I have a 24v (20Ah SLA) cordless mower, and the batteries only seem to last 2 seasons, and they require a 12-hour charge. I also have two EGO 56v 5Ah Li-ion batteries for another power tool. The mower with its current batteries runs 45-60 minutes, and the wiring to the battery is no more than 16awg, so I assume the motor takes 20-30A under load. Would it work well to use a 30A DC-DC buck converter I found on Amazon to convert 56v to 24v? Theoretically, the amp-hours would double to around 10Ah at 24v, which would be fine since I have two batteries and they quick charge in 45 minutes. I'm just wondering if the buck converter would handle that kind of a load for a sustained period of time, and would it produce an output a high-power motor like this could use properly?
Sure, I could buy more batteries, buy a mower that goes with the battery, or build my own Li-ion battery pack, but these would be expensive (and in the case of building the battery pack, difficult for me to build a proper charger), and seeing as I already own a battery pack and charger which also works with other tools, a $25 investment would be much better than the other options. Plus, it would make the mower lighter and I should have no slow down, even as the Li-ion pack gets at the very end because the buck converter should minimize any voltage drop until the pack shuts itself down.
Similarly, I have a 14.4v cordless vacuum cleaner, about 10 years old, I purchased at a garage sale, with 12 NiCd D-size batteries which don't hold a charge. Again, I could put $70 into larger NiMH batteries but I wouldn't be able to use the pack for anything else. Could a similar DC-DC buck converter (one with an adjustable voltage output, rated at 20A) with an 18v Ryobi cordless tool battery run the vacuum? This one has a computer-controlled variable-speed motor in it so I would not want to over-voltage it at 18v for fear of frying something. Or would I be better to use some diodes to drop the voltage a couple of volts? Again, I do not have a current rating for this, and not even an Ah rating for the batteries, but I would assume since they're 10-year-old D cell NiCD, the wouldn't exceed 4Ah.
Since DC-DC converters claim to be 90% or more efficient, it seems to me that these conversions would work, but I don't want to purchase them and then fry them, or my tools. I have already used the 18v Ryobi batteries to overvolt my 4-year-old son's power wheels extensively, and have found they can really take a beating. But those are simple brushed motors with somewhat lower power ratings than I'm thinking of here. So am I crazy for wanting to try this, or is it feasible?
Sure, I could buy more batteries, buy a mower that goes with the battery, or build my own Li-ion battery pack, but these would be expensive (and in the case of building the battery pack, difficult for me to build a proper charger), and seeing as I already own a battery pack and charger which also works with other tools, a $25 investment would be much better than the other options. Plus, it would make the mower lighter and I should have no slow down, even as the Li-ion pack gets at the very end because the buck converter should minimize any voltage drop until the pack shuts itself down.
Similarly, I have a 14.4v cordless vacuum cleaner, about 10 years old, I purchased at a garage sale, with 12 NiCd D-size batteries which don't hold a charge. Again, I could put $70 into larger NiMH batteries but I wouldn't be able to use the pack for anything else. Could a similar DC-DC buck converter (one with an adjustable voltage output, rated at 20A) with an 18v Ryobi cordless tool battery run the vacuum? This one has a computer-controlled variable-speed motor in it so I would not want to over-voltage it at 18v for fear of frying something. Or would I be better to use some diodes to drop the voltage a couple of volts? Again, I do not have a current rating for this, and not even an Ah rating for the batteries, but I would assume since they're 10-year-old D cell NiCD, the wouldn't exceed 4Ah.
Since DC-DC converters claim to be 90% or more efficient, it seems to me that these conversions would work, but I don't want to purchase them and then fry them, or my tools. I have already used the 18v Ryobi batteries to overvolt my 4-year-old son's power wheels extensively, and have found they can really take a beating. But those are simple brushed motors with somewhat lower power ratings than I'm thinking of here. So am I crazy for wanting to try this, or is it feasible?