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Deep Cycle Battery San Diego

GEM Car Battery Charging Troubleshooting

GEM Car Battery Charging Troubleshooting

Questions We Get Asked Daily Regarding GEM Car Battery Maintenance and Charging


Q: Which batteries are best for Gem Car?

A: 12V Group 30 or 31 deep cycle batteries

Strong, deep cycle batteries. Not wal-mart, Costco or mid-grade marine/RV deep cycle batteries.

Q: Are sealed deep cycle batteries better for Gem Car?

A: The discussion has many opinions but the decision is based upon if you don’t mind monthly hydration required by flooded cell batteries.  The Crown 31DCHD, Trojan 30XHS, US31DCXC

Are flooded cell type and will consume water when the batteries are recharged.

Typically, the flooded cell type deep cycle batteries have higher amp hours and lifecycles compared to AGM or Gel deep cycle batteries.



1999-2003 GEM Car OE was flooded cell deep cycle batteries - 12V 130 ah

Two batteries in the front hood and four under drivers seat.

2004 and up GEM placed all six batteries are under drivers seat and GEM sourced Deka 8G31 as OE


Sealed Battery Choices: Gel & AGM

A Gel deep cycle battery will cost more and should be 12V Group 31 with 98 ah or higher.

Gel batteries work better in hot climates, Arizona etc


An AGM deep cycle battery has good lifecycle and is sealed so no watering required.

Do not use UPS style AGM batteries. UPS AGM batteries are less expensive but are not designed to discharge the recharge hundreds of times like deep cycle AGM are.

Examples of good AGM for GEM are Trojan 31 Overdrive and Crown 12CRV110


Q: Where is the GEM Car charger located?

A: Inside the dash next the GE controller


Q: Why won’t the batteries stay charged when car is left plugged in?

A: The early model GEM Cars used Zivan and the charger will complete one charge cycle and shut off regardless if left plugged in. Zivan will not maintain the batteries.

The green light will come on telling you charging is complete - Don’t be tricked by the green light.

Unless you unplug and replug in the car to restart the Zivan on-board charger, the battery state of charge rapidly decreased.

After one day, even at rest, the car is no longer 100% charged.

After five days, the car has drained the batteries to 75% state of charge.

Deficit Charge Syndrome


Undercharged batteries are a major cause of system failures in GEM Cars.

Deficit Charge is a charge cycle in which less charge is returned to a battery bank than what was withdrawn on discharge. Deficit charge can occur in situations where AC power supply is poor due to oversharing an 110 ac outlet with the GEM car or the extension cord is too long and undersized

If lead acid batteries experience repeated deficit charge cycles and left at partial state of charge for long periods, they will become progressively more difficult to charge and suffer a loss of capacity. When charged, voltage will rise more quickly in batteries with sulfation than in normal batteries, falsely indicating a high state of charge. The Delta Q charger will falsely report 100% state of charge. Recovery from this condition can sometimes be accomplished by an equalization charge.