Here's some perhaps more clear pictures of the same thing (using cr2032), on system11, wpc, and wpc95.
The jumper wire across the bottom is to tie the original three AA battery holder connections together, so the two pole cr2032 holder makes contact at negative and positive points.

The cr2032 voltage (about 3.2 volts) is plenty to keep 6264 RAM alive. these rams keep their memory until you get under about 2 volts. though this doesn't seem like much "head room", it is actually plenty.

Lithium batteries work differently than standard AA batteries. Lithiums keep their voltage at their advertised voltage, until they "die", and then then drop off voltage quickly to zero. AA batteries are more of a downward straight curve. that is, they start at 4.5 volts (1.5 volts times three), and over time, dissipate on a straight line (over time) to zero volts. When Lithiums dies, they were at 3 volts yesterday, and then today at 0 volts. this is unlike a standard AA battery system.

If you go to ebay.com, cr2032 batteries are available in lots of 100 for about $10 (name brand cr2032 batteries can be more, but i just get the generic ones that come in individual blister packs). Also the holders (there are several different kinds, i like the style shown below), are available in lots of 100 for about $15. That's enough batteries and holders to do 100 games for $25 (25 cents per game)! You can't get cheaper than that.

cr2032 on system11. (pinrepair.com)

cr2032 on wpc89. (pinrepair.com)

cr2032 on wpc95. (pinrepair.com)

I prefer this style of cr2032 holder...
ebay.com link: Wholesale 100 x CR2032 2032 Cell Coin Battery Socket Holder Case 4 1

On WPC 89, actually the battery holder does not have to hit the reset transistor device. When the reset transistor is in the way, which happens only sometimes, what I do is heat the two bottom legs of the reset transistor device and just angle it up a smidge. This is enough so that the battery holder fits into the existing battery holder holes. I'm not big on drilling holes through circuit boards unless it's absolutely needed (which it is not on WPC 89 boards). It's just a little too invasive for my tastes.

I have a cr2032 mounted in probably 15 of our WPC games. One game was "eating" these, at about 6 months per battery. The rest have had cr2032 mounted battery for several years, without any change. In fact, i don't think i've change *any* of the cr2032 in our games (except for one, see below.)

the one game i was having problems with was Junkyard. The bottom line is this... the brand of 6264 on that particular game was different than all the other games (in fact, it's a Rottendog CPU board.) Perhaps it wasn't the low power 6264 variety? I don't know. But since there was already a socket in for the RAM, i just used a RAMtron on that particular game.

I use cr2032 batteries because they are a) inexpensive, b) very common (probably the most common coin battery), and c) you can, in a bind, buy them at the drug store.

The battery holder has two legs. each leg, conveniently, fits into the existing holes for the original AA battery holder. That's why drilling a hole seems really silly to me. But hey, there's different ways to skin a cat i guess.

the problem I have is just that I have so many games spending $4.50 per machine for batteries is just not a viable option. Frankly at that dollar amount the nv ram is a better choice. the nvram is actually cheaper now then three AA lithium's. The CR 2032 option is an excellent option with a very low cost and the batteries last for years and don't leak.

i'll buy that thinking. it just comes down to volume i guess.
also i use cr2032 for nearly everything. actually for everything. it's pretty rare i have a game where the cr2032 does not work. so it really pushes that number north of 200 machines which get cr2032.

Here's some other applications that use a cr2032 battery.
Note on the system80 and the Bally -35/-17, a blocking diode must be used, since the original battery was re charage-able. The dataeast application does not need a blocking diode (the board has one built in, like WPC does too.) Same situation with Williams system3-7, no additional blocking diode needed.

I would like to add that if you are running an AMI brand 5101 ram on a williams system3-7, the cr2032 does not work well. The AMI branded 5101 is power hungry, and drains a cr2032 in about 6 months. AMI branded chips suck, by the way, and i generally replace them (be it PIA, CPU or RAM) with a different brand.

Dataeast:
cr2032 on Dataeast. PinRepair.com

Williams system6. Note the legs on the battery holder must be bent a bit to make it fit in the existing holes.
cr2032 on Williams sys6. PinRepair.com

Bally -35 (blocking diode on back side of board. Also a hole was drilled for this application.)
cr2032 on Bally -35 with blocking diode. PinRepair.com

Gottlieb system80 (blocking diode on back side of board, no hole drilling needed.)
cr2032 on System80 with blocking diode. PinRepair.com

Please, The nvram discussion should be in the nvram thread not here.
This thread is about cr2032 installations.

The only WPC game that killed the cr2032, in my experience, was the Rottendog wpc95 i had. They used a different brand of 6264. I think it's the brand of RAM that makes the difference. I notice this on games with 5101 AMI brand RAMs. those don't work well with cr2032 either.

Post #15 with the pictures is self explanatory.

At the vfw museum we have every WPC game made (except for popeye and gilligan, yeck). And they nearly all have a 2032 coin battery. So we have a pretty good example of data points. i would say average life is about 2 years. Though a couple games kick their coin battery after one year. It's probably the brand of RAM perhaps...

personally i just use the cheap 2032 batteries. i have not found the name brand versions to last any longer.

you need to check with the DMM that the last pin of the ram is getting battery voltage (game off). if it's not (and trust me, it's not), you have done something wrong...

that diode could be open. that would do it! check it with DMM set to diode function, black lead on banded side of diode, red lead on non-banded side of diode. should be .2 to .6

I prefer to stay with the cr2032, because it’s so readily available. But on WPC games, it only lasts between one and two years. So I’ve started trying this modification… the two batteries are running parallel (not series) so you still have 3.2v. But it doubles the mA power. The cr2032 has nice spacing compared to other batteries. That is, the holder fits right into the stock battery holes on the cpu board. other larger batteries won't afford that. When doing this mod make sure you check pin32 of the RAM to verify it's still 3.2v, and not 3.2+3.2v (6.4v)...

IMG_7707 (resized).jpeg

IMG_7708 (resized).jpeg

battery life will be different using two cr2032 in series versus parallel. series is a bad idea... parallel is the way to go.