Horizontal Barrel Battery Blaster: A CR2032-based barrel battery drop-in replacement

[@shaunclarke94]

Gotta be honest, was disappointed when the build started and we didn't have our usual theme lol. I know not everyone liked it but it was your signature and I vote for its return.

[@monad_tcp]

but how ? who didn't like the Stalker music from Duke Nukem ? must have been a " "Doomed" Space Marine "

[@llamallarry]

Love these videos! I like how the PCB "is use the diode you have"

[@NaoPb]

Neat! I'm about to solder some of the original ones and then install them in 2 pc's I am fixing. I have some other old pc's that take a 4-pin "external" battery that I have to find some replacements for though.

[@Megatog615]

we're lucky that these old clock chips tolerate 3V batteries. I believe the original Varta batteries were 4.5V.

[@davidcameron648]

The Varta batteries actually had too high a voltage for the clock chip and needed a resistor to drop it to 3 volts (if I remember correctly). Many later main boards (including the first one shown in this video), have PCB footprints for both the rechargeable barrel batteries and a coin cell holder. Some also had headers for a wired battery pack.

[@Krivulda]

@@davidcameron648 This is complete nonsense. The time chip usually requires 3-6V of operating voltage (HM6818A/146818 3-6V, DS12885 2,5-4V, 82C206 has 6V battery specified in datasheet). Resistor would only drain the battery flat in basically no time.

[@alexloktionoff6833]

Perfect fit!

[@ichemnutcracker]

I think I liked the Duke Nukem music more.

[@monad_tcp]

who doesn't ? show yourself now !

[@xero110]

Would a CR1025 work? Holders are available and have a width of 10 mm vs 20 mm. You loose capacity, but sometimes space on the main board is more important.

[@davidcameron648]

It should. 3 volts DC is 3 volts DC, regardless of how you get it. Used to solder in a wired two AA battery holder with a diode as a replacement back in the day.

[@xero110]

@@davidcameron648 I thought so, how about the 235 mAh vs 50 mAh? We just need to replace them 4 times as much?

[@elamriti]

bat wil drain fast on 386 systems and lower

[@scrap_computing]

True, older systems may require a beefier battery.

[@shaunclarke94]

Are older systems more draining on the battery?

[@Constantin314]

hello SC. i have an intel RC440BX ATX version board with PIII @ 500MHz that does NOT boot with the battery ON. I remove the battery, the board boots with no issues. Have you encountered something like this? it's so strange, for me, at least

[@scrap_computing]

Indeed really strange. Could it be that the CMOS chip is bad, so when the configuration is read from it, it's always corrupted?

[@timschonherr7674]

Would you be able to design such an adapter for the CR2032 that fits that typical 3 hole design of a BR2335? So basically allowing the usage of a CR2032 in Mainboards that used BR2335?

[@scrap_computing]

It shouldn't be too hard. I am not sure I have a motherboard with such a battery so that I can test it, but I will check.

[@Vanessaira-Retro]

I love the "No Leaky symbol" XD

[@piotrludorowski9529]

Schottky? How about a reverse leakage current? Just compare leakage for 1n5818 is 1mA and for 1n4148 is 50 nA. These are for 25*C.

[@scrap_computing]

Yeah reverse leakage is something to consider when picking parts. 1mA seems a bit too high, perhaps you are looking at MAX values? I would expect it to be in the range of uA at ~5V.

[@zacmitchell_1984]

Cool thanks

[@sthen622]

Lovely - very useful as I'm about to fix my old 486 PC mainboard with a leaky barrel battery 🙂 While I'm at it - may I ask for an older video of yours (kzbin.info/www/bejne/bnnYqaihpcemd6c) about the awesome music that is played from ~ 1:30 mins until 4:10 mins? Artist and song title would be super highly appreciated ! 🥰

[@scrap_computing]

It is "Stalker" from the "Duke Duke Dance Party" album by the Space Quest Historian (link in that video's description).

[@AladimBR]

Please keep using the Duke Nuken music ❤

[@PROSTO4Tabal]

H3B PROJECT

[@Krivulda]

I don't want to be a bearer of bad news, but this project is completely worthless. You see - the BAS40 schottky diode has 380mV forward voltage drop. That value means how much of the power will be consumed by the diode and converted to heat. Also, by that much the voltage of the battery will be lessened. Let me give you an example. The most widely used time chip among these boards is HM6418A. This chip power requirement is between 3-6V, with my experience at around 2.8V the chip stops advancing time and around 2.5V it starts losing data. CR2032 has the nominal voltage of 3V, brand new out-of-packaging is around 3.2V and all it lifespan it follows a strict curve - it drops quite fast to 3V, where it stays for a long time and then it starts falling down gradually (of course this applies only to quality brand cells. Cheap off-brand has the lifespan way shorter and way steeper). Now, if you take the BAS40 diode and put the power of brand new CR2032 through it, you get 3.2V-0.38V=2.82V. So we have only 0.02 margin until the chip starts to behave erratically. If the voltage drops a little bit and stabilises on the 3V mark, after the diode there would be 2.62V. And the chip is stone cold. So, with this setup you have to change the battery about every month or so. And if you think I am babbling nonsense - there are A LOT of cases where people made the original design and then complained it is not working. This problem already was remedied by project Not-A-Varta by Wiretap-Retro, available on GitHub. It comes in two sizes, with CR2032 and CR1220 and it uses the MAX40200 chip which was engineered specifically for this purpose and its voltage drop is around 20mV. 3V-0.02V=2.97V. WAY more suitable for this application. Don't get me wrong, you get a thumbs up from me for the initiative, but in this case the attempts to re-invent the wheel were not good for anybody, actually it was quite the opposite because now more people will create this marginally functional design.

[@scrap_computing]

Thanks for the feedback! Yeah the MAX40200 is a great way to reduce the voltage drop. I just added solder pads for it in revision 0.2.

[@HW_Printing]

Kermit