Battery charging: correct procedure for NZ Toyota?

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geekIT

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#243250 3-Dec-2018 15:00

Just been asked to charge a Toyota car battery for an absentee neighbour, so thought I'd better do it right.

Which method is best?

1) Leave battery cables connected and attach the charger cables to the battery terminals (ie, on top of the main cable terminals)?

2) Leave battery cables connected, attach the charger's positive cable to the positive terminal, but attach the charger's negative cable to chassis?

3) Disconnect the battery from car altogether, then charge it?

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trig42

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#2138607 3-Dec-2018 15:03

I'm not sure, but I wouldn't disconnect the battery - it could screw with the car's computer (and radio etc.)

A charger should only out put as much as a car alternator (or less) so should not cause any havoc with the cars electrical system. I'd just put a charger clamp on each pole of the battery.

Jase2985

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#2138613 3-Dec-2018 15:18

what kind of car is it?

how long are they away for?

what kind of charger do you have?

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#2138614 3-Dec-2018 15:20

Charge for 12 hours at least once every 6 - 8 weeks

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#2138615 3-Dec-2018 15:21

Dont disconnect it as mentioned above - did that once on my old Cynos, scared the hell outta me afterwards because the car ran like crap, thought I had killed something - turns out disconnecting the battery reset the factory ECU and took it a few days to get itself back in line.

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davidcole

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#2138622 3-Dec-2018 15:41

I've got a power socket trickle charger that keeps my car topped up. And since my battery is in the boot underneath the spare wheel, it actually has terminals under the front bonnet.

Makes it fairly easy to leave it charged in.

Normal battery chargers dont normally have the trickle mode.....and varying battery chemistries sometimes take different chargers. I would have thought if you neighbour was asking you to do this they'd supply the charger.

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frankv

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#2138625 3-Dec-2018 15:42

geekIT:

2) Leave battery cables connected, attach the charger's positive cable to the positive terminal, but attach the charger's negative cable to chassis?

The reason for doing this is (if you don't have a sealed battery, which you probably do have) that charging causes hydrogen gas to be released from lead-acid cells. In theory, when you disconnect the charger, there *could* be a spark, which *could* ignite any hydrogen gas which *could* be near the battery. So you connect the positive to the positive, then connect negative to the chassis (somewhere away from and preferably below the battery), and disconnect negative from chassis first.

If you choose not to do it this way, do place your phone for a selfie video... in the more-lilekly-to-be-struck-by-lightning chance that you cause an explosion, you'll be ready to Go Viral.

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geekIT

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#2138648 3-Dec-2018 17:05

frankv, thanks for that, it's kinda what I thought but wanted to be sure, seeing as it's not my car. If it was mine I'd just leave everything the way it was and clip the charger leads on top of the main ones.

But I can see the reason for the chassis connection.

Someone else asked which model. I don't know for certain because I'm just advising his daughter over the phone - they're on a remote sheep station - but I think it's a latish model Camry.

Thanks to all who responded :-)

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Technofreak

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#2138651 3-Dec-2018 17:12

Some of the more modern battery chargers won't charge properly with the battery still connected to the car. My battery charger has some smarts and changes the charge rate dependent on the batteries state of charge. It gets confused if the battery is still connected as the draw from the various items still powered up interfere with the chargers sensor. I disconnect the battery on my car when I charge the battery.

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Aredwood

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#2138672 3-Dec-2018 17:28

And some old style chargers will stuff a battery from overcharging if you leave them connected too long.

And there are some other chargers that will slowly discharge the battery if you leave them connected to the battery without also being plugged into mains power.

The other rule of thumb, is to disconnect and connect the charger terminals to the battery, only while the mains is switched off. Idea being to reduce the chance of sparks from breaking or starting a current flow.

Agree with other recommendations of leaving the battery connected. But check what kind of charger you have first.

Scott3

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#2138912 3-Dec-2018 22:36

How long are they away for?

Ideally take the car for a drive (30min+, take it for a weekend outing or something) every three or four weeks. Not only will that charge the battery, but it will stop moving parts from jamming up, and tires from getting flat spots etc. Of course probiably not a good idea if the car is not insured etc.

When I had a usable garage, I would just leave my car with a smart charger on it (no wires disconnected) when I went overseas. That battery was at the end of it's life, so would be dead when I came back in 2 weeks if I didn't. That car now has a new battery, and lives outside. I ask somebody to take it for a drive if I will be overseas for more than a month.

geekIT

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#2139050 4-Dec-2018 10:15

Heads-up:

My mate's daughter managed to get the car started but it sounds like they need a new trickle charger, or a jump-start kit, or both.

Recommendations?

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wratterus

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#2139055 4-Dec-2018 10:22

CTek chargers. Great things. There are a bunch of various models/power outputs. The 5 amp one is a good fit for normal charging, they also make chargers specific for maintenance/cars that sit for long periods of time. Very minimal draw if they are left connected too.

robjg63

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#2139105 4-Dec-2018 10:47

Scott3:

How long are they away for?

Ideally take the car for a drive (30min+, take it for a weekend outing or something) every three or four weeks. Not only will that charge the battery, but it will stop moving parts from jamming up, and tires from getting flat spots etc. Of course probiably not a good idea if the car is not insured etc.

I would agree that this would be the simplest thing to do. An alternator charges a battery pretty quickly.

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allio

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#2139220 4-Dec-2018 13:06

wratterus:

CTek chargers. Great things. There are a bunch of various models/power outputs. The 5 amp one is a good fit for normal charging, they also make chargers specific for maintenance/cars that sit for long periods of time. Very minimal draw if they are left connected too.

Heartily recommend the 5 amp CTek.

One thing to note about charging the battery without disconnecting it from the car: it may set off your car alarm. And not necessarily right away - maybe after about six hours of charging, at 2am...