Hi all,
I mentioned some months ago on another thread that I was putting together a lithium cell replacement for an old but good 18V power tool.
Someone one here (Pommie? Correction - Mickster) pointed out that battery adapters were available for many existing power tools, to use the more commonly available battery packs with them. That seemed a far better idea than manufacturing my own special batteries!
Aldi battery packs seem to be the cheapest available at present, far lower prices than other makes - £15 for a 20V 5AH battery, or £30 for the 20/40V one, which has two separate 20V 5AH sections giving 20V 10AH or 40V 5AH.
Unfortunately I could not find any ready made adapters for either the tool, or the Aldi battery.
So, I designed a battery holder to take the Aldi batteries. It's got a plain flat upper face and can be drilled & screwed or glued etc. to an old battery body as required - or used just to power projects, using good interchangeable batteries.
The two .stl files for 3D printing these battery holders are attached as a .zip
It took me some time to find suitable long-blade pins for the connector block; I ended up with RS 245-1731 blades for the power connections and 680-6952 for the thermistor and ID pins.
The main body is made to be a snug fit on the battery so it does not rattle around with tool vibration; it will need support in the side channels for printing and then need the support material cleaning out carefully.
The connector block should be pretty much OK as it is, if printed with the wire side of the openings upwards.
All I had to do was push the end of a connector blade in to each hole from the battery side, just to clear the slight flash where the first layer had flowed out and reduced the openings.
The pins are also snug, but can be seated until they click in place (for the power blades) by pulling them with a small pair of pliers once part way through.
The thermistor pin is just a friction fit; again pull through to completely seat it.
I'd suggest tightly folding the "crimp" part of each terminal around the stripped end of the wire using small pliers, then solder it as well to ensure minimum connection resistance. Fold the strain relief part of the terminal after it's cooled fully.
Make sure the main part of the holder fits the battery and latches properly first, then fit the connector block after assembling that; I'd suggest positioning the main body on the battery about half a mm beyond the latch point, then the connector block hard against the battery, so the overall assembly will have a fractional end float when fixed - but don't overdo the float, especially if you wish to use the thermistor or ID contacts, as those pins are only just adequate length.
Once you are sure of the positioning, put a few drops of superglue around the back of the connector block, with the unit not fitted to the battery!
I will be adding some heatshrink sleeving to cover the exposed metal on the wire side of the block, before it's bolted to the old battery top case.
Connections, looking at the wire colours & positions I've used: for 20V, connect both reds for + and both blacks for -
That will work with both 20V and 20/40V batteries.
For 40V, connect the inner red to the inner black positions, to put the two 20V sections in series & use the outer red and black.
A 20V battery will not connect (or be harmed) with that wiring, as the connector positions for one half are not used.
Note that these batteries do not have over-discharge protection, so that must be added externally.
Any questions or mods needed, let me know!
I mentioned some months ago on another thread that I was putting together a lithium cell replacement for an old but good 18V power tool.
Someone one here (
Aldi battery packs seem to be the cheapest available at present, far lower prices than other makes - £15 for a 20V 5AH battery, or £30 for the 20/40V one, which has two separate 20V 5AH sections giving 20V 10AH or 40V 5AH.
Unfortunately I could not find any ready made adapters for either the tool, or the Aldi battery.
So, I designed a battery holder to take the Aldi batteries. It's got a plain flat upper face and can be drilled & screwed or glued etc. to an old battery body as required - or used just to power projects, using good interchangeable batteries.
The two .stl files for 3D printing these battery holders are attached as a .zip
It took me some time to find suitable long-blade pins for the connector block; I ended up with RS 245-1731 blades for the power connections and 680-6952 for the thermistor and ID pins.
The main body is made to be a snug fit on the battery so it does not rattle around with tool vibration; it will need support in the side channels for printing and then need the support material cleaning out carefully.
The connector block should be pretty much OK as it is, if printed with the wire side of the openings upwards.
All I had to do was push the end of a connector blade in to each hole from the battery side, just to clear the slight flash where the first layer had flowed out and reduced the openings.
The pins are also snug, but can be seated until they click in place (for the power blades) by pulling them with a small pair of pliers once part way through.
The thermistor pin is just a friction fit; again pull through to completely seat it.
I'd suggest tightly folding the "crimp" part of each terminal around the stripped end of the wire using small pliers, then solder it as well to ensure minimum connection resistance. Fold the strain relief part of the terminal after it's cooled fully.
Make sure the main part of the holder fits the battery and latches properly first, then fit the connector block after assembling that; I'd suggest positioning the main body on the battery about half a mm beyond the latch point, then the connector block hard against the battery, so the overall assembly will have a fractional end float when fixed - but don't overdo the float, especially if you wish to use the thermistor or ID contacts, as those pins are only just adequate length.
Once you are sure of the positioning, put a few drops of superglue around the back of the connector block, with the unit not fitted to the battery!
I will be adding some heatshrink sleeving to cover the exposed metal on the wire side of the block, before it's bolted to the old battery top case.
Connections, looking at the wire colours & positions I've used: for 20V, connect both reds for + and both blacks for -
That will work with both 20V and 20/40V batteries.
For 40V, connect the inner red to the inner black positions, to put the two 20V sections in series & use the outer red and black.
A 20V battery will not connect (or be harmed) with that wiring, as the connector positions for one half are not used.
Note that these batteries do not have over-discharge protection, so that must be added externally.
Any questions or mods needed, let me know!
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