After reading how many have had battery problems with their 350h, I do not think I would offer to help jump start anyone. I own a large portable jump starter but it is heavy and required charging every once in a while.

 

I wouldn't do it. The 12v battery is only designed to power up the hybrid and run a few accessoroes, it doesn't have the crakinng amps to start an engine. My personal recommendation to anyone (hybrid owner or not) is to buy one of those small jump starter packs and keep it in the car. That way you can not only start your own car if your battery goes flat, but also give someone else a jump start with it if they need help. I got a reasonably inexpensive one from Amazon a few years ago, and it's started everything up to a Jaguar V8.

 

If I were to feel a strong need to jump another vehicle from an RX hybrid, I would do it directly from the battery with the RX completely shut down. That is actually the safest way to jump start from any vehicle. I've found that to be sufficient most of the time in starting another vehicle and, if that doesn't work, then starting the donor vehicle usually won't work either.

Basically, you are using your vehicle's battery in the same way that you'd use a portable jump starter. There is a concern that it could leave your own battery dead if the jumped vehicle doesn't start right away though.

 

So I wanted to confirm, given that I seem to foresee having to do this very soon: What is the correct order for connecting the leads in terms of positive/red and the negative/black ? This video shows connecting the black/negative first, followed by the red/positive to the battery last, which seems to make sense. However, in many other videos they seem to do the opposite order. Or does it not matter ?

 

This is a relatively old thread, but I'd like to add my input to it because I just went through the same issue with my daughter.

Electrically, the order doesn't matter.

But for safety, the order when connecting a jump start box to the vehicle is positive first, then negative.

There is no danger of short circuit for the first connection because the vehicle and the jumping battery are still two separate systems.

If you connect the negative first, the chassis of the vehicle is negative. While connecting the positive, if the positive end of the cable accidentally touched a metal part of the vehicle, there will be a short circuit.

If you connect the positive first, most of the metal parts of the vehicle is still neutral. When connecting the negative, the risk of a short circuit is much much less (you'll have to connect the negative end of the cable to the vehicle chassis any way).

 

Yes, I had figured out this logic eventually. I had to do my jump starts roughly 1 month after posting my question above.

Funny thing is, in all my car ownerships before owning a Lexus - I never had to learn/worry about any of this. The knowledge-gained is interesting and worthwhile, of course, but the fact that the knowledge is a must-have for a $80000 new "Lexus", isn't surely what I had expected before actually owning Lexus. Sure batteries can turn out to be defective or die in all makes of cars, but it isn't a disease I had encountered before.

 

From what I have read, a lot of these videos are wrong for the RX hybrid, even the ones from some dealers. They show connecting the negative cable to ANY bolt or metal surface under the hood. There is a designated connection point shown in the manual. Randomly grounding to any metal part could blow your ECU if you select a connection close to it.

If you are using a jump pack with short cables, you can use standard jumper cables as an extension to reach the correct negative connection point if needed. But be wary of these online videos. The one referenced has two issues if applied to an RX hybrid. One, they start with connecting the negative, and two, they connect it to the wrong place (any metal surface). While it may work, you may blow your ECU or some other circuit. If you ever call roadside assistance for a jump, make sure they know what they are doing. Not all are properly trained.

 

This is also an good assumption and its dangerous to follow Roadside Assistance advise or allow them to do what they want. Here's the evidence of that: https://www.clublexus.com/forums/rx-...23-rx350h.html

Roadside Assistance are not Lexus-trained, just sub-contracted and outsourced to outfits like AAA drivers - who have no knowledge or understanding of the specific car/make - just generic knowledge, such as what is there in the Youtube videos. The linked use in the above thread, for example, notes that they are probably done with Lexus - given how he was treated by Lexus and their "Roadside Assistance" - and the run-around he got. I would be too.

 

1. RED to DEAD: Connect the red clip to the positive terminal on your dead battery.
2. RED to DONOR: Connect the red clip to the positive terminal on the donor vehicle’s working battery.
3. BLACK to DONOR: Same car! Connect the black clip to the negative terminal on the donor vehicle’s working battery.
4. BLACK to METAL: Back to the dead battery. Connect the black clip to an unpainted metal part of the dead car (like a bolt or bracket) that is not directly next to the battery.

 

That's why I got the jump pack below that has cables long enough for the Lexus recommended site. I got it on sale for under $80.

Schumacher Electric Lithium Jump Starter and Portable Power Pack SL1648, 3-in-1, 1250A, 12V, for 6.0L gas, 3.0L diesel engines- works on cars, trucks, motorcycles, marine batteries, SUVs, and more

 

Very useful and timely service video which helps the Lexus hybrid ownership get over sometimes unclear and misleading conversation about the jump-start of the 12-battery. Thank you for posting this video, appreciated.