MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: ade1971 on October 13, 2020, 09:25

Title: Weekend car and flat battery
Post by: ade1971 on October 13, 2020, 09:25
Hello
As my mr2 is my weekend car my battery often goes flat and I have jump start it . I wish to know if it would a good idea to start it up in the drive and run the engine ( at a standstill) simply charge that way so my Toyota mr2 battery doesn't go flat between drives
Good idea or waste of petrol and time
Title: Re: Weekend car and flat battery
Post by: Joesson on October 13, 2020, 09:42
@ade1971, my understanding is that doing as you suggest will do neither your engine or your battery any good.
As you are on your drive you likely are not so far from mains power.
I have two cars, my 2 is garaged and generally on trickle charge when not in use. As my daily, is seldom used I now park close to the garage door and borrow the charger from my 2 and run the charger cable under the garage door and under the engine lid. The charger sits in the engine bay, connected to the battery, I close/ lock the engine lid and it's reasonably secure. Just a mains power cable on view, if you can do similarly, perhaps using a suitable extension cable  I believe that will extend your battery life and be better for the engine than running at idle /stationary.
Title: Re: Weekend car and flat battery
Post by: Topdownman on October 13, 2020, 09:43
If the battery keeps getting discharged then it damages the battery. Maybe this is why you are having trouble?

I would get some sort of solar panel to plug in when not in use and that should hopefully top up the residual drain. You may need to wire in a cigarette lighter socket to the battery (so its always on) to plug in to or look for one that connects to the obd socket.

I wouldnt run the car just to charge the battery myself, I would rather go for a drive! Remember, starting the car runs down the battery.

When my other car was sorned for 3 months on the drive, I had my charger connected with the plug coming out of the bonnet and sitting on top of the wheel. Once a week I would just plug it in on a trickle charge of 0.8amps for the day to keep that topped up.
Title: Re: Weekend car and flat battery
Post by: ucb on October 13, 2020, 09:46
I left my old Z4 on a CTEK battery conditioner. That would seem to be the most prudent and straightforward solution
Title: Re: Weekend car and flat battery
Post by: Carolyn on October 13, 2020, 09:55
Put an isolator on it?
Title: Re: Weekend car and flat battery
Post by: shnazzle on October 13, 2020, 09:56
Or just disconnect the battery?

I'm currently building battery isolators operated by remote control. I have it on my car at the minute.
So if the car goes unused for a while (Helen doesn't drive hers over winter usually) then I just need to tap the remote and it disconnects the battery.
When I want to drive again, I just flick the remote again and it engages battery.
It used an absolutely miniscule amount of battery to run the remote receiver but I dare say it'll last a winter.
Title: Re: Weekend car and flat battery
Post by: paulj on October 13, 2020, 11:28
If it goes flat in a week it might be a battery issue. How old is it? Go for trickle charge but keep an eye on motor factor special offers as The battery will come up on a deal - My replacement battery does 2 weeks without issue!
Title: Re: Weekend car and flat battery
Post by: Gaz mr-s on October 13, 2020, 11:49
Quote from: ade1971 on October 13, 2020, 09:25Hello
As my mr2 is my weekend car my battery often goes flat and I have jump start it . I wish to know if it would a good idea to start it up in the drive and run the engine ( at a standstill) simply charge that way so my Toyota mr2 battery doesn't go flat between drives
Good idea or waste of petrol and time

A bit more detail needed... how long is it left unused, & when you do use the car how many continuous miles do you do? How old is the battery?
Title: Re: Weekend car and flat battery
Post by: Jimbo on October 13, 2020, 11:50
If it has gone completely flat then it might be time for a new one as they don't really like it. After that as above, trickle charger or disconnect it.
Title: Re: Weekend car and flat battery
Post by: Rallyeluke on October 13, 2020, 11:54
A battery optimiser is best :) i use them on my bikes when needed
Title: Re: Weekend car and flat battery
Post by: Carolyn on October 13, 2020, 12:28
It's not always practical to use a charger.  It depends on where you park and where the nearest plug socket is!

My JDM car has an aftermarket alarm/immobiliser that draws a lot of current, so flat batteries were always a potential issue.

I installed a simple battery disconnect isolator and it worked fine - just a pita to have to keep popping the engine lid to use it. (Picture below).  But if it's only a 'once-a week' thing I think they are quite adequate.

Then I went for a solar panel sitting on the parcel shelf - but they do require direct sunlight to produce much current -so not entirely a reliable solution.

I did the prototype remote isolator that Shnazzle is making- and I now have that on the car.  It's deluxe!
isolator.jpg
Title: Re: Weekend car and flat battery
Post by: 1979scotte on October 13, 2020, 14:20
I have a battery that was manufactured in Feb 2017.
Official toyota battery bought from a dealer.
Its fubar due to just not being used.
Get the battery tested if you need to buy a new one so be it and either fit an isolator or if easy access get a trickle charger.
Simples.