I want to be able to attach a converter to step down my 72 volt LI-ION battery to around 18-21 volts DC so if I get a flat on the road, I can just plug the air pump into the ebike battery . I do not see any dc-dc buck step down converters that can handle high voltages of 72-84 volts and step it down to 18-20 volts . Any suggestions > ?
How to " step down " 72 volt battery to 18 volt for accessory tire pump
- Thread starter rumme
- Start date
eee291
100 kW
https://www.aliexpress.com/item/250W-20A-Car-Truck-Autos-E-bike-Lights-108V-96V-80V-72V-64V-60V-48V-36V/32601986884.html
You could step down to 12v with this thing, and then boost to 18v :lol:
Or you could make your own converter it's not too difficult.
You could step down to 12v with this thing, and then boost to 18v :lol:
Or you could make your own converter it's not too difficult.
Alan B
100 GW
It might be cheaper and easier to get a high voltage tire pump.
If you get a DC-DC converter it must be able to handle the pump's motor, which can draw a lot of current, so a cheap DC-DC converter may just fail when you need it most. It probably won't be very small either.
If you get a DC-DC converter it must be able to handle the pump's motor, which can draw a lot of current, so a cheap DC-DC converter may just fail when you need it most. It probably won't be very small either.
skeetab5780
1 MW
Get a small 5s1p 18650 pack to power it. It will be tiny and pack enough power. If you have access to old cordless tool packs a small 18-20v slimpack would work perfect. Keep the battery display and housing to make it even easier just add a xt-60 lead to plug into
Ohbse
10 kW
I use a Lenovo laptop power supply. It's tiny, solid state, super reliable and I had a bunch lying around. It delivers ~19v and they come in a variety of sizes/current capacities. These types of power supplies will happily run off a wide variety of DC voltages. I run all my lights from one of the docking station sized units.
All you need to do is chop the AC connector from the power cable and re-terminate to suit your battery, polarity doesn't matter.
All you need to do is chop the AC connector from the power cable and re-terminate to suit your battery, polarity doesn't matter.
Ty for replies..
would this work ? It is rated 80 volt input max...I wasn't sure if a fully charged battery at 82-84 volts would harm this converter or not.
https://www.ebay.com/itm/DC-DC-Buck-Step-Down-Converter-6V-80V-24V-36V-48V-72V-to-5V-9V-12V-Power-Supply/302507103754?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649
it says it is rated for 7 watt output.....
Here is the portable air pump I would be using this on with my 72 volt LI=ION ebike battery pack . Would this air pump draw to much watts to use with this dc-dc step down converter above ?
https://www.ebay.com/itm/PORTABLE-AIR-COMPRESSOR-Ryobi-18-Volt-Cordless-Car-Bike-Tire-Power-Inflator-Pump/112424599647?epid=28017807150&hash=item1a2d07405f:g
7UAAOSwpuBZ1h8P
would this work ? It is rated 80 volt input max...I wasn't sure if a fully charged battery at 82-84 volts would harm this converter or not.
https://www.ebay.com/itm/DC-DC-Buck-Step-Down-Converter-6V-80V-24V-36V-48V-72V-to-5V-9V-12V-Power-Supply/302507103754?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649
it says it is rated for 7 watt output.....
Here is the portable air pump I would be using this on with my 72 volt LI=ION ebike battery pack . Would this air pump draw to much watts to use with this dc-dc step down converter above ?
https://www.ebay.com/itm/PORTABLE-AIR-COMPRESSOR-Ryobi-18-Volt-Cordless-Car-Bike-Tire-Power-Inflator-Pump/112424599647?epid=28017807150&hash=item1a2d07405f:g
7UAAOSwpuBZ1h8POhbse said:
Could you give me a link to this ? It would need to be able to accept 60-84 volts DC in and output somewhere between D.C. 12-24 volts out.
this says input must be AC voltage...not DC.
https://www.ebay.com/itm/20V-3-25A-65W-AC-Adapter-Charger-for-Lenovo-Laptop-Power-Supply-Cord-5-5-2-5mm/152201459855?epid=1281205694&hash=item236fe9f88f:g:NToAAOSwCMFaOMWs
kdog
10 kW
A lot of ac-dc SMPS with work on DC, they usually just need over about 60v to work. The AC is rectified straight away anyway. Your issue is going to be the current that the pump wants, I think they suck a few too many for your average SMPS. If it doesn't say you'll have to measure it.
miro13car
100 kW
you do it by stepping down voltage with SMPS step-down converter.
just Google it , there are schematics out there.
just Google it , there are schematics out there.
kdog
10 kW
Just checked your links. Im tipping that pump is going to suck ~20 amps peak so go the small battery option. SMPS usually turn off +/or die much over their rated current... And, no those combos will not work for this reason.
At 72v, most switching power supplies made for 120vac will work fine. Something like a laptop brick.
You might check out some of the other ideas here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=92171&hilit=pump
I got a "48v" tire pump that works fine on 60v. 80v might be pushing it a little, but I bet it works OK. It will just pump a little faster and get hotter. A 48v pump may be less expensive than a dc-dc converter for a 12v pump and will take up less room.
You might check out some of the other ideas here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=92171&hilit=pump
I got a "48v" tire pump that works fine on 60v. 80v might be pushing it a little, but I bet it works OK. It will just pump a little faster and get hotter. A 48v pump may be less expensive than a dc-dc converter for a 12v pump and will take up less room.
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