Voltage spike took my battery tester out! Easy fix? 💊💉 Part I

This was not the problem of the tester itself but the power supply. It had an overvoltage and killed the EBC-A20 tester, my favourite battery tester... 💀
After a bit of digging and testing, I found the problem. This should be relatively easy to fix...
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[@henvan8737]

When smoke comes out it's always difficult to get the smoke back in.

[@DIYwithBatteries]

DIY fog machine ;)

[@showmequick2245]

haha 🤣

[@randycarter2001]

Any 7812 regulator will work. just about any local electronics store will have it. Don't trust anything on eBay they lie like there is no tomorrow. There is still something wrong. 1 amp is the limit of this device. The power loss of 7 watts is a lot of heat. That little heat sink can not take it.

[@kevinmills5293]

Agreed. Either it’s very poor design and the 7812 is inadequate or there is something else wrong. I would power up the tester and feel around for anything getting hot.

[@chrishartley1210]

The L7812CV is rated at 1.5A which would suggest that a standard 7812 would be insufficient (1A maximum). It also has a maximum temperature rating of 150°C (300°F) which is higher than the 7812. Those heatsinks are typical for use with these devices.

[@randycarter2001]

@@chrishartley1210 The L7812CV does look like a high performance version of the 7812. The other point I made was the heat sink is way to small to dissipate the 7 watts of lost power (Vi 19v - Vo 12v) x I 1a = 7w.

[@DarkZoneV]

I thought you have the part already... 🤔 i remember i saw it on a previous videos 📹.... might be wrong... Can't wait to see next video.... cheers 👍

[@showmequick2245]

me too. i think he is making these videos and scheduling the or something. plus he likes to keep us on our toes. i don't mind it tho.

[@zaprodk]

What on earth is using upwards of one amp on the 12V rail?! - That regulator is going to get HOT and burn itself out. I think you have another fault after that regulator. If you are drawing 1A and feeding 19V into that regulator it needs to dissipate w watts of heat. That is not going to happen with that heatsink!

[@nerdrulesu]

nooo the magic of video editing also failed, now we gotta wait for the epic finale...damn movie studios always milking ya for more ;-)... loving the videos

[@OffGridGarageAustralia]

That's how you create tension 😊 (Film Academy Chapter 1, Lesson 1)

[@skysurferuk]

@@OffGridGarageAustralia 🤣

[@peterdkay]

I saw >1A at 6V as you were winding up voltage. That sounds like another problem! I doubt if another 7812 will fix it.

[@sergeyblinov4957]

Andy, please, try to power up tester with 12 V, but without fan attached to it - maybe, failed fan can draw all this excessive current from 12 V rail, as it used for fan. If fan is not a source of failure, then, a ceramic (MLCC) capacitors at 12 V rail can leak such high current with associated heating after 27 V "hit" it. Also, 12 V is used for powering 3.3 V linear regulator for MCU and other logic, and, it seems, it is used to drive gate of power MOSFET (it is under the heatsink). So, if 27 V could go past LM7812, it could probably create a short circuit in MOSFET's gate. So, this excessive 1 A and more current can flow to gate through damaged driver and low-Ohm gate resistor.

[@OffGridGarageAustralia]

The fan is only for cooling the FET if a load is connected.

[@Pneumaticcannon]

Some lab PSU can have a different output voltage other than what is displayed. Always good to check with a voltmeter for really sensitive stuff !

[@dirkaust5107]

There seems to be more broken than just the regulator, don't know what the hack draws 1A for just the display, its illumination and a small controller.

[@OffGridGarageAustralia]

I hope you absolutely NOT correct.

[@john_in_phoenix]

Then why would zketech go to the trouble of using a power brick that puts out multiple amps?

[@OffGridGarageAustralia]

@@john_in_phoenix for charging the batteries connected to the tester. It can charge up to 5A.

[@john_in_phoenix]

@@OffGridGarageAustralia That makes sense. I would check that power brick, cheap ones die often. The 40 amp cell tester has what seems to be a pretty decent internal switching supply.

[@stevetobias4890]

Lack of power protection redundancy built into the circuit

[@chuxxsss]

Well Andy, when I was an apprentice a follow Technician said to me, 'them regulators are bullet proof. After I put the power back to forward. Now I know he was wrong, only took 26 years mate. Have a great day. WES components is the best place for parts over night.

[@sia3540]

Wow! Love your videos!

[@marlonbramble2485]

That is a common voltage regulator. You will get it at any electronics shop that sells electronics parts. I have a few in my work shop, but it will cost a lot to send it to you from the Caribbean. :) Love your channel

[@tinasholly2434]

I would like to see you do the bus-bars on the shelf. I’m building one myself in the very near future. I just picked up two shelves from our local grocery store because they were upgrading.

[@skysurferuk]

Damn! I've just bought one of these things... will use a better PSU. Thanks, Andy!

[@stevetobias4890]

Just keep the power off when connecting the wires

[@dredre9484]

Funny story one of the kayak motors I had built had these on my speed controller (it had six of these voltage regulators) knowing me I had to test to the limit well blew my controller it was spectacular fire and smoke so poor me had to paddle for three hours to get it back to the car

[@dh2rl]

Andy, you should mount a bigger heatsink on this 7812 because the loss is trade in to heat.

[@rvprepperwayne]

I would try Digi key. The have fast shipping here in the US and have always had what I needed.

[@johnearle2601]

I used to build my own linear Voltage regulator circuits together on some of my smaller solar panels. The one I started with came from Radio Shack store. It was a Motorola part number LM317T which was a 1.5-Amp 35-Volt max input. Then later on I switched over to a LM350T which is 3-Amp with a slightly lower voltage threshold. And now they even have a 5-Amp one available I don't think it's a Motorola one. The only difference is pin 1# one both the LM317 & LM350 is used with a 5K pot to very the Voltage. But if you just want 12-Volts, then a MC7812 should suffice.....A-N-D its 1.5-Amp but you need to ground pin 1# to negative and pin 3# is input & pin 2# is output......its also blow proof as long as you don't over voltage the input. Dead shorts will only cause the chip to heat up thus causing the chip to shut down. Remove the short and the chip comes back to life and not becomes night of the living dead part 10!!!!

[@timdixon1166]

Jaycar in QLD will have them. Also Altronics if they are there... 7812 regulators are very common.

[@alexschulein7002]

Hi Andy The 7812 supplies 12 volts at 1 amp. If your external supply needs to put in close to 1 amp to light up the display other things are broken. I suggest you feed it a lower voltage with some ma and see what gets hot, the auwie test from Louis Rossmann, it should help you diagnose your tester

[@OffGridGarageAustralia]

I don't think the display or electronics use even close to one amps, that will be rather 50-100mA max.

[@Pneumaticcannon]

Yeah I was thinking that's allot of current for just a display. How is your MOSFET / transistor under the heatsink? Could have maybe failed short circuit with a slightly higher resistance. Agreed with using thermal imaging to help diagnose !

[@lyfandeth]

The LM 78xx regulators and 7812 are quite common and cheap. The 7812CV appears to be a cheaper off-brand chip, no real reason to look for it. But every 78xx chip should have input and output capacitors used with it, and since an overvoltage should have damaged these too, you might want to replace those even if they look good. A dime each? And since the meter is important to you, maybe a fuse and 15v zener diode as power input protection? The 7812 will still be happy, but the zener will kill a high input at 15v. Another dollar for parts.

[@bascomnextion5639]

There is also another voltage regulator next to it , the package with 5 leads, looking at your pictures it appears the 7812 is mounted upside down with its writing side facing the board if this is so and there is room under the board when mounted in the case put it on the opposite side of the board , first cleaning off the green coating where it will go so you can solder the tab to the copper ground plane on the underside of the board which will form a large heat sink as it probably failed due to over heating.

[@junkerzn7312]

Wow, that is fairly rare. Linear regulators don't usually implode like that. You should be able to find a replacement... any 3-pin linear regulator with a 12V output and input within specifications should do the job. Max input voltage for the L7812CV is 35V. 27V should not have killed it. In fact, 27V is probably the intended output of that wall power supply. For the L7812CV, 19V is the minimum input voltage. So there's a bit of a mystery here... what blew up that linear regulator? -Natt

[@OffGridGarageAustralia]

I assume, the power supply had a problem and spiked maybe far above that 35V and caused the death of the VR. Only when I measured the voltage of it, it showed 27V and shortly after 0V, so it was on it's way down form something higher.

[@Aconda]

Good video. I have not yet open my box with EBC-A20 tester. Soon. Any week now. Why not run your EBC-A20 on the external wanptek power supply until the replacement voltage regulator will be delivered?

[@stevetobias4890]

You should have firstly set your power supply to 12v 1.5a then turned it off, touch the leads together to disperse any powered up caps then connected your leads before powering up the power supply. The circuit will only draw the current it needs, this unit can be powered by your solar setup using a voltage regulator circuit with a LM7812 standard circuit with a filtering capacitor on both the input and output sides. In fact a LM7812 might even replace that blown transistor if you only need 12v. Also when connecting a live wire use a ceramic power resistor between the positive wires to reduce any sparks.

[@dig1035]

Nice magic smoke tester teardown! Component level repair, warranty? Bad power supply? No ground strap?

[@budmartin3344]

So the units comes with crappy power supply that caused damage to the tester. It uses regulated 12V to run the main controller. It seems to me that it uses the 19V for charging circuit that is why the unit is supplied with 60W power supply, I hope the charging circuit is not damaged.

[@OffGridGarageAustralia]

Yes, the power supply is crap. and undersized. The 19V are needed as the tester can charge batteries up to 18V. The electronic tun on 12V though. That's my understanding.

[@michaelbouckley4455]

Andy, I have a question about the ZKE output chats, bitmap and excel format. Downloaded the ZKE software, but the excel data does not behave like you showed; being able to run cursor along curve, to read voltage and current? I have Smart ANT BMS, which can calibrate SOC, by voltage, and can set the re-initialise SOC to 100% at other percentages, I tried 90% and hit it, once; so upped it to 95%. I only charge to 27.2v max, on 24v Lifepo4. 3.4v / cell. Was hoping to get a more realistic SOC, using your data for the 280Ah cells. BMS has 11 voltage levels to calibrate SOC. My 0% is 2.5v 100% is 3.5v. 0.1v steps. But the curve is much flatter than that. Maybe you could make a Table of data? Thanks.

[@plan9channel7]

"My battery tester today shit itself" .... 🤣🤣🤣🤣

[@OffGridGarageAustralia]

That's what it did! 🤷‍♂️

[@DIYwithBatteries]

You need big Heatsink for 7812 regulator Or just buy a Buck converter so you can adjust the O/p ;)

[@launacorp]

Holy Moly. 19V - 12V = 7V @ 1A... 7W heat on a 7812 with this little heat sink 🔥 Hey Andy, get a Victron Orion TR and make your own 12V from your big battery. Put some Banana connectors to the battery tester (with a 1,5A Fuse) and use it this way. Btw then you should take out the 7812 or use one with a very very low drop out voltage. This is Btw the way I use my offgrid system. I have no inverter but lots of electronics which use 12V DC as main input. From a pc over a router to the switch all use 12V. many of my led lights are 12V so I use my PV for that too. Have some sunny days. ☀️

[@bogdangiurgiu3952]

Hi. From where did you bought your baterryes?

[@NaughtyGoatFarm]

That's a bummer

[@donshortjohn2108]

First: there are no problems, just challenges. The 78xx series is bloody basic. If a shop have at least 5 components to sell, it will have a 7812. Linear regulators with more legs are adjustable, but they are anyway burn the defference in voltage to current and produce a lot of heat. With 0.8 amps it makes totally sense to replace it with a tiny switching supply module. Put it on the list of your next order from china as a by-catch.

[@DazzaDirect]

LM317 is the adjustable with same TO220 package with three legs ;-)

[@martehoudesheldt5885]

use a buck unit till you get a new one. warranty from mfd, vr and pwr supply??

[@johnearle2601]

Sorry about this......the output Amps on that MC7812 is only 1-Amp.....that's what I get for "not" putting mind in gear before putting mouth in motion heh-heh...

[@cheetahkid]

When I saw this, I just went "UH-OH!"... so 7812 is the easy part, I got some here.. what about the adaptor?

[@felaxchow207]

Hate it when that happens. It picked a bad day to start smoking.

[@jasondevine6014]

How did you go with this? Jaycar had them lm7812. If you need assistance you cann send it down to me.

[@Jsak666]

Your in Australia mate don't miss represent

[@MarcusPocus]

the last power supply reading look around 6v/1amp when the display start to work.. but where go all this current?? (this blue LCD need less than 50ma to work at 5v).. the 7812 is able to take 1.5amp max but here nothing is connected, just the supply.. the CPU look to work fine but it’s very strange to have this current.. have you tried 12v/1amp (limited) for to see what happen with the current?? ..i’m just curious because look not normal for me..

[@OffGridGarageAustralia]

That's my concern too. Hence I took the power off quickly. The current is not good...

[@lnxpro]

why not just modify it to work on 12v directly and find a 12v 10A power supply.

[@petermerle]

Twice you referred to being in Austria!

[@MarkPrince1317]

Good morning brother good morning Australia 🇦🇺 Congratulations 👏👏👏 to repair it One question why lithium cells 3v and why 12v cell not available ? 12v single cell

[@pau1phi11ips]

Because that's the voltage you get from that particular mixture of chemicals. Lithium-ion 3.6 or 3.7V, Lithium Polymer 3.7V, Lithium Iron Phosphate 3.2V. Every mixture is slightly different.

[@MarkPrince1317]

@@pau1phi11ips thank you brother I really don't know about that

[@petrdjak]

I wonder.. why there is not 12V DC power supply when the device runs on 12V?

[@OffGridGarageAustralia]

Because it can charge batteries up to 18V.

[@solarute5486]

Jaycar will have a 7812 (I think) if push comes to shove, I'd have one and I'm just in Brisbane

[@OffGridGarageAustralia]

Thank you! I looked at them first but they only have the 5 pin variant. I've got one here now from eBay, just need more time...

[@solarute5486]

@@OffGridGarageAustralia Cheers, can't help you with Time :-)

[@rv10flyer84]

Great. Another piece of junk I’ve ordered. Waiting on the 40 Amp unit. So what caused the VR to go bad?

[@stevetobias4890]

It was the power supply and a lack of protection in the circuit. I would be building a protection circuit between the power supply and the unit.

[@excillisbank2611]

Bien !!!

[@camolas71]

You must have that part in a lot electronics in yours garage ;)

[@OffGridGarageAustralia]

I looked everywhere. I have 7805 but no 7812. Dam it!

[@camolas71]

@@OffGridGarageAustralia 🤔 for now you need a setpdown dc-dc and a laptops charger

[@john_in_phoenix]

Amazon should have a 7812.

[@OffGridGarageAustralia]

Yes, got one from eBay now...

[@john_in_phoenix]

@@OffGridGarageAustralia I of course can't speak for the price in Australia, but in the USA they are a very common 79 cent part.

[@rokask]

Would like to see inside the power supply, I am interested to see what failed.

[@sergeyblinov4957]

It is regular "chinese" and "laptop-like" cheap PSU, where AC input filter is missed. This PSU has MX2269 flyback PWM controller and a few required components. I suspect, that voltage feedback optocoupler U4 was failed and output voltage was raised to 27 V. This "817" type optocopler has many "no-name" clones, which could easily fail in random order.

[@loranmorash8532]

Ok, I am confused, are you living in Austria or Australia cause in earlier videos I have heard you clearly say Australia. Cause you claimed to be in the winter which would mean you are in the southern hemisphere not sure if it is some inside joke you are doing but now I see and hear you emphasizing Austria which would mean you are not in winter but in summer way to mess with my head.

[@carlosgaspar74]

Time to open the power supply, also... 😉

[@OffGridGarageAustralia]

Nah that's gone already. I've got a new one now with more amps. It's all about the amps here!

[@carlosgaspar74]

@@OffGridGarageAustralia The bigger the better! 😁👍 There are people who would like to see what the ... 💩 went wrong. 😅

[@daskasspatzle2396]

Just take a 7805 with a 7V Z-Diode in series with the ground pin...

[@OffGridGarageAustralia]

I had a 7805 actually in stock...

[@daskasspatzle2396]

Probably everyone does, but the Z-Diodes are usually limited... And it is easier to fit in the matching 7812.

[@offgridwanabe]

Nice testing and troubleshooting

[@OffGridGarageAustralia]

Thank you.

[@ralph9987]

well done on blaming the display connector, when all the while you failed to initially connected the switch :-P

[@ferlanfb]

5:29 Austria oi oi oi..

[@timos144]

Bei dem Strom, bau keinen 7812 wieder ein. Nimm einen Pinkompatiblen DC/DC wandler. 7812 sind stink normale längsregler und bei 19V Eingangsspannung muss das ding knappe 7 Watt in Wärme umsetzen. DC/DC Wandler haben einen Wirkungsgrad von 80-90% und vertragen wesentlich mehr. Traco oder Floeth haben da gute. Aber wie andere schon schrieben, scheint da auch was anderes nicht zu stimmen. Guck mal was daneben sitzt für ein IC und meld dich mal bei mir. LG

[@OffGridGarageAustralia]

Mach ich, danke Dir. Leider war es nicht nur der Regler 😑

[@pmacgowan]

Good for parts now? Maybe not

[@guysgt5003]

??? Trainwreck!!

[@OffGridGarageAustralia]

Nah, just need repair... I hope at least...

[@guysgt5003]

@@OffGridGarageAustralia I’m sure you already have it fixed and working like a top! Thanks for the great videos.

[@rilosvideos877]

I wander why it draws more than 1 Amps in standby mode? At 12V this means more than 12 W of power going where? I guess there's something else wrong with your battery tester...

[@kevinroberts781]

Something else is wrong with it. That's why the voltage regulator died. Trace it down

[@OffGridGarageAustralia]

The external power supply was wrong. It's at the beginning of the video.

[@waynescheepers145]

Not the right way but what about a buck converter

[@OffGridGarageAustralia]

Would be a better solution, absolutely.

[@phoenixcrp]

Natürlich wird sie magischen Rauch freisetzen, wenn Sie ihre Beine anheben, Andy. It is called "a fart" Which colour was it? Black or blue? It's going to be good and she will be back in business in no time at all. Cheers mate.

[@OffGridGarageAustralia]

Hahahaha 🤦‍♂️😂