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Perhaps some of you are concerned about what happens to HT & LT batteries if you cannot use the car for some time. Well, I left mine standing for 5 weeks and 5 days and here is some of the information that I have gleaned.
I left the HT battery at 73% state of charge (as per instructions to leave it some way off full charge) and I made sure that the 12 volt battery was fully charged with an external charger. The average temperature over the period would have been about 14C so no high or low temperature issues. On my return, the car doors unlocked with the remote and everything operated normally. I raised the bonnet and checked the 12 volt battery and it was down to 12.01 volts. So I put a charger onto the battery and an 8 amp charger needed some 2.7 hours to charge. That doesn't quite necessarily mean a simplistic 2.7 x 8 = 21.6 Ah but it does mean that the little battery took a lot of charge. After charging, the battery voltage measured 12.86 volts after a couple of minutes.
Now for those of you who don't want to read the next paragraph of numerical ramblings, please just go to the conclusions. For those of you who like detail and perhaps can help me, here is what I did next. I drove the car for 20 minutes and then returned home but left the car in "Ready" mode. I measured the charge potential at the battery as 14.14 volts. Then, I pressed the stop button and the battery voltage decreased for a little over 2 minutes to 12.45 volts. (The water circulating pump was definitely stopped!) With nothing apparently happening, the voltage then rose to 12.68 volts until there was a clanking of relays about 4 minutes from stop. Then the battery voltage went up quickly to 12.78 volts. This held steady for about 9 minutes until more small relays were heard and the voltage dropped again over a minute to 12.35 volts (I am lost as to what was happening). I gave up at this point and locked the doors with the voltmeter still on the battery and the voltage went down further. So, I tidied up from everything that I had been doing and went back after 10 minutes or so to remove the volt meter and close the bonnet. The battery was showing 12.76 volts!
So, I conclude the following.
1. Left in a temperate climate, long term storage of the HT battery is not an issue. It would appear to lose much less than conventional wisdom of 3%/month. Of course, battery heating in very low temperatures is not considered in this post.
2. The 12 volt battery cannot be left for months. I don't know the minimum voltage at which the 12 volt system can no longer pull in the HT breaker or open the door locks but I suspect that mine could have been in trouble after another couple of weeks. So, it's battery disconnect or trickle charging if one wants to leave the MX-30 for months. I know that 5 weeks and 5 days was OK but??????
3. The more I learn about this car, the less I seem to know. If anyone can cast some light on what is going on, please enlighten me. There is clearly all manner of electrical use occurring for 9 or 10 minutes after one presses the stop button!
I left the HT battery at 73% state of charge (as per instructions to leave it some way off full charge) and I made sure that the 12 volt battery was fully charged with an external charger. The average temperature over the period would have been about 14C so no high or low temperature issues. On my return, the car doors unlocked with the remote and everything operated normally. I raised the bonnet and checked the 12 volt battery and it was down to 12.01 volts. So I put a charger onto the battery and an 8 amp charger needed some 2.7 hours to charge. That doesn't quite necessarily mean a simplistic 2.7 x 8 = 21.6 Ah but it does mean that the little battery took a lot of charge. After charging, the battery voltage measured 12.86 volts after a couple of minutes.
Now for those of you who don't want to read the next paragraph of numerical ramblings, please just go to the conclusions. For those of you who like detail and perhaps can help me, here is what I did next. I drove the car for 20 minutes and then returned home but left the car in "Ready" mode. I measured the charge potential at the battery as 14.14 volts. Then, I pressed the stop button and the battery voltage decreased for a little over 2 minutes to 12.45 volts. (The water circulating pump was definitely stopped!) With nothing apparently happening, the voltage then rose to 12.68 volts until there was a clanking of relays about 4 minutes from stop. Then the battery voltage went up quickly to 12.78 volts. This held steady for about 9 minutes until more small relays were heard and the voltage dropped again over a minute to 12.35 volts (I am lost as to what was happening). I gave up at this point and locked the doors with the voltmeter still on the battery and the voltage went down further. So, I tidied up from everything that I had been doing and went back after 10 minutes or so to remove the volt meter and close the bonnet. The battery was showing 12.76 volts!
So, I conclude the following.
1. Left in a temperate climate, long term storage of the HT battery is not an issue. It would appear to lose much less than conventional wisdom of 3%/month. Of course, battery heating in very low temperatures is not considered in this post.
2. The 12 volt battery cannot be left for months. I don't know the minimum voltage at which the 12 volt system can no longer pull in the HT breaker or open the door locks but I suspect that mine could have been in trouble after another couple of weeks. So, it's battery disconnect or trickle charging if one wants to leave the MX-30 for months. I know that 5 weeks and 5 days was OK but??????
3. The more I learn about this car, the less I seem to know. If anyone can cast some light on what is going on, please enlighten me. There is clearly all manner of electrical use occurring for 9 or 10 minutes after one presses the stop button!
