Clock Battery Mod CR2032

[megavolt85]

I want to say right away that I am not a supporter of this mod and I think it is not right to change the rechargeable battery to a disposable CR2032.
If you use your Dreamcast frequently, then use the ML2032 as shown in this manual.


You ask if there is a normal replacement with a rechargeable battery, then why am I writing this instruction about the CR2032.
The answer to this question is simple, there are users who use their DreamCast once a month and play no more than an hour, the ML2032 simply does not have time to charge.

Many who choose CR2032 make a number of mistakes.
Someone simply solder the battery holder and assembles everything as it is, but in this case the battery is charged and it quickly fails.
Someone solders a diode instead of or in series with a resistor, but many use the first diode that comes to hand, and even if it is a Schottky diode, 0.2 volts still drops on it, which leads to a decrease in battery life.

I suggest using the correct option, i.e. disable charging on the motherboard.
from the RTC power diagram it can be seen that R612 and D603 are responsible for charging

all you have to do is remove or move to the side of the R612

For VA0 board you can remove R612 on mother bard or simple remove R2 on controller board

[Blehstor]

Thats really cool to know. How long do you say it takes to charge the ML2032 battery?

[OatBob]

A big THANK YOU for this tutorial.

I see CR2032 substitue frequently proposed as an alternative to the ML2032 in different forums, with zero instruction on mitigating the difference in electrical performance. I want to say VEGETA was working on publishing his method which involves adding a small circut with diode. Once again for the same situation of infrequent use.

I may apply this method to my Treamcast(s). They sit mostly in storage, but do see occasional use on vacations.

[megavolt85]

I haven't measured so I can't say for sure. According to user reviews, the charging time is 1.5-2 hours, but I cannot say that this is really the case.

[mistamontiel]

I don't know the wizardry the rev0 the VA0s possess. I've had two of them since the previous one must be board failure it *might* flicker power on n back off. Change power supply no result

So it feels so good with them to power on and boot straight into MIL-CDs not being halted by time+date prompt>BIOS>restart! If they're not powered off too long I *think* I've done six-seven days n they just hold forever. If not if waited too long just keep periodically power cycle and continues to holds time+date forever

Maybe something to do with since they were most if not all rental units before the big 9/9/99..?

[amcpartymix]

Just so I understand this right, if you want to use a CR2032 which is non-rechargeable, all you have to do is desolder that one pin on the motherboard and you're good to go?

[megavolt85]

Just so I understand this right, if you want to use a CR2032 which is non-rechargeable, all you have to do is desolder that one pin on the motherboard and you're good to go?

Yep

[amcpartymix]

Do you need to do anything to D603 like mentioned in your post or is R612 all that is needed to be desoldered?

[MoeFoh]

https://www.retrosix.wiki/schematics-dreamcast
Note: Board VA2.1 has a different layout - but D603 & R612 are probably used the same way.

[megavolt85]

Do you need to do anything to D603 like mentioned in your post or is R612 all that is needed to be desoldered?

Desolder only R612