DIY 9V Rechargable Battery Replacement (850mAh @ 7.4V) by OutFoxD

Last crawled date: 3 years ago

Since I was sick of buying low capacity 9V alkaline batteries, using shitty NiMH rechargeables, or buying overpriced LiIon ones, I ordered fitting LiPo cells and connectors from China.
The resulting battery has a nominal voltage of 7.4V, peaking at 8.4V when fully charged (s cells in series) resulting in a capacity of 850mAh. The lower voltage should not matter, since devices using 9V batteries usually run them down to below 5V and the cutoff for the LiPo cells is ~5.5V.
Since the packs are equipped with a protection circuit you don't have to worry about balancing, just make sure to charge them to the exact same voltage before assembling to minimize cell drift.
Before assembling you have to disassemble the 9V-connector and clip it's sides off.
Then desolder all the battery leads and connect them in series and then to the connector.
BE CAREFUL! don't short the batteries. Make sure you connect the black wire of the connector to + and vice versa (it's switched since it's ment for the load).
Check polarity before finishing and cover blank connections with tape!
Put the top part over the connector and hotglue it onto the batteries.
Links from AliExpress:https://www.aliexpress.com/item/4pcs-L055-3-7V-850mAh-802540-PLIB-polymer-lithium-ion-Li-ion-battery-for-SMART-WATCH/32640381350.html?spm=a2g0s.9042311.0.0.27424c4dz6ShLDhttps://www.aliexpress.com/item/10pcs-9V-Battery-Snap-Connector-clip-Lead-Wires-holder/32810031927.html?spm=a2g0s.9042311.0.0.27424c4dz6ShLD
The shipping cost won't rise much if you order more, so I paid like 4USD per cell, which gets you one high capacity non-rechargable 9V cell, if you are lucky