Black & Decker hand held cordless vacuum

Hi looking for suggestions. i have an old B&D PHV1800 handheld vac with a docking station. it seems it doesn’t want to charge anymore. it’s 18V and packed with 15 Nicad cells. Replacement parts are discontinued. Charging adapter says output is 24V~200mA. Is there a way i can use 18650 cells instead and use a different charger? don’t really want to junk it.

For 18v if you went lithium ion you need a 5S (series) configuration. Here’s the issue though, you’d need a bms of some kind with integrated balance charging, or a balance charger. You could use the existing charger if you got a bms with integrated balancing, but that’s not ideal since it charges super slow and isn’t meant for li-ion. The other option is to rebuild the battery with nickle metal hydride cells. You wouldn’t need to change anything else and could use the stock charger. Nimh cells self balance pretty much. The downside is that it might be expensive. I bought 6 sub-C 3000mah cells from Tenergy (the real ones, not fakes) to rebuild an inflator in 2018 and I paid $25 shipped. It was like $5 for each cell. I don’t know if prices have gone up or down though so it might be cheaper, but for 15 of those it will be a bit spendy. Might be better to buy a new vacuum.

Thanks for your input. i’ve never used 18650s in series and definitely didn’t think about a BMS. They are cheap enough from the looks of it. this one will work? Page Not Found - Aliexpress.com
If i solder 2 leads from the docking station to a dummy cell/adapter and use my xtar 2 bay charger, that should be ok? going the Nimh route doesn’t seem worth it as you said. i think i have 5 harvested cells lying around that i can use for this.

You can get generic 18V tool-batteries that have a built-in BMS. If they’re 5S1P you’re probably fine. If they’re 5S2P you might have to snip off one bank to make it 5S1P. Depends how much room you have in the dustbuster.

Involves lots of hacking’n’slashing, dunno if I’d bother, vs trying to snag some NiCd sub-C cells or whatever it uses now.

Couldn’t help but goggle around for s&g, found a vid where a guy replaces a cell in a Li pack instead.

Unfortunately, he buys a 10pak of Ultrafire button-tops to replace the bad cell. :person_facepalming:

Anyhoo, even 4S1P looks like it’d work in an “18V” dustbuster.

It will have a ton of room once i remove those 15 cells. They are 21mmdia x 42mm long each. Yeah that guy is nuts to buy ultrafire. Especially to mix it like that.

I have “18V MAX” drill and grass trimmer, so when the battery died on my old dust sucker I opted to buy one that takes the same 18V MAX battery packs. Snap in and slurp up the dust, then pop it off the tool and recharge the pack. The suckers tend to outlast the batts, so I figure why buy one with a built-in batt?

That BMS would work. You’d need to assemble the battery pack though, and that requires soldering, etc. Or you could get a cell holder that does 5S, downside is they’re not meant for high currents like a vacuum pulls so you’d need to mod it, bypass springs, etc. There would be some hacking and slashing and finagling involved. The nimh switch would be a similar deal, sans BMS. It would be an interesting project.

You can then probably just buy a reputable but cheap 18V pack, and stuff it in. Sounds like there’d be a whole bunch of room, so why not?

If you don’t have to have Li cells, you can stick with NiCd. Those cells you described sound close to sub-C size, and you could buy some with the tabs already spot-welded to ’em.