Adapter to use Lithium batteries in Nicad tools

[EvilTwin]

Probably like many folks, I have a BUNCH of older Bosch cordless tools in both 14.4 and 18 volt flavors that are perfectly fine as long as they have a good battery underneath.  The problem is that Nicad replacement batteries tend to be either very expensive or crappy quality, esp aftermarket versions and don't have the run times nor the overall longevity of their newer lithium cousins.  

Some manufacturers have come out with Lithium batteries that will run in the older tools but wont fit in their chargers since the technology to charge the batteries is different so they won't explode and burn down the house.   While perusing Amazon, I saw an adapter for a different brand and more searching led me to a guy on Ebay that is making adapters that let you run a newer lithium battery under an older tool.  I'm intrigued by this idea since it is easy enough to find a deal on a drill with 2 batteries and a charger and then to use those batteries with my older tools.  

As far as I know, the tools don't care where the power is coming from, and 14.4 volt tools will work just fine on 18v, albeit a bit faster.  And I have several 18v versions as well since I got a collection off CL including a recip saw and a hammer drill that are really well made and handy.  Has anybody tried this, bought one of the adapters or does this sound like a disaster waiting to happen?  

[JDuke]

Tag for interest.

I have a bunch of dewalt 14.4 tools and a few 18v

I have considered getting dewalts adapter for the 18v tools and seeing if it also does ok with 14.4 tools just haven't made the leap yet because I still have several good nicad batteries.

Duke

[EricU]

there are many Chinese options for the dewalt adapter.  Unfortunately, they all decided to go upscale and add a usb port.  I would love to find one that costs $10 and just does the adapter function, but no, they cost at least $25 and have a usb port.  Some of them are trying to get more than Dewalt's $40.  There was one vendor selling 4 for $20, which I thought was about right for some plastic, wire, and 4 metal strips, but it turned out they were a scammer.  4 would have been nice because I would like to have an adapter for all the tools.  $25 for one starts to push my limits on how much I want to spend.  Unfortunately, I'm down to one nicad battery, so something is going to have to happen soon

I have a dewalt lithium charger from my weed whacker, so that isn't a problem.

is the ebay vendor called "adapt-it-to"? $35 is too much.

[pprobus]

Tag for interest.

I have a bunch of dewalt 14.4 tools and a few 18v

I have considered getting dewalts adapter for the 18v tools and seeing if it also does ok with 14.4 tools just haven't made the leap yet because I still have several good nicad batteries.

Duke

Yeah, back in the day, I bought a few of the DeWalt 14.4V tools as I thought they were the best compromise between weight and power.  When a local HW store was going out of business I bought the 12V angle light they had on clearance for a great deal and used it with my 14.4V batteries, it worked fine.  The bulb probably didn't last as long as it could have, but it lasted longer than I thought it would, when it blew, I put in the 14.4V bulb. I highly doubt that the 14.4V tools will be affected too much by the 20V batteries, they'll run faster and perhaps put out more torque, but I am sure they are robust enough to put up with the overvoltage (i.e. I am sure that DeWalt and plenty of owners have "tested" them with 18V batteries).  I bought the 20V to 18V conversion kit that DeWalt offered during the Holidays at HD and Lowes.  Came with two 1.5 ah or 2.5 ah (can't remember which) batteries, a charger and an adapter.  I have yet to use them with my old DeWalt tools because I have to dig them out, but I am not too worried, if they kill the 14.4V tools, I have already gotten my money's worth.

[geek2me]

As far as I know, the tools don't care where the power is coming from

And that is the risk.  Performance characteristics and therefore controller requirements are different for both types of batteries.

It's rather unsafe to run a LiIon battery in a tool designed for NiCads.  You might get lucky and it only destroys the battery or burns up, or you may well have an explosion.

Not worth it, don't do it.

[crokett™]

It's rather unsafe to run a LiIon battery in a tool designed for NiCads.  You might get lucky and it only destroys the battery or burns up, or you may well have an explosion.

Not worth it, don't do it.

Not true. I have a Ryobi 18v cordless drill. I've had it for at least 10 years.  After the original NiCad batteries died (they outlasted a 14.4V Dewalt by at least 5 years)  I replaced them with Ryobi LiIon which were approved to use in my drill.  The 18v LiIon were still cheaper than the replacement DeWalt  14.4v batteries.

[EvilTwin]

And that is the risk.  Performance characteristics and therefore controller requirements are different for both types of batteries.

It's rather unsafe to run a LiIon battery in a tool designed for NiCads.  You might get lucky and it only destroys the battery or burns up, or you may well have an explosion.

Not worth it, don't do it.

Not trying to be argumentative, but.... Can you explain the science/technology behind why this is so?  I know that you wouldnt want to have a direct short across the terminals, that would cause the battery to overheat and that may cause a fire.  But do you know for a fact that there is some circuitry in there that is specific to tools with lithium batteries that prevents this?  One of the reasons I thought about this was specifically that Ryobi did market Lithium batteries that could be used in older tools but not used in older chargers.  

And most manufacturers did not, but my thought was it was more a marketing thing to get you to buy new tools rather than just new batteries.

[Stwood_]

I'm buying replacement NiCad (new, not old stock) from a Ebay vendor. When my NiCad Bocsh and milwaukee tools give up, then I'll quit buying the replacement batteries.

I'm not going the adapter route, etc, as when the tools do die, there I'll have less than useful adapters and such.

[EricU]

I really want to switch, but the Chinese replacement nicads on amazon are pretty good for $25.  The Chinese Dewalt Liion only seem to be available in 5mah, which seems like a pretty big battery for some tools.  2mah seems a little low, that is the combo meal that Dewalt is serving with their converter right now, 2x2mah liion, a charger, and a converter.

I don't see anything wrong with using a liion battery in a nicad tool.  Battery powered tools have to be pretty robust to voltage, and the difference between 20v liion and 18v nicad is mostly in the marketing department.  Sure, you can pump the liion up to 20v, but it droops down to closer to 18v pretty quickly. And if the tool isn't brushless, it's dead simple inside.

on edit: the dewalt adapter says not to use "premium" liion with compact drills, so whatever that means. I suppose the premium cells probably have a faster discharge rate.

I just bought one of the Chinese adapters and a couple of 5mah packs. See how it works out. I have two 18v tools I use all the time, a drill and a sawzall, so I would need a second adapter if I like this one.

[EdL]

on edit: the dewalt adapter says not to use "premium" liion with compact drills, so whatever that means.  I suppose the premium cells probably have a faster discharge rate.  

IIRC, on DeWalt 20v the circuitry that limits battery draw is in the tool, a 2amp/hr battery is the closest thing to a 2.4 nicad, so the draw will be a little less than original. Put a 5 or 6 amp/hr battery in an old tool and your likely to burn it up under high load since nothing will stop the power draw.

Bigger batteries are for longer runtime, not extra power.

Ed