensive is same or equal quality. Cheap is junk and the thinking your saving money is wrong because you end up buying multiple of the same item vs. 1 that last a lifetime.