populariconian | Staff posted Nov 20, 2025 05:15 PM
Item 1 of 2
Item 1 of 2
populariconian | Staff posted Nov 20, 2025 05:15 PM
100Ah EcoFlow 12V Deep Cycle LiFePO4 Battery w/ BMS $94 + Free S/H
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Car starter batteries generally do not have 100ah capacities.
The other issue is the output of the alternator. Assuming you bought three of these and paralleled them, you will get enough starting amps. Issue is that when the engine finally kicks over the lithium batteries also will take every single available amp the alternator can put out. At idle this load may overheat the alternator if run for a few minutes.
There are alternative battery styles that work better. Nmc and lfp battery tech isn't ideal in extreme hot or cold. That's why lead acid batteries are still around even in ev's.
The BMS amperage (A) continuous output limit is not entirely relevant to starting a vehicle; the continuous rating is typically above 10-30 seconds. I've tested just about every Chinese brand -- not one BMS has ever cut current in less than the 10 seconds to start a modern petroleum engine.
The BMS amperage rating is specifically for continuous current -- however, you need 10 seconds or less, which a prismatic LiFePO4 (CATL, EVE, etc.) can push 3c for at least that length.
In other words, with a 100AH battery and 100A BMS, you can typically get 300A (3c) max current. With a 200AH battery 3c would be 600A, however, you would run into issues with the short spark-current-limit in that event, likely 300-400A.
The short version is that, if you were to parallel two of these and you have a smaller, modern car that can start with about 580A in 10 seconds or less, and don't charge it below it's temperature range, then you could use the set of two to start that vehicle.
Another tip -- if you buy items that are shipped by/from AliExpress (similar to how Amazon does fulfillment for other resellers), those items have always arrived reliably, in my experience.
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