Substituting 3 'C Type' Batteries for a single '9V' Battery??

[lettuce]

So I bought a pet food dispenser for our 12 week old puppy but the little WITCH has bitten through the USB cable that powers the unit, luckily she is unharmed but now I'm paranoid she'll do it again!.

The unit can also be run from batteries (in the instructions it says if there is a power outage then the batteries kick in), it needs 3 x Type C Batteries to operate however (seriously what year is it?, 1990 still!), I believe each of these is 1.5 volts so a total power of 4.5volts (3 x 1.5)? or though on the unit itself it says to use only a 5v power supply but I'm guessing 4.5 volts that the batteries supply is also just enough!!?

As 3 Type C batteries will work out fairly expensive (depending on how long they last) I was thinking is it possible to use just a single 9v battery with a resistor installed on the Live side to reduce the 9v down to 4.5-5v and solder a 9v battery socket/plug to the neg and pos in the battery bay??.

In my head this would work but not sure in practice!??

 

[RandomGrinch]

If desperate, an AA battery is the same length as a C, and should be held in nicely enough from the springs

A decent AA battery can have as much life as a poor C anyway.

...and just for trivia, many 9V PP3's are made up of 6 X 1.5V AAAA batteries!

 

[lettuce]

If desperate, an AA battery is the same length as a C, and should be held in nicely enough from the springs

A decent AA battery can have as much life as a poor C anyway.

...and just for trivia, many 9V PP3's are made up of 6 X 1.5V AAAA batteries!

Really??, so what on earth is the point of C type batteries if AA's can supply the same amount of voltage?

 

[Mottie]

They can supply the same voltage for longer.

 

[RandomGrinch]

Really??, so what on earth is the point of C type batteries if AA's can supply the same amount of voltage?

I'm sorry, I was being a bit flippant - a very cheap zinc carbon C may struggle to match a very expensive Duracell Ultra Power AA.
Comparing like for like, a C will last a good deal longer than an AA.

 

[lettuce]

Ok, so my originally question still stands as i want a more premiant solution.

I'm not in bind where I don't have any Type C batteries (i can pop to tesco and get some) but using a 9v would work out cheaper and possible last much longer if used with a resistor no???

 

[lettuce]

Ive seen these Buck step down converters on Amazon, this will do just what i need i think right??

Buck step down converter

 

[JohnW2]

So I bought a pet food dispenser for our 12 week old puppy but the little WITCH has bitten through the USB cable that powers the unit, luckily she is unharmed but now I'm paranoid she'll do it again!.

It may be tedious (and/or expensive) to keep replacing the cable (assuming you can) but, for what it's worth, the USB cable will presumably only be carrying 5V, so she shouldn't come to harm no matter how many of the cables she bites through

Kind Regards, John7

 

[JohnW2]

Ok, so my originally question still stands as i want a more premiant solution. I'm not in bind where I don't have any Type C batteries (i can pop to tesco and get some) but using a 9v would work out cheaper and possible last much longer if used with a resistor no???

In concept, yes, but your problem would be in determining what value of resistor to use, because that would depend upon what current was being drawn.

Kind Regards, John

 

[flameport]

but using a 9v would work out cheaper and possible last much longer if used with a resistor no???

No, it won't.

One 9V battery has a much lower capacity than 3x C cells.
Using a resistor will throw away a good proportion of that already lower capacity as heat.

AA to C adaptors exist, https://www.amazon.co.uk/Zerone-Battery-Conversion-Switcher-Converter-default/dp/B07FKLVQWC/

 

[RandomGrinch]

Ive seen these Buck step down converters on Amazon, this will do just what i need i think right??

Buck step down converter

Ignoring the losses from a resistor/Stepdown converter (and again comparing like for like batteries with similar energy densities), 3 x C batteries have a volume of approx 80'000mm³ and a single PP3 has a volume of 21'000mm³ (even less if it is a battery derived from AAAA's!(14'000mm³?)).
A PP3 will not last as long, or be cheaper.

Either as above, stick with USB cable, or a far easier modification may be to use a USB power bank.

 

[lettuce]

It may be tedious (and/or expensive) to keep replacing the cable (assuming you can) but, for what it's worth, the USB cable will presumably only be carrying 5V, so she shouldn't come to harm no matter how many of the cables she bites through

Kind Regards, John7

Its not so much replacing the cables John, that I'm fine with. Its the possibility of her ingesting parts of the cable and fine copper threads hence why using the battery option so removing cables altogether

 

[Taylortwocities]

Just get a few rechargeable C cells. Sorted.

 

[JohnD]

C type batteries are not expensive, and last a long time

https://www.aldi.co.uk/activ-energy-c-batteries-pack-of-12/p/000000467854500

Also in Screwfix and Wilko I think

 

[JohnW2]

Its not so much replacing the cables John, that I'm fine with. Its the possibility of her ingesting parts of the cable and fine copper threads hence why using the battery option so removing cables altogether

Fair enough - but is there something specifically attractive to her about the cable? If not, she is presumably just as likely to chew and ingest anything else in your house which is within her eyesight and takes her fancy - such is the case with many puppies

Kind Regards, John