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Post by holmz on Aug 27, 2020 4:26:29 GMT -5
is anyone's interested in an AC wall plug to 18V battery adapter?
a young fellow has a 3D printer and for LED lights and drills batteries make sense, but for a vacuum or saw, in my mind a 220v plug makes sense.
or when the batteries are flat, then a ute with an inverter can still power the tools for remote work.
If anyone is interested, then I can sync you up, and he can figure out price and whether it makes sense to do a run more than mine.
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Post by alvychippy on Aug 27, 2020 15:41:12 GMT -5
is anyone's interested in an AC wall plug to 18V battery adapter? a young fellow has a 3D printer and for LED lights and drills batteries make sense, but for a vacuum or saw, in my mind a 220v plug makes sense. or when the batteries are flat, then a ute with an inverter can still power the tools for remote work. If anyone is interested, then I can sync you up, and he can figure out price and whether it makes sense to do a run more than mine. I'm sorry, but I'm not sure, I'm following you... sounds as someone has made 120?-240v? adapter to be as 18v CAS (Mafell) battery like? |
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Post by holmz on Aug 28, 2020 0:44:42 GMT -5
Yeah 230v from the wall goes into a transformer/rectifier/capacitor... then an 18v cod comes out with the metabo battery shape on the end of that cord.
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Post by alvychippy on Aug 28, 2020 13:02:16 GMT -5
Yeah 230v from the wall goes into a transformer/rectifier/capacitor... then an 18v cod comes out with the metabo battery shape on the end of that cord. Clever idea! Still, as for Mafell... Not sure going to be many takers on it, but have I not tried something similar to get my old DeWalt 28v set up to run via (US 120v) charger... It turned out amperage output was half of battery discharge rate.... Hope those figures have been taken in to account  |
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Post by holmz on Aug 28, 2020 17:09:27 GMT -5
Yeah 230v from the wall goes into a transformer/rectifier/capacitor... then an 18v cod comes out with the metabo battery shape on the end of that cord. Clever idea! Still, as for Mafell... Not sure going to be many takers on it, but have I not tried something similar to get my old DeWalt 28v set up to run via (US 120v) charger... It turned out amperage output was half of battery discharge rate.... Hope those figures have been taken in to account That is also part of the reason for the capacitors. So one needs the steady state current the tool uses, and also enough of a whack at the beginning to supply the current that a battery provides should the tool draw more current on startup. So I t would (IMHO) be more sensible if one was looking at a vacuum or saw, and chin scratching about cordless or not... (and the expensive battery cost), if running a cordless hog, off the wall with a cord was an option. |
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Post by kraftt on Aug 28, 2020 21:46:23 GMT -5
Isn’t there a microprocessor in some batteries that talks to the motor on newer drills (?) I don’t know just thought some did.
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Post by holmz on Aug 28, 2020 23:08:41 GMT -5
Maybe?
There are 4 contacts... so I will have to see if that is for balancing the charging, or for the tool to talk with the battery.
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Post by hecon5 on Sept 16, 2020 12:26:55 GMT -5
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kozn
New Member
Posts: 35
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Post by kozn on Sept 17, 2020 11:51:17 GMT -5
Maybe? There are 4 contacts... so I will have to see if that is for balancing the charging, or for the tool to talk with the battery. Balancing is done inside the battery with electronics. There's 5 connection points:2 for +/- 2 for temp control 1 for diode I think but I have no clue what that's for. I took apart a hilti battery adapter, you can hook it up to the tool and the battery, so you can wear the battery on your belt. The diode connections from the battery goes to a capacitor which is then connected to the ground if my memory serves me well. I think its for providing the initial current rush needed to start the motor? Not sure about that. The temp sensor is not connected on the adaptor, only 3 cables leave the battery side. |
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Post by huntsgemein on Sept 17, 2020 12:04:59 GMT -5
Making the interface is the easy & inexpensive part. Just cannibalise an old dead battery, even from an older generation of non-Li-HD, or even an old NI Cad or Ni-MH one would do. You only need the interface form factor & relevant steel power paddles.
The hard part is sourcing the correct power supply. If, say your mangle grinder or saw draws, as Metabo states "up to 1600w", which is what the latest Li-HDs can deliver, then you'll need a supply to deliver that fuss-free in DC as well. That's an 240v/18V supply that will deliver an unstressed peak of 90 Amperes! That a huge ask!
For those power factors, I suspect you'd need a dummy battery with a lead running to the dedicated power supply/rectifier/tranny using some seriously heavy duty cabling, say 2-core 2.5mm squared flex at a minimum to reduce voltage drop. You'd never be able to miniaturise such a power supply into a battery jacket. You'd be much better off with a nice heavy duty heat-finned remote supply just like Mirka's CEROS uses.
Not saying that it can't be done, but merely pointing out some salient limitations.
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Post by holmz on Sept 17, 2020 15:28:17 GMT -5
Maybe? There are 4 contacts... so I will have to see if that is for balancing the charging, or for the tool to talk with the battery. Balancing is done inside the battery with electronics. There's 5 connection points:2 for +/- 2 for temp control 1 for diode I think but I have no clue what that's for. I took apart a hilti battery adapter, you can hook it up to the tool and the battery, so you can wear the battery on your belt. The diode connections from the battery goes to a capacitor which is then connected to the ground if my memory serves me well. I think its for providing the initial current rush needed to start the motor? Not sure about that. The temp sensor is not connected on the adaptor, only 3 cables leave the battery side. Likely that is exactly what the capacitor is for. So putting the capacitor at the tool, then buffers the current needed to be carried in the cable leading to the tool. If it is a 5AHr battery and it lasts 1/2 hour, then the average current would be 10A. And the inrush would dump out of the capacitor, so I guess I need to know current versus time profile while the tool spins up. |
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Post by alvychippy on Sept 18, 2020 8:49:04 GMT -5
Bleedin genious! The whole 50-60hrz and DC, then conversion to battery power, then consumption.... Something that is above my head. I'll keep checking on this thread for all of your expertise 😉 (for future reference) |
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Post by huntsgemein on Sept 18, 2020 9:04:22 GMT -5
OK, they're recommending 6mm squared conductor cross sectional era. For 600w. So, for higher peaks???
That's seriously heavy duty cable! For example, standard (240v; North American 110V are probably thicker) mains domestic household extension cords typically use 1.5 mm squared conductors. Heavy duty leads & industrial extension cables use 2.5mm squared.
It's just like automotive jumper cables, where very low voltages (12v DC) are transferred at extreme currents. Skinny ones get very hot, very quickly. Only the thickest ones are capable of safely carrying high cold cranking currents at such low voltages.
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Post by holmz on Sept 18, 2020 16:54:41 GMT -5
OK, they're recommending 6mm squared conductor cross sectional era. For 600w. So, for higher peaks??? That's seriously heavy duty cable! For example, standard (240v; North American 110V are probably thicker) mains domestic household extension cords typically use 1.5 mm squared conductors. Heavy duty leads & industrial extension cables use 2.5mm squared. It's just like automotive jumper cables, where very low voltages (12v DC) are transferred at extreme currents. Skinny ones get very hot, very quickly. Only the thickest ones are capable of safely carrying high cold cranking currents at such low voltages. What higher peaks? One would ideally remoVe the battery by enough room to measure the current draw... 600w/20v is 30A... so a 2AHr battery would last 4 minutes. So the peak is probably just a few seconds. Then use a small cable to the adapter and a few capacitors in there, to buffer for a large peak current draw... that can only be sustained for a few seconds. |
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Post by hecon5 on Sept 18, 2020 20:55:45 GMT -5
6mmsq (you Europeans!) Seems about right for a 30A intermittent loading with 15-20A nominal. Probably a tad high, but with lower voltage DC, your losses really stack up with a smaller cable. Remember, your voltage drop on the cable is I^2×R, so tiny increases on current drop the output voltage on the other end of the cable. This means you need a bigger cable, or you'll start seeing the tool not start. Alternatively, you raise the supply voltage, but this has the downside of causing potential overvoltage during low draw times.
Compromise is a 6mmsq (10AWG) cable that has better efficiency and weighs a tad more.
The capacitor is probably helps with inrush starting, but honestly is probably more to protect the PSU than the motor. Motor starting current is a big whack of energy, so you'd need a big capacitor to ride that out...which weighs a lot. Batteries are really great at that as their internal resistance allows them to get close to the peak draw, and they're close the the load, so you don't notice the motor didn't turn on as quickly.
With a converterbob you'll have 5' or more cable between the motor and the supply, and when you press the trigger, it's all dropped through the cable, so you need a way to make sure the PSU doesn't think you're dumb and shorted the outputs. Enter a capacitor. You can get a bigger supply, that doesn't care, but that costs more, and weighs more, so your portable battery tool isn't portable as much.
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