Wiring a usb port to high voltage battery

Thread Starter

DesertCrawler

Joined Feb 5, 2020
32
Hey everyone. I would like to wire a usb charging port to my 60v scooter battery so I can charge things on long trips. How would I go about doing this?
 

dl324

Joined Mar 30, 2015
10,708
Is the scooter battery 5 12V batteries in series? If so, you could wire a fused cigarette lighter socket to one of them and use a USB charger that plugs into a cigarette lighter socket.

Just be aware that draining one battery more than the rest isn't a good thing to do.

Are these long trips on the scooter? Or in a vehicle carrying the scooter. For the latter, I'd use the vehicle charging system to charge devices.
 

ebeowulf17

Joined Aug 12, 2014
3,274
There are step down voltage converter modules that would make this pretty straightforward. If you're ok with default (slow) charging rates you can just do direct wiring to the power leads. If you want phones and other smart devices to see it as a fast charging port, there's a bit more work involved, but I don't remember those details.

Here's one example:
https://www.digikey.com/product-detail/en/recom-power/R-78HB5-0-0-5-W/945-2444-ND/5765379
Recom Power R-78HB5.0-0.5/W
MFG_R-78HB^W-Series.jpg


Here's a Digikey search which I think is filtered appropriately (still verify specs on any particular item you pick.)
https://www.digikey.com/products/en/power-supplies-external-internal-off-board/dc-dc-converters/132?k=&pkeyword=&sv=0&pv1471=305478&pv1471=116509&pv1471=119717&pv1471=143803&pv1471=197370&pv1471=215305&pv1471=219212&sf=1&FV=1525|249171,ii1|2211,-8|132,573|106024,573|213650,573|275665,573|278186,573|278851,573|95304,573|95694&quantity=&ColumnSort=0&page=1&stock=1&nstock=1&pageSize=25
 

Thread Starter

DesertCrawler

Joined Feb 5, 2020
32
There are step down voltage converter modules that would make this pretty straightforward. If you're ok with default (slow) charging rates you can just do direct wiring to the power leads. If you want phones and other smart devices to see it as a fast charging port, there's a bit more work involved, but I don't remember those details.

Here's one example:
https://www.digikey.com/product-detail/en/recom-power/R-78HB5-0-0-5-W/945-2444-ND/5765379
Recom Power R-78HB5.0-0.5/W
View attachment 204945


Here's a Digikey search which I think is filtered appropriately (still verify specs on any particular item you pick.)
https://www.digikey.com/products/en/power-supplies-external-internal-off-board/dc-dc-converters/132?k=&pkeyword=&sv=0&pv1471=305478&pv1471=116509&pv1471=119717&pv1471=143803&pv1471=197370&pv1471=215305&pv1471=219212&sf=1&FV=1525|249171,ii1|2211,-8|132,573|106024,573|213650,573|275665,573|278186,573|278851,573|95304,573|95694&quantity=&ColumnSort=0&page=1&stock=1&nstock=1&pageSize=25
Ill check that out.I don't care about speedy charging, it is mostly just to keep my bluetooth speaker alive.
 

dl324

Joined Mar 30, 2015
10,708
I cant tell what its internals. It is a big sealed blue box. The long trips are on the scooter. I cant drive
If it doesn't have terminals for the individual batteries, then you need to use the full 60V to power a USB charging port. You'll want to use a switching regulator to avoid excessive power dissipation. Few regulators support a 60V input so you may need to drop the voltage with a power zener diode.
 

ebeowulf17

Joined Aug 12, 2014
3,274
I'm pretty sure that would do it. I did look a little bit at the datasheet for more details, and it looks like they recommend an external capacitor across the inputs if the input is over 50V:
Screenshot_20200421-063317.png
So, you might need to get one of those too. Here's one example:
https://www.digikey.com/product-detail/en/tdk-corporation/FG16X7S2A335KRT06/445-173163-1-ND/5811768

I haven't looked carefully at their datasheets, but I think any of the following would probably be fine:

https://www.digikey.com/products/en/capacitors/ceramic-capacitors/60?k=3.3uF&k=&pkeyword=3.3uF&sv=0&pv14=69629&pv14=157291&pv69=411897&sf=1&FV=-8|60&quantity=&ColumnSort=0&page=1&stock=1&nstock=1&pageSize=25
 

ebeowulf17

Joined Aug 12, 2014
3,274
If it doesn't have terminals for the individual batteries, then you need to use the full 60V to power a USB charging port. You'll want to use a switching regulator to avoid excessive power dissipation. Few regulators support a 60V input so you may need to drop the voltage with a power zener diode.
For what it's worth, I made sure to filter my first Digikey voltage converter list for models that accept over 60V so they should be ok in that respect, although you have to read the datasheets to find details like what I pointed out in my last post - the unit in question requires an extra cap on the input for use over 50V.
 

ebeowulf17

Joined Aug 12, 2014
3,274
Alright,cool I ordered one. When wiring it do I just tape off the brown lead
Why would you do that? You need all three leads, connected as shown in the datasheet. There's a pic of the basic wiring, from the datasheet, in post 8 above - it also shows where the capacitor should be added.
 

Thread Starter

DesertCrawler

Joined Feb 5, 2020
32
Why would you do that? You need all three leads, connected as shown in the datasheet. There's a pic of the basic wiring, from the datasheet, in post 8 above - it also shows where the capacitor should be added.
I thought since it is rated for higher than 60v I didnt need a capacitor. I am Not experienced and pretty much need this spelled out for me. The red and black wire are obvious but I do not know what to do with the brown wire
 
Last edited:

dendad

Joined Feb 20, 2016
3,514
I thought since it is rated for higher than 60v I didnt need a capacitor. I am Not experienced and pretty much need this spelled out for me. The red and black wire are obvious but I do not know what to do with the brown wire
Always add capacitors! Input and output.
And a Tranzorb as well to clip the spikes that will be produced. https://www.digikey.com/products/en?mpart=P6KE68A-E3/54&v=112 may be ok.
And a series fuse or Polyswitch on the regulator input. https://www.digikey.com/product-detail/en/littelfuse-inc/RXEF050/RXEF050HF-ND/5015994

I have used those Recom regulators in quite a few of my products. They work well, and have a 72V max input. That is a bit close for my liking. Make sure you do get the "H" versions as the standard ones have lower input voltage rating.
The caps I use are 100nF ceramic and 10uF Tants on both sides of the regulators.
But first, you need to determine what the max voltage of your battery actually is. Measure it while charging.
It could go to close for comfort to the 72V max of the regulator.

You may get away with using a switch mode 110V or universal mains plug pack. That could be worth a try. Full plug pack power probably would not be reached, but it may be enough.
 

Thread Starter

DesertCrawler

Joined Feb 5, 2020
32
Always add capacitors! Input and output.
And a Tranzorb as well to clip the spikes that will be produced. https://www.digikey.com/products/en?mpart=P6KE68A-E3/54&v=112 may be ok.
And a series fuse or Polyswitch on the regulator input. https://www.digikey.com/product-detail/en/littelfuse-inc/RXEF050/RXEF050HF-ND/5015994

I have used those Recom regulators in quite a few of my products. They work well, and have a 72V max input. That is a bit close for my liking. Make sure you do get the "H" versions as the standard ones have lower input voltage rating.
The caps I use are 100nF ceramic and 10uF Tants on both sides of the regulators.
But first, you need to determine what the max voltage of your battery actually is. Measure it while charging.
It could go to close for comfort to the 72V max of the regulator.

You may get away with using a switch mode 110V or universal mains plug pack. That could be worth a try. Full plug pack power probably would not be reached, but it may be enough.
Are you saying put a tranzorb on the input and out put as well or just the input?
 

Thread Starter

DesertCrawler

Joined Feb 5, 2020
32
I have ordered all the parts you guys suggested. If someone could be so nice to make a diagram for me. I do not know how to read circuitry so the diagram above is useless to me. So I request it be made in a way that a kid could understand, straight forward labeling without the official labeling. I have no clue what to do with the brown wire. Trying to figure this out is about to put me in a seizure. I have severe neurological issues,thus why I ride a scooter instead of drive.
 

ebeowulf17

Joined Aug 12, 2014
3,274

dendad

Joined Feb 20, 2016
3,514
But first, you need to determine what the max voltage of your battery actually is. Measure it while charging.
It could go to close for comfort to the 72V max of the regulator.
As I mentioned above. You do need to find out what the actual battery voltage is. For example, a "12V" car battery runs at about 14V during charge. If the same ratio applies to your 60V battery, you are looking at 70V.
I'd advise to aim for a 100V input regulator.

But here is a diagram..
Reg60_5.jpg
The big problem is the input voltage is way too close to the max, and motors generate spikes.
That will kill your regulator and the result could be 60V applied to your 5V device. Just think hard about that before you connect it up.
 
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