'smart' chargers versus 'dumb' chargers.

[phucheneh]

With battery chargers, my hatred for them has generally followed the curve of technological 'advancement'.

I hate the hell out of five-figure (in some cases, in the 5-8k range) computer-controlled chargers. The ones I've used will try to charge anything, and they'll do it in the most dangerous way possible. And when you actually WANT them to charge, the best you can do is set a 'preferred' voltage or amperage setting. It doesn't matter what you put; you're gonna get a ~2a trickle any way about it.:|

I picked up some free tools a while ago and got this:

I'm not sure how old it is. I'm guessing 1960's, maybe 70's?

It's become my standard go-to battery charger. No, it doesn't shut off automatically or do any kind of metering on-he-fly. It just puts out a constant voltage and current at or above its rated capacity so long as the battery needs it.

I can't remember what I measured the output voltage at. But it's dead-on with the manual (found one online). When a battery is being charged, it sticks around the rated output (5-7a). A very-dead battery will take about 8a. When it hits 3a, according the manual, it's fairly well charged (and it is...not 100%, but a good 60-80, at least). Actually damaging a battery with it is possible but would probably take a pretty long while.

Anyway...I think I forgot what my point was. I think it's that I like old bulletproof tools over some cheap Chinese circuitry, however much more complex it may be.

 

[phucheneh]

In the same lot of stuff, I also got a handmade tool cart.

Pardon the mess. And ignore that broken-in-half camshaft.

I think it's a bare minimum of fifty years old. You can tell it's made out of random bits of furniture/house and it's pretty awesome. The castors on the bottom roll better than any cart I've had.

 

[franksta]

My dad has that same blue charger. It's easily late 70's - early '80s vintage, if not older.

 

[JCH13]

The more battery tech the better! Especially in chargers.

There are somewhat reasonable "made in USA" options, which is always better than Chinese.

http://www.batterystuff.com/made-in-usa/#a8800

 

[phucheneh]

Meh, I think my point was simply that I don't really 'get' smart chargers when a much more basic one of good quality can essentially do the same thing (charge at a decent rate and gradually taper off as the battery reaches capacity).

Basically, smart charges vary output, resulting in...the same thing that would happen if their output was kept constant. At least I think that's what goes on with this one; I havn't checked the charging voltage to see if it is in fact constant as the current decreases.

And yeah, I can't imagine this one being any later than 70's. The fact that 'solid state' is so proudly proclaimed makes me think it can probably be dated to whenever that started to become common (but not universal) in batt chargers.

 

[JCH13]

A decent smart charger will (generally) provide a constant current to charge the battery. Voltage will rise as the battery is charged. It will monitor the change of voltage or some time increment. When the voltage change per unit time goes below some threshold value the charger switches to a 'float' or 'tend' mode which switches from a constant current charging mode to a constant voltage charging mode. Current will gradually decrease until it's at the same current at which the battery self-discharges.

There are also 3-state chargers (I'm not as familiar with those).

http://www.chargetek.com/resources/battery-charger-basics/

If a battery is at float voltage, but the charger is still pumping a fixed current through it, bad secondary electrochemical and chemical reactions can occur. These reactions can (and will) damage the electrodes, separator, and electrolyte in the battery. At work we've measured electrolyte pH jumping from 2.0 to 1.0 due to overcharging the increased pH would totally fry the separator after one charge, and the electrodes were not far behind. These were not lead-acid batteries, but they are liquid electrolyte batteries and the general principals are the same.

The point is that just shoving a constant current into a battery until it's at full capacity can damage the batteries capacity, discharge power, and reduce the number of useful charge/discharge cycles. Smart chargers (good ones) don't do this.

 

[LTC8K6]

Manual chargers do taper off, but they do not stop charging the battery, or go into float mode, so they will damage the battery more quickly than an automatic charger.

An automatic charger will go into float mode, but it is still not designed to be left on the battery indefinitely. It can also damage a battery but it would take much longer. They cycle between charging and maintaining according to the battery voltage.

Small maintainer/chargers are designed to be left connected indefinitely.

The newest computer controlled chargers can also be left connected indefinitely.

 

[phucheneh]

The point is that just shoving a constant current into a battery until it's at full capacity can damage the batteries capacity, discharge power, and reduce the number of useful charge/discharge cycles. Smart chargers (good ones) don't do this.

I was saying the opposite: this one charges at constant voltage (in theory; again, I haven't checked it repeatedly during a charge). I don't think it's '6 amp' because they thought 6 amps was best...that just happens to be about what it charges at on a <12v battery. At 12.4-12.6 or so, it's down to ~3a, which the manual I found online calls 'done.' In reality, 2a is probably closer to the truth.

If you really got into 'overcharge' territory (12.8-13), I think current might eventually drop below self-discharge. But I'm not looking to find out...I'm certainly not saying to leave old chargers unattended for great lengths of time. But the relevant point is that I'm not terribly comfortable doing the same on an 'auto' charger, either. Unless a timer (that I trust) is set.

 

[phucheneh]

On maintaining...you know what really baffles me? These:

http://www.jbtoolsales.com/midtroni...ly-charger-and-maintainer-55-amp-for-12-volt/

I've used those with multiple makes. The manufacturers make the shops buy them and instruct you to use them any time you're doing a software update (loss of battery voltage can 'brick' an electronic module).

$400 is the discounted online price...I'm sure the dealers paid more.

...I cannot tell how they are different from the switching power supply in a computer. In fact, I have an old enermax PSU I use as a 12v bench tester, and I can't kill the damn thing. Those Midtronics boxes drop like flies, however. (in case anyone has noticed a theme: I hate midtronics)

edit: oh, and the reason I'm so tickled with that old Schumacher charger, I think, is because I had never previously used benchtop chargers. Just the big old-school rollarounds (or a computer-controlled one). I had written off these little things off as overly cheap/simple...then I realized the output of this little guy is enough for all of my purposes, and just feel I had to give it a pat on its older-than-I-am back.

 

[LTC8K6]

I have a vintage Schumacher charger around somewhere. It's a 10A 6/12V manual charger. Just one big ass transformer, one clicker circuit breaker, and a couple big ass diodes on a giant heat sink plate, iirc.

I believe I popped a diode in it when I was a boy and we had to get it repaired.

 

[JCH13]

I was saying the opposite: this one charges at constant voltage (in theory; again, I haven't checked it repeatedly during a charge). I don't think it's '6 amp' because they thought 6 amps was best...that just happens to be about what it charges at on a <12v battery. At 12.4-12.6 or so, it's down to ~3a, which the manual I found online calls 'done.' In reality, 2a is probably closer to the truth.

If you really got into 'overcharge' territory (12.8-13), I think current might eventually drop below self-discharge. But I'm not looking to find out...I'm certainly not saying to leave old chargers unattended for great lengths of time. But the relevant point is that I'm not terribly comfortable doing the same on an 'auto' charger, either. Unless a timer (that I trust) is set.

Well, at best it's very inefficient, will take a long time to charge a battery, and maybe not bring it to a complete state of charge. At worst that charger is going to damage the battery, if only slightly.

Note that 12.8-13v is "not quite charged" territory, not at all in 'overcharge' territory. Lead acid battery float voltage is around 13.1-13.6V depending on the exact type of battery. If float voltage is below 13.0V the battery either isn't charged or is damaged or worn.

If you're scared to use an auto-charger, well, that's nice. There is no real reason for your discomfort though. Multi-step charging is a mature technology and any decent auto-charger will do the job just fine.

 

[fredBloggs]

well yeah these so called "smart" chargers are in fact pretty dumb. It should be called artificial dumbness rather than intelligence. If your use case does not fit the narrow parameters of their "smartness" then they dont work and no overrides are available e.g. most of them require some charge in the battery for them to function at all and they wont flag the battery as kaput either.You can see why that is though as how else would it know that youve connected the terminals the wrong way round or whether to charge fort 6 or 12V. though it would baffle me and it as to how it could distinguish a 1v charge on a 6v battery from a 1v charge on a 12v, which is why I think they need some "substantial" charge in the battery which is why I hate them as you can nolonger override their faulty and limited "programming". The other thing is the implication by these capitalist pig corporations that assume you are are all dumb idiots who dont know what batterythey might be charging or are'nt aware of terminal markings, sure there probably are such people and sometimes they may short the chargers leads but is that reason to assume all are likewise and leave them unable to charge despite having payed good money.I'm sure their lawyers recommended that, but why worry thats why they have the Darwin awards and indeed the human race can not evolve when "ruled" by such wimp shysters...
So now I am looking to build my own dumb charger by viewing you tube vids...