[Makerspace] 18650's, series or parallel?

Felix Sheldon darkpaw at internode.on.net
Thu Mar 21 22:41:43 AEDT 2019


Awesome, thanks for the advice Greg.

I was trying to avoid radio noise from switching style power components,
but I suppose I should try them and see if it really is a problem.

On Thu, 21 Mar 2019 at 22:04, Greg Hall <greghall at brushbox.info> wrote:

> A couple of thoughts below.
>
> Greg
>
> PS: I'll take some photos of the 7 segment flipper displays.
>
> Greg Hall
> 0265504481
> 0428850144
> -
>
> On 21/3/19 6:58 pm, Felix Sheldon wrote:
> > Thanks Greg,
> >
> > Aha, yep, that makes sense!
> >
> > Yes, I might well be able to use 7-segment displays!
> >
> > It turned out that 4.2 ish Volts was about right for the LEDs and the
> > computer with a 3.3V regulator.
> >
> > But I want it to run all day, so I think that's going to take 4 18650s
> > in parallel.
> >
> > Do you think it would work to have 1 battery protection module and one
> > 18650 charger module hooked up to each of them, then run 5V into the
> > charger modules for charging?
> >
> >
> https://www.ebay.com.au/itm/5V-Mini-USB-1A-TP4056-Lithium-Battery-Charging-Board-Charger-Module-/351094408792
>
> I suspect that the IN- and BAT- will have a DC path, so all your 5V USB
> would need galvanic isolation. A difficult way to do it.
>
> Consider using your 18650's in series, and a switchmode converter to
> bring it down to your operating voltage. They are only a couple of $$ on
> eBay
>
> Alternatively, it's not at all uncommon to open up a Li-Ion laptop or
> drill battery to find cells welded in parallel (with fuses ;)
>
> > https://www.ebay.com.au/itm/153327870301
>
> The LED's really should be run from a constant current supply, something
> like
>
>
> https://www.ebay.com.au/itm/3W-Watt-Output-LED-Driver-Power-Supply-Module-3-1W-Model/391246816222
>
> https://www.onsemi.com/pub/Collateral/TND328-D.PDF
>
> Not a big effect, but a switcher has to be better than a resistor, esp
> at 3 watts!
>
> Greg
>
>
>
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