08-19-2020, 10:18 AM | #1 |
Not Yet Wild
Join Date: Jun 2020
Location: Greensboro, NC
Posts: 10
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State of Charge Meter
I recently purchased a used 2018 RXV Elite 2.0 and would like to add a Digital State of Charge Meter. Not sure why Ezgo didn't install one at the factory. I tried a plug n play model like this but it does not work correctly since it was designed for lead acid carts.
https://www.ebay.com/itm/Digital-Cha...-/324012435471 Have any of you added one? Is there one you can recommend that works? Thanks, |
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08-19-2020, 10:47 AM | #2 |
Not Yet Wild
Join Date: May 2013
Location: Southport, NC
Posts: 6
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Re: State of Charge Meter
I'd like to know too as we just picked up a new Elite also.
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08-19-2020, 11:12 AM | #3 |
Not Yet Wild
Join Date: May 2013
Location: Southport, NC
Posts: 6
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Re: State of Charge Meter
I think something like this will work. It's similar to my Victron setup in my RV with lithium batteries. Anything with a shunt that is programmable should work.
https://www.amazon.com/AiLi-Voltmete...a-569360505489 |
08-26-2020, 01:35 PM | #4 | |
Not Yet Wild
Join Date: Jun 2020
Location: Greensboro, NC
Posts: 10
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Re: State of Charge Meter
Quote:
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08-26-2020, 04:42 PM | #5 |
Not Yet Wild
Join Date: May 2013
Location: Southport, NC
Posts: 6
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Re: State of Charge Meter
The only way to get accurate SOC reading on the battery is to know the current going in and out. Either a shunt or a current sensor can accomplish this.
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08-29-2020, 02:29 PM | #6 |
Gone Wild
Join Date: Oct 2012
Location: Southwestern Pa.
Posts: 6,204
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Re: State of Charge Meter
Well.....IMHO a SOC meter isn't any better than just looking at\watching a volt meter. My max charge setting on my lithium pack is 57V and I know that when the pack reaches 50.0V at rest that it's time to charge or I'm not gonna go far.
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08-29-2020, 02:42 PM | #7 |
Gone Wild
Join Date: Sep 2014
Location: Orlando, FL
Posts: 1,308
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Re: State of Charge Meter
I'm with Dave on this one. I've never seen any SOC that is as accurate as the digital voltmeter and common sense. Put on charger at 50V...
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09-01-2020, 04:23 PM | #8 |
Gone Wild
Join Date: Jul 2018
Location: Ramer, AL
Posts: 1,447
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Re: State of Charge Meter
I'm no expert by any means, but I was under the impression that lithium continued to put out 51 volts until it was about dead, then stop (like our cell phones do)...not like FLA that will gradually decrease voltage as it gets down below 50% SOC? I was told that I didn't need a volt meter (SOC meter will do) because by the time the pack decreases below 51 volts, battery will shut down. Maybe some of the battery experts will chime in...
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09-01-2020, 06:08 PM | #9 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,125
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Re: State of Charge Meter
Lithium battery voltage has a curve but it's different than FLA. Fully charged cells like Leaf cells are at 4.2V. I normally discharge mine to about 3.65V per cell which is roughly 15% remaining capacity. So the cell voltage changes about .5V from near 100% to about 15%.
For a 14S pack, that means your pack voltage changes about 7 volts over that range. The drop is very nonlinear so reading the voltage does not give a direct indication of state of charge (SOC). What I did which is somewhat rough is use an Arduino to read the cell voltage and convert it to an approximate SOC reading along with the voltage. I used the discharge curve published for the Leaf cells. I would say that it's probably good to about 5% over the range I use it. Calculating SOC accurately using Coulomb Counting can be done but it's not a trivial effort given the nature of the battery current in a running cart so I have not even attempted to do that. |
09-02-2020, 07:57 AM | #10 |
Gone Wild
Join Date: Jul 2018
Location: Ramer, AL
Posts: 1,447
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Re: State of Charge Meter
To put that in terms that a dummy (me) can understand, the Lithium output stays high until it gets down to about 15% SOC and then falls like a rock? FLA's have a more steady/continuous decline through out the depletion? Just trying to understand why I was told that my meter that read volts (digital) needed to be replace with the provided SOC (bars) when I got my lithium pack (Roypow)
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