[TriEmbed] Battery Power for Projects (informal survey)

[Pete Soper]

On 11/18/19 6:14 PM, Tadd Torborg via TriEmbed wrote:
> I'm using a 2.5amp-hour 12v Gel Cel - PS-1220  Costs $10 in quantity 10.
> https://www.amazon.com/gp/product/B077Y9FT5K
> I'm using it as a backup supply to keep a Raspberry PI alive if the 
> main 14.2v supply goes away.  I have the two main and battery diode 
> ORed through a bridge rectifier to a DROK switcher supply which 
> outputs 5.2v on USB to run the Raspberry PI 4B. Another leg of the 
> bridge rectifier provides 13.8v only from main supply, which I run 
> through a 10watt 50ohm resistor back to the +DC lead on the gel cel.  
> This gives me a really cheap trickle charger.

If the battery is warmer than room temp a schottky or regular diode in 
series will avoid exceeding the recommended maximum standby charge 
voltage. The 13.8 limit is for 25C. Reference here 
<https://www.powerstream.com/SLA.htm>.

Pete

>
> Objectives:
> 1. feed stable power to the Raspberry PI with 5.2v even if main supply 
> glitches or goes off
> 2. run off a main power supply supply which can also feed power to 
> 12-15v peripherals
> 3. have backup capability for at least several hours of running the 
> Raspberry PI 4 and it's daughter cards.
> 4. be cheap
> 5. be easy to get now and into the future
>
> Details on the trivial circuit are here:
> http://tarpn.net/t/builder/builders_robust_power_for_raspberry_pi.html
>
>   Tadd / KA2DEW
>
> On November 18, 2019 at 12:41 PM, Robert Henry via TriEmbed 
> <triembed at triembed.org> wrote:
>
>> (--sending from correct e-mail this time--)
>> Hey all,
>>
>> *Question for group*: I'm curious what battery packages folks in this 
>> group use for their projects? If there is quite a variety - perhaps 
>> offer your favorite/most flexible.
>>
>> *Background:* I'm currently selling ~12v LiFePO4 battery packs (4s1p) 
>> that I had as surplus from a consumer product.  Product launched with 
>> limited success, but the battery packs are selling well enough that 
>> I'm considering sourcing other chemistries / configurations.  Would 
>> like to keep with the embedded project market to start (that is - 
>> capacities less than 100 Watt-Hours).
>>
>> Any insight would be greatly appreciated.  Thank you!
>> Rob Henry
>>
>> Rob Henry
>> LT Cage Productions, LLC
>> ph: +1.919.245.7684
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