Car battery during lockdown

castle96

Slightly off topic but may help some/me
I have a Mitsubishi Eclipse Cross. You can only start with the clutch fully down. If I need to bump start, that just wont happen will it? If I let the clutch up when rolling then it won't start ??

oldagetraveller1

Is there a microswitch that the clutch pedal lever contacts? If so it could be posible to "fool" that switch with some tape or even a clothes peg etc.?

AdrianC

castle96 said:

Slightly off topic but may help some/me
I have a Mitsubishi Eclipse Cross. You can only start with the clutch fully down. If I need to bump start, that just wont happen will it? If I let the clutch up when rolling then it won't start ??

The clutch pedal is a cut-out for circuit operating the starter motor. If you're bump-starting, you aren't using the starter motor.

castle96

thanks AC (if you're right). I should try it to ensure...

ChemistryTeacher

tedted said:

ChemistryTeacher said:

With modern battery chargers there is very little damage you can do to the car when charging with everything still connected. Any ripple voltage is smoothed out by the massive battery (a large buffer). Never connect a battery charger to the car without the battery. If you do disconnect the battery then you run the risk of a voltage spike when reconnecting, or electronics losing settings or reporting disconnection faults etc. to the ECU.
Alternators charge batteries pretty quickly these days, so it usually only takes about 30s for the starter-motor current to be replaced on the battery (assuming a normal first start). Alternators don’t charge differently at different engine speeds (hence the name). Longer starts will require more running charge time commensurately. However, repeated cold starts increase engine wear etc. so best to avoid if possible.
To answer the original question, the best thing you can do is to leave a smart charger connected to the battery (direct + to + and - to -) if it’s going to be left unused for weeks. If only days then if it’s a healthy battery then no problem.
Even the lowest power smart charger (Ctek are a very reputable brand - can be found easily online) will keep a healthy battery topped up (but to charge a large battery from dead you’ll need a higher power charger), so if it’s a healthy battery perhaps just get a cheap one for now. Lead-acid batteries also have a finite life span (depending on engine size etc.). If you get more than 8 years out of one then you can consider yourself lucky. Yes, a lot of factors to consider, but if the car normally starts normally then you’ll probably do best to just get a cheap smart charger and leave it hooked up. If the battery’s in the boot (rather than under the bonnet) then it’s even safer to leave hooked up in all weather since you should be able to weather-proof the extension lead by carefully shutting the boot gently over the mains cable.

a lot of the above is nowhere near right.

Please do elaborate. I’m happy to explain the underlying physics/chemistry. Otherwise just another unhelpful post.

Ectophile

ChemistryTeacher said:

tedted said:

ChemistryTeacher said:

With modern battery chargers there is very little damage you can do to the car when charging with everything still connected. Any ripple voltage is smoothed out by the massive battery (a large buffer). Never connect a battery charger to the car without the battery. If you do disconnect the battery then you run the risk of a voltage spike when reconnecting, or electronics losing settings or reporting disconnection faults etc. to the ECU.
Alternators charge batteries pretty quickly these days, so it usually only takes about 30s for the starter-motor current to be replaced on the battery (assuming a normal first start). Alternators don’t charge differently at different engine speeds (hence the name). Longer starts will require more running charge time commensurately. However, repeated cold starts increase engine wear etc. so best to avoid if possible.
To answer the original question, the best thing you can do is to leave a smart charger connected to the battery (direct + to + and - to -) if it’s going to be left unused for weeks. If only days then if it’s a healthy battery then no problem.
Even the lowest power smart charger (Ctek are a very reputable brand - can be found easily online) will keep a healthy battery topped up (but to charge a large battery from dead you’ll need a higher power charger), so if it’s a healthy battery perhaps just get a cheap one for now. Lead-acid batteries also have a finite life span (depending on engine size etc.). If you get more than 8 years out of one then you can consider yourself lucky. Yes, a lot of factors to consider, but if the car normally starts normally then you’ll probably do best to just get a cheap smart charger and leave it hooked up. If the battery’s in the boot (rather than under the bonnet) then it’s even safer to leave hooked up in all weather since you should be able to weather-proof the extension lead by carefully shutting the boot gently over the mains cable.

a lot of the above is nowhere near right.

Please do elaborate. I’m happy to explain the underlying physics/chemistry. Otherwise just another unhelpful post.

"Alternators charge batteries pretty quickly these days, so it usually only takes about 30s for the starter-motor current to be replaced on the battery (assuming a normal first start). Alternators don’t charge differently at different engine speeds (hence the name)" isn't a good start.

Just because it's an alternator, not a dynamo, doesn't mean it can magically produce huge currents when on tick-over.

Several years ago, I was at a particularly wet event.  At the time, I was driving a 2.5 litre diesel Land Rover, with a particularly big battery.  Unusually, the Landy had a battery voltage gauge on the dashboard.

The Landy stared fine (it was a diesel, damp doesn't matter).  The car next to mine didn't.  So it was out with the jump leads, and I left the Landy idling to stop the battery going flat.

After many attempts to start the car next to mine, the battery gauge had dropped alarmingly close to the red "flat" end of the dial.  When I spotted that, I booted the accelerator to bring the engine up to a normal driving speed.  Within seconds, the battery gauge was back to normal, as the alternator was generating at full power.

The other car did eventually start, and I left the Landy idling until it was time to drive off - there was no way I was going to turn it off until the battery got a really good charge driving home.