Ni MH batteries compared to Lithium Ion for tools?

I have a good assortment of Dewalt battery powered 18 volt tools. The set only came with two batteries and now at least one of them will not recharge. This is only for home use as I retired back in 2015 and got these tools as part of my retirement so not like they are getting heavy use these days. Couple questions: Is there a big advantage of Li Ion over Ni Mh batteries? I'm seeing some after market sources that sells them to fit the 18 volt tools. I also have a 20 volt pole saw from Dewalt that runs on a Li Ion battery. Just wondering if I would be better off getting one of the aftermarket adapters to use the 20 volt battery on the 18 volt tools and maybe buy a couple 20 volt batteries?

Yes. The Ni MH batteries were never popular. Ed

Lithium is better than ni-mh. Batteries will cost almost as much by themselves as a kit with new tools especially with black Friday and Christmas deals coming up

Don't even mess with Hi-Mh just not worth it I have a few left over 18V tools and the Ni-Mh never lasted and especially with the skill saw. Put an adapter to 20V on the tool and it is night and day different in performance

AllDodge said: Don't even mess with Hi-Mh just not worth it I have a few left over 18V tools and the Ni-Mh never lasted and especially with the skill saw. Put an adapter to 20V on the tool and it is night and day different in performance Click to expand... Think that's what I'll do, convert to the 20 volt. Guess the next question would be if there is any big advantage to the higher amp hour batteries in the 20 volt series? I believe the pole saw I have has just a 2 amp hour battery and looking on line see them all the way up to maybe 10 amp hour! Would the higher amp hour battery just last longer before needing to be charged? If so thinking I might just buy one of say 4 amp hour rating as use would be pretty low.

They just last longer I have 4 and 5 ah and really like that they last a long time, even with non use. Also the standard charger will take several hours to recharge a larger bat. Get a higher rate charger takes less time

Lithium batteries make cordless tools work like you want cordless tools to work. Long run time, quick charge, plenty of power, and large batteries for high consumption tools. I cut my fenced in backyard and trim with a 40V 6AH lithium battery mower, weedeat and blow with the same tool series, and then have cordless impacts, drills, ratchets, and grease guns for the mechanical work.

The new lithium tools are no comparison to the old nimh stuff. How many tools do you have and how many do you need? If you can swing it, just ditch the old nimh tools and batteries and get a whole new set up. The new ones are that much better. And I don't even like cordless tools.

Problem with nimh is drawing down too low, lithium has the same problem but the tool shuts down before the batt suffers damage. The old nicad were better in some regards, they liked to be fully discharged, but you were forced to swap them out before that because the tool was pretty much unusable long before they hit bottom. Ni-mh likes to be recharged when they reach about 30% charge, the trick to make them last was to swap them out as soon as you noticed the tool start to lose power. One thing to keep in mind if you get an adapter to run lithiums on the old 18V tools. AS SOON AS the tool slows, even a little, swap it out. Over-discharging a lithium is a death sentence for the batt, and can wreck the tool as well.

kshansen said: I have a good assortment of Dewalt battery powered 18 volt tools. The set only came with two batteries and now at least one of them will not recharge. Click to expand... Take it to Interstate battery, they will rebuild your bad battery. IF you get an adapter and a couple of lithiums, just be careful not to run them down too far. It does work well, we have a few 18V tools we use this way, but only as a last resort if we are busy enough that all the Milwaukees are in use.