Optimate or C-Tek car battery charger?

[SmartShack]

I don`t know anything about Optimate but I know the C-tek works really well and simple to use and plug in when needed !

 

[Fulcrum29]

Every time I see threads like this I wished that we had our own local Project Farm.

 

[Foxhound5366]

Aaaaaaand final update, she works.

Charger in maintenance mode:


After disconnecting charger, with only a 1 hour top-up, battery was at a perfect 12 volts (up from 11.7 before).

 

[Foxhound5366]

But the ground terminal is connected directly to the negative terminal on the battery? What is the difference to connecting it directly?

Dunno, the VW technician who came out to jump my car the one time told me that's important ... all I can see is that the top of the battery has way more wires in that little black box than just the usual two battery terminals, so maybe connecting directly to the battery during a jumpstart is somehow more harmful to those wires than connecting to the ground terminal.

Edit: I've heard about this explosion risk described here before, but the tech was specific about saying it could fry the electronics so I dunno: "Typically, when a person jumpstarts a car, sparks can occur. That’s why it is recommended that you connect the negative jumper cable to the vehicle body and not the negative post of the battery. This is so you can avoid sparks from occurring near the battery where flammable hydrogen gas may be present, resulting in a possible explosion."

 

[Smugs]

Full charge is actually 12.6 volts.

 

[Geoff.D]

Aaaaaaand final update, she works.

Charger in maintenance mode:
View attachment 996162

After disconnecting charger, with only a 1 hour top-up, battery was at a perfect 12 volts (up from 11.7 before).

11.7V before you started trickle charging after running the car on trip?

That battery is limping along basically already ruined.

 

[Foxhound5366]

11.7V before you started trickle charging after running the car on trip?

That battery is limping along basically already ruined.

I dunno, that was just the reading through the VW Connect dongle, which you plug into the OBD port, and not across the battery directly. I suspect VW's onboard voltmeter isn't that accurate. The battery was tested recently by the VW workshop for a week and given a clean bill of health. One day I'll get a voltmeter.

 

[Geoff.D]

Has the alternator been checked? What is the charging voltage when running?
How do you test a battery in a workshop for a week?

 

[Foxhound5366]

Has the alternator been checked? What is the charging voltage when running?
How do you test a battery in a workshop for a week?

I presume VW checked the alternator. Besides which, if the alternator weren't charging, the vehicle electronics would shut down when driving (e.g. no aircon and no electric windows), but it doesn't do that. My problem was around the battery discharging, but it did charge up fine. And they just kept the car for a week to test the battery discharging and current retention, and claimed everything was within spec at the end. That's when they fobbed it off to the tracker, and the tracker technician came and did his own checks.

 

[Geoff.D]

I presume VW checked the alternator. Besides which, if the alternator weren't charging, the vehicle electronics would shut down when driving (e.g. no aircon and no electric windows), but it doesn't do that. My problem was around the battery discharging, but it did charge up fine. And they just kept the car for a week to test the battery discharging and current retention, and claimed everything was within spec at the end. That's when they fobbed it off to the tracker, and the tracker technician came and did his own checks.

Seriously suggest you get a friend with a multimeter to help you verify that the battery voltage is about 14.4 volts when the car is running. That ensures enough power available to properly charge the battery in the shortest time after starting.
Then, verify what the voltage drops to when the engine is off. The voltage should be about 12.7 to 12.8 volts. If it immediately drops below 12 volts, you have a real problem on your hands and no amount of trickle charging is going to save that battery.

 

[Foxhound5366]

Seriously suggest you get a friend with a multimeter to help you verify that the battery voltage is about 14.4 voltsxwhen the car is running. That ensures enough power available to properly charge the battery in the shortest time after starting.
Then, verify what the voltage drops to when the engine is off. The voltage should be about 12.7 to 12.8 volts. If it immediately drops below 12 volts, you have real problem on your hands an no amount of trickle charging is going to save that battery.

Thanks Geoff ... I don't have such a friend, but I'll buy one myself. Can you recommend one on Takealot that would do the trick?

For now the Bosch charger is happy with the battery (it does diagnostics to ensure the battery is full and holding charge), so that's a start. I'd expect to see red lights if things weren't ok.

 

[johnjm]

I presume VW checked the alternator. Besides which, if the alternator weren't charging, the vehicle electronics would shut down when driving (e.g. no aircon and no electric windows), but it doesn't do that. My problem was around the battery discharging, but it did charge up fine. And they just kept the car for a week to test the battery discharging and current retention, and claimed everything was within spec at the end. That's when they fobbed it off to the tracker, and the tracker technician came and did his own checks.

Dude, it’s either the tracker draining the batter, or the battery is a bit old now.

You can try tighten the terminals on the battery because you would be surpirsed how sensitive car electronics are.

 

[Foxhound5366]

Dude, it’s either the tracker draining the batter, or the battery is a bit old now.

You can try tighten the terminals on the battery because you would be surpirsed how sensitive car electronics are.

Orrrrr I just don't drive it enough during lockdown (thanks to working from home now). I typically take it for a drive once every two to three days ... and try and put at least one 30km trip in, but most of my trips are short. Over time I think it just keeps compounding and the battery gets nailed.

Driving my car just to charge the battery is a waste of time and petrol, so the charger solution addresses the short-term problem

 

[Foxhound5366]

Ok so some good news is I got one of these from Takealot, and it seems to do the job just fine: https://www.takealot.com/major-tech-mtd30-digital-multimeter-2000-count/PLID52289708

According to that, my battery is delivering 12.75 volts at the terminals ... so I'm guessing the Volkswagen 'WeConnect' OBD data-plug just uses some approximation or downstream reading that's not as accurate.

I'll keep an eye on it now that I've got a multimeter and just see how it goes, but so far the Bosch charger is earning its keep: it's a cinch to unplug when I leave and reconnect when I'm back, and I don't have to waste time going on unnecessary trips just to charge my car's battery anymore

 

[Suspect99]

Ok so some good news is I got one of these from Takealot, and it seems to do the job just fine: https://www.takealot.com/major-tech-mtd30-digital-multimeter-2000-count/PLID52289708

According to that, my battery is delivering 12.75 volts at the terminals ... so I'm guessing the Volkswagen 'WeConnect' OBD data-plug just uses some approximation or downstream reading that's not as accurate.

I'll keep an eye on it now that I've got a multimeter and just see how it goes, but so far the Bosch charger is earning its keep: it's a cinch to unplug when I leave and reconnect when I'm back, and I don't have to waste time going on unnecessary trips just to charge my car's battery anymore

Is it still 12.75 volts when the car is running?

 

[Foxhound5366]

Is it still 12.75 volts when the car is running?

No I didn't try it out while the car is running. Will add that to the list of things to do I'm expecting it to be higher as the alternator charges the battery. I also want to check what the voltage is while being trickle charged, coz that should also be higher.

In unrelated news I got myself a really spiffy digital tyre pressure monitor at the same time from Takealot, so I'm officially sorted with gadgets to poke and prod my car with

 

[Geoff.D]

No I didn't try it out while the car is running. Will add that to the list of things to do I'm expecting it to be higher as the alternator charges the battery. I also want to check what the voltage is while being trickle charged, coz that should also be higher.

In unrelated news I got myself a really spiffy digital tyre pressure monitor at the same time from Takealot, so I'm officially sorted with gadgets to poke and prod my car with

That would be interesting.
Also got one of them digital jobs but went back to an analogue one because it doesn't have batteries to go flat on you in the middle of nowhere!
The Alternator voltage should be about 14.4 V

 

[Foxhound5366]

Is it still 12.75 volts when the car is running?

Ok, so here's all the readings I took tonight.

Disclaimer: I don't actually know what I'm doing, but I tried waiting between readings and double and triple-checked (voltage could change quite a bit during these phases so I waited around five minutes for it to stabilize).

13 volts on charge from the Bosch charger (in maintenance mode), up to a short pulse of 14.5 volts that drops down to 13v again.

12.67 off charge

12.22 when car is idling

12.65 afterward turning car off again

So I think the interesting thing there is the voltage with the car running ... The VW technician had explained to me previously that if the car battery is charged, the Polo will idle at 1000 rpm (which it was doing now), but if it is discharged then the car will idle at 1300 rpm to allow the alternator to charge the battery. It's all part of fuel-saving. The only way I could measure the voltage with it charging is to discharge the battery for a few days and then letting it idle ... which I don't really feel like doing for obvious reasons.

 

[KhoisanX]

The VW technician had explained to me previously that if the car battery is charged, the Polo will idle at 1000 rpm (which it was doing now), but if it is discharged then the car will idle at 1300 rpm to allow the alternator to charge the battery. It's all part of fuel-saving. The only way I could measure the voltage with it charging is to discharge the battery for a few days and then letting it idle ... which I don't really feel like doing for obvious reasons.

Just over 12V with the car running doesn't seem right, turn on all lights, demister etc and test again. If the voltage drops any further you definitely have an issue.

 

[Foxhound5366]

Just over 12V with the car running doesn't seem right, turn on all lights, demister etc and test again. If the voltage drops any further you definitely have an issue.

Yeah ok, will try that next