bloodem wrote on 2021-07-27, 15:39:

darry wrote on 2021-07-27, 15:01:

That is on my list as well . Maybe somebody can give some recommendations as to what to get .

I've been using this one for a few years and it's been great.
There is a learning curve, though. And, of course: The. Tip. Must. Always. Be. Clean 😁

Thank you! I have a few other priorities right now (among which a McCake) but will look into that soon .

I already have a decent soldering station so would need a dedicated desoldering thing...

bloodem wrote on 2021-07-27, 15:39:

There is a learning curve, though. And, of course: The. Tip. Must. Always. Be. Clean 😁

Yeah, I apply this rule to all my tips 😀

Ordered a desoldering gun!

I'm curious about something.

When the battery juice leaks you can see it forming crystals or some kind of deposit as it dries. Most of the time it's greenish, but sometimes it's blue. Like the deposit in the ram slots around badscrews PC.
Since Copper Salt is blue, is the blue deposit from the battery juice a visual sign that it has actually gotten to copper and has eaten a damaging amount of it?

I'm just curious since if I'm right you could potentially just look at the deposit on the traces to know how much of a repair job the pc will be.

CalamityLime wrote on 2021-08-03, 18:56:

I'm curious about something. […]
Show full quote

I'm curious about something.

When the battery juice leaks you can see it forming crystals or some kind of deposit as it dries. Most of the time it's greenish, but sometimes it's blue. Like the deposit in the ram slots around badscrews PC.
Since Copper Salt is blue, is the blue deposit from the battery juice a visual sign that it has actually gotten to copper and has eaten a damaging amount of it?

I'm just curious since if I'm right you could potentially just look at the deposit on the traces to know how much of a repair job the pc will be.

I believe it is indeed copper salts you are seeing. You keep calling it "juice" 🤣 it's electrolyte

Copper(II) hydroxide maybe?

https://en.wikipedia.org/wiki/List_of_copper_salts

maxtherabbit wrote on 2021-08-03, 23:19:

CalamityLime wrote on 2021-08-03, 18:56:

I'm curious about something. […]
Show full quote

I'm curious about something.

When the battery juice leaks you can see it forming crystals or some kind of deposit as it dries. Most of the time it's greenish, but sometimes it's blue. Like the deposit in the ram slots around badscrews PC.
Since Copper Salt is blue, is the blue deposit from the battery juice a visual sign that it has actually gotten to copper and has eaten a damaging amount of it?

I'm just curious since if I'm right you could potentially just look at the deposit on the traces to know how much of a repair job the pc will be.

I believe it is indeed copper salts you are seeing. You keep calling it "juice" 🤣 it's electrolyte

Squeeze a lime, you get juice. Squeeze a battery, you get juice.
It's all very logical when you don't think about.

verysaving wrote on 2021-08-04, 01:36:

Copper(II) hydroxide maybe?

https://en.wikipedia.org/wiki/List_of_copper_salts

That would make sense yeah. Looks about right for the lesser blue but the darker blue could be a further reaction with additional copper or something.
Battery juice is spooky stuff.

I must tell the 30 plus year old rechargeable battery pack in my 1990 Zenith 286LP Plus need replacing because they should be leaking by now......

Caluser2000 wrote on 2021-08-04, 06:18:

I must tell the 30 plus year old rechargeable battery pack in my 1990 Zenith 286LP Plus need replacing because they should be leaking by now......

I guess you talk about a laptop battery pack. Such packs are used in a different way compared to CMOS batteries on board. I observed no leakage problems with CMOS baterries in computers that were in regular use. Usually, I got the problems only when reviving old retro hardware. The CMOS battery pack contains of three cells in series, which are kept full by a trickle charging circuit, which puts charge into the cells all the time the system is turned on. If the cells are full, the charging current causes electrolysis of the water contained in the electrolyte, producing oxygen and hydrogen. The electrical energy is taken up by this reaction. These are gases that build some pressure in the cell. A properly working cell can contain this pressure. It also has some catalyst built in, at which oxygen and hydrogen gather together and re-form water. The energy taken up by electrolysis is released as heat.

The charging current of CMOS batteries is low enough that the heat emitted by the recombination of oxygen and hydrogen to water is low enough to not cause significant heating. Classic NiCd cells were designed to take a small amount of continous overcharge without damage, the "trickle charge" method is explicitly allowed by most data sheets. You get leakage only when the seal of the cell breaks down, so it can not contain the pressure from the gases anymore.

A critical problem with all battery stacks (not only NiCd ones, you have the same problem with non-rechargeables too) is that possibly not all cells are depeleted at the same time. This problem is mitigated by the instructions to "never mix fresh and used cells" and "never mix cells of different types" in the case of non-rechargeables. If one cell is empty, the other cells (in case of CMOS packs there are two of them) still push current through the empty cell, charging it in reverse (you could also call it "charge it negatively"). The process of charging nickel-based cells in reverse is well-known to damage cells by chemical destruction, especiallly if the reverse charging pertains for a long duration. There are studies that momentary reverse charges, if the cell gets re-charged within some minutes or hours are benign, but continuous reverse polarity slowly kills cells. If a 486 board is in storage for years, the pack goes flat and one of the cells typically gets reversed and deteriorates, which decreases the capacity of that single cell in the pack and makes it even more prone to reverse charging.

My theory is that reverse charged cells do not just lose capacity but also get severely prone for leaking. Possibly the button cell form factor contributes to constructing the cells in a way that they easily get leaky. It might also be just old age that contributes to seal failure.

Laptop cells are usually treated differently: They are not permanently trickle-charged, but only charged when you request charging. In the 286 days, schemes where charging or operating from AC where exclusive options existed. The manual usually warned you to take care of charging time yourself (or they had some timer). As there is no permanent trickle-charge, you also don't get a permanent pressure in these cells. Furthermore, the main laptop battery pack might not be used for CMOS backup, so there is no continous discharge while the system is in storage. If you completely stop discharging a laptop pack when it can't supply the required operation power anymore, you do not reverse cells for a long duration. And even if CMOS backup current is still drawn from the main pack, compared to the pack capacity, the CMOS backup current is way lower than in the barrel-battery scenario (comparing a 60mAh barrel battery to a 1500mAh 20V or 5000mAh 4.8V laptop pack).

I've been using a ZD-915, cheaper but efficient nonetheless.

mkarcher wrote on 2021-08-04, 07:48:

I guess you talk about a laptop battery pack. Such packs are used in a different way compared to CMOS batteries on board. I obse […]
Show full quote

Caluser2000 wrote on 2021-08-04, 06:18:

I must tell the 30 plus year old rechargeable battery pack in my 1990 Zenith 286LP Plus need replacing because they should be leaking by now......

I guess you talk about a laptop battery pack. Such packs are used in a different way compared to CMOS batteries on board. I observed no leakage problems with CMOS baterries in computers that were in regular use. Usually, I got the problems only when reviving old retro hardware. The CMOS battery pack contains of three cells in series, which are kept full by a trickle charging circuit, which puts charge into the cells all the time the system is turned on. If the cells are full, the charging current causes electrolysis of the water contained in the electrolyte, producing oxygen and hydrogen. The electrical energy is taken up by this reaction. These are gases that build some pressure in the cell. A properly working cell can contain this pressure. It also has some catalyst built in, at which oxygen and hydrogen gather together and re-form water. The energy taken up by electrolysis is released as heat.

The charging current of CMOS batteries is low enough that the heat emitted by the recombination of oxygen and hydrogen to water is low enough to not cause significant heating. Classic NiCd cells were designed to take a small amount of continous overcharge without damage, the "trickle charge" method is explicitly allowed by most data sheets. You get leakage only when the seal of the cell breaks down, so it can not contain the pressure from the gases anymore.

A critical problem with all battery stacks (not only NiCd ones, you have the same problem with non-rechargeables too) is that possibly not all cells are depeleted at the same time. This problem is mitigated by the instructions to "never mix fresh and used cells" and "never mix cells of different types" in the case of non-rechargeables. If one cell is empty, the other cells (in case of CMOS packs there are two of them) still push current through the empty cell, charging it in reverse (you could also call it "charge it negatively"). The process of charging nickel-based cells in reverse is well-known to damage cells by chemical destruction, especiallly if the reverse charging pertains for a long duration. There are studies that momentary reverse charges, if the cell gets re-charged within some minutes or hours are benign, but continuous reverse polarity slowly kills cells. If a 486 board is in storage for years, the pack goes flat and one of the cells typically gets reversed and deteriorates, which decreases the capacity of that single cell in the pack and makes it even more prone to reverse charging.

My theory is that reverse charged cells do not just lose capacity but also get severely prone for leaking. Possibly the button cell form factor contributes to constructing the cells in a way that they easily get leaky. It might also be just old age that contributes to seal failure.

Laptop cells are usually treated differently: They are not permanently trickle-charged, but only charged when you request charging. In the 286 days, schemes where charging or operating from AC where exclusive options existed. The manual usually warned you to take care of charging time yourself (or they had some timer). As there is no permanent trickle-charge, you also don't get a permanent pressure in these cells. Furthermore, the main laptop battery pack might not be used for CMOS backup, so there is no continous discharge while the system is in storage. If you completely stop discharging a laptop pack when it can't supply the required operation power anymore, you do not reverse cells for a long duration. And even if CMOS backup current is still drawn from the main pack, compared to the pack capacity, the CMOS backup current is way lower than in the barrel-battery scenario (comparing a 60mAh barrel battery to a 1500mAh 20V or 5000mAh 4.8V laptop pack).

let's be honest NiCd batteries fucking suck balls as batteries even when they don't leak

they were absolute trash when they came out, and still are

maxtherabbit wrote on 2021-08-04, 12:01:

let's be honest NiCd batteries fucking suck balls as batteries even when they don't leak

they were absolute trash when they came out, and still are

I tend to strongly disagree here. NiCd batteries were actually quite impressive when they came out. They could be recharged hundred of times (when used properly). They could deliver higher currents than alkaline (don't even get me started on Zink/Carbon) cells of the same size. Yeah, they did have a lower capacity than alkalines (around one third at higher currents), and they were heavy. The idea to build stacks of up to 20 cells, charge them without any kind of balancing, and discharge them without any low-voltage cutoff or individual cell monitoring is indeed quite crappy. Using cells that way makes them fail very fast, and is the cause for the bad reputation.

Later on, when NiCd/NiMH cells got standard items you could buy at the local supermarket, they were marketed on price and capacity only. This made reliability plummet to previously unknown low records. When the low-discharge cells started to take off, you got AA Eneloops at 1800mAh, kind-of reliable non-LSD-cells at 2300mAh, and utter crap at 2500mAh to 2800mAh. The drop down to 1800mAh to get cells that do not only look good on paper if you compare one single number, but actually delivered an all-around acceptable product shows how much the battle over highest capacity impacted other cell parameters.

If lithium ion cells wouldn't catch fire on overcharge, an weren't completely dead after the first deep discharge, I would expect we still would use them the same way as we used nickel cells earlier on. Granted, they still have the advantage of a trippled cell voltage, so the ridiculous stack sizes of NiCd cells would drop to reasonable stack sizes of lithium cells, which will indeed increase reliabilty.

mkarcher wrote on 2021-08-04, 07:48:

Caluser2000 wrote on 2021-08-04, 06:18:

I must tell the 30 plus year old rechargeable battery pack in my 1990 Zenith 286LP Plus need replacing because they should be leaking by now......

I guess you talk about a laptop battery pack.

Nope.

It was a nice story though......