The Perils of a Tired Battery

Mr Tidy

Mr Tidy

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 North West Surrey
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I hadn't used my Z4 for 3 weeks or so but as we finally had a dry day today I thought I'd take it for a drive with no destination.

It cranked slowly, but did start but then I got amber lights for DSC and Brakes and the OBC had lost it's mind so no date, time or mpg/mph averages. 😦😦

Still it drove brilliantly as ever, but whatever I did with the Climate controls it would only blow out heated air. 😵‍💫

Looks like I'll be reading codes next time it is dry. Hopefully the battery will be OK - it had a new AGM one in April 2021.
 
This winter has been so bad. Had not taken my Mx5 out for weeks. Went to start it and the battery was dead. If we ever get a dry day I will push it out and jump start it. Then at minimum I need a new battery. But will it ever stop raining? 😟
 
It was another dry day today so when I went out I took my Z4.

It fired up easily and no amber lights came on - happy days! 😌
 
Get a Battery tender lads....CTEK are the best imho. plug it in and leave it....failing that if you havent got a wall socket, get a solar one.

more info

A Battery Tender solar is a small solar panel system designed to maintain (not fully recharge) a 12 V battery using sunlight. It’s commonly used for cars, motorcycles, boats, RVs, or equipment that sits unused for long periods.

Here are some typical options 👇

Battery Tender 12V 5W Solar Battery Charger with Windshield Mount​

€72.00

Battery Tender 12V 17W Mountable Solar Battery Charger​

€140.01

Battery Tender Solar Controller​

€29.67

VEVOR 20W 12V Solar Panel Battery Maintainer​

€25.90

What it does​

  • Converts sunlight into electricity to keep your battery topped up.
  • Prevents discharge and sulfation during storage.
  • Works without mains power — useful for outdoor parking or garages without outlets.
Most Battery Tender solar chargers include a built-in charge controller to avoid overcharging and reverse discharge at night. (Battery Tender®)

They’re designed mainly for maintenance current (trickle charging) rather than bringing a dead battery back to life. (Battery Tender®)

Typical power sizes​

  • 5 W → motorcycles, occasional maintenance, small batteries.
  • 10–20 W → cars that sit outside for weeks.
  • 17–35 W+ → faster maintenance, winter storage, higher drain vehicles.
For example, the 17 W model can automatically charge and maintain multiple battery types (AGM, gel, lithium, lead-acid) with weather-resistant construction. (Battery Tender®)

When it’s useful​

✅ Car stored outside
✅ Seasonal vehicle (motorcycle, classic car)
✅ No electricity nearby
✅ Battery slowly draining from alarms or electronics

Important tip​

Solar maintainers only work well if the panel gets direct sun for several hours daily. Shade through a windshield reduces output a lot.

If you want, tell me:

  • vehicle type (car, bike, boat)
  • outside or garage
  • how long it sits
…and I can recommend the right wattage 👍.
 
My Zed has a parasitic drain so the battery goes dead flat if I leave it more than a week or two. The last time it happened, I bought a CTEK charger to recondition the battery and it survived the experience. That's not bad considering the battery pre-dates shipping the car here in 2018 (the car is on only its second battery in 20 years).
I leave it connected to the CTEK so the car is always ready to go...except for the minor problem of a coolant leak!
 
TIMMOS29 said:

Important tip​

Solar maintainers only work well if the panel gets direct sun for several hours daily. Shade through a windshield reduces output a lot.
Click to expand...

And there is the fatal flaw with these.....I can count the days on the one hand I've seen the sun this year, let alone for several hours :LOL:
 
What no fairy dust? :LOL:

TBF I bought a solar charger years ago but my parking space at the time was in the shade most of the day. Since I moved a few years ago my Z4 is parked in a South facing space so I think I need to start using it.

Maybe TIMMOS29 can offer some advice on the best way to connect it, cigarette lighter, direct to battery or to starting points under the bonnet?
 
Mr Tidy said:
What no fairy dust? :LOL:

TBF I bought a solar charger years ago but my parking space at the time was in the shade most of the day. Since I moved a few years ago my Z4 is parked in a South facing space so I think I need to start using it.

Maybe TIMMOS29 can offer some advice on the best way to connect it, cigarette lighter, direct to battery or to starting points under the bonnet?
Click to expand...
Ill ask my mate Mr GPT
 
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