Advice re battery charger (rating)

peckerhead

Howdy all. A quick question, if I may, for them what knows about these things.

To charge a battery for a 1.9 TDi Octavia (61 Ah), am I wasting my time buying a lower rated (cheapo) charger like this? I see some people saying that a 4A charger is only good for cars up to 1.2l, others who say it'll do the job fine but will be very slow — like a day or two rather than just overnight (and isn't slower, low-amp charging better for the health of the battery, anyway?)

Opinions? (or even facts? ) I don't want to spend any more than necessary and don't really mind if charging takes a bit longer — as long as it does actually charge the battery reasonably fully (I know that 'rechargeability' diminishes as the battery gets older...)

TIA

visual

the 4 amp charger will work but will be slower as you said.
the length of time depends on how much the battery is discharged.
would be much better to use a 8 amp charger, should charge your battery over night or even quicker depending on how much it is discharged.

Longer charge time isn't needed as long as you don't over charge the battery, plus as battery gets nearer its full charge the current drops down anyway.

Not a lot of people buy chargers these days as the cars alternator is more than capable of keeping a good battery charged. A poor or faulty battery needs replacement anyway and regularly recharging is only a short term gap.

dr.fuzzenstein

Get 8 amp at least. My 8 amp charger still takes hours to charge up my battery if it's really flat(1.8 TDCI), which I had to do since there was a fault with a fuel line and it took hours of noodling the engine to get it back working again.
I love reviews like the one guy who gave it one star, because it didn't work for him. I work in tech support and I have to deal with flutes like that every day, just because it doesn't work for him, doesn't mean every single one of them doesn't work.
I'm sure it works just fine, but for a heavy duty battery for a diesel it's just too puny.

visual

there is one review saying you don't need to disconnect the battery to charge :eek:

have to take the reviews with a pinch of salt

Esel

peckerhead wrote: »

Howdy all. A quick question, if I may, for them what knows about these things.

To charge a battery for a 1.9 TDi Octavia (61 Ah), am I wasting my time buying a lower rated (cheapo) charger like this? I see some people saying that a 4A charger is only good for cars up to 1.2l, others who say it'll do the job fine but will be very slow — like a day or two rather than just overnight (and isn't slower, low-amp charging better for the health of the battery, anyway?)

Opinions? (or even facts? ) I don't want to spend any more than necessary and don't really mind if charging takes a bit longer — as long as it does actually charge the battery reasonably fully (I know that 'rechargeability' diminishes as the battery gets older...)

TIA

Divide the #Ah figure of the battery by the #A rating of the charger to calculate the no. of hours needed to fully charge a completely discharged battery. You are right in thinking that slower charging is better for a battery.

bbam

visual wrote: »

there is one review saying you don't need to disconnect the battery to charge :eek:

have to take the reviews with a pinch of salt

It is dangerous, but it does work...
I do it on occasion with our tractor as access to the terminals is very tight, actually I clip it onto the live up at the solenoid - no chance of the battery exploding then, I always charge on the low setting as there is less chance of damaging the battery..

peckerhead

Cheers all, much appreciated. I take the point about it being a bit puny for a big diesel battery, but I don't mind if it takes 15/16 hours (thanks for the formula, Esel!) and I don't see myself having to use it all that often. My battery is only a couple of years old, but has been a bit iffy lately when the temperatures dropped below 0°. A new one costs €90/€100 locally, so I'm hoping that I might get a couple more winters out of this one.

Also have an old motorbike sitting up in the garage that will need a charge when I take it out again... 12V, 8 Ah — so a couple of hours, right?

Esel

peckerhead wrote: »

Also have an old motorbike sitting up in the garage that will need a charge when I take it out again... 12V, 8 Ah — so a couple of hours, right?

Yeah, 2 hours from flat. You would be well advised to charge it regularly during the period it is sitting up - a battery can die if left flat for long enough.