Help Please! Car Battery/Electrics (non Z4)

inkey$ · Post by **inkey$** » Wed May 31, 2023 3:24 pm

I need non-Z4 car help!

My mother-in-law has a Nissan Micra K12 (2005) and I'm trying to get it back on the road for her after 6 months off.

The relatively new battery (12 months old) was fully charged and put back on the car, and whilst the dash lights worked, it would start, just click a lot. I used a jump pack on the car and it started immediately then ran fine.

After leaving it ticking over for 30 mins, she started up again fine. A few days later though, dash lights and central locking all work, but the car wont start again.

Want to take for an MOT this week, and can jump it to get going, but any experts know what I should be looking for with this issue? A few observations/questions:

- If it was a parasitic drain wouldn't the dash and central locking both be inoperable?
- How could I best check for parasitic drain bearing in mind I own a multi-meter, but barely know how to use it?

- I had thought starter motor, but the car started fine after 30 mins warning up at the weekend.
- Alternator seems to be charging the battery fine.

Any help or advice would be amazing. I want to get this tested and sorted for her asap as she's pretty immobile without it.

smorris_12 · Post by **smorris_12** » Wed May 31, 2023 5:35 pm

I'd start by assuming the battery, especially if it's a cheapie.

If it's the sort of car to do short journeys and was then left not fully charged for the six months (particularly if they're was a bout of moving it 6' here and there to park it up) I can imagine it ending up flat from sitting there. Leaving a battery flat for a period wrecks the capacity and ability to hold charge. Result, as battery that'll just about hold one good start for a day or so.

inkey$ · Post by **inkey$** » Wed May 31, 2023 5:42 pm

smorris_12 wrote: ↑Wed May 31, 2023 5:35 pm I'd start by assuming the battery, especially if it's a cheapie.

If it's the sort of car to do short journeys and was then left not fully charged for the six months (particularly if they're was a bout of moving it 6' here and there to park it up) I can imagine it ending up flat from sitting there. Leaving a battery flat for a period wrecks the capacity and ability to hold charge. Result, as battery that'll just about hold one good start for a day or so.

Thanks

I'll start there. Once in, I've been reading up on checking for parasitic draw, and there seems to be a few methods with a multimeter. Any tried and tested ways you could recommend?

smorris_12 · Post by **smorris_12** » Wed May 31, 2023 6:09 pm

Start with just putting it between battery terminal and lead. That'll tell you if there is actually a high draw when the car's off (make sure the inside light is off, particularly if you start on the 200mA setting rather than the 10A one.)

I don't think Micras of this era will have anything that stays awake for 20 minutes like later BMW's do so you can do the test straight away.

inkey$ · Post by **inkey$** » Wed May 31, 2023 6:12 pm

smorris_12 wrote: ↑Wed May 31, 2023 6:09 pm Start with just putting it between battery terminal and lead. That'll tell you if there is actually a high draw when the car's off (make sure the inside light is off, particularly if you start on the 200mA setting rather than the 10A one.)

I don't think Micras of this era will have anything that stays awake for 20 minutes like later BMW's do so you can do the test straight away.

Will do. And thanks again. Very much appreciated smorris_12

smorris_12 · Post by **smorris_12** » Wed May 31, 2023 6:21 pm

A pleasure. Let us know how it goes.

inkey$ · Post by **inkey$** » Fri Jun 02, 2023 4:52 pm

smorris_12 wrote: ↑Wed May 31, 2023 6:21 pm A pleasure. Let us know how it goes.

All went well. Measured the battery this morning and it was only 10v with ignition off, so put in a new battery and got the car through its MOT. Now taxed, tested and ready for sale (after some fettling from me). Added a physical battery isolator too, until I can see what if anything is drawing current from the battery over time.

inkey$ · Post by **inkey$** » Fri Jun 02, 2023 7:33 pm

smorris_12 wrote: ↑Wed May 31, 2023 6:21 pm A pleasure. Let us know how it goes.

Just checked for parasitic drain too. Disconnected the negative cable, set the multimeter to 20A and created a series across the battery. Results came out as 0.26. Is that okay do you think?

smorris_12 · Post by **smorris_12** » Fri Jun 02, 2023 7:47 pm

Hmm. 260mA is on the high side. That would fully flatten a 40Ah battery in a week. Might be worth leaving it for 20 minutes or so with all the doors shut and ignition off etc and see if it drops down to something more sensible.

inkey$ · Post by **inkey$** » Fri Jun 02, 2023 7:49 pm

smorris_12 wrote: ↑Fri Jun 02, 2023 7:47 pm Hmm. 260mA is on the high side. That would fully flatten a 40Ah battery in a week. Might be worth leaving it for 20 minutes or so with all the doors shut and ignition off etc and see if it drops down to something more sensible.

Will do. Might start pulling fuses too, see if anything drops. So I’m aiming for 20V test resulting in around 0.02mA?

smorris_12 · Post by **smorris_12** » Fri Jun 02, 2023 10:34 pm

"20V test"?

But, yes, quiescent current for a car should be lower. 20mA (0.02A) wouldn't be unreasonable. Mind you, I reckon a Micra would be lower again.

Just found this thread:

https://www.honestjohn.co.uk/forum/post ... -k12-1-2--

while wondering what idle current ought to be.

inkey$ · Post by **inkey$** » Sat Jun 03, 2023 10:08 am

smorris_12 wrote: ↑Fri Jun 02, 2023 10:34 pm "20V test"?

But, yes, quiescent current for a car should be lower. 20mA (0.02A) wouldn't be unreasonable. Mind you, I reckon a Micra would be lower again.

Just found this thread:

https://www.honestjohn.co.uk/forum/post ... -k12-1-2--

while wondering what idle current ought to be.

My mistake. I meant setting the multimeter to 10A and testing

Thanks for the Honest John link too. I read that a while back, so if none of the fuses help drop the draw I’m going weigh up my options on next steps.

smorris_12 · Post by **smorris_12** » Sat Jun 03, 2023 10:20 am

It was the coincidental current that got me. I reckon that fuse 7 is the first one to try.

inkey$ · Post by **inkey$** » Sat Jun 03, 2023 10:47 am

smorris_12 wrote: ↑Sat Jun 03, 2023 10:20 am It was the coincidental current that got me. I reckon that fuse 7 is the first one to try.

You and the HJ thread are now confirmed correct. I just pulled Fuse 7 and the draw dropped right down to acceptable levels immediately. Problem found. Now to try and fix! (Or live with a battery cut off switch)

inkey$ · Post by **inkey$** » Thu Jun 08, 2023 2:44 pm

smorris_12 wrote: ↑Sat Jun 03, 2023 10:20 am It was the coincidental current that got me. I reckon that fuse 7 is the first one to try.

Considering a fuse bypass switch for inside the car so I don't have to open the bonnet every time and connect the battery. Do you reckon one of these would work on the immobiliser fuse okay? Think they're primarily designed for towing, but thought the theory must be the same for any fuse. Just unlock the car with the key, jump in and 'switch on' the immobiliser.
https://shop.mazacio.com/products/car-fuse-bypass

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