[2ndcivic]

I have a very old battery charger, basically a transformer/rectifier with ampere meter on the front.

I used it several times before the fusebox recall, but that has now totally fixed the occasional flats I had before the fusebox swap.

However I do not use the car everyday and need a charge up during cold weather etc.

Nowadays we have electronic switching chargers with auto trickle on sensing full voltage etc. Is it worthwhile buying one of these for the Civics sealed battery? Or is my old charger good enough?

I see the meter start off at an amp or so on connection and go down to very small current after several hours charging so it must be self compensating as the voltage reaches optimum. I'm just wondering if you electronic experts would regard it as necessarily a bad idea for modern batteries.

thanks

 

[TommyLamb]

Hi 2ndcivic.

As mentioned on another post, somewhere, I'm a battery engineer. This involves industrial batteries, chargers, UPS etc...

How long are you leaving your car for before turning the engine over? I left mine, whilst we went on holiday for 4 weeks to Australia in January. Luckily we missed the 2ft of snow and -16DegC temps while we were away and by the time we got back it was all gone. Jumped in the Civic, that had been kept on the road outside and it started up straight away.

A modern rechargeable battery should keep it's charge for 6 months before it starts to loose voltage.

If you still feel the need to charge you battery your charger sounds fine to me. As you say when the charger has been on for a while you see the current drop.

The only problem I could see from what you've written is that I often work with batteries, in series, up to 600V. When the UPS/charger is charging them to float, you call it trickle, then it's normally around 4A. A single 12V block charging at a current of 1A for a period of hours seems a bit strange to me.

 

[TommyLamb]

Hi 2ndcivic,

I should also mention that the charging current would depend on how flat your battery is. If it is completely flat, less than 1.8v per cell, then it may pull 1A for a longer period. Thinking about it... Then if your chargers max out put is around 1A then it makes sense.

Tommy

 

[2ndcivic]

Hi there, and thanks for your reply.

I drive it maybe once or twice a week for short urban journeys, then maybe 200 to 400 mile trips every month or two.

Since the fusebox change it has been fine even if left for 2 weeks or more - fast turnover and quick start. You can always tell from the strength of the indicators when you turn the alarm off. Before the fusebox fix they were insipid on the few occasions it went flat.

The dealer did change the battery before the fusebox was identified as a problem, and this new battery has been flat maybe twice before the recall, and I seem to remember reading that once flat a battery will never regain its full power even again after recharging.

However my previous generation Civic went flat a few times over Xmas when not used for a couple of weeks in the snowy weather and needed a trickle occasionally in the garage, albeit with a not new battery.

I probably did not give an accurate description of charging on a good battery. On connection the needle will be around 1 to 1.5 A and soon come down, not necessarily stay there, after some hours it will hover just above 0, but the meter is a 10A scale and probably not that accurate for low levels.

If there's nothing wrong with old "analogue" chargers in principle I've saved a few quid... Thanks very much for putting my mind at rest.

 

[TommyLamb]

No problem 2ndcivic.

Just a bit more info, I'm a bit of geek when it comes to batteries :facepalm:.

If for instance the battery were 100 Amp/Hr. Then a flat battery would take 100 hours to charge at 1Amp. However like you say a completely flat block is very hard to bring back. The max normal charge you want to put into it would be 10%. So 10 Amps for 10 hours. You may get away with bringing it back to life, below 1.8 Volts per cell (6 cells in a 12V block), at 20%. 20 Amps for 5 hours. If charging like this though I would keep an eye on the temperature of it. They do like to explode!

Also a flat battery could be due to an alternator problem. Does anybody know the alternator output current? I assume it would be easy to test just by putting an ameter on it?

Tommy