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Releasing the Magic Smoke
#1
The guy on whose land I park a few miles from mother Pacific, handed me a harbor freight Nicad cordless 18v drill and asked me to see if it could be charged.

I was suspicious of it, but then I saw the origignal prop whatever california cancer warning sticker was still bridging the body of the drill to the battery. It appeared whoever bought this drill, used it upto the point the battery died and then placed it next to their garbage with a free sign upon it.

So I look up how to charge Nicad batteries,  opened up the battery pack to count the number of cells. When i applied 19.6v it took almost no current for very briefly. But Nicads apparently you constant current them until they get warm then the voltage drops indicating full charge.  Only way to get the current up was up the voltage.

I was monitoring current with my Windynation 'Watt's up' wattmeter clone which never worked well, but which did come with 8awg leads and was good enough for this task.

i was using my 150 watt voltage booster step up converter I bought for cheap a few years ago.  very similar if not exactly the same as this one:

https://www.ebay.com/itm/150W-DC-DC-Boos...100623.m-1

[Image: s-l1600.jpg]

I had voltage up in the 27v with the battery accepting 65ish watts range when i noticed the battery started getting warm, and I pulled the Anderson powerpole inbetween the wattmeter and the Nicad battery.

Apparently, when i did so, removing the 65ish watt load, and even though the wattmeter is rated at 60voltsDC, a voltage surge smoked my Wattmeter. I should have disconnected the andersons on the other side of the wattmeter, or cranked voltage back down to the point the battery was accepting little to no amperage before disconnecting it.

So while I smoked my wattmeter, this wattmeter never worked well in terms of recording AH or WH accurately, even though instant amps or watts were very accurate, sometimes, other times the display would jump around 20% of actual voltage and amperage, and sometimes the thing would freeze up entirely.  I bought it primarily as it came with 8awg highly flexible leads, to which I added 45 amp anderson powerpoles.

i am going to buy another wattmeter that comes with 12awg leads, and transfer these 8awg leads and powerpoles to it.

[Image: 61nXT6%2B1LjL._SL1500_.jpg]

I have had one of these wattmeter clones on my meanwell power supply since 9/2014.  Very great seeing how much amperage at what voltage and how much AH and WH has passed to the battery being charged. I have another wattmeter more portable i use on loads, like my fridge.

These wattmeters are hardly perfect, especially at very low currents, but I still find them useful enough and nothing better to replace them for what i want them for.

So Consider the potential voltage spike of removing a load while a charging source is delivering it amperage, attempting to hold it at a certain voltage.  The cheap step up converter i was using apparently has nothing to prevent the damaging voltage transient, and if it did, like most devices should, these spikes are likely cumulatively damaging to whatever is designed to suppress it ether on output or input side.

Which is why one should never unhook a solar controller from a battery while the sun is shining on the panels, and to a lesser extent, removing solar panels in full sun,  that are delivering a significant portion of their rated capacity to a load, which would be the charge controller.  Diodes in the panels, especially if they are in series, might smoke.
  
Always best to slow the flow before quickly disconnecting.

There could be a 'thats what she said!" joke in there somewhere.

By the way the harbor freight drill battery is apparently still quite capable, i used it to drive several #8 4 inch long wood screws into stacked pine 2x4's.   This sub 3$ step up voltage boost converter might have smoked my ~ 20$ wattmeter due to my ignorance/arrogance combo, but it has now made 12v fans levitate, EQ'd a group 31 flooded battery at 16.2v, and now sucessfully recharged  a 'disposable' drill battery into full usefulness.

I will leave out the details of the  story of the 'free'  Hedge clipper 24v Nicad battery I also used it on, as I missed that short window where the battery got warm and the charger should have been removed.  

Thermal runaway, pop gurgle smoke!!! ARGHHHHHH. WHERE'S MY  eye protection  hold breath run towards fireproof container please don't explode or set fire to my workshop story.

But on a positive note the cheapo 150 watt rated converter linked above, with an additional 60mm computer fan atop the heatsink, has no issues passing ~200 watts for a few to several minutes.
Smile
[-] The following 6 users say Thank You to sternwake for this post:
  • Scott7022 (08-11-2019), rvpopeye (08-11-2019), heron (08-11-2019), Texjbird (08-11-2019), Gapper2 (08-11-2019), frater secessus (08-11-2019)
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#2
Dang, that sucks when the smoke escapes. I could use a few of those in-line amp/volt meters. They look super useful. 
  It pays to be extra cautious with nicads but it happens. I bought a enormous disconnect switch from a guy in Spokane when I noticed he was modifying and building batteries including Nicads. This guy gets batteries by the pallet load cheap at auctions. He had a nice little work station but the ceiling above the station was marred by a big Nicad explosion. He said that was “instant learning”. I’ve wanted to experiment with battery building but have not yet as I’m too distracted to do it safely. When the big projects are done I’ll try experimenting. 
 On a side note I wonder if a big electrolytic capacitor in parallel with the charge circuit would help with voltage spikes?? I forget how that works. Brain needs a bigger memory chip.
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#3
The inline wattmeters are great, but not so much at low currents, at least those GTpower 130 clones I employ two of. The one i just smoked was quite good reading low currents accurately, when it was not having one of its inevitable manic episodes.

I had one other clone of these wattmeters, which also read low currrents well but it was a project for a friend and sent off with him, but i found the link I used back then(2015) and it is still viable.

These wattmeters are limited in that there is a source and load side, and will not act like a battery monitor counting current in both directions. They also only go to 64 amp hours before flipping back over. The included 12AWG very flexible very high temp silicone sheathed leads do get quite hot at a constant 40 amps which is why I open up the wattmeters and use 8awg instead. I messed one of them up as the solder bridged + and - . That was back when my soldering skills were less developed and i only had a 40 watt weller iron, and now pretty much use the 140 watt weller gun exclusively.

This is the one clone which I ordered, installed 8awg and found it read currents as low as 0,03 amps accurately, in comparison to an inline digital multimeter. That was in 2015, and I just ordered it again, although I will retask the plastic casing of the smoked wattmeter as it is made to accommodate 8awg leads, and does not need time with a round file.

https://www.amazon.com/gp/product/B00LNS...B00C1BZSYO

This is supposedly the original 'watts up' meter that all the clones are based off:

https://www.rc-electronics-usa.com/watt-...meter.html

https://www.amazon.com/gp/product/B001B6...1d172afccf

I've passed the starter current for my v8 engine through two of these wattmeter clones in parallel before, at about 90 amps each so that '130 amp' rating is valid, for short term loads at least. Heck some clones will say 200 amps. I wish there were burlier versions available that were also accurate at low currents. The smoked one would have been great had it lived up to its marketing, and i would have been much more bummed to have smoked it.

The voltage spike suppressing capacitor is a bit above my pay grade. The caps on teh voltage booster itself, i though would take care of it, but perhaps they are undersized or too cheaply made, or somethig else.
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#4
Caps do have a voltage rating.

No
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#5
Caps have lots of ratings and quality levels.

Not My Forte, but I do want to replace all the caps in my original engine computer and see if it returns to function. Might have to inspect them all for ratings and see Mouser's offerings, and ask my electronics guru friend what their best replacement would be.

A replacement engine computer for a 30 year old vehicle is not a simple goto the parts store thing, should it fail. A beefed up back up ECM would be nice for peace of mind.
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#6
I've been recently giving some thought to buying a back-up computer for my 20 year old van. Hopefully they may still be available?
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#7
There are ecm or pcm rebuilding services. And rockauto might have some in stock. Not easy to get exact specific model needed. Likely more so with ford.
[-] The following 1 user says Thank You to sternwake for this post:
  • S Cello (08-13-2019)
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#8
Clinebarger on the Bob the Oil Guy forum said the symptoms on my Chevy transmission may be due to intermittent problem in the PCM circuit board. I’ve been wondering about a back up also. It’s bumping up the priority list.
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#9
I read clinebargers response as an intermittent connection inside the ecm.

I had one of those on my rebuilt ecm causing random stalling no restart. Depotted the 14 pin Connector and reflowed and added more solder early 2015. No ecm problems since.

Granted these connector pins were large. If the 60 pin Connector had broken intermittent solder joints id likely be near helpless.

The backup ecm would be great for.diagnostics when Weird stuff starts occurring that might be the ecm. Withiut a known good backup one is stuck checking every other possibility first.
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#10
It sounds like a weak area on those ECM units, so many connections. I suppose under the driver seat keeps it away from the elements for the most part. For the reconditioned units I started reading about flashing the PROM, that’s a chip I think, and gave up for now. Too much technojargon for that late in the day. 
  Hey computer, what condition is your condition in? As Sternwake mentions he got a reconditioned unit with some conditions. And then who can do the flashing from the old ECM to the reconditioned ECM?. I’ve never asked a shop about it. A spare ECM is not much use if it doesn’t work right.  
 The connectors on electrical are a big issue I’m realizing. I’m not satisfied with the power in connector on the Victron Energy control panel. For such an expensive unit that was disappointing. 
 I saw some of those inline watt meters on Amazon where someone installed powerpole connectors and is selling them for 4 times the price of the meter.
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