lifted club cars - lifted ezgo
Home FAQDonate Who's Online
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Electric Yamaha > Lithium Yamaha


Post New Thread  Reply
 
Thread Tools Display Modes
Old 11-05-2022, 09:33 PM   #1
naustin
Not Yet Wild
 
Join Date: Oct 2022
Posts: 2
Unhappy Weird battery voltages after lithium conversion

I swapped to four 12V Dakota Lithium LiFePO4 batteries in my Yamaha Drive and added a Victron Energy BMV 712 Smart Battery monitor (that uses a shunt). I also swapped from using one battery for the 12V circuit to having a step down voltage regulator supplying 12V to a marine fuse block for the existing 12V with plans to add more 12V accessories later.
It charged up and ran great until today when I left it sitting off for several hours and it seems like some kids played with switches because it was in reverse (which usually makes a loud tone) but the lights won't come on or anything once I turned the key.
I checked voltage overall and it is reading 2.873V... But when I check 3 batteries they are 12.8V to 13.4V each and the last battery shows -34.7V! I double checked everything again and am stumped.
I have 4 - 12V batteries in series with + charger connection, + voltage regulator, and + of motor controller on the + of the battery series, then the negative of the battery series connected to one side of the shunt for the battery monitor and on the other side of the shunt there is - of charger connection, - of voltage regulator, - of motor controller.
When I have the lights off and the key off, the battery monitor shows no amp draw and stays on continuously. When I found it tonight the battery monitor is not lit up.
Has anyone seen anything like this before?
naustin is offline   Reply With Quote
Alt Today
BGW

Golf car forum Sponsored Links

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum
   
Old 11-06-2022, 02:48 PM   #2
Pat911
Gone Wild
Club Car
 
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 816
Default Re: Weird battery voltages after lithium conversion

That last battery has shut down. What you're reading is the other three in series. There are plenty of threads on here about problems with series connected 12v lithium batteries.

Did you balance the batteries prior to installing them? I would guess that you didn't. You need to remove the batteries, connect them all in parallel (pos to pos, neg to neg) get a 12v lithium charger and charge them like that. Once charged, leave them connected for at least 24 hours, preferably longer. Disconnect and reinstall in the cart.

What you're experiencing is common for 12v series connected lithium batteries. You will have this problem from time time time depending on usage. You should have purchased a 48v battery as a 48v battery won't experience this problem.

Another common mistake is to use your old Lead Acid charger with Lithium. Did you purchase a 48v lithium charger to use with your new batteries? This is a MUST.

Cheers
Pat.
Pat911 is offline   Reply With Quote
Old 11-06-2022, 03:40 PM   #3
naustin
Not Yet Wild
 
Join Date: Oct 2022
Posts: 2
Default Re: Weird battery voltages after lithium conversion

Thanks @Pat911, That does seem correct.
Yes, per Dakota Lithium's instructions I charged each battery individually with their included 12V battery then tested that the voltages were within 0.007V of each other before connecting in series then waited 24 hours before connecting Dakota's 48V charger to the cart and ran it until it turned off automatically - which was about 8 minutes. Then the cart ran great for a few days.

When I disconnect the end battery, it measures the same voltage as the others.
I will try your suggestion of connecting them in parallel and charging that way.
Their chargers do turn off automatically when charged (I'm assuming a voltage setpoint).

If this is common for LiFePO4 batteries connected this way, is there a work around when it happens away from home?

FWIW, Dakota Lithium does sell a 48V battery but they advised to use the 4 12V in series for better performance and longevity. I hope this doesn't continue.
naustin is offline   Reply With Quote
Old 11-06-2022, 03:57 PM   #4
Pat911
Gone Wild
Club Car
 
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 816
Default Re: Weird battery voltages after lithium conversion

Hi Naustin,

Sorry, but Dakota Lithium gave you bad advice. Series connected Lithium batteries will always give balancing problems

I just had another read of your initial post, the other three batteries ranged from 12.8v to 13.4v. Those three are also out of balance. Once the batteries are out of balance, the total pack Ah is reduced to the least charged battery. So if the most charged battery is at 100Ah and the least charged battery is only at 50Ah, you whole pack is reduced to 50Ah. If you're using the shunt to be guided as to how far you can go you'll be stuck away from home. Your cart will shut down when your SOC meter reads 50Ah.

How long did it run for before experiencing this problem, weeks, months? Unfortunately there's no easy way to fix it in the field as the battery that has shut down is simply flat. Nothing except charging it will get it going again.

The best fix for you is to get a 12v 4 port lithium charger that will charge all the batteries individually and ensure that each one gets to 100% capacity at each charge. This will eliminate your balancing problems. Noco have such a charger but it's not cheap. I believe its the Genpro 10x4.

Cheers
Pat.
Pat911 is offline   Reply With Quote
Old 11-07-2022, 12:02 PM   #5
augiedoggy
Gone Wild
 
augiedoggy's Avatar
 
Join Date: Apr 2008
Posts: 226
Default Re: Weird battery voltages after lithium conversion

a single 48v battery uses a single BMS unit which works to keep all the cells in balance. in your case you have 4 individual bms units that are not communicating with each other.

Too bad they dont make external BMS units that will monitor and keep the individual 12v batteries in check... You would think there would bee a real market for such a device? I wonder do they at least make balancer units for this like they do for individual 3.2v cells? Otherwise even with charging individually the cells will keep wandering out of spec from each other and the problem will only get worse no?
augiedoggy is offline   Reply With Quote
Old 11-07-2022, 02:30 PM   #6
Pat911
Gone Wild
Club Car
 
Join Date: Dec 2020
Location: Melbourne, Australia
Posts: 816
Default Re: Weird battery voltages after lithium conversion

A 12v balancer is available but it has not totally eliminated problems experienced by some members here. The problem is that the LiFePO4 discharge curve is so flat and since the balancer can only balance depending on voltage (and it operates continuously I believe), it cannot accurately detect SOC at anything between 5% and 95% SOC. If operating inside this range it could actually be making things worse.

The above is the reason a cell balancer should not operate at under 3.4v on LiFePO4. SOC could be anywhere at under 3.4v

Cheers
Pat.
Pat911 is offline   Reply With Quote
Old 11-07-2022, 02:31 PM   #7
augiedoggy
Gone Wild
 
augiedoggy's Avatar
 
Join Date: Apr 2008
Posts: 226
Default Re: Weird battery voltages after lithium conversion

Quote:
Originally Posted by Pat911 View Post
A 12v balancer is available but it has not totally eliminated problems experienced by some members here. The problem is that the LiFePO4 discharge curve is so flat and since the balancer can only balance depending on voltage (and it operates continuously I believe), it cannot accurately detect SOC at anything between 5% and 95% SOC. If operating inside this range it could actually be making things worse.

The above is the reason a cell balancer should not operate at under 3.4v on LiFePO4. SOC could be anywhere at under 3.4v

Cheers
Pat.
that actually makes total sense.
augiedoggy is offline   Reply With Quote
Reply
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Electric Yamaha > Lithium Yamaha


Thread Tools
Display Modes


Similar Threads
Thread Forum
Battery Evo Lithium Conversion Electric EZGO
Lithium Battery Conversion Electric Club Car
Lithium Battery Conversion Electric Club Car
Lithium Battery Conversion Lithium Club Car
'97 Ezgo solenoid not clicking & weird voltages Electric EZGO


All times are GMT -5. The time now is 01:26 AM.


Club Car Electric | EZGO Electric | Lifted Golf Carts | Gas EZGO | Used Golf Carts and Parts

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
This Website and forum is the property of Buggiesgonewild.com. No material may be taken or duplicated in part or full without prior written consent of the owners of buggiesgonewild.com. 2006-2017 Buggiesgonewild.com. All rights reserved.