Convert coreless trimmer to wired

I'd like to convert a coreless string trimmer (18 Volt B&D GrassHog) to wired A/C. I know this seems counter-productive, but I'm beyond sick of this POS. It always was underpowered and barely provided enough charge to finish the yard (even with 2 batteries). This is just the second season of owning, and now the batteries will not provide more than 5 minutes run-time combined. I can safely do the conversion; however, any thoughts/advice are greatly appreciated. Also, any thoughts on trying something with the batteries first (18v nicad)? They never seemed to hold their charge without just keeping them on the charger, and they take about 4+ hours to fully charge.

http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?ProductID=6427

Thanks,
Anthony

I'd definitely try something with the batteries -- looks like you take them off to charge, so you don't even have to worry about the charging circuit being right, just ditch the old one. I'm thinking I would make a fannypack battery with a cable running up to the old housing. It could even be as simple (and heavy!) as 3x 6v SLA, but I'd probably go for NiMH or one of the safe Li-ion chemistries. That'd be 15 cells of NiMH or NiCd, 5 cells of LiMn, or 6 cells of LiFePO4. LiMn is the most expensive, but that all depends, and it does offer the best capacity/weight. LiFePO4 is suppose to be the cheapest, even cheaper than SLA, per Wh, but again it all depends on what deals you can find, especially if you can pick up an entire prebuilt battery pack and charger cheap (maybe for some other power tool?). If you build the pack yourself, I think sub-C are the most optimized NiCd/NiMH size, while 18650s are the most-optimized LiCo -- but I'm not sure that holds true in the safe chemistries. For sure the big ones (26650 and 26700) are not far behind, and being twice the size, have more capacity. I'd tend to stick with the 26xx0s, rather than paralleling 18650s, for this project, just to keep it simple. A 6s2p pack of A123 cells should blow the original packs away.

I guess I should have mentioned that I don't have any rechargeable components on hand. Still a newb. So a true 'aholic would say "no time better than the present to get started". :thumbsup: I'll start digging for info.

ALiteZ said:

I'd like to convert a coreless string trimmer (18 Volt B&D GrassHog) to wired A/C.
http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?ProductID=6427

Thanks,
Anthony

Click to expand...

$0.02

These things draw so much current that an 18V high current power supply would end up costing more than a new 120V trimmer.

I'm running into the same problem, batteries geting old after just a couple summers. I'm thinking about getting a better charger, mine is the three position hang on the wall that is just a trickle charger, never shuts off. I have the new porter cable drill set that is just the rebadged black and decker but the changer is smarter. Seems like I could just file the little plastic tab off the packs so they will slide in.