RX400h 12v battery removal and replacement

[welland]

Hi All, 

I'm planning to remove and replace the 12v Battery in my 2006 RX400h in the very near future (this week if I can manage it).  I find that it's going flat too often, and after shorter periods of inactivity. 

Are there any precautions I should take before removing the old one?  

Any recommendations for which type of new Battery to choose?  I have read other threads which mention the original is a glass mat type, instead of conventional flooded acid design.  The car is used almost daily, though mainly for short journeys of 2-4 miles.  Longer journeys perhaps weekly or less frequently. 

[Britprius]

The OEM Battery is almost certainly an AGM. You can use an ordinary flooded lead acid Battery if you wish, but if the Battery is in the passenger compartment you should consider what happens in a collision, and the Battery get smashed. Will the acid be likely to splash on the occupants of the car or is this not a danger. I use a mobility Battery in my GS450H because they are higher capacity size for size than OEM batteries, are better built, and cheaper. The downside is the terminals are different to the standard car Battery posts.

The only thing when removing the old one for safety disconnect the negative lead first, and connect to the new Battery last. 
The auto windows, sun roof, and possibly radio presets will all need to be reset.

John.

[welland]

27 minutes ago, Britprius said:

The OEM battery is almost certainly an AGM. You can use an ordinary flooded lead acid battery if you wish, but if the battery is in the passenger compartment you should consider what happens in a collision, and the battery get smashed. Will the acid be likely to splash on the occupants of the car or is this not a danger. I use a mobility battery in my GS450H because they are higher capacity size for size than OEM batteries, are better built, and cheaper. The downside is the terminals are different to the standard car battery posts.

The only thing when removing the old one for safety disconnect the negative lead first, and connect to the new battery last. 
The auto windows, sun roof, and possibly radio presets will all need to be reset.

John.

Thanks John.

The Battery is fitted under the bonnet in the engine compartment.  

The current Battery is a Yuasa 3000. Might this be the original Battery, or is it a brand not fitted as OEM?

 I cannot see any marks to identify how old it is, though when removed, I may be able to see more.  

[Britprius]

I think the OEM Battery is usually a Panasonic but could be wrong.

Being under the bonnet I would fit a normal flooded type Battery or a leisure Battery designed for caravans or boats. I know that sounds strange, but the hybrids do not need high cranking amps. Capacity is more important so buy the highest amp hour capacity Battery that will fit in the space provided. 
Flooded, and leisure type batteries will be cheaper than AGM.

Virtually all batteries have a date stamp on the top usually pressed into the black case. It may be slightly coded, but can usually be worked out.

John.

[welland]

23 minutes ago, Britprius said:

I think the OEM battery is usually a Panasonic but could be wrong.

Being under the bonnet I would fit a normal flooded type battery or a leisure battery designed for caravans or boats. I know that sounds strange, but the hybrids do not need high cranking amps. Capacity is more important so buy the highest amp hour capacity battery that will fit in the space provided. 
Flooded, and leisure type batteries will be cheaper than AGM.

Virtually all batteries have a date stamp on the top usually pressed into the black case. It may be slightly coded, but can usually be worked out.

John.

I've just had another look at the Battery and still cannot see a date of manufacture.  But I did spot the place where the installer is suppose to mark the date of fitting.  It offers 2015 to 2018, though it appears to have no installers markings.  I conclude from this that the Battery must be no older than 2015.  I only bought the car at the start of the 2018 and it did not look new at that time.  There is a serial number, but I cannot see any mention of the length of the warranty.  

[Britprius]

3 minutes ago, welland said:

I've just had another look at the battery and still cannot see a date of manufacture.  But I did spot the place where the installer is suppose to mark the date of fitting.  It offers 2015 to 2018, though it appears to have no installers markings.  I conclude from this that the battery must be no older than 2015.  I only bought the car at the start of the 2018 and it did not look new at that time.  There is a serial number, but I cannot see any mention of the length of the warranty.  

I agree from your description the Battery is probably a 2015. 

John

[ColinBarber]

OEM isn't AGM, it is flooded with a 38 Ah rating. One improvement of the RX450h is they switched to AGM which has a better ability to deep-cycle and therefore holds up better when repeatedly leaving for a couple of weeks or more.

There aren't too many options that will fit correctly. I replaced mine with a Bosch Battery S4 model 158 which has a higher 45 Ah rating and a 4 year guarantee. Managed to get it on sale for around £57, normal price is nearer £80.

[Britprius]

Search the bay for 55AH mobility Battery you will find many at circa £75 with the same physical dimensions. Some are rated at 55AH but at a 10 hour rate a much higher rate than the standard 20 hour rate usually used for car batteries. This actually puts them at well over 60 amp hours for a true comparison. 
The Ritar 12/55 is such a Battery there are others. Slight terminal modification is required , but this is not a problem. Standard terminal bolt on posts can be bought on line to convert the terminals to standard posts.

John.

[Gliderpilot]

Not all batteries will fit. If it has a sill on the bottom then it wont fit. The bottom has to be flush to fit into the recess. The one on my 400h when I got it was a Bosch S4-021 45 ah the same as fitted.

[Britprius]

Mobility batteries have no sill or fixing points at the bottom. They tend to be very flat sided with no protrusions.

John.

[ColinBarber]

On 9/23/2018 at 9:37 PM, Britprius said:

Some are rated at 55AH but at a 10 hour rate a much higher rate than the standard 20 hour rate usually used for car batteries. This actually puts them at well over 60 amp hours for a true comparison. 

That's a good point. The OEM one is rated at 38 Ah @ 5 hour.

[Britprius]

2 hours ago, ColinBarber said:

That's a good point. The OEM one is rated at 38 Ah @ 5 hour.

That is a very high test discharge rate, and would equate to around 45 AH at the standard 20 hour rate.

John.

[Landcrabmechanic]

On 9/23/2018 at 7:24 AM, Britprius said:

The OEM Battery is almost certainly an AGM. You can use an ordinary flooded lead acid Battery if you wish, but if the Battery is in the passenger compartment you should consider what happens in a collision, and the Battery get smashed. Will the acid be likely to splash on the occupants of the car or is this not a danger. I use a mobility Battery in my GS450H because they are higher capacity size for size than OEM batteries, are better built, and cheaper. The downside is the terminals are different to the standard car Battery posts.

The only thing when removing the old one for safety disconnect the negative lead first, and connect to the new Battery last. 
The auto windows, sun roof, and possibly radio presets will all need to be reset.

John.

I replaced my 12V Battery on my RX400H and now my HV Control ECU is fried. When connecting my 12V Battery, I attached the positive frist and then checked the negative from the post to the terminal. Is this normal or where am I getting a 12V backfeed from?