Questions about Waiting for a BetterBattery

[Green Hills]

I've been a lurker here for a long time, and thank you for making sure that information about the hybrid battery replacement warranty is available for all! About two years ago, I used the extended warranty for a dealer replacement of my Insight 2000 battery.

About three months ago, the IMA light came on again, and then the check engine light came on about a month ago, so I've ordered a BetterBattery. The new battery should be available for installation in May. Unlike the first time this happened, the length of time between the IMA light coming on and the appearance of the check engine light (and no recharge/assist action registering) was only about 7 weeks, and the recals were fast and thick no matter how carefully I drove.

I have a few questions:

1) What's the easiest way to minimize the risk that the 12V battery is going to suddenly cut out on me between now and when I get my new battery? I'm thinking that I should turn off the IMA battery switch which looks (from the pictures) like it isn't too hard to access if I pull up the carpet in the cargo bay.

2) Are there any signs that the DC-DC system for charging the 12V battery is no longer working, short of the 15 minute warning provided by the battery light? Does it become harder to start the car, for example, or will the dome light be dim? I don't have any voltage checking equipment or any way of monitoring it while I'm driving or even when I'm not. I'm not anxious to spring for $90+ equipment if I can avoid it, given the BetterBattery costs that I'm facing. If I'm being penny wise and pound foolish, though, please let me know.

3) Should I avoid night driving and using the radio, or anything else to take it easy on the 12V battery?

I work from home, so don't drive the car much, which probably contributed to the problems I'm having now. I would like to take a couple of trips before the installation - one to my daughter's place (which is about 100 miles each way), and another to meet my son (about 75 miles). Then there's the trip to Staten Island to get the battery installed, which will be about 250 miles. Other than that, I might make a couple of shopping trips of about 20 miles each.

Thanks for helping me out, and I never knew how much I loved my car until now when it has an expensive problem!

[Right Lane Cruiser]

Welcome to the realm of non-lurking!!

Here are some answers with the corresponding numbers:

1. I believe the DC-DC converter remains active with the IMA switch turned off but the most effective way to to ensure you are in good shape is to not only turn off the IMA switch but also unplug the BCM connection. This will turn on the DC-DC all the time, though it will turn off if you spike up to 4K RPM (something you wouldn't ever do as a hypermiler). Just so you know, it will turn back on after a pause when you drop under that level again.
2. If you are worried about the 12V status I'd recommend stopping by an automotive store like AutoZone or Pep-Boys and taking a look at their selection of cigarette lighter gauges. I believe you can get one very cheaply there. Here is an example from Amazon currently listed at $10.99
3. With the suggestions above I wouldn't worry about it, honestly.

Good luck and keep us posted!

[WriConsult]

If you have a ScanGauge, you can also use its VLT setting to monitor your 12V battery. Although not a hybrid owner, I rely on this gauge very heavily to make sure I don't drop too low while FASing.

[Green Hills]

Thanks so much for the quick and reassuring replies! I don't have a ScanGauge, but I do think I could spring for a cigarette lighter gauge as Sean suggested. This should give me a welcome layer of added confidence. I will turn off the IMA switch and disconnect the BCM before I make the drive, though :-)

Will definitely keep you posted - though I still can't believe I'm posting at long last!

[Green Hills]

So, I took a more careful look at what accessing the BCM entails, and I'm not sure I'm up for that. Also, I'm not clear on whether it's necessary to disconnect only the BCM connection that is to the side below the Danger sticker on the BCM, or if all three connections to it (including the two on the side above the Danger sticker) should be unplugged. Also, how difficult is it to remove this connection (or these connections)? Do they slip out fairly easily by hand, or will I need to go at them with some sort of tool?

Until I get enough courage to disconnect the BCM, should I leave the IMA switch on or off? Will the 12V battery no longer be charged if the IMA is switch is off while the BCM is still connected, (in which case I shouldn't turn off the IMA switch without also disconnecting the BCM)? Or should I switch the IMA off to protect the large battery from being used to start the car (which makes sense if flipping the IMA switch doesn't prevent the 12V battery from being charged)?

Sorry for so many questions....

[msirach]

Have you tried taking the negative cable off your 12 volt battery for a few minutes to do a reset? I did that before each 50 mile commute. It would allow me to get to work without any recals. Even when I got the IMA code of death, it would still work to allow a commute without multiple recals.

[Right Lane Cruiser]

There is only one plug that needs to be removed and it doesn't require a tool to do it. Here's a picture of the one you want to pull (facing the back of the car from between the seats) -- in the picture it is the connector with the twisted white bypass wires hooked up:



Just reach under the plug and squeeze the release latch while pulling. I know getting to that point looks really intimidating but it isn't as bad as it looks -- just time consuming. Take a look at my FAS switch install thread to get a better idea of what it takes to get into that box here.

If you are concerned about the battery just turn off the IMA switch and leave it at that -- the DC-DC converter should still work (based on experimentation by DiamondLarry in his Insight) and the high voltage battery won't be used for starting. You'll lose assist/regen and autostop as well. If you disconnect the BCM the DC-DC converter will simply stay on all the time rather than the typical cycling it normally does so that the 12V only gets charged as needed.

Don't worry about asking questions -- we're here to help and you never know how many other people are just dying to ask the same questions but haven't yet.

[sno779]

Green Hills

Just turn off the big IMA switch in the back and drive it. That's what I did while I waited the 3 months and 2600 miles for my Better Battery and everything worked out fine. I posted about it under the "Impact of turning off the IMA battery switch" thread in this section. My Better Battery is also working fine. Good luck.

Louis Hudgin