looking for a battery

Thread Starter

Kardo22

Joined Mar 12, 2014
47
Hi,
As there is a lot to choose from then I thought I'd ask for recomendations.

I'm looking for a 12V battery that has to output 250W for 20min. Shouldn't be too big or heavy (5kg would be absolute max but not desirable).
Any recomendations what kind is best? Or has someone used something similar?

thanks
 

MrSoftware

Joined Oct 29, 2013
2,013
Hi,
As there is a lot to choose from then I thought I'd ask for recomendations.

I'm looking for a 12V battery that has to output 250W for 20min. Shouldn't be too big or heavy (5kg would be absolute max but not desirable).
Any recomendations what kind is best? Or has someone used something similar?

thanks
Do you have any other requirements? Physical size, orientation limitations (upside down, ..), service life, temperature tolerance, number of useful cycles, safety, price, etc..? There are several chemistries to choose from, each with unique and significant pros and cons. For example Lithium will give you the most energy density (smallest, lightest) but do not work well in freezing temperatures, are more prone to catching fire and you have to be sure they are never over charged or completely discharged. Flooded lead acid are inexpensive and more forgiving in regards to charging and discharging, but relatively heavy, need to stay upright and produce hydrogen gas during recharging. Sealed lead acid are one of the safer options and can be mounted in any orientation, but again relatively big and heavy. So many options, need more info. :)
 
Last edited:

KeithWalker

Joined Jul 10, 2017
1,681
That works out to be 7AH. so you should be looking for at least a 10AH 12V battery. There are lots of sealed lead acid batteries of that size available.
Regards,
Keith
 

Ian0

Joined Aug 7, 2020
1,897
That works out to be 7AH. so you should be looking for at least a 10AH 12V battery. There are lots of sealed lead acid batteries of that size available.
Regards,
Keith
Don’t forget the Peukert effect.
Capacity won’t be anywhere near the rated capacity at a discharge current of 3C.
For 20 minutes’ operation, down to 10.5V, you would need 12Ah at the absolute minimum.
Also, VRLA batteries don’t take too kindly to being fully discharged. How often will it be used? If the answer is “regularly” then limit the discharge to 50% of capacity i.e. double the size of the battery. Even then, VRLA will still be cheaper and safer than lithium.
 
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