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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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I was given an electric drill that uses 12V lithium ion batteries
because the charger didn't work and the batteries died and the owner lost interest. I hack sawed the transformer case open and found that the primary winding was open somewhere that I couldn't see, so I didn't try to repair it. Also the charge adapter that the battery slides into has a burnt out resistor on the circuit board. It's a very simple circuit board, there are 4 diodes on the input side which I assume is a full wave bridge rectifier. After the rectifier there is a small series resistor (R1) powering an LED across the dc power lines coming out of the rectifier, and a larger resistor (R2) which got hot enough to char the circuit board near it as it was blowing up. I'm guessing it was over-voltaged, or maybe more likely the outputs were shorted together. The V+ output voltage passes through R2. I don't have a schematic, and would like to repair the ct. board if I can choose a replacement resistor that doesn't unsafely charge the batteries. If I get a transformer with the same V and I ratings (14.5V 200mA) I'm wondering what value Resistor to replace R2 with. I am including a picture. http://tinypic.com/m/k2ck8j/3 I read this, "Most consumer orientated lithium ion batteries charge to a voltage of 4.2 volts per cell and this has a tolerance of around ± 50 mV per cell. Charging beyond this causes stress to the cell and results in oxidation that reduces service life and capacity. It can also cause safety issues as well." https://www.electronics-notes.com/ar...n-charging.php Since the batteries are labeled "12V", if it uses the same LiIon technology the article is referring to, I assume it has 3 cells totaling 12.6V. The transformer was clearly labeled 14.5V 200mA. Also from the web page, "Charging lithium ion batteries can be split into two main stages: Constant current charge: In the first stage of charging a li-ion battery or cell, the charge current is controlled..." It seems like it might be a simple matter of trial and error, power the charge adapter attached to the battery, and find a value of R2 that leaves 12.6V on the output side, when the battery is fully charged. The adapter has no current regulation, other than the series R2. Is that a safe approach? Would a 12V car trickle charger work safely, with a maximum charging current of 2A (based on the web page)? The transformer had a much lower current rating. I'm surprised the charge circuit is so simple after reading this web page! TIA, Mike |
#2
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On 4/5/2019 12:58 AM, Mike S wrote:
I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. I hack sawed the transformer case open and found that the primary winding was open somewhere that I couldn't see, so I didn't try to repair it. Also the charge adapter that the battery slides into has a burnt out resistor on the circuit board. It's a very simple circuit board, there are 4 diodes on the input side which I assume is a full wave bridge rectifier. After the rectifier there is a small series resistor (R1) powering an LED across the dc power lines coming out of the rectifier, and a larger resistor (R2) which got hot enough to char the circuit board near it as it was blowing up. I'm guessing it was over-voltaged, or maybe more likely the outputs were shorted together. The V+ output voltage passes through R2. I don't have a schematic, and would like to repair the ct. board if I can choose a replacement resistor that doesn't unsafely charge the batteries. If I get a transformer with the same V and I ratings (14.5V 200mA) I'm wondering what value Resistor to replace R2 with. I am including a picture. http://tinypic.com/m/k2ck8j/3 I read this, "Most consumer orientated lithium ion batteries charge to a voltage of 4.2 volts per cell and this has a tolerance of around ± 50 mV per cell. Charging beyond this causes stress to the cell and results in oxidation that reduces service life and capacity. It can also cause safety issues as well." https://www.electronics-notes.com/ar...n-charging.php Since the batteries are labeled "12V", if it uses the same LiIon technology the article is referring to, I assume it has 3 cells totaling 12.6V. The transformer was clearly labeled 14.5V 200mA. Also from the web page, "Charging lithium ion batteries can be split into two main stages: Constant current charge:Â*Â* In the first stage of charging a li-ion battery or cell, the charge current is controlled..." It seems like it might be a simple matter of trial and error, power the charge adapter attached to the battery, and find a value of R2 that leaves 12.6V on the output side, when the battery is fully charged. The adapter has no current regulation, other than the series R2. Is that a safe approach? Would a 12V car trickle charger work safely, with a maximum charging current of 2A (based on the web page)? The transformer had a much lower current rating. I'm surprised the charge circuit is so simple after reading this web page! TIA, Mike Short answer...don't do anything until you figger out what you're doing. Are you sure that they're lithium? Is the picture showing EVERYTHING that is in the charger path? That ain't nearly enough stuff to charge a lithium battery. The picture suggests that you have the typical symptom of what happens when a NiCd battery shorts and the crap unregulated charger melts trying to charge it. |
#3
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On Friday, 5 April 2019 08:58:51 UTC+1, Mike S wrote:
I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. I hack sawed the transformer case open and found that the primary winding was open somewhere that I couldn't see, so I didn't try to repair it. Also the charge adapter that the battery slides into has a burnt out resistor on the circuit board. It's a very simple circuit board, there are 4 diodes on the input side which I assume is a full wave bridge rectifier. After the rectifier there is a small series resistor (R1) powering an LED across the dc power lines coming out of the rectifier, and a larger resistor (R2) which got hot enough to char the circuit board near it as it was blowing up. I'm guessing it was over-voltaged, or maybe more likely the outputs were shorted together. The V+ output voltage passes through R2. I don't have a schematic, and would like to repair the ct. board if I can choose a replacement resistor that doesn't unsafely charge the batteries. If I get a transformer with the same V and I ratings (14.5V 200mA) I'm wondering what value Resistor to replace R2 with. I am including a picture. http://tinypic.com/m/k2ck8j/3 I read this, "Most consumer orientated lithium ion batteries charge to a voltage of 4.2 volts per cell and this has a tolerance of around ± 50 mV per cell. Charging beyond this causes stress to the cell and results in oxidation that reduces service life and capacity. It can also cause safety issues as well." https://www.electronics-notes.com/ar...n-charging.php Since the batteries are labeled "12V", if it uses the same LiIon technology the article is referring to, I assume it has 3 cells totaling 12.6V. The transformer was clearly labeled 14.5V 200mA. Also from the web page, "Charging lithium ion batteries can be split into two main stages: Constant current charge: In the first stage of charging a li-ion battery or cell, the charge current is controlled..." It seems like it might be a simple matter of trial and error, power the charge adapter attached to the battery, and find a value of R2 that leaves 12.6V on the output side, when the battery is fully charged. The adapter has no current regulation, other than the series R2. Is that a safe approach? Would a 12V car trickle charger work safely, with a maximum charging current of 2A (based on the web page)? The transformer had a much lower current rating. I'm surprised the charge circuit is so simple after reading this web page! TIA, Mike A 14.5v transformer when rectified would give over 20v output. A resistor that will let the cells charge then drop the V_out to 12.6 when current falls does not exist. I suspect Mike may be correct that the battery is NiCd or NiMH. If you can verify that it is, they usually use 1.3Ah sub-C cells with a card case. Those typically have a 5hr charge time in power tools. The burnt resistor & oc transformer both indicate a significant overload. One plus with 12v & 14v tools is that if all else fails you can run them off a car. Thick wire is necessary. NT |
#4
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On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote:
I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#5
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On 4/5/2019 9:16 AM, Jeff Liebermann wrote:
On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote: I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. Thanks to everyone who replied. I screwed up assuming it was Lithium Ion, it is not. Black & Decker FSB12 FireStorm 12-Volt 1.2-Amp Hour NiCad Battery |
#6
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On Saturday, 6 April 2019 00:21:02 UTC+1, Mike S wrote:
On 4/5/2019 9:16 AM, Jeff Liebermann wrote: On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote: I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. Thanks to everyone who replied. I screwed up assuming it was Lithium Ion, it is not. Black & Decker FSB12 FireStorm 12-Volt 1.2-Amp Hour NiCad Battery Battery failure leaves them with a residual value of zero. You could cobble a battery pack together from other dead packs, putting test-good cells together, but once one cell dies the others follow. NT |
#7
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#8
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On Saturday, 6 April 2019 01:31:55 UTC+1, Mike S wrote:
On 4/5/2019 5:17 PM, tabbypurr wrote: On Saturday, 6 April 2019 00:21:02 UTC+1, Mike S wrote: On 4/5/2019 9:16 AM, Jeff Liebermann wrote: On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote: I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. Thanks to everyone who replied. I screwed up assuming it was Lithium Ion, it is not. Black & Decker FSB12 FireStorm 12-Volt 1.2-Amp Hour NiCad Battery Battery failure leaves them with a residual value of zero. You could cobble a battery pack together from other dead packs, putting test-good cells together, but once one cell dies the others follow. NT I'm sorry if I wasn't clear, I don't know if the batteries work or not, the charge adapter ct. bd. had R2 blow up, and the transformer had a bad primary winding. The batteries may be good. IIRC it was already been explained that those are most likely the result of bad batteries. You might be lucky & it was just caused by accidental shorting. Bodge-charge the battery pack (safely) & find out. NT |
#10
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On Friday, April 5, 2019 at 7:21:02 PM UTC-4, Mike S wrote:
On 4/5/2019 9:16 AM, Jeff Liebermann wrote: On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote: I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. Thanks to everyone who replied. I screwed up assuming it was Lithium Ion, it is not. Black & Decker FSB12 FireStorm 12-Volt 1.2-Amp Hour NiCad Battery I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. (then again, I'm just not in the business right now - just my 2 cents) |
#11
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On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote:
I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. I have a modest collection of DeWalt cordless tools that run on LiIon batteries. I don't own one (yet), but you can get just about any power tool with LiIon battery power. For exmple: https://www.dewalt.com/products/power-tools/shop-by-cordless-platform https://www.dewalt.com/products/power-tools/flexvolt/flexvolt-tools I recently had to clear a fallen tree and borrowed a LiIon powered chain saw because of a noise problem. It worked very nicely. However, I didn't rush out and buy one because of the $500 tool+battery cost. https://www.youtube.com/watch?v=N5J9pI8bUno I've also converted my ancient Makita NiCd and NiMH electric drills to run on LiIon batteries. The battery has to be charged externally using a RC model airplane charger, but that was easy enough. Or, just go to Home Despot and look at the power tool section. I would guess(tm) that about 90% of the cordless tools offered use a LiIon battery. You can still find NiCd and NiMH powered cordless tools, but those are decreasing in number. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#12
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On 4/6/2019 3:29 PM, Jeff Liebermann wrote:
On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. I have a modest collection of DeWalt cordless tools that run on LiIon batteries. I don't own one (yet), but you can get just about any power tool with LiIon battery power. For exmple: https://www.dewalt.com/products/power-tools/shop-by-cordless-platform https://www.dewalt.com/products/power-tools/flexvolt/flexvolt-tools I recently had to clear a fallen tree and borrowed a LiIon powered chain saw because of a noise problem. It worked very nicely. However, I didn't rush out and buy one because of the $500 tool+battery cost. https://www.youtube.com/watch?v=N5J9pI8bUno I've also converted my ancient Makita NiCd and NiMH electric drills to run on LiIon batteries. The battery has to be charged externally using a RC model airplane charger, but that was easy enough. Or, just go to Home Despot and look at the power tool section. I would guess(tm) that about 90% of the cordless tools offered use a LiIon battery. You can still find NiCd and NiMH powered cordless tools, but those are decreasing in number. FWIW, Ryobi 18V is the tool of choice for cheapskates. Not the best, or the most reliable, but for occasional use, I've never had one fail. Their old 18V NiCd tools run just fine off the new 18V lithium batteries. The newer chargers can charge NiCd or lithium. And NiCd is always dead when you need it. Lithium holds it's charge forever, or thereabouts. There are a lot more of them in the wild, so they make up a high percentage of garage sale and Goodwill Bargains. I've never bought a bad battery operated tool at a garage sale. But the batteries themselves are always bad...that's why they're there. Just picked up a Ryobi 18V circular saw at Goodwill for $7, no battery. The like-new carbide blade would have cost more than that. $70 on sale at Home Depot will get you two brand new tools with batteries and charger. Then fill out the set from garage sales and thrift stores. Sure beats having five different brands with incompatible (and likely dead) batteries. I tried to sell my box of random tools/batteries/chargers and nobody made an offer at all. |
#13
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On 4/6/2019 4:50 PM, Mike wrote:
On 4/6/2019 3:29 PM, Jeff Liebermann wrote: On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries.Â* I have a modest collection of DeWalt cordless tools that run on LiIon batteries.Â* I don't own one (yet), but you can get just about any power tool with LiIon battery power.Â* For exmple: https://www.dewalt.com/products/power-tools/shop-by-cordless-platform https://www.dewalt.com/products/power-tools/flexvolt/flexvolt-tools I recently had to clear a fallen tree and borrowed a LiIon powered chain saw because of a noise problem.Â* It worked very nicely. However, I didn't rush out and buy one because of the $500 tool+battery cost. https://www.youtube.com/watch?v=N5J9pI8bUno I've also converted my ancient Makita NiCd and NiMH electric drills to run on LiIon batteries.Â* The battery has to be charged externally using a RC model airplane charger, but that was easy enough. Or, just go to Home Despot and look at the power tool section.Â* I would guess(tm) that about 90% of the cordless tools offered use a LiIon battery.Â* You can still find NiCd and NiMH powered cordless tools, but those are decreasing in number. FWIW, Ryobi 18V is the tool of choice for cheapskates. Not the best, or the most reliable, but for occasional use, I've never had one fail. Their old 18V NiCd tools run just fine off the new 18V lithium batteries. The newer chargers can charge NiCd or lithium. And NiCd is always dead when you need it.Â* Lithium holds it's charge forever, or thereabouts. There are a lot more of them in the wild, so they make up a high percentage of garage sale and Goodwill Bargains.Â* I've never bought a bad battery operated tool at a garage sale.Â* But the batteries themselves are always bad...that's why they're there. Just picked up a Ryobi 18V circular saw at Goodwill for $7, no battery.Â* The like-new carbide blade would have cost more than that. $70 on sale at Home Depot will get you two brand new tools with batteries and charger. Then fill out the set from garage sales and thrift stores. Sure beats having five different brands with incompatible (and likely dead) batteries. I tried to sell my box of random tools/batteries/chargers and nobody made an offer at all. Great idea, thanks. |
#14
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On Saturday, April 6, 2019 at 6:29:45 PM UTC-4, Jeff Liebermann wrote:
On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. Well, I haven't worked in construction for a few years. |
#15
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On 4/7/2019 6:33 PM, wrote:
On Saturday, April 6, 2019 at 6:29:45 PM UTC-4, Jeff Liebermann wrote: On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: I was about to say... I don't do much electrical work any more, but an electric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. Well, I haven't worked in construction for a few years. NO worries, I appreciate all of the replies, after this discussion, and reading about NiCads I did a simple test of the batteries and they look ok so I bought a smarter charger than the original. |
#16
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On Fri, 05 Apr 2019 09:16:02 -0700, Jeff Liebermann
wrote: On Fri, 5 Apr 2019 00:58:45 -0700, Mike S wrote: I was given an electric drill that uses 12V lithium ion batteries because the charger didn't work and the batteries died and the owner lost interest. The photo is NOT a LiIon charger, which would include an IC to control the voltage and current to the battery. Perhaps it might be useful if you would disclose the maker and model number of the drill and charger? The battery type could then be easily researched. It is possible to convert a NiCd or NiMH drill to operate from a LiIon battery. Is this what the former owner has done? If so, you will need a much better LiIon battery charger designed specifically to charge a LiIon battery. I bought a new NiMH battery for my RC car. 7.2 volts 3500 mah. Would it do any harm to try to charge it with a small plug pack charger made for use with NICAD? |
#17
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#18
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On Sat, 06 Apr 2019 15:29:38 -0700, Jeff Liebermann
wrote: On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: was about to say... I don't do much electrical work any more, but an ectric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. I have a modest collection of DeWalt cordless tools that run on LiIon batteries. I don't own one (yet), but you can get just about any power tool with LiIon battery power. You say you have a modest collection of DeWalt cordless tools that run on LiIon batteries, but you don't own one (yet). For exmple: https://www.dewalt.com/products/power-tools/shop-by-cordless-platform https://www.dewalt.com/products/power-tools/flexvolt/flexvolt-tools I recently had to clear a fallen tree and borrowed a LiIon powered chain saw because of a noise problem. It worked very nicely. However, I didn't rush out and buy one because of the $500 tool+battery cost. https://www.youtube.com/watch?v=N5J9pI8bUno I've also converted my ancient Makita NiCd and NiMH electric drills to run on LiIon batteries. The battery has to be charged externally using a RC model airplane charger, but that was easy enough. Or, just go to Home Despot and look at the power tool section. I would guess(tm) that about 90% of the cordless tools offered use a LiIon battery. You can still find NiCd and NiMH powered cordless tools, but those are decreasing in number. |
#19
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On Tuesday, 16 April 2019 07:26:25 UTC+1, Lucifer wrote:
I bought a new NiMH battery for my RC car. 7.2 volts 3500 mah. Would it do any harm to try to charge it with a small plug pack charger made for use with NICAD? No problem. Just unplug it when it's had it's charge time, NiCd chargers can't be counted on to shut off. NT |
#20
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On Mon, 15 Apr 2019 23:57:51 -0700 (PDT), wrote:
On Tuesday, 16 April 2019 07:26:25 UTC+1, Lucifer wrote: I bought a new NiMH battery for my RC car. 7.2 volts 3500 mah. Would it do any harm to try to charge it with a small plug pack charger made for use with NICAD? No problem. Just unplug it when it's had it's charge time, NiCd chargers can't be counted on to shut off. Thanks. NT |
#21
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On Tue, 16 Apr 2019 16:35:09 +1000, Lucifer
wrote: On Sat, 06 Apr 2019 15:29:38 -0700, Jeff Liebermann wrote: On Sat, 6 Apr 2019 13:40:38 -0700 (PDT), wrote: was about to say... I don't do much electrical work any more, but an ectric drill battery that is lithium ? I've never heard that. Most every cordless electric drill made in the last 3 years uses lithium ion batteries. I have a modest collection of DeWalt cordless tools that run on LiIon batteries. I don't own one (yet), but you can get just about any power tool with LiIon battery power. You say you have a modest collection of DeWalt cordless tools that run on LiIon batteries, but you don't own one (yet). Sorry. My sloppy editing. When I originally wrote that paragraph, I included mention of a DeWalt 60v LiIon powered electric chain saw that I was interested purchasing. It's powerful and very quiet. However, when I deleted the mention of the electric chainsaw, I neglected to also delete my comment that I don't currently own one. I do have two fairly new DeWalt DCD710 12v LiIon cordless drills. I use them quite often. These use brush type motors, which are not as good as brushless motors. I burned out one motor ($25 replacement cost). The brushes are sealed inside the motor and are not replaceable. If I had to do it again, I probably would have bought the larger DCD777 20v model instead, which uses a brushless motor. https://www.dewalt.com/products/power-tools/shop-by-cordless-platform/20v -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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