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Whats your recommended 12v auto battery charger?
#21
Late 2007, I was where you are. I wanted something just for the times I did have AC to plug into. The 3 years previously I had been spending a lot of time remote camping inf Baja and very occassionally parking a few hours and rarely overnight at a friends house in town. I had a 2/12 amp metal cased NON automatic schumacher and ,unknowingly at that time, rarely got more than 7 amps from it. I'd had 230 Ah of house battery, plug in for 3 hours and the maximum I could return into them was 21 Amphours. I had no ammeter, all I knew is that I plugged in a charger for hours, yet it did not seem to help very much and voltage when I checked it was still disappointly low and the inverter alarm would come on way sooner than expected.

So in 2007,still confused by what an RV converter was, I bought the highly recognizable name schumacher sc2500a 'intelli'charger with upto 25 amps available.

NOw I still have this charger, it still works, I still use it.
But there are times when it is nearly useless, as I can't get it to seek and hold absorption voltage. it and many many smart chargers, will decide to drop to float voltage, where little to no charging occurs very prematurely.

It is a shame when one can plug in, yet they can't get their charger to actually charge the batteries. Its like putting quarters into a gas station tire filling aircompressor, yet never having the tire pressure increase, yet deciding more quarters and more time is needed, or worse that while the tire still looks underinflated, the machine made a bunch of noise for a while, and consumed a bunch of quarters therefore the tire must be inflated properly, rather than realizing the piece of shit is simply not working and finding an alternate solution.

So with the schumacher and an Ammeter/ amphour counter and still disappointed in its ability to recharge my 345Ah battery bank, I learned to load the bank, drag its voltage down below 12.6v with headlamps and other loads, then restart the charger. Sometimes this works, sometimes it just shuts off/reverts to float in a minute or 3. I had an amp hour counting battery monitor at this point and I could see I was still 25 or more AH from full, but the charger refused to hold any voltage over 13.6v( AGM setting float voltage) and the batteries might be accepting 1.3 amps when at 14.7v they would be taking 8 amps or more.

Often I would go check on it just to find it shut off completely, and the batteries were nowhere near fully charged. Unplug it from AC and DC, replug in both, restart it, and 5 minutes later, same thing. either it was in float shining its green light, or it would shut itself off as the fridge compressor shutting off or starting up would make it thing there is an issue with the battery. I'd even shut the fridge off to get it to try and continue charging, with little success.

Just last night I had my Meanwell power supply on the workbench installing a new ammeter and ideal Diode and voltmeter into it and was using the schumacher to charge my 55% battery as it was cloudy/rainy all day. I had to go run some errands and when I came back, with the battery still accepting 20+ alternator amps at 14,6v when I parked for the night, I tried restarting the schumacher and within 2 minutes it reverted to float. A battery which can still accept 20+ amps is nowhere near full, but the schumacher refused to even try. it just kept reverting to float voltage. I turned on my lights and fans and dragged battery voltage below 12.6v, restarted the charger on the 12 amp setting. it went for about 5 minutes, and reverted to float. I tried 3 times to get it to seek and hold 14.4+ volts and it refused.

I said F this and went back in the workshop to Finish the meanwell, just leaving the schumacher charging the battery accepting 2 amps at 13.5v. When I finished the meanwell a while later I came in and looked at my battery monitor which was still saying 16Ah from full, the schumacher stuck in float feeding 1.9 amps. When I plugged in the meanwell and set it to 14.7v and plugged it into the battery 13 amps were required to bring it to 14.7v, and it took 3 more hours before amps tapered to the 0.5 range where it could be considered fully charged. So that whole time I was in the workshop with schumacher in float, almost no actual charging occurred and I was only able to reach full when I returned with the meanwell power supply and let it rip at 14.7v for several more hours.

So basically if I had left the schumacher on overnight at 13.6v, full charge would not occur until mid/late morning the solar was able to bring the voltage higher and amps tapered at Absv to the prerequisite 0.5 amps.

Most automatic garage chargers are going to do this same exact thing. Not only will they refuse to fully charge the battery, they will refuse to even get it close when there are loads on the battery, or there is a surface charge voltage from having just driven the vehicle.

So for your intended use, the garage charger will likely not be able to do what you want it to do, or do only a fraction of what you hoped for. It could just be a lesson in frustration if you have to go back in and keep restarting the charger, and they will only restart once you load it to drop the voltage below 12.8 or 12.6v or somewhere in that range. So you have to load the battery, unplug the charger from AC and DC, the plug it back in hook it to the battery start it, then remove the load. Then you walk away, come back in two hours and see it is in float, providing little to no charging current or perhaps shut off completely flashing an error sign, and know the batteries are nowhere near full. You have AC grid power available to charge your depleted softly sulfated batteries, you have a charger, and yet you cannot get the charger to do the job you bought it for.

I don't know about you, but futility enrages me, and these so called smart chargers are some of the best teachers of futility I have come across in this lifestyle.

The solution for me was removing the 'smart' and Automatic.

Even the PD9245, while an excellent charger/ converter,will only hold absorption for so long before reverting to lower voltages. Pressing the button once will have it seek 14.4v for 4 more hours, but I would much rather set my power supply to 14.4v and just check the ammeter every few hours. I am also happy to not be limited to 3 voltages, not able to influence them if the battery is way outside the 77f range where all manufacturers make their recommendations. Say a 77f battery spec's a absorption voltage at 14.7, well if the battery is 27f that voltage should be raised upto 15.3v or so. If it is 99f outside that should be lowered to 14.25 or so.

So in a few years, when your batteries seem to have lost capacity/no longer hold a charge, whats the plan, just replace them? Try and get your smart charging source to do what it never could from Day one? which is fully charge them? That would be even more futile.

Only then buy a charging source capable of holding a constant voltage for as long as required? What if you'd bought this charging source instead, initially?........Well its likely the batteries would still be performing well.

So many people freak out at the thought of a manual charger, Yet compared to using my schumacher it is 1/20th the effort and can actually fully charge the battery back to its full remaining capacity and thus allow it to retain its capacity for much longer.

So often 'plug and play/automatic' is aim gun at foot, then shoot, then call the gun a piece of shit or yell at your foot for being in the way.

Most Anybody who has bought the gun, not yet shot themselves in the foot, will say the gun is great, i have one therefore you should too, but they will not tell you 6 months after you bought the samr gun they then shot themself in the foot. Few are honest with themselves, much less strangers.

Amazon ratings given by the ignorant, should be ignored. There might be a few actual reviews by someone who knows the product, but they tend to be longer with some tech talk and are often ignored by those who only read reviews favorable to their desires for inexpensive as possible but expect 'works just as good' as the more expensive options.

This guy says this is the cheapest and works 'just fine', whooohoo! place order.

Regarding the trolling motor battery users, used actually trolling. They are charging a battery not with the trolling motor still running on and off. They have ZERO idea the actual state of charge of the battery, they do not know about surface charge voltage retention, not what a hydrometer is, all they know is the battery either lasts or it does not. when new they last all day, a few weeks later they do not.

My sister's ex was one of these, and boy was he proud of his Schumacher similar to the one I own and know to be a lying incapable piece of shit, but kept complaining about the batteries, and the warranty not being honored more than once. He is one of those who is simply smarter than anybody in the room in his own mind, and would not listen to me that the Schumacher he was so proud of, was failing to fully recharge the battery that it was not even getting it close and this was prematurely reducing the capacity of the batteries. His logic was that when the battery was new it could power the boa all day and now not even half the day, It was the battery not the charger, in his mind.

What to do in this situation?. Prove him wrong while teaching, with absolute irrefutable proof.

After the next fishing session, rowing back to the dock, we put his dead as a doornail battery onhis charger. Dip the hydrometer when it flashed the green light and all cells were 1.220 or less, deep in the red on the hydrometer.
I'm like:
'see this green area, 1.265 or higher, this is where it should be, if the relatively newish battery( which it was) was fully charged.'

I wound up restarting that charger time and again, a dozen times and forcing him to watch the hydrometer float, testing the specific gravity each time it quit, and basically never got any cell to rise over 1.250. I'd even rigged up an old sealed beam headlight as a 7 amp load in order to be able to restart the charger more quickly. Once he acknowledged that his charger even after restarting a dozen times was unable to get the specific gravity above 1.250, I then got my Meanwell power supply, set it to 14.7v and the battery was taking 5 amps. 12 hours later it was taking 1.2 amps, and 5 of cells were 1.270, one was lagging 0.005 behind. Well into the green.

This was irrefutable proof. it was so incredibly obvious, that there was no ability to argue and boy was he pissed off at being proven wrong. I then raised voltage to 15.5v and once amps tapered to less than 4 , raised voltage upto 16.2v, and all cells in about 15 more minutes read 1.280 or higher and I stopped charging completely. 12 hours later resting voltage was 12.97v and SG read 1.285 on all but one cell which was still 1.280.
We used the battery that day, and it outperformed the Newer larger marine battery he had bought 3 weeks earlier. When we were done we checked the specific gravity and it was 1.190, and put the schumacher back on it, and when it flashed the green light, 1.225. We had just established that when fully charged specific gravity was 1.280, and the schumacher refused to bring it over 1.225.

He was then online, furiously reading reviews on Automatic chargers, what about this one, what about that one as my temper got shorter and shorter. I was like buy it then!!! I'll leave you my hydrometer and you can see how good or how bad it is. Because its impossible to guess as to how it will perform based on the stickers or reviews! He cursed at me, i returned the curses and a few more and he walked away.

I pulled up the 55$( at that time) 33 amp Megawatt power supply online, bookmarked it, and closed the lid on the laptop and said nothing more on the subject.

When it arrived I cut off the cord on an old power strip, and told him to buy the cheapest drug store jumper cables he could find, but he already had some in his truck. They were perhaps 10 gauge. I cut them in half, wired up the power supply set it to 14.8v and said to run it for 8 hours after each day fishing. That was 2015 or so and every time I go back there, I hear about that megawatt power supply/charger and how awesome it is and how everybody wants to borrow it. If Florida had any hills there would be minstrels up in them writing and singing songs about the Megawatt power supply that 'magically' restores trolling motor batteries. My sister has a new boyfriend now, yet when i meet some of her friend's boyfriends they are like , hey you are the guy you set up that small ugly silver rectangular battery charger.... Dude!!!, I borrowed that thing and it saved my battery...

All it is doing is actually fully charging them, something no automatic battery charger can do.

So when i see these threads about which automatic battery charger is best, I am like the best one is one that is not automatic as automatic chargers are designed to never overcharge a battery, not to actually fully charge one( depsite teh marketing claiming exactly that), and only get it enough charged that it can start a car. For 99% this is more than good enough.

But those 99% are totally ignorant when it comes to electricity, much less charging lead acid batteries.

Makes me want to make a sexy plastic box with a green light and market as the answer to every human ill/angst on the planet.

Whatever charger you get, you should get a ammeter, and a hydrometer, but there is NO arguing Ignorance is indeed Bliss, at least until it gets too expensive.

Be wary of reviews, reviewers, and remember product marketing in this day and age is nothing but lies mistruths, deception, manipulation, and amoral douchebaggery, but that seems to be par for the course.
[-] The following 2 users say Thank You to sternwake for this post:
  • Roadtripp (12-09-2019), TWIH (12-10-2019)
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#22
That was a fantastic rant Sternwake and very deserved by the mediocre products out there. There are so many shams. Buyer beware eh. Eternal vigilance. 
 My old Diehard 12/2 automatic charger has a manual override switch thank goodness and been on manual for years. I never use the automatic switch. I’d might go to garage sales and looking for old chargers with the manual switch. Or I imagine one can open the old transformer type charger and wire them for manual?. I might get around to trying that on one. My Diehard also has a Deep Cycle switch but Ive not used it. I prefer the manual setting. But it needs a clone amp meter on it so I ordered one. 
 Ordered a new Brady Instruments hydrometer today for some industrial pocket plate Nickel cadmium cells I’m experimenting with. They are charging now on the Diehard just under the gassing voltage. Also ordered another of those clone amp-hour meters for the load. As they are not bidirectional it takes one on the load and one on the charger. 
 Next on my list is some kind of adjustable power supply. I may try a Drok “1500 watt” DC to DC buck boost converter regulator as I have one. The Megawatt or Meanwell Sound power supplies sound more reliable and convenient. . 
 The “1500 watt” DC to DC buck boost units on Amazon look like they are good for maybe 900 watts somewhat reliably. One biker got a few months out of one boosting his electric bike voltage from 36 to 48 at 1000 watts.  He was able to solder a new FET (or was it MOSFET?) and fix it. These units are roughly $20-$30 on Amazon. I got the Drok converter unit as it came with some instructions unlike some of the other brands. It looks to be assembled very shoddily but Ive not tested it yet. 
  Opened my Trace Engineering inverter and Todd Engineering Charger. What a difference in workmanship. But what can I expect for a  $30 converter.
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#23
(12-09-2019, 06:50 PM)Roadtripp Wrote: https://frederick.craigslist.org/bpo/d/f...05431.html
https://stjoseph.craigslist.org/for/d/be...50907.html
 Here’s a couple used Marine chargers. I have loads of chargers. If your in NW WA I’d give you one of my 10 amp chargers.
Thanks for the offer, unfortunately we are some 2700+ miles apart!  I'd better use that gas $ to just buy one!
"Life is short, smile while you still have teeth."
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#24
Just to be clear about the 12 A Shumacher I use: It is for occasional battery charging and is not ever used as the sole charging source for a battery.

It is not a battery 'maintainer' and is not designed to be used for full-time, 24/7 charging.

Still, it is a good little charger for occasional use, to hook up to a generator or shore power and boost a starting battery up to the level needed to start a vehicle, or maybe provide an overnight charge for house batteries when parked on a friend's driveway during your travels.

For that use, it works fine.
_______________________
Wondering about wandering
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#25
OK all, from SW and others (to include Handy Bob in another article) it's pretty evident that the "automatic" chargers are unreliable (detecting surface charges and shutting off, having unknown setpoints, resort to low float voltages too quickly so as to not overcharge). A good way is to use either what SW does or an old school manual adjustable charger set at or above 14.4 (if such can be found) then monitored. That's the rub, "nobody" wants to monitor, they all want to "set it and forget it", which only results in undercharged batteries. The same thing with solar (different topic but kinda the same) as the cheaper non-adjustable charge controllers will have times and setpoints set to not damage batteries.

I see from all this effort from you responders that it's a guessing game if one simply uses a 12v automatic charger, and if you don't invest in test equipment (above a simple voltmeter) then you'll not know what your SLA or AGM battery is really doing. At least we have the ability for GC's to check with the hydrometer, another vote for "old tech". Handy Bob says the same thing in his more dated article from 2010, saying that he doesn't trust AGM's as far as determining SOC.

So what do I get from all of this? I either have to face replacing whatever battery(ies) I get that are FLA based if I don't get some amp meter instruments, or I invest in the amp meter/DC clamp on amp meter ($70+) in order to monitor the amps going in.

This is all good info that should be stickied (perhaps edited but stickied the same) for future questioners.

Thanks again, I won't ask any more about 12v chargers!
"Life is short, smile while you still have teeth."
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#26
https://www.amazon.com/bayite-6-5-100V-D...013PKYILS/

It is an amp and amp hour meter for $16.  The external 100 amp shunt resistor goes in series with the battery.  It will measure one way, charge or discharge, reverse the two little wires to measure the other direction. 

"Monitor" doesn't have to be painful.  Set the voltage lower than 14.4 and set the alarm on your phone for 12 hours.  A battery can handle 14.2 volts with the current tapered down to 1 amp for a day.  Two weeks is bad.
Say good night, Dick.
[-] The following 1 user says Thank You to Trebor English for this post:
  • TWIH (12-10-2019)
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#27
I have solar ,but every day isn't sunny. Sometimes several days ..
That's my current locational disadvantage....
Soooooo.
I use the auto chgr to help out but have to run the gen for it usually .
(Sometimes , very rarely I have access to an outlet or am workamping.)

I also have an old Heart inverter charger I picked up along the way.
There's a 2800 msw inverter + a 90a three stage charger in that.
It only weighs 90# so might be a little copper in there..
I can use it on shore power but haven't wired it up due to no power here except
the Honda but doubt it is up to it ,,,,,
The Honda does have an 8a 12v "charger" output but never measured it.

Everybody has different devices and needs for 12v service.
We strive to provide information , tried and true.
Use it how it fits your situation.
Never a problem with that !

Batteries don't last as long here as they did when I was in Death Valley.
I'm OK with that.
I never get a bill from the power co.
It's all compromise.......
stay tuned 
  Cool
[-] The following 1 user says Thank You to rvpopeye for this post:
  • TWIH (12-10-2019)
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#28
One of the reason no automatic source can truly fully charge every battery, is the battery changes its needs as it ages, and all batteries will be starting from slightly different starting points and all will age differently in their specifica discharge recharge regimen

The best marine chargers allow one to set battery capacity, float and absorption voltage, absorption duration/tail current and have battery temperature sensors. These are hundreds of dollars, and they are only automatic and trustworthy once they are set up, and they can be set up wrong or not adjusted as the batteries age and need longer and longer in absorption. When batteries start requiring longer absorption durations and don't get it, then their rate of capacity decline starts accelerating exponentially.

I'm big on collecting data, as without data your just another person with an opinion. I've tried to reason out why my schumacher behaves as it does, what its trying to do when it does what it does, what the programmers were thinking, and what it comes down to is, It is batcrap crazy.

When there is surface charge on a still well undercharged battery, from driving, and I set it to 12 or 25 amps, it starts out with boom 12 or 25 amps, and voltage climbs quickly uptowards absorb. Good right? but then it stops entirely. no amps, while battery voltage falls. hey OK I understand, it wants to see how fast it drops, perhaps get an idea of state of charge. Once it drops into the low 13v range sometimes less, it starts putting out some amperage, slowly climbing from 0.5 upwards and battery voltage starts climbing upwards. Ok this is acceptable, i guess.

Once 7 or 10 amps get it to absorption voltage, it say enough! and quits again. Battery voltage drops back to low 13's and then it goes to float mode. making just enough amperage to maintain 13.2 or 13.4 v.

Mine does not flash the green light anymore, and the display always says 18.8 no matter what, but safe to assume that green light would have come on .

A battery still accepting 7 to 10 amps at 14.7v is still way far away from being fully charged, a hundred Ah battery is still 2 or 3 hours away from full charge, assuming absorption voltage is held for that duration. At float triple that number, quadruple it, and heck if the battery is old float will never ever bring it to full charge.

So this is one attempt at playing battery charger psychologist, with one charger, but experience on many batteries, and it does behave differently on different batteries and on its 3 different amperage settings and three different battery types. If i had to rely on this charger I would always be having to keep in mind its past behavior and basically know that once it decides enough is enough, the battery is anywhere from 85 to 92% charged, except for those times it decides to not stop putting out 12 or 25 amps and send battery into a bubbling acid spewing positive plate chewing mess at 16.4v+, which it will decide to do with no reason I could ever determine.

Compare this behavior with an adjustable voltage power supply. With it plugged into AC power but not hooked to the battery, I set it to 14.7v. I then connect it to the battery, and it outputs its maximum amperage until that voltage is reached at the output terminals of the power supply. The power supply will not allow voltage to go any higher, and less and less amperage is needed to maintain that voltage as the battery charges. When amps taper to 0.5a for a 100Ah AGM battery, it is full. When amps taper to 1 to 2 amps( use a hydrometer to double check) on a flooded battery, it is full. At this point reduce output voltage or remove charger completely.

One will find that this takes about 5 or 6 or 7 hours in their specific use, and from then on can just plug it in, attach it to the battery, set their smart phone to 7 hours and know when they come back the battery will be 99% or more charged, and just about as happy as it can possibly be. If it only took 6 hours to fully charge, but got 7 hours of absorption voltage, is it going to be destroyed, heck no, Not even an AGM whose water level cannot be topped off. My northstar -27AGM probably spent hundreds of hours at absorption after it was fully charged and I got 6 years and 1300 deep cycles from it,in my Van, and it is still a viable workshop battery.

With an Ammeter on the output at absorption voltage, if one comes back at hour 7 and see it is still accepting 2 amps, let it go and set timer on smart phone for another hour and note this new behavior is either an indicator of a deeper discharge starting point, or just the battery aging easily determined by future recharges.

A clamp on Ammeter is a great tool to have, they can now be had for under 30$ online, just make sure it says both AC and DC in regards to the clampmeter portion of the multimeter. Many are AC only and these AC only clampmeters can be had even cheaper.

The wattmeters I have been using which one can place inline on the output cables of any charging source( upto their 25 or 45 amp continuous max rating) can be had for as little as 7$, if one slow boats an Ebay/alibaba order.

My favorite inline wattmeter is this one:
https://www.ebay.com/itm/200-Amp-Watt-Me...2024!US!-1

but its KWH reading is to be ignored as is its clock. Amperage, voltage, peak amps and watts minimum voltage, and amp hours are all accurate, at least on the model i am using.

When using these inline on a charging source, on can see that the charging source returned say 56 amp hours into the 100AH battery. The battery was 12.15 when they hooked up the charger. 6 of those AH got turned into heat once absorption voltage was reached, and this data point can be used the next discharge cycle that 12.15v is the general 50% range for that specific battery in that point in its lifespan. When 12.15v starts happening sooner and sooner then one can see the battery capacity declining before their eyes.

Will an extended overcharge return some of that capacity?
With an Automatic garage harger, you will never, ever, know.

Only you can determine what is good enough for you. Armed with Data and experience from others, who have collected data and understand things, you can make a better choice, if you knew what the automatic charging sources being considered were actually going to do.

I can only read the marketing mumbo jumbo of any given charger and try to infer its capabilities and test the occasional charge somebody else owns, usually after their battery fails to respond and they come to me to both determine the health of their battery and see if it needs to be replaced or what.

Marketers are schooled in lies deceit and manipulation just to get someone to place click order. Maximum profit ,right now, screw honor and morality, wins again.

a Universal consensus on forums about a product, is largely parroting of others opinions, and rarely is that original opinion based on actual Data

On the Bitog forum, the solar prologix charger was the golden child charger for a few years. Those who owned one ( i think 3 members) praised it sand said it works perfectly and fully charges their batteries, indicated by that green light. Then somebody's failed and the collective gasped, denied the possibility, implied that the failure was induced by the user.

Dozens of people previous to this would praise the solar prologix charger and whenever anybody would ask about a good battery charger, those who didn't even own one, would praise this charger, and there would be a Dozen +1's afterwards to help convince the original poster that this charger was awesome, until one failed. Now it is reviled, except for those that never saw the new data indicating one had failed and praised it ,like the good consumer parrot they have been trained to be, they were then jumped on by the newly enlightened parrots who did read about the failure of the golden child charger. I had to stop reading that forum entirely, much less contributing.

Not one of these parrots, even those that owned one of the golden child chargers, ever even saw how much amperage it was outputting, or verified the voltage reading display on the charger or have any understanding at all of the relationship between amperage and voltage on a charging battery, or a discharging one for that matter. Some of them highly edumacated and highly intelligent and professionals in their specific field, but in regards to products for charging a lead acid battery as emotionally involved as a child who did not get their way.

These ignorant clueless parrots are the ones leaving product reviews on Amazon, and they are based on hearsay/sawread and complete misunderstanding of the physics involved. The only useful reviews by such people are of outright product failures, but then one also has to take into effect that the reviewer could be so dimwitted to not have plugged it into a working outlet or not have attached a clamp on a battery post correctly, or shorted the clamps and fried the charger, or left it outside underhood in a rainstorm.

Generally any forum thread title that asks "What is the best.........?" is only useful for the comedic replies and the overwhelming ignorance of those largely parrotted data free opinions. There are exceptions of course. Weeding out all but the exceptions is the challenge, and one must realize there might be no exceptions.
[-] The following 1 user says Thank You to sternwake for this post:
  • TWIH (12-10-2019)
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#29
Good reading. I looked up an IOTA with the “4” IQ thing, 45 amp, that seems reasonable. Said it goes up to 14.8 volts. Under $200.
"Life is short, smile while you still have teeth."
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#30
Ah, that explains the charger buzzing then silence, the cycle repeating for some time.
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