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Question:How to use Alkaline Batteries with the Riffle?

pdhixenbaugh asked on March 09, 2017 18:47
43 | 1 answers | shortlink


The question in general

How do you use readily available batteries with the Riffle?

Background story

The current version of the Riffle (v1.18) usually ships with a 3.7 V rechargeable lithium battery with a JST connector, like this one. But since lithium batteries may not be available everywhere, and are difficult to send through Air Mail, the Riffle was also designed to be compatible with any type of battery chemistry, as long as it uses a JST connector and is at the right voltage.

Specific questions

What do you need to know to use other batteries with the Riffle?

  • What are the voltage requirements: are there upper and lower limits?
  • How many AA/AAA equivalent batteries do you need to use, and can those be rechargeable?
  • Can commercial lithium rechargeable batteries like these be charged from the Riffle's JST circuitry?
  • How does JST work with conventional batteries? What are the easy methods and expert methods to attach JST connectors to batteries?


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1 Answers

What are the voltage requirements: are there upper and lower limits?

The silkscreen on the Riffle says 3.5v to 6v for the "general" power connection. That's different from typical 328p Arduinos (e.g., Uno, Nano) which can be powered by 7v to 12v. Maybe @donblair can confirm the range (oops, he won't see this because this is not a comment).

How many AA/AAA equivalent batteries do you need to use, and can those be rechargeable?

So assuming 3.5v to 6v, the Riffle can use four AA or AAA batteries. Four alkalines would supply 6v, and four rechargeable NiMH (e.g., eneloop) would supply 4.8v (when the batteries are fresh).

Can commercial lithium rechargeable batteries like these be charged from the Riffle's JST circuitry?

Don't know. Those require a special size battery case -- they are not AA or AA. You might want a dedicated charger.

How does JST work with conventional batteries? What are the easy methods and expert methods to attach JST connectors to batteries?

You can buy battery cases for AA and AAA batteries with JST connectors. For the Riffle you want JST ph 2-pin. It might not be easy to find a four battery case with a JST ph 2-pin connector. But cases are just a couple of bucks and JST connectors are cheap too.

4 AA case at Adafruit, $3.00: https://www.adafruit.com/products/830

IMG_20170309_180008271.jpg
Above: Case for three AA batteries with JST ph 2-pin connector from Adafruit (left), case for four AA batteries from eBay (no connector) and a wired JST ph 2-pin connector which can be soldered on (right).

I bought some JST ph 2-pin connectors but they don't quite fit in the ones on the Riffle. It was easy to shave the plastic so it fit. You can buy a few here.

Chris


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