400H Aux Battery Discharge

[ColinBarber]

Had a look at my 12v aux Battery in the engine bay this evening. Noticed there was quite a bit of dirt covering it so decided to check for any discharge across the top of the Battery.

Using a volt meter, one probe on the Battery -ve terminal and with the other probe touch various points across the top of the Battery.

Any reading of 0.5v and above could contribute to Battery discharge, but the maximum I got, near the -ve terminal, was around 0.1v. Still decided to give it a clean anyway with water and baking soda and then dried off. The voltage reading were now down under 0.01v across the plastic top of the Battery.

I then noticed that on the OEM Battery there is a channel in it. It still had some dirt and I guess moisture in it. Putting the meter probe in there gave me a reading of up to 7.0v near the +ve terminal!



Some WD40 and cleaning later and the reading was back down to under 0.01v in the channel. I am however wondering if this is a common issue. Unfortunately I didn't take a reading in the channel before cleaning the Battery with water so I probably made it worse than normal however I still feel this could be a minor source of the Battery discharge issues which plague the 400h for two reasons:

• Normally the Battery is covered up so rarely gets a clean.
• When filling the screenwash you often get water spill/splash over the side which would fall onto the Battery and collect in the channel which would then take a very long time to dry out.

something to keep an eye on

[katabrontes]

A very useful post which may go some way to solving a problem which has best many owners of 400H. Even with the larger Battery on the 450 this is still a useful tip.

Personally I think the Hybrid is a poor choice and the benefits don't, in my view, justify the extra cost. On a new one you would be unlikely to recover the extra cost in fuel savings over the time you kept the car given the high cost of servicing by a Lexus main agent. A nice idea but,like many green options, the business case is, sadly, very weak.

[ColinBarber]

Personally I think the Hybrid is a poor choice and the benefits don't, in my view, justify the extra cost. On a new one you would be unlikely to recover the extra cost in fuel savings over the time you kept the car given the high cost of servicing by a Lexus main agent. A nice idea but,like many green options, the business case is, sadly, very weak.

The GS, RX and LS hybrids are all about delivering a package of performance vs economy. I'm able to average around 32mpg in my 400h, I wouldn't get near than in a 4.3 V8 powered RX - which is the engine I would need to get the same level of performance.

[DanD]

Colin - thanks for your very useful post re Battery.

I also agree with your last comments. It would be wrong to assume that people choose the hybrid model over the petrol ones for economy alone. Personally, I chose the car for its refinement, comfort, reliability, equipment and prestige. I enjoy driving in near silence a low speed (in fact I often keep the audio off!). I equally enjoy the immediate and powerful response afforded by the 276bhp of the hybrid + petrol engine combination... it never fails to put a grin on my face. The fact that economy is decent for a car that size is a bonus even though I have always struggled to better 29mpg (and I blame my driving style rather than the car).At the end of the day, if economy is your priority, this type of car is not for you.

Incidentally, are servicing costs really much higher for the 400h than for the 300/350?

[ColinBarber]

Incidentally, are servicing costs really much higher for the 400h than for the 300/350?

No, less in fact. The standard services are the same cost but the 400h goes through brake disc and pads at half the rate of the 300/350.

[katabrontes]

I take the point about performance however since, as I understand it, Hybrids need the facilities of Lexus agents to carry out the service whereas the 300/350 does not then the lower costs of an independent garage should be taken into account. My point was not based on a need for economy but simply on my perception that the "business case" for the hybrid is weak.

[ColinBarber]

for normal servicing the requirements are the same as the petrol version, the hybrid system isn't touched except the inverter coolant needs to be changed at 100k miles, which itself isn't a difficult task so independents can easily service them. If repairs are needed on the hybrid system then I would agree - main dealer only.

From a pure financial viewpoint then I would agree with you that the numbers don't stack up, certainly not at the moment with current petrol prices and tax based on CO2. However there are other benefits, benefits which I'm willing to pay for.

[fulmar]

I bought my RX450 hybrid because I liked the concept of the car -- the Lexus quality, the performance, the comfort and the novelty of the hybrid engine.

I don't know what the on-cost of the hybrid is, but at a rough guess it will be half the difference in price between the RX450h and the GS250 -- half for the hybrid and half for the greater engine power. The saving in petrol costs is going to take me 7 to 10 years to recover the extra cost of buying the hybrid, so I have to agree that is not a business case. But if I was a regular visitor to London, and avoided the congestion charge, the economics would be transformed.

In any case, as long as the car doesn't reveal some nasty feature in the future, I am well satisfied. My quibbles are few. I would like back the button on the panel that turns the air-con on and off rather than messing about with the 'mouse'. And I wish Lexus would redesign the alarm system so that it doesn't go off if I leave a metallic object in the centre console!

I shall be interested to find how well the car copes in snowy conditions. I may fit winter tyres which I note my Lexus centre are pushing. Any views on this?

[katabrontes]

On-cost is actually less than I expected for earlier models - about £2.500 but this is still over 10 years to cover the reduction in Road Tax.. Parkers list the last 350SE ICE (2010 59 plate) at £41,295 and the 400H at £43,740. The big change is in the used values however since the 350 is currently about £13,000 and the 400 about £22,000 so maybe the business case is better than I thought if you bought a new one but not if you bought a used one when you start at £9K lower.. The 350 seems to have been dropped in 2010 and only the 450 is now available new.