[Dprglist] For your next robot - handy dc-dc converters - 3S LiPo to RPi

[Carl Ott]

Yes - those protection circuits could likely work for DPRG use cases.

You can find ready made and protected packs from Tenergy. They're nice, but
they're at a premium.

I understand that most hobby packs don't use them because, e.g. you need
50+ amps peak for cases like drones and planes. I understood those devices
run so close to the max peak capacity of the pack, that there's no point in
having a protection circuit...



On Wed, Feb 6, 2019 at 8:43 AM <deltagraph at aol.com> wrote:

> Looking at gizmos to disconnect pack from load
>
> Something like this (only prob did not see price and 1000 units here... )
>
> http://www.all-battery.com/PCBfor11.1VLIPO_Li-Ion_Li-MnNiBatteryPack-32071.aspx
>
> Here $10 -- would assume not getting put in most hobby li-po batteries.
>
>
> http://www.all-battery.com/PCB11-1V32048.aspx?utm_source=GoogleShopping&utm_medium=GDF&gdffi=fb520bc42d4e46cbab702234d35f7d38&gdfms=035D4896756F4B048ACF314139800B9C&gclid=CjwKCAiAqOriBRAfEiwAEb9oXb6wTFeIxqMP7oYxr6O--SDNpFQJl-caWL56UZPRG4jMzg4eviUjCBoCW0YQAvD_BwE
>
> Of course more interest would be simply monitor and disconnect due to
> discarge, not  overvoltage protect during charge since that is managed by
> charger...
>
> Ron
>
>
> -----Original Message-----
> From: Carl Ott <carl.ott.jr at gmail.com>
> To: Ron Grant <deltagraph at aol.com>
> Cc: DPRG D-List <dprglist at dprg.org>
> Sent: Wed, Feb 6, 2019 7:26 am
> Subject: Re: [Dprglist] For your next robot - handy dc-dc converters - 3S
> LiPo to RPi
>
> These packs show ratings of 8 ~ 20 volts, or 8 ~ 50 volts so, even when
> starting at a full 4.2v charge, 2S probably wouldn't work, at least not for
> long...
>
> In terms of voltage monitors, I've been using one of these for a while -
> they're pretty nice
>
> https://us.banggood.com/Wholesale-Warehouse-0_28-Inch-2_5V-30V-Mini-Digital-Voltmeter-wp-Usa-974258.html?akmClientCountry=America&rmmds=myorder
>
> The 2016 club robot came with one of these
>
> https://www.amazon.com/Battery-Monitor-Voltage-Checker-Indicator/dp/B013U1CP08/ref=asc_df_B013U1CP08/?tag=hyprod-20&linkCode=df0&hvadid=167139094796&hvpos=1o1&hvnetw=g&hvrand=8040392104640112483&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9026796&hvtargid=pla-304998738630&psc=1
>
> looks like it can work nicely if your battery has a balancing port. it
> monitors the voltage on each cell in the pack. you can set the alarm
> threshold voltage to your preference.  But it does beep every time you
> power it up, and seems to cycle the display through each of the cell
> voltages - so it looks like a good alarm but is not as simple as a voltage
> gauge on the entire pack.
>
> - Carl
>
>
> On Wed, Feb 6, 2019 at 7:02 AM <deltagraph at aol.com> wrote:
>
> Hey Carl/All,
>
> Looks nice, but would be nice to have auto disconnect of converter on low
> voltage -- of course that can be addressed separately, up line at the input
> of the dc-dc converter.
>
> Voltage monitoring by MCU (with suitable voltage divider)  or display with
> one of those $1 LED display modules is handy, just thinking more about
> accidental leaving converter/load connected to battery.
>
> Maybe someone can shed some light on how many li-po packs have auto
> low-voltage shutoff these days.
>
> At first I was thinking about this converter being used with a 3 cell
> pack, wonder if it would work with a 2 cell pack?
> If so, at least the pi would die before the battery. You still would need
> to disconnect battery, but at least brain death would precede battery death.
>
> Ron
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Carl Ott via DPRGlist <dprglist at lists.dprg.org>
> To: DPRG D-List <dprglist at dprg.org>
> Sent: Tue, Feb 5, 2019 8:07 pm
> Subject: [Dprglist] For your next robot - handy dc-dc converters - 3S LiPo
> to RPi
>
> FWIW
>
> Found these - should come in handy powering Raspberry Pi from a 3S LiPo
> pack.  Haven't powered them up yet - but the specs look good
>
> this one is a little smaller, with just Micro-USB out
>
>
> https://smile.amazon.com/gp/product/B00O6RJLQC/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1
>
>
> this one has both a micro-USB and a USB female:
>
>
> https://smile.amazon.com/gp/product/B016XI9CZQ/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1
>
> it's also branded DROK
> DROK sells a ton of handy modules like this - dc-dc converters of all
> sizes, I/O, control & display options. I've used them a bunch and haven't
> been disappointed yet.
>
> - Carl
>
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