Has anyone measured / have data on LiFePO4 battery "internal resistance"*.
By this i mean cells + wiring + BMS.
In building my first battery, i was very worried about overcurrent, having taken onboard anecdotes like "a Li battery will suck up all the charge you can throw at it". Also looking at individual cell spec sheets showing very low mOhms.
If i do a simple test such as apply 1V more than the battery rest voltage and measure the induced current one could think of this as an ohmic resistance.
To my surprise the resistance i measured was around 26 mOhm. Finding a spec sheet for my BMS (Daly Smart 60A), the resistance is quoted as < 20 mOhm, so this seemed about right. The 100A JBD BMS thats on its way to me claims < 10 mOhm. Has anyone measured similar for their assembled battery?
My application is direct alternator charging a secondary battery, and so if i limit the low voltage cutoff to 13V, and consider the max voltage i observe from my alt, and use 5m of 16mm2 cable (purposely enabling a voltage drop). the BMS is limiting the maximum current flow to around 1/3 my alternator capacity (which im comfortable with).
* I realize im blurring the term 'internal resistance'.
By this i mean cells + wiring + BMS.
In building my first battery, i was very worried about overcurrent, having taken onboard anecdotes like "a Li battery will suck up all the charge you can throw at it". Also looking at individual cell spec sheets showing very low mOhms.
If i do a simple test such as apply 1V more than the battery rest voltage and measure the induced current one could think of this as an ohmic resistance.
To my surprise the resistance i measured was around 26 mOhm. Finding a spec sheet for my BMS (Daly Smart 60A), the resistance is quoted as < 20 mOhm, so this seemed about right. The 100A JBD BMS thats on its way to me claims < 10 mOhm. Has anyone measured similar for their assembled battery?
My application is direct alternator charging a secondary battery, and so if i limit the low voltage cutoff to 13V, and consider the max voltage i observe from my alt, and use 5m of 16mm2 cable (purposely enabling a voltage drop). the BMS is limiting the maximum current flow to around 1/3 my alternator capacity (which im comfortable with).
* I realize im blurring the term 'internal resistance'.