Electrical gurus, I need a little help.

[I.B. Washincars]

I have several cordless Dewalt tools that I carry in my truck. I bought a vehicle charger so I would always have a fresh battery for them. The problem is that the battery is always dead when I remove it from the charger. I contacted Dewalt and they told me that the charger shuts down after 16 hours to prevent draining of the truck battery. If the battery is left on the charger it will discharge fairly quick.

The power port in the truck is hot all the time. What I want to do is interrupt the power to the port so the charger will reset itself and begin another 16 hr. cycle. I don't want to need to conciously do something because I will always have a dead battery because I will forget. I was thinking of using the dome light circuit to do this. I was thinking of putting a relay in the power port wire and powering it with the dome light circuit so it would reset every time I open the door.

Any ideas what I would need or any better ideas?

BTW, my truck is a 2008 F-250.

 

[Waxman]

My friend Scott, who's certified in auto. electronics, says,

'use the pin on the drivers door to trigger the relay, not at the dome lite. if i'm geting this right you need to interrupt power just long enough to re-set charger, wire relay triger to pin switch and put relay inline with acc outlet(cig lighter) you are useing relay to interupt power going throuh it so when door is open power goes away and when closed power comes back to complete circuit. if door pin goes to ground when open this will be the ground for relay, open door and ground goes away= no power through relay!

 

[MEP001]

You will find that continually recharging the batteries will quickly kill them. Have you considered an AC power inverter for your standard charger? If you use your cordless tools a lot, you could get into a habit of putting a battery straight onto the charger as soon as you pull out the tool case, which is what I used to do whenever I was in the field with no AC.

 

[Jeff_L]

Aren't you worried about draining your truck battery? Or do you think the pull off of the battery while parked will be minimal?

 

[mac]

Why does it take more than 16 hours to charge the battery? MEP001 is right also about leaving the recharges on the charger too lond. Personally I think they could give away cordless tools so they can sell you the bleeping batteries.

 

[I.B. Washincars]

I'm not worried about draining the truck's battery since the charger will shut down after 16 hrs. Besides, when I open the door there's a pretty good chance that I'm going to start the engine and replenish the truck battery anyway.

Mac, it only takes an hour or so to charge the battery and then the charger goes into a stand-by mode. According to Dewalt it is ok to leave a battery on the charger in stand-by indefinitely. I do it all the time on the AC chargers at the washes. The vehicle charger will only stay in stand-by for 16 hrs. and then it shuts off to protect the vehicle battery. Leaving the battery on a non-powered charger drains it quickly.

MEP, I don't understand why I would need an AC inverter when I already have a DC powered charger?

 

[MEP001]

MEP, I don't understand why I would need an AC inverter when I already have a DC powered charger?

Because I misunderstood your post - I thought it was a 16-hour DC charger and was suggesting that you keep your batteries charged more frequently rather than leave them on the charger to drain.

 

[I.B. Washincars]

I still haven't tackled this project. Anyone have any suggestion as to what to ask for at an auto parts house or order online?

 

[RykoPro]

I have timer relays that will reset every 15 1/2 hours (or from .01 seconds to 999 hours). They require very little amps to run and the supply voltage range is 240 VAC down to 5 VDC with no modifications. They are Omron timers and last for a very long time. I have used them in my race car to run the cooling fan between rounds. I am sure I have a used one around that I can make you a deal on.

 

[RykoPro]

Here is a pic of a foam brush purge kit I made using these relays.

 

[Greg Pack]

I'm not familiar with their charger, but I really don't care for the idea of continually starting a charge cycle on a full battery. I wonder if you could disassemble the charger and install a diode in the charging circuit.....

 

[I.B. Washincars]

Wow Mark, that would be like using a bazooka to kill a mouse !

cfcw, I guess anything is possible if I had the knowledge. I feel my way is very simple and should work just fine, but I just don't know exactly what to ask for. I can also see that from this forum subject that I will get more suggestions of different ways to do this which may or may not work.

All I want is a relay that would need 12V to power the coil. It would need to be NC so it would break the circuit when powered up (killing power to charger, starting a new 16 hr. cycle). I'm sure there are other specs I would be asked for and I wouldn't really know how to answer. I guess what I want is someone with more knowledge than me tell me that this XYZ relay will handle what you want to do. So now get off your butt and find me something .

Also, I do try to take the battery off the charger after it is charged. I'm sure that the time I forget I will be on the side of the interstate trying to remove my spare tire. The tire winch will be stuck and I won't be able to cut the cable with my grinder/sawzall because the battery is dead.

 

[Red Baron]

Not to get off topic but my Dewalts are the only brand I've found that won't ruin the batteries by constant charging. My Ryobi and B&D will ruin the batteries in short order if I leave them on the charger. One day I'll kick that stupid habit of buying something other than Dewalt when I need a drill but don't want to spend the extra $100.

 

[jcollins]

Pat, This is still not the answer your looking for, but if the charger has a 16 hr. cycle, it has to has some kind of timer built into it. Could it be easier to disable/jumper out the timer in the charger?

 

[I.B. Washincars]

Pat, This is still not the answer your looking for, but if the charger has a 16 hr. cycle, it has to has some kind of timer built into it. Could it be easier to disable/jumper out the timer in the charger?

Actually I never thought of that angle, but after thinking about it I see a problem. If I do leave the truck sitting for several days (like at the airport while in Vegas) and forget and leave the battery on the charger, my truck will be dead. I think it is run on a couple of flashlight batteries anyway. I have already run the battery down three times this winter. Twice while tinkering in the garage (radio on) installing toolboxes etc., and another time when I left the parking lights on for about 4 hrs.

 

[RykoPro]

You would only need one relay, I was just showing you a pic of what they look like. As I staed I use them for controlling circuits in the race car and they work great. Too bad could have made you a deal......

Wow Mark, that would be like using a bazooka to kill a mouse !

cfcw, I guess anything is possible if I had the knowledge. I feel my way is very simple and should work just fine, but I just don't know exactly what to ask for. I can also see that from this forum subject that I will get more suggestions of different ways to do this which may or may not work.

All I want is a relay that would need 12V to power the coil. It would need to be NC so it would break the circuit when powered up (killing power to charger, starting a new 16 hr. cycle). I'm sure there are other specs I would be asked for and I wouldn't really know how to answer. I guess what I want is someone with more knowledge than me tell me that this XYZ relay will handle what you want to do. So now get off your butt and find me something .

Also, I do try to take the battery off the charger after it is charged. I'm sure that the time I forget I will be on the side of the interstate trying to remove my spare tire. The tire winch will be stuck and I won't be able to cut the cable with my grinder/sawzall because the battery is dead.