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George H.
George H., Hyundai Technician
Category: Hyundai
Satisfied Customers: 2091
Experience:  Hyundai Gold certified, ASE Master tech 15+ years
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It is a hybrid sonata but shows low battery and the car

Customer Question

It is a hybrid sonata but shows low battery and the car don't start, can I jump start a hybrid battery?
JA: How old is the battery? And have you tested it with a voltmeter?
Customer: The same when I bought the car, 4 years or five
JA: What year is your Sonata?
Customer: 2012 sonata hybrid
JA: Are you fixing your Sonata yourself? What have you tried so far?
Customer: Have done anything yet but wanna try myself
JA: Anything else you want the mechanic to know before I connect you?
Customer: Don't know where is the battery in the car
Submitted: 4 months ago.
Category: Hyundai
Expert:  Chad Farhat replied 4 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 4 months ago.

Hey we have a 12 volt battery and Hybrid battery , the Hybrid you can not jump

but if the small 12 volt battery is dead ,it will cause the no start

on Your dash there is a display that shows Hybrid charge level ,is showing you full

2012 Hyundai Sonata L4-2.4L Hybrid

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Removal and Installation 1. Disconnect the battery negative terminal (B) first, then the positive terminal (A). Tightening torque : (+) terminal (A) : 7.8 - 9.8N.m (0.8 - 1.0kgf.m, 5.8 - 7.2lb-ft) (-) terminal (B) : 4.0 - 6.0N.m (0.4 - 0.6kgf.m, 3.0 - 4.4lb-ft) 2. Disconnect the vent hose (C).

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3. Remove the battery upper bracket (A) and then remove the auxiliary 12V battery (B).

Tightening torque :
19.6 - 29.4N.m (2.0 - 3.0kgf.m, 14.5 - 21.7lb-ft)

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4. Remove the battery tray (A).

Tightening torque :
19.6 - 29.4N.m (2.0 - 3.0kgf.m, 14.5 - 21.7lb-ft)

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5. Installation is the reverse order of removal.

Install the battery upper bracket after locating the battery at the closest position to the side panel.


Battery Diagnostic Flow

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Vehicle parasitic current inspection
1. Turn the all electric devices OFF, and then turn the ignition switch OFF.
2. Close all doors except the engine hood, and then lock all doors.
(1)Disconnect the hood switch connector.
(2)Close the trunk lid.
(3)Close the doors.
3. Wait a few minutes until the vehicle's electrical systems go to sleep mode.

For an accurate measurement of a vehicle parasitic current, all electrical systems should go to sleep mode. (It takes at least one hour or at most one day.) However, an approximate vehicle parasitic current can be measured after 10 - 20 minutes.

4. Connect an ammeter in series between the battery (-) terminal and the ground cable, and then disconnect the clamp from the battery (-) terminal slowly.

Be careful that the lead wires of an ammeter do not come off from the battery (-) terminal and the ground cable to prevent the battery from being reset. In case the battery is reset, connect the battery cable again, and then start the engine or turn the ignition switch ON for more than 10 sec. Repeat the procedure from No. 1.
To prevent the battery from being reset during the inspection,
1) Connect a jump cable between the battery (-) terminal and the ground cable.
2) Disconnect the ground cable from the battery (-) terminal.
3) Connect an ammeter between the battery (-) terminal and the ground cable.
4) After disconnecting the jump cable, read the current value of the ammeter.

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5. Read the current value of the ammeter.
A. If the parasitic current is over the limit value, search for abnormal circuit by removing a fuse one by one and checking the parasitic current.
B. Reconnect the suspected parasitic current draw circuit fuse only and search for suspected unit by removing a component connected with the circuit one by one until the parasitic draw drops below limit value.

Limit value (after 10 - 20 min.) :Below 50mA

Cleaning the 12V battery area

1. Make sure the ignition switch and all accessories are in the OFF position.
2. Disconnect the battery cables (negative first).
3. Remove the battery from the vehicle.

Care should be taken in the event the battery case is cracked or leaking, to protect your skin from the electrolyte.
Heavy rubber gloves (not the household type) should be wore when removing the battery.

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4. Inspect the battery tray for damage caused by the loss of electrolyte. If acid damage is present, it will be necessary to clean the area with a solution of clean warm water and baking soda. Scrub the area with a stiff brush and wipe off with a cloth moistened with baking soda and water.
5. Clean the top of the battery with the same solution as described above.
6. Inspect the battery case and cover for cracks. If cracks are present, the battery must be replaced.
7. Clean the battery posts with a suitable battery post tool.
8. Clean the inside surface of the terminal clamps with a suitable battery cleaning tool. Replace damaged or frayed cables and broken terminal clamps.
9. Install the battery in the vehicle.
10. Connect the cable terminals to the battery post, making sure tops of the terminals are flush with the tops of the posts.
11. Tighten the terminal nuts securely.
12. Coat all connections with light mineral grease after tightening.

When batteries are being charged, an explosive gas forms beneath the cover of each cell. Do not smoke near batteries being charged or which have recently been charged. Do not break live circuit at the terminals of batteries being charged.
A spark will occur when the circuit is broken. Keep open flames away from battery.

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Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 4 months ago.

How old is that Auxiliary 12 volt battery ,since you bought it ,has it ever been changed prior ?

Please let me know

Thank You


Expert:  Chad Farhat replied 4 months ago.

Rear Trunk Area ,Passenger side ,did you find it ?

Please let me know if you can not find it