Lithium Battery Voltage Monitor

[2nd House]

Hello All
I'm having a little trouble finding a relatively inexpensive battery voltage/percentage monitor for my Lithium batteries.
The victron is nice, especially with the Bluetooth functionality, but at $150...too expensive.
Can someone suggest a simple battery voltage monitor, with a percent indicator, for Lithium batteries. I'd like to keep the budget at $50.
Thanks for the help

 

[Dzl]

Is voltage all you want to measure? If so I think there are tons of cheap options but voltage isn't a reliable way to measure state of charge / depth of discharge with lithium. The Victron unit you references also measures 'State of Charge' using a shunt. I believe this is the cheap Victron knockoff Will featured in one of his videos a while back and some other forum members have used.

 

[sed6]

I like this one for $24.

CellMeter-8 Digital Battery Capacity Checker LiPo LiFe Li-ion NiMH Cell Meter US | eBay

Lipo Batteries. Hard-Case Lipo Plug Harnesses. Also functions as servo tester. Battery Connectors/Plugs. Balance Board Adapters. 32DP, 3.2mm. 32DP, 5.0mm. Battery type/cells: LiPo/LiFe (1S-8 cells), NiCd/NiMH (1-8 cells).

www.ebay.com

 

[2nd House]

I like this one for $24.

CellMeter-8 Digital Battery Capacity Checker LiPo LiFe Li-ion NiMH Cell Meter US | eBay

Lipo Batteries. Hard-Case Lipo Plug Harnesses. Also functions as servo tester. Battery Connectors/Plugs. Balance Board Adapters. 32DP, 3.2mm. 32DP, 5.0mm. Battery type/cells: LiPo/LiFe (1S-8 cells), NiCd/NiMH (1-8 cells).

www.ebay.com

View attachment 13108

Questions:
1. I have two batteries, do I need two meters?
2. Did you have to discharge the batteries to 0% to set a baseline for the % reading?

Thanks for the help

 

[Ampster]

I like this one for $24.

I used to use 4 CellLog8s for my EV conversion that ran on 96 volts until I found out that it drew a few millivolts from only the first cell. Long term that was going to lead to some voltage imbalance on those cells. At the time I was not running a BMS. I don't know if that is the case with the Cellmaster.

 

[Andreas]

What about this one? https://www.amazon.com/AiLi-Voltmet...dp/B07FGFFHC6/ref=psdc_14244451_t1_B07CTKYFTG

I just bought one and waiting for it to arrive. looks like it measures amps in both directions (discharge and charge).

 

[ScoTTyBEEE]

What about this one? https://www.amazon.com/AiLi-Voltmet...dp/B07FGFFHC6/ref=psdc_14244451_t1_B07CTKYFTG

I just bought one and waiting for it to arrive. looks like it measures amps in both directions (discharge and charge).

I have one of those. They're quite a bit cheaper on aliexpress, I don't think they're worth the amazon price. Mine has an annoying habit of sensing a small charge when there isn't one, keeps flicking between zero and an amp over and over which makes it useless, typical Chinese junk. I did have an even cheaper Chinese bms on my last battery which worked flawlessly though, so luck of the draw really.

 

[sed6]

Questions:
1. I have two batteries, do I need two meters?
2. Did you have to discharge the batteries to 0% to set a baseline for the % reading?

Thanks for the help

One meter for each battery, so still at your $50 goal. No discharge and no baseline needed. It uses the cell volts to determine the percentage full, which has been pointed out isn't the most accurate but better than nothing.

I used to use 4 CellLog8s for my EV conversion that ran on 96 volts until I found out that it drew a few millivolts from only the first cell. Long term that was going to lead to some voltage imbalance on those cells. At the time I was not running a BMS. I don't know if that is the case with the Cellmaster.

Great point and considering these are Chinese junk they probably do too. However the meter also shows highest and lowest voltage between any two cells and it's always random between cells 1-6, maybe 2&4 or 1&3 or 4&5, it's not stuck on 1&X so it's not a concern. Plus it's a passive balancer and likely balances at a higher rate than it consumes.