ePlate HPW-600 Battery Rebuild

Hello everyone,

I've finally picked up a Hitachi HPW-600ET searching around for SH4 devices that's practically new in box, with a predictably dead battery that probably hasn't been charged since 2000 or so...

Has anyone ever been able to revive a battery this dead or otherwise tried rebuilding an HPW-600 pack? I'm not sure what cells it would use and if it's worth taking a knife to it or if I should just gamble on a scrap one that's hopefully been charged a little more recently to the point that I could move it from one desk to another without having to restore a backup every time.

Thanks.

That seems highly doubtful to me, but what I came in here to say is that I'd suggest posting pictures of the battery for more concrete recommendations. Just looking around GIS, it looks like it might be 2x 18650 cells in there which is typically a fairly easy rebuild if you've done it before (and there are lots of videos and guides if you haven't).

I ended up deciding to just open it after I couldn't figure out where I put my ruler and found four 14650s inside. It doesn't seem like a complex design, but I haven't done a repack before... I'll look at some tutorials and see if I can give it a try at some point this month.



Edited by ict 2023-10-25 7:22 PM

Wow, you already did the hard part!

If you are handy with electronics, the rest is pretty straightforward. You'll need to buy replacement cells (everyone here seems to advocate for purchasing from a vape shop- not sure how ocmmon the 14650's are but you'll need to investigate). You also need a spot welder to put the batteries together (I have this one: ) and possibly/probably a soldering iron to re-solder the wires/connections at the charging circuit board. I also purchased some thinner nickel strip than what comes with that spot welder kit (this one: ).

Warning/disclaimer: you're working with Lithium batteries. You have to be careful and there is always a danger/risk to the device, to yourself, etc. Make sure you educate yourself and know what you're doing before proceeding very carefully and safely.

Edit: p.s. you probably need flat top cells, not button top. The button top probably won't fit, but do inspect the current cells closely to make sure.

Edited by thenzero 2023-10-25 7:38 PM

Will do, thank you for the tip on the spot welder, didn't realize they were that small... I'll have to grab one of those and maybe I can try my hand at it within a month or two when I get a workspace together. Thanks again!

You're welcome. The purpose of the spot welder is to avoid overheating the lithium cell as it only applies the heat long enough to create the weld. I have seen people around who say you can use a normal soldering iron but I personally wouldn't try it, especially since these spot welders are so cheap.

Edit: p.s. one thing I like about the particular kit I got is that it comes with some nickel strip and it comes with these little battery holders that turned out to be VERY handy for me.

Edited by thenzero 2023-10-25 10:04 PM

Oh and yeah, it's crazy how small they've gotten!

That spot welder was exactly what I needed. I know it's a bit of a 'duh' question given how simple repacks generally are in theory, but I don't think I would have considered it otherwise based on what I was finding on Google, since I didn't realize you could get them that cheaply nowadays... So thanks again for that!

14650 cells are bit harder to come by and what I could find online was a little odd since the Hitachi factory cells were 3.6V but 14650s seem to all be 3.7V nowadays, I ended up taking a risk on some generic looking "AMT" 3.7V flat top cells from an eBay listing and it turns out they worked just fine. The biggest challenge of the whole thing was mostly just re-attaching the weird right-angled controller PCB (which involved getting a soldering iron a little close to the cells the way I was doing it) and getting the right length/width on the nickel strips, they're a little wide so I ended up cutting them in half down the middle which gave a much better fit.

I covered most bare metal I could see with electrical tape just out of paranoia which resulted in something a little bulky that didn't seal perfectly when you put the top case back on, but even in two pieces it will still hold together enough to go back into the tablet and lock just fine with no bulging or otherwise badly fitted look on the back. Tried just turning the tablet on after and it worked! I'm planning to use it as sort of a mini-terminal/desktop on a stand with a mouse and keyboard but now I can take it wherever I want...



The battery seems to charge properly with the AC adapter and the charging light will turn from orange to green after a while which gives me hope that the overcharge protection circuit is still working with these new batteries, but ResInfo doesn't seem to be able to get the voltage levels or any other figures from the battery controller. Is that really concerning at all or normal for repacks? With that aforementioned use case I'm hoping to still leave it plugged in for long times and preferably unattended, but I don't know if the overcharge prevention is trustworthy now...

In any case, thanks for the assistance! Excited to try kludging up my dead Clio and Aero 8000 batteries with this thing next.

Congrats! Sounds like it came out great.

As far as ResInfo, had you peeked at it before? I know it doesn't work properly on some devices. Does the normal % readout still seem about right?

After a pack rebuild I typically charge the device all the way up (meaning I leave it on the charger a few hours past when it thinks it's full), run it all the way to power off, charge it up again, and run it down again. That seems to be enough to recalibrate everything.

Edited by thenzero 2023-10-30 1:24 AM

Thanks! I'm thinking there's a good chance it might not have ever really supported the advanced voltage/capacity readouts but I didn't think to check before the repack, it does give a general % readout in increments of 20 regardless that so far seems accurate, I'll try and keep using it over the next couple days on battery until it drains out and I'll see if it becomes more accurate after a couple of those cycles.