Plain bearing example

Are you quite a bit more wary of Li now?

Talk about -iffy-!

Almost all of the new LiFePo4 batteries come with BMSes (Battery Management System) built for that specific pack.

At Segway is one thing. At home, how many people do you know who either could or would manage them correctly? Batteries pretty much need an electronic nanny because we (most of us) can't or won't monitor them properly.

I wonder how pulsing affects battery life and cycles.

OK. I confused the two.

I have an 80' redwood right behind my house, so it would likely contain any lightning, but I think I'll put an arrestor on the solar array, too. Not the 45W HF mini, but the 1kW I someday may get onto the roof. The racking is in!

I hear that. Even with warnings, potential Darwin Awardees would certainly be buying them and blowing things up, eh?

Did you get the 100 or 500W model? Was it worth it? I used to have a nice Sun battery tester with pile at work. 0-500W with a huge dial-up knob and built-in VOM. Wish I had one now.

I've lost new AGM batteries to neglect too. Left them in the box and forgot them for a couple of years.

-jsw

My metal chimney is well within the cone of protection of the taller TV mast which is grounded. I heard distant thunder and while I was unplugging the antennas and camera on the mast there was a loud SNAP from the unlit (summertime) wood stove which I think was a static discharge. Soon a wire extended from the ground rod to the chimney.

I had hoped to use it as a discharge test load but the current is unstable at low settings and the carbon disk stack doesn't seem big enough to dissipate much continuous power. I have enough power resistors to run 25A at 28V continuously, or at least for the 1/2 hour temperature rise test of my Variac + welding transformer charger.

--jsw

The one I had was a 500 amp one - thats 6000 watts.

The HF carbon pile has a 15 second timer to warn you to grab the reading and turn the current down. Since it's unstable at low current / light pressure I didn't attempt to determine how much power it could handle continuously. My guess is less than 100W, from comparing the disk stack to wirewound rheostats of similar size. The timer circuit limits the voltage it could withstand.

The manual specifies: "15 seconds per test with 1 minute cool down" "3 tests in 5 minutes maximum"

When the battery on my main vehicle was drained by leaving the hatch ajar for a week I replaced it to avoid the risk of getting stuck somewhere in frigid weather - right now it's 3F outside.

I traded in a junk battery and kept it and it's still good for 150A at

--jsw

ich uses plain bearings in a demanding application? I'm not talking about t he extremes (like dental drills and steam turbines), but more common applic ations such as supporting lathe spindles and engine crankshafts. It used to be common to have plain bearings in these machines, and some were incredib ly durable, but I haven't seen any in a new product for a long time. Are th ere any examples, or have they been entirely displaced by standardised ball and roller bearings?

see the "Very clever machinist, Keith Fenner." thread.

I got lucky with the deep cycle battery for the HF setup when I checked it 14 or so months later and it needed only a little bit of water. Oops! I cleaned and gooped the battery terminals at that time, too. The red battery protectant spray works well. My riding mower battery had lots of corrosion problems until I sprayed the terminals on it.

I'll bet. Good call.

-snip-

I see your logic.

Yeah, the old Sun was considerably more linear than what they're putting out today, unless you spend $1,500 on a tester.

Yeah, they'll load a battery down pretty darned well. Almost as much as a Chebby starter which has been put in without shims. Remember that loud, whining gear noise from a non-reduction starter? Hehehe. I did a lot of quick fixes like that in my spare time when I was wrenching.

I used a large water-cooled active load to test battery packs at Segway. I don't need that much expense and complexity at home since I don't sell a product that I have to guarantee. I do have enough large fixed and variable power resistors to pull up to 65A continuously from a 12V battery.

Instead I use DC-AC inverters as constant-power discharge loads with low voltage shutoff to protect the battery. My standard loads are a

The inverters draw more current as the battery voltage drops and reflect the available runtime of a real load better than a non-compensating constant current or resistance load would, although a resistor load is simpler and may be a better long term indicator of a battery's age deterioration.

I bought a battery protector that I haven't tested yet, too many outdoor projects. It's intended to switch a boat or RV to a backup battery before the primary one drops too low to start the engine. I'd have it switch the battery under test from the discharge load to a charger. The datalog will capture the time of the jump.

Serial- or USB-connected DVMs are fine for logging batteries because their 1 or 2 readings per second rate is good enough and being optically isolated they're unaffected by the common-mode ground voltage differences that high currents produce in cables.

Plus they can't accidentally short-circuit the battery through the laptop. I was fortunate to be facing away and slightly outside the fireball when the tech next to me caused that type of accident with scope probes.

-jsw

Have to check that out.

Ceramic wirewounds? That's some watts! I'm switching to a 20gal water heater and using the 1kW of solar to heat it with a 900w 24v element. One of the two original 3,800W elements will be left installed and put on a timer to run for one hour (while power is available) to bring it up to heat if the solar doesn't make it. The bursitis is easing so I'll be back on the project some day soon, weather permitting.

Why would you run accessories on anything -but- the acc battery, Jim? Relay charges both when power on/engine running, but only the acc battery is used when the engine is off. Your main starting battery stays full at all times. Install that protector, mon. They should draw no power when the switch is off, and the coil only takes a dozen or two watts when it's on, so it's not a noticeable drain on the alternator. That's a half hour project.

Good call.

Oops! Lucky man, you are.