Flattened auxiliary battery - any consequences?

[Regulo]

You need to get the tailgate open thus:
View attachment Screenshot (24).jpg

 

[FleetOfFoot]

Thanks Ray. Very useful.

 

[DerekT]

My Phev has also been struggling from a weak aux battery. It all began on the Friday after lock-down started, after the car had (unusually) been standing idle for a week. I got in the car to run to the supermarket, but on trying to 'start' it, I got the 'EV System Service required', etc, messages.
I tried a few more times, and it did start eventually (phew!). Dealer support was unavailable, as all the garages were closed!

To cut a long story short, I eventually determined that the aux battery was not holding its charge.
The car could be successfully jump-started, but after a couple of days of the car being idle, back to square one!

I made the following observations, which I hope may be useful to others.

When the aux battery dropped below 10.5 V, the car could not be started.
Furthermore, neither it nor the car could be charged (catch 22)!

I stood by the car to observe the daily 2 pm aux-battery charge, and I saw on the dash, the
'EV System ....' error msg(s) come up at that time. I plugged the EVSE into the car and - same thing!

The only way to get the car charged was to jump-start it, and leave it in 'Ready' for about 1/2 hr.
This lifted the aux battery to above 11 V. Plugging in the EVSE led to the satisfying sound of the relays
clonking in, and the car charged OK (as did the aux battery) - until the next time......

When this first happened, I thought I had a real fault, of course. And the Phev was parked in its usual charging spot,
in front of our garage, stuck in Park, with no way of being able to push it out of the way, so I couldn't even have got my wife's car out!
Corporal Jones' advice came to mind - "Don't Panic!".

Then, I remembered a tip I'd read on this forum when I got my first Phev, in 2016.
To get a dead Phev out of Park, do the following:

Power off, foot on brake, handbrake on. Move the selector to the right, and press the power button.
That puts the car in Neutral - it works!
But fortunately, I didn't need to push it, because eventually it did start, and it has always jump-started OK since.

 

[FleetOfFoot]

Thanks to all for your advice.

My situation was pretty much identical to the post above. 12V battery wouldn't accept charge. Local dealer very helpful and said he has had a lot just like this.

To cut a long story short, the 12V battery will be replaced under warranty this week.

Appreciate the education and advice from all on here.

 

[littlescrote]

Then, I remembered a tip I'd read on this forum when I got my first Phev, in 2016.
To get a dead Phev out of Park, do the following:

Power off, foot on brake, handbrake on. Move the selector to the right, and press the power button.
That puts the car in Neutral - it works!

Interesting. The manual doesn't say anything about that 'method', just that the vehicle needs to be 'ON' and then put the selector in the N position.

 

[DerekT]

Quite correct. However, this is an Emergency procedure for when you can't get the car to come 'ON', but you need to move the car (by pushing it!).

 

[ed2353]

How does the Aux. battery get charged normally?
If it was flat and then got a booster charge, how can I make sure that it stays charged when my car is sat in the driveway for weeks because I'm old and self-isolating from Covid-19?
Do I need to keep booster charging it regularly?

 

[DerekT]

The aux battery is charged in 3 ways:
1. Whenever the car is in 'READY'; whether it's stationary or moving.
2. While the car is being charged
3. If you have the remote-control WiFi enabled, at 2 PM every day for 10-20 minutes, IF the car has not been in
READY since midnight that day. This is to allow for the drain caused by the WiFi itself.

I am in the same position as you, so not using the car much at all these days.

In this situation, Option 3 should keep the aux battery 'topped up', providing it is in reasonable condition.

If you're worried about it going flat in these unusual times, then you could put the car in READY once a week, for about 1/2 hour.
If not using / charging the car at all for a long enough period, the main drive battery, (which is used to charge the aux battery) could get low enough to stop doing it, after which the aux battery will go flat, and the car will no longer 'start'.

If that happens, the only way is to jump start. You need a small 12V battery (say 5 AH, burglar alarm type),
and a pair of leads. You don't need meaty cables, since it's only turning on the car electronics, not cranking an engine!

If you're not using the car at all, I'd consider plugging it in for a charge periodically, say every couple of months.
This will keep the main drive battery topped up, which in turn will keep the aux battery up.

 

[FleetOfFoot]

That is a great post Derek. Thanks for the enlightenment! Our car came back today, with new 12V battery. It's plugged in, with wifi on, so as I understand it, we shouldn't encounter any more problems. I'll be sure to put in drive periodically just to be sure.

Thanks again

 

[DerekT]

Thanks for the kind comment.

If you have a voltmeter, you can easily check the aux battery voltage from time-to-time at the jump-start terminal. It should be above 12V. If it drops below 11, put the car in ready for 1/2 hour, should bring it back to 12+.

Referring to my original post, I would have done exactly what you did, take the car for a warranty battery-swap,
but I couldn't find a dealer in my area that was open! I did call Mitsubishi Assistance; they came out, diagnosed a duff aux battery, but it wasn't an item that they carried. Ah well, have to wait 'til this crisis is over.

 

[FleetOfFoot]

If it's any help, Mitsubishi Assist arranged for the car to be taken away to the garage, and its subsequent repatriation back to us a couple of days later. I couldn't fault the service. We barely lifted a finger!

 

[ed2353]

Thank you Derek.
Your comprehensive reply was very helpful. I will follow your advice.
I will also now check more regularly!

 

[jaapv]

Thanks for the kind comment.

If you have a voltmeter, you can easily check the aux battery voltage from time-to-time at the jump-start terminal. It should be above 12V. If it drops below 11, put the car in ready for 1/2 hour, should bring it back to 12+.

Referring to my original post, I would have done exactly what you did, take the car for a warranty battery-swap,
but I couldn't find a dealer in my area that was open! I did call Mitsubishi Assistance; they came out, diagnosed a duff aux battery, but it wasn't an item that they carried. Ah well, have to wait 'til this crisis is over.

I'm sure that any battery service can replace your 12V battery. That shouldn't set you back more than 75 Euro equ.

 

[FleetOfFoot]

Mitsubishi say they’re >£500. The cheapest I could find the exact one for was on Amazon...£205

 

[FleetOfFoot]

Yuasa HJ-S46B24L(S) 12V 45Ah 325A GS Auxiliary AGM Battery https://www.amazon.co.uk/dp/B07F8Q3WGX/ref=cm_sw_r_cp_api_i_3r.OEb2ZEDR5G

 

[ThudnBlundr]

There have been cases where the WiFi turns itself off after some time without use. In that case the car will not keep the 12V battery topped up automatically, so you will need to do it manually. If the WiFi is off, putting the car into full 'Ready' mode will turn it back on, but it may well turn itself off again after a while...

 

[DerekT]

I'm sure that any battery service can replace your 12V battery. That shouldn't set you back more than 75 Euro.

Thanks, I found this , from a different thread on this forum:

https://www.tayna.co.uk/car-batteries/yuasa/ybx3053/

It costs £53, inc delivery.
It has identical dimensions, terminal config and capacity, although it is a wet battery, and not ideal
for fitting inside the cabin, rather than outside in the engine bay.

I got fed up with jump-starting, so I purchased the above and fitted it, as a temporary measure.
It is working fine, as you would expect.

But I shall be round to the dealer ASAP, to get the original replaced under warranty. I only purchased the car in February, 2 years old, replacing my MY14 Phev.
This car has low mileage (only 5K), but I see from the service history that it had only done 20 miles(!) in the last 12 months. This probably did not do the battery any good at all, and I feel that the dealership should have considered this possibility before they sold me the car.

Mitsubishi say they’re >£500. The cheapest I could find the exact one for was on Amazon...£205

Thanks also for that info; I see no reason why Mitsubishi choose to fit such an expensive battery.

 

[jaapv]

I don't even believe that it is an expensive battery - just vastly overpriced.

 

[michael8554]

The Aux battery doesn't have the enormous current demands an ICE battery does, doesn't need a large capacity, so ought to be much cheaper.

But I don't know how much the sealed battery aspect impacts on the cost.

 

[greendwarf]

Volume manufacturers gave up long ago on making money on new cars. Their profits come from spares which, with longer service intervals, last longer. You also have to remember that this battery is transported from the other side of the planet, so it is never going to be cheap. :roll: