Where is the negative pole on 12V battery?

[Flekoun]

I have Toyota corolla 2020 TS 2.0 hybrid. My 12V Battery keeps discharging and I have to always jumpstart the car. I want to try to recharge the Battery but I cannot find where is the negative pole of the Battery? The positive is hidden under the red plastic flap but the negative is nowhere to be found. Can someone help me? Also the manual does not mention it as it only shows how to jumpstart which attaches the negative pole to any iron bolt of a car body. 

[Gray86]

I have a CTEC charger which I used on my Auris Hybrid prior, but plan to use it on the Corolla. 
 

you use the positive under the red flap in the fuse box, and negative goes to the nearest earth - I think there is one on the strut tower behind the fuse box. 
 

these days, you never go negative to negative when charging or jump starting. 
 

good luck! 

[AKLZ]

Why does it keep going flat? Are you not using it much? Surely such a new car shouldn't need jump starting?

When I recently bought my demonstrator, it was completely flat at the dealership as it had been sat there since March. Salesman told me once I took it away and started driving it, it wouldn't go flat again (unless I didn't drive it for a few weeks)

[TonyHSD]

Why never go negative to negative? Negative terminal of the Battery is always on the other side , perhaps covered with black plastic cover that makes it hidden. The front terminals for jump start the car should only be used for that purpose and not for charging the 12v Battery. , that what said in older hybrids manual. 👍

[bigblock]

As with AKLZ,  I too would like to know why the 12v Battery keeps going flat in the first place. Can you explain more please Flekuon?

[Gray86]

5 hours ago, TonyHSD said:

Why never go negative to negative? Negative terminal of the battery is always on the other side , perhaps covered with black plastic cover that makes it hidden. The front terminals for jump start the car should only be used for that purpose and not for charging the 12v battery. , that what said in older hybrids manual. 👍

I’m not sure why never negative to negative, but my CTEC charger asks for an earth. I’ve jump started a couple of cars over the last few years and the owners manuals have always asked for an earth rather than negative to negative. 
 

just doesn’t appear to be the ‘done thing’ 

[Timmon]

30 minutes ago, Gray86 said:

I’m not sure why never negative to negative, but my CTEC charger asks for an earth. I’ve jump started a couple of cars over the last few years and the owners manuals have always asked for an earth rather than negative to negative. 
 

just doesn’t appear to be the ‘done thing’ 

Is it to do with risking a spark close to the Battery, risk of explosion from hydrogen gas? So you connect positive first, then earth (Negative).

[Rosgoe]

31 minutes ago, Gray86 said:

I’m not sure why never negative to negative, but my CTEC charger asks for an earth. I’ve jump started a couple of cars over the last few years and the owners manuals have always asked for an earth rather than negative to negative. 
 

just doesn’t appear to be the ‘done thing’ 

I may be wrong but I think you should not go negative to negative for jump starting to reduce the possibility of sparking when you connect the lead to the host vehicle. 

[TonyHSD]

Yes, risk of spark that can cause eventually a fire. This may happen when making last connection on the negative and if there is some flammable vapour like from fuel or Battery acid. I actually most of the time had done exactly what I should not and never been a problem, it’s like precaution. 
The way I connect the jump leads: 

1. positive on the dead battery 

2. positive on the jump battery 

3. negative on the dead battery 

4. negative on the jump Battery itself or ground if available  (little spark possible) 

once the car starts I leave all connected for about a 2-3 minutes, then disconnect in exact opposite order. Golden rule: never give power to bigger car with bigger engine or bigger Battery.
Regards 
 

[Jiff]

From my  manual it says

Before recharging

When recharging, the 12-volt Battery produces hydrogen gas which is flammable and explosive. Therefore, observe the following precautions before recharging: ●If recharging with the 12-volt Battery installed on the vehicle, be sure to disconnect the ground cable. ●Make sure the power switch on the charger is off when connecting and disconnecting the charger cables to the 12-volt Battery.

[Flekoun]

Thanks a lot guys. The iron bolt as a ground did the trick. Did not know why I haven't simply tried this first. I was sure it have to be negative on battery for some reason.

As for why my Battery is going flat. Do not worry, it is my fault. I have Comma 2 open-pilot HW add-on installed. They pushed an update which had a bug and drained your Battery really quick. It is fixed now but it caused me some troubles for few days. 

[APS]

On 12/21/2020 at 3:42 PM, Timmon said:

Is it to do with risking a spark close to the battery, risk of explosion from hydrogen gas? So you connect positive first, then earth (Negative).

Tim is right. I experienced this first hand when a friend was jumpstarting his car. Luckily the Battery was up front and bonnet fully open. The top of the Battery went skywards and landed quite a few meters away from us after about 5-10 seconds. Goodness knows how high up in the air it went. We were both nearly deaf and my friend had to go to hospital to get Battery acid rinsed off his face and burns dressed.

To avoid similar 'experiments', on a car with negative earth:

• ALWAYS connect plus lead to battery first
• ALWAYS connect negative to chassis, well away from the battery
• Reverse to disconnect (first earth then positive)