Battery not holding charge

Gerard2017 · January 8

Hi. I've a 6 year old RC300f and the engine Battery is not holding charge even though I've been doing decent length runs. The Battery was changed 3 years ago as the alarm, tracker and dashcam was pulling too much out of it when unused for a while.

I'm now using the vehicle more but disconnected these, recharged overnight and within 2 days the Battery drops below 12v.

Before I take it back to the dealer, I was going to check what discharge there might be indicating something is wrong or whether discharge rate is normal and I'll just get myself a new Battery.

I have a multimeter so how would I do about getting an accurate reading and what is normal?

If I decide to try a new Battery, do I just disconnect the existing one and drop in a new one or do I need to do something else to ensure I don't lose the radio codes or otherwise mess up data storage in the vehicle?

TIA

Malc1 · January 8

many brand new batteries come with a warranty of 3 or 4 or 5 years ........ which was your's when replaced i wonder ?

If it's just about to expire then the local Lexus / Toyota spares dept could probably supply and fit, on the spot, a good value Yusua from their stores . they will make sure everything is kept when doing the changeover, but remind them just in case .. and enjoy their free coffee too

Over the decades I've found the Toyota Main Dealer spares Dept very competitive on new Battery price too

Malc

Gerard2017 · January 8

Cheers. Booked in for Wednesday. Lets see how much this is going to hurt

Linas.P · January 15

The Battery from RC300h will cost you an arm an a leg from Lexus. Hybrids needs AGM batteries and they are costly. Also Yuasa batteries in my experience are junk, they last their warranty period and that is about it. Again, at least in my experience they all died after ~3-4 years.

As for why... for batteries to last car has to be regularly used and if not regularly used then they have to be trickle charged. I have never thought about it before, but since covid and since I started using car less I have ruined several batteries as I simply don't drive regularly enough and I don't have option of trickle charging.

Malc1 · January 15

On 1/8/2024 at 6:12 PM, Gerard2017 said:

Cheers. Booked in for Wednesday. Lets see how much this is going to hurt

any thoughts ?

Malc

SH20 · January 15

With the Battery in place fully connected place a volt meter across the 2 terminals The standing Battery voltage should read 12.6v when the car is off. When the vehicle is on /Ready /engine running or not it should read 14.4 or very close to that.

If the Battery is not holding charge after a couple of days and the standing voltage is less than 12.6v and the running voltage is less than 14.4v then the Battery would be suspect in my opinion.

Suggest you fully charge the Battery with an external source like a CTek Battery conditioner or similar. As soon as the Battery reaches fully charged, disconnect the charger and then check the standing and running voltages immediately with your volt meter. They need to be 12.6v and 14.4v If not the Battery is the problem.