How do I calibrate the panel to display correct battery SOC?

toddbailey

New Member
I have a Voliamart 1500 watt rear wheel drive kit and having issues with the poor design of the display panel configuration.
In the setup menus I can select 24,36,48,60 or 72 volts. I selected 48 since that is what the 4 batteries add up to.
but not exactly, I'm using lifepo4 12 volt batteries and the combined voltage is 53.6, at 20% it's more like12.9

on the displsy is a fuel gauge that's supposed to tell you what your battery soc is, problem is it's always full using the 48v setting and mostly empty on the 60v setting

ideally, i'd like to be able to enter the top and bottom figures and get a good idea of where it's at.

So question of the day is there anyway to calibrate the panel or is there a different model I should use?

btw the panel is a sw900a with mini din connectors


thanks
 

J.R.

Well-Known Member
48 volt is the correct setting. Unfortunately the more modest systems do not have the best, most accurate battery gauge. You'll find a lot of posts here where a rider will say they rode 20 miles and the gauge still reads full. Or the first half of the battery will go 25 miles and the second half only 10 miles.

It's one of those things you'll learn over time and experience how far you can go on a charge. Usually means you'll have to drain the batteries a few times to understand the system limitations.
 

toddbailey

New Member
Thanks, I was watching some utube videos and came across a chart of soc for lifepo4 batteries
briefly, 13.6 to 14.4 is 100%, 13.2 is 70% 13.1 is 40% and 12.9 is 20%. I multiplied by 4 to get a chart for my config.
Since I can't rely on the fuel gauge, I plan to equip the bike with a 5 digit digital volt amp meter and plan to use it to monitor battery condition.
yeah if I use the 48 v setting, the battery gauge always shows full. rather disappointed that the designers didn't include a better way of battery selection

do you know if there are other panels that i could look at ? I found one that had a 52 volt setting. thanks
 

harryS

Well-Known Member
I'm using lifepo4 12 volt batteries and the combined voltage is 53.6, at 20% it's more like12.9

Hi Todd. if you're using LiFEPO4 batteries, they have a different voltage than typical lithium cells. These are 3.2V nominal and 3.6V max. Something like the Miady 12V pack is really 12.8V nominal and 14.4V max. Four of these in series is 51.2V at half charge and 57.6V max.

So adjust your SOC voltage charts accordingly,

By the way, when the battery guys talk 20%, they refer to the capacity, not the voltage. Minimum voltage on a lithium cell is still around 2.5V, regardless of chemistry. That makes that Miady pack 10V minimum, and protection circuits probably ho;d it above 12V.
 

toddbailey

New Member
yes i'm using 4 12 v lifepo4 batteries in series. with all the different battery chemistries, the ebike designers really dropped the ball on offering flexibility on what the end user decides to use as a power source.
The video I watched compared the lifepo4 battery soc and battery voltage. for the miady 16ahr battery after a full charge i'm seeing 53.4. yes according the the spec sheet states 10v or in my case 40v is the cut off voltage. I am under the impression that running the pack down to it's cutoff voltage is not desirable, as it can damage the battery, but especially if one is miles away from "civilization" which as I understand it once the battery cutoff voltage is reached, the battery goes offline ie into sleep mode and you'll need a recharge to activate the pack. I'm ok with only using up to 80 % of the total. the difference on the soc chart is a bit of a concern, since they are saying 20 % soc is 12.9 or 51.6 which makes be wonder what happens between 10 v and 12.9

regardless, i need a gauge that a I can rely on to provide accurate soc info. I currently don't have that trust in the sw900 lcd panel that reads a full charge even after putting 40 miles on the clock
 

AguassissiM

Well-Known Member
This is what I have added to one of my rides to get a clear picture of the battery status:
Digital Multimeter DC 6.5-100V 20A Voltage Amperage Power Energy Meter DC Volt Amp Tester Gauge Monitor LCD Digital Display with Blue Backlight Measuring Volts Current with Built-in Shunt
 

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harryS

Well-Known Member

toddbailey

New Member
hopefully the 2.2 digital volt meter will be accurate enough so i can use it as a monitoring device so once the batteries hit a 11.0 volt output (or in my case 44.0) I know it's time to recharge. yes I know 10(40 volts) is the absolute minimum but why push your luck.