Lithium Battery Monitor Question

Thread Starter

DC_Kid

Joined Feb 25, 2008
796
i am not a guru with lithium batts, but i am working with LiFePO 24v 24Ah batt and i need a simple led/lcd "full empty" monitor, displays a scale and/or %, etc.
i see some inexpensive items on e bay, but i am not sure if they are of proper scale. as example, a 24v LiFePO might be full at ~29v and on empty near 21v, so a monitor must be scaled in that range. a programmable scale would be excellent. looking for that sub $10 item, etc.

any suggestions on items that work properly.
 

ronv

Joined Nov 12, 2008
3,770
i am not a guru with lithium batts, but i am working with LiFePO 24v 24Ah batt and i need a simple led/lcd "full empty" monitor, displays a scale and/or %, etc.
i see some inexpensive items on e bay, but i am not sure if they are of proper scale. as example, a 24v LiFePO might be full at ~29v and on empty near 21v, so a monitor must be scaled in that range. a programmable scale would be excellent. looking for that sub $10 item, etc.

any suggestions on items that work properly.
All depends on how fancy you want to get. Here is a nice write-up with some chips:
https://www.digikey.com/en/articles/techzone/2014/jan/fuel-gauge-ics-simplify-li-ion-cell-charge-monitoring
 

ian field

Joined Oct 27, 2012
6,539
i am not a guru with lithium batts, but i am working with LiFePO 24v 24Ah batt and i need a simple led/lcd "full empty" monitor, displays a scale and/or %, etc.
i see some inexpensive items on e bay, but i am not sure if they are of proper scale. as example, a 24v LiFePO might be full at ~29v and on empty near 21v, so a monitor must be scaled in that range. a programmable scale would be excellent. looking for that sub $10 item, etc.

any suggestions on items that work properly.
Specification is pretty tight if you want to avoid a fire.

Monitoring the total battery voltage won't do - you need to monitor each individual cell, and implement some form of balancing while charging.

Everyday Practical Electronics magazine published a balancer project - but it probably won't handle as many cells as you're talking about.
 

Thread Starter

DC_Kid

Joined Feb 25, 2008
796
Last edited:

ronv

Joined Nov 12, 2008
3,770
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