Question Do I need a PCM?

[GC64]

Looking over multiple wiring diagrams for the n64, I've noticed some do and some do not include a protection circuit board. For instance:

PCM:

No PCM:

Does the first one have something to do with the fact that it's using two 3.7v batteries as oppose to two 7.4's like the second (and every other diagram)? And I know most of these camcorder batteries have a PCM built in, but I've heard that they're not compatible.

 

[Luke]

Yes, you need a pcb, you can't have 3.7v cells unprotected. It's nothing to do with 3.7v vs 7.4v; I would assume those batteries in the bottom diagram are made up of two 3.7v cells, and include a pcb.

Really makes me want to make a decent n64p wiring diagram for bb. There are some okay ones and there are some not-so-great ones, but they're all from different sites.

 

[Providencial]

It is about whether you use a battery pack, or seperate cells.

Any li-ion pack (a group of battery cells connected together in series and/or parallel) should have a PCM providing safety as well as combining the voltage and/or current.

Camcorder batteries will always have a PCM built in as mentioned.
Any other battery pack you find which is 7.4v li-ion (or poly) chemistry should also. (But obviously check!)

When you buy single cells it depends entirely on what you buy.
They are sometimes sold as "protected", and have a small circuit built in. These cells are a little more expensive, and a bit longer typically.

Yes, you need a PCM in your project.
Whether you need to buy and wire up a seperate one depends on your plans and materials.

(About li-ion camcorder packs being "not compatible"; They output a nominal 7.4v, under normal conditions your portable won't know if there is a protection circuit in there or not.

The PCM will only come into play in case of charging more than the rated current, discharging more than the rated current, charging to above the rated voltage, and discharging to below the rated voltage.)

 

[Noah]

@Luke Yeah I keep seeing the MBB one float around the most (even ModRetro uses it in there official N64 guides) and it leads to a lot of uncertainty amongst modders. I'd love to make a new guide (not just diagrams!) for the N64 once I'm done with the rest of the BB store stuff so feel free to shoot me a PM sometime and we can work on it together if you'd like.

 

[GC64]

@Noah @Luke I do agree that a proper diagram is needed for BB and I would love to see one.

@Providencial Thanks! So, from what you've told me, the first diagram's two 3.7's are individual cells, not packs? Does that mean the second diagram's info is incorrect when it says I need two 7.4v packs?

 

[Luke]

What you need is 7.4v. Most people do this by wiring two 3.7v cells together, along with a pcb.

You could use any number of 7.4v camcorder packs in parallel, but no, it is not mandatory to do it this way.

 

[GC64]

What you need is 7.4v. Most people do this by wiring two 3.7v cells together, along with a pcb.

You could use any number of 7.4v camcorder packs in parallel, but no, it is not mandatory to do it this way.

Well I currently own two 7.4v packs, each with 2.5 amps, so if I wired those in parallel I'd simply double the amps right? They each have a pcm built in already.

 

[Providencial]

Wiring two 7.4v packs in parallel sounds like an ideal solution, just as shown in that (ugly!) diagram.

It would double the amperage yes.

@Noah @Luke Maybe it's a bit far-fetched, but you could make up a set of standardised BitBuilt symbols (with templates etc.) And anyone making wiring diagrams to put up here would have a set of decent looking and functional sprites to work with.
Would make wiring diagrams quicker to draw up too.
Just an idea.