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This question already has an answer here:

If I connect 2 1000mAh battery in parallel would I get 2000mAh over 3.7V?

https://www.aliexpress.com/item/1000mAh-3-7-V-Lithium-ion-Polymer-Battery-102050-For-MP3-MP4-MP5-GPS-KTV-Household/32952678499.html?spm=a2g0s.8937460.0.0.18452e0e5myegg

would it be safe to connect two of the above? i understand that i can buy 2000mAh battery but just want to understand the basic concept.

Should I add any safety mechanism for that?

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marked as duplicate by Finbarr, winny, Elliot Alderson, Greg, StainlessSteelRat Mar 13 at 17:14

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • \$\begingroup\$ The referenced other question deals this, more focused on the charging, but the same applies. Not sure how well these batteries will work out, but everything must be identical or they will self-discharge. \$\endgroup\$ – StainlessSteelRat Mar 13 at 17:13
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Once connected, it's safe to charge and discharge a pair of permanently paralleled cells as if it's a single cell of their combined capacity.

However, the process of connecting them must only be done when they have the same terminal voltage. A large and dangerous current will flow if you connect two cells of significantly different charge state. A good technique is to initially connect them with a resistor for a while to let them self balance at a safe current.

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  • \$\begingroup\$ Got you, so having the above batteries connected together with resistor should work fine? \$\endgroup\$ – USer22999299 Mar 12 at 10:29
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    \$\begingroup\$ remove the resistor once they're equal in voltage. \$\endgroup\$ – Neil_UK Mar 12 at 11:05

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