Battery Charger Technical Stuff

Dead battery on the Landy today, cos it hasn't been used for about three weeks. Got a pulsing through the breaks and a bit of a death wobble on the steering, so the Mrs isn't keen to use it. I've got far to far a commute to use her as a daily drive. Anyway, been checking the wheel bearing for the break pulsing. Checked the fronts about three weeks ago and all ok. Been involved in a beer festival and so too busy to check rears out. Did that today though and there was quite a bit of play on the rear offside bearing. Tremendous! Hopefully that will be the breaks sorted now that I've nipped the bearing up. Come test drive the battery was dead as a dodo. I know I've got some leakage and suspect the tracker, anyway I'd just let time get away from me. Put mu Halfords fully automatic charger on and nowt happened. Tested it with a multimeter and it looks like the transformer is carped.
So, here is the info I'm after. I've been looking at chargers online and they have statements in their descriptions that say stuff like 'only suitable for diesel engines up to 1400cc'. My Halfords one said suitable for 4x4's so I'm presuming it should have been ok. HOWEVER! I've got a 105Ah battery. Surely that couldn't have carped my charger? This 1400cc statement must be related to the presumed Ah rating of the battery. Can someone educate me and tell me why that is so important? Why isn't it just a case of taking more hours to fully charge? Cheers.

How flat was the battery as some intelligent chargers will not charge if to low as it thinks there is no battery, I have an Optimate 2 motor bike charger that I use on 120ah battery's it just takes longer, I have tricked it to charge very flat battery`s by connecting a couple of leads to the flat one from a good one to get the charger to start then remove leads.

What @brianp38dse said .. clever chargers are sometimes too clever.

Ctek chargers all the way. Will start charging and de-Sulphating a battery that's as low as 2Volts.

brianp38dse said:

How flat was the battery as some intelligent chargers will not charge if to low as it thinks there is no battery, I have an Optimate 2 motor bike charger that I use on 120ah battery's it just takes longer, I have tricked it to charge very flat battery`s by connecting a couple of leads to the flat one from a good one to get the charger to start then remove leads.

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Now that's interesting cos I reckon it is completely and utterly dead flat. Hmm,so some how I need to convince it that there is a batter there? What if I connect it via jump leads to another battery in one of the other cars?

Al2O3 said:

Now that's interesting cos I reckon it is completely and utterly dead flat. Hmm,so some how I need to convince it that there is a batter there? What if I connect it via jump leads to another battery in one of the other cars?

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That will do worth a try if it saves the battery nothing to loose, I know I check my charger with a multimeter and got nothing as they are first reading the state of the battery as to what it needs to do be it charge or disulphate.

brianp38dse said:

That will do worth a try if it saves the battery nothing to loose, I know I check my charger with a multimeter and got nothing as they are first reading the state of the battery as to what it needs to do be it charge or disulphate.

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Cheers, mate. I really appreciate this. Yeah, I checked the croc clips with a bulb first and nothing. Tried a few other 12v bulbs and still nothing. Put the multimeter on and it was showing -0.4V I did check the output from the coil though and it was still showing about +0.4V The battery is only about 2yrs old. What does disulphate mean? Is that bringing it back to life?

As the battery voltage goes down the plates in side get a deposit on them from the acid and this effects the battery, when a charger disulphates (if it is capable of it) it pulses a higher voltage say 16v and this brakes down the deposit back in to the acid to restore the battery.
if the battery is only 2 years old is it still under warranty.

brianp38dse said:

As the battery voltage goes down the plates in side get a deposit on them from the acid and this effects the battery, when a charger disulphates (if it is capable of it) it pulses a higher voltage say 16v and this brakes down the deposit back in to the acid to restore the battery.
if the battery is only 2 years old is it still under warranty.

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It might still be under warranty, but I've carped it by letting it go flat. I'll try the charger on another car tomorrow and see it it starts charging. If it does, I'll try fooling the charger in to charging my defender battery by putting it in parallel with the car. If I can get a bit of charge in it, then the charger might go in to the disulphate mode when I connect it on it's own. Hopefully, the charger isn't simply carped!

Ctek are the way to go. I had a charger previously Thant needed 11v to start charging which is rubbish. I’ve used my dads old bog standard charger on low a few times to get a battery over 11V, then hook up the maintenance charger. Just be careful cross wiring battery’s and chargers, you don’t want one to explode!

Huddy84 said:

Ctek are the way to go. I had a charger previously Thant needed 11v to start charging which is rubbish. I’ve used my dads old bog standard charger on low a few times to get a battery over 11V, then hook up the maintenance charger. Just be careful cross wiring battery’s and chargers, you don’t want one to explode!

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How will one explode?

I don’t understand the specifics but I know it doesn’t take much. the risk is when you disconnect the good battery to let dead one charge whilst the charger is on it could go pop. Forcing charge into such a dead battery may also cause it to let go pop. Leaving 2 batteries attached to a charger only intended for one could cause issues also at the charger end.

I’m a very ‘play it safe’ kind of guy, Please be very careful if you do try it.

Huddy84 said:

I don’t understand the specifics but I know it doesn’t take much. the risk is when you disconnect the good battery to let dead one charge whilst the charger is on it could go pop. Forcing charge into such a dead battery may also cause it to let go pop. Leaving 2 batteries attached to a charger only intended for one could cause issues also at the charger end.

I’m a very ‘play it safe’ kind of guy, Please be very careful if you do try it.

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Pop, is such an insignificant word. Is it a pop, or a big fecking bang? With acid all over the place?

It could be a pop and dribble of acid, could be a fireball. I just had a quick look on google and found this; https://mechanics.stackexchange.com...-what-are-the-reasons-a-battery-would-explode

I had a feeling it was relating to risk of sparks, and this says it’s the hydrogen given off by lead acid batteries that ignites. So primary thing is to avoid doing anything to create a spark whilst charging.

The other thing is if your plates in the battery are warped or damaged and you force charge into the battery, the spark could occur inside with same effect. I think this is why some chargers require 11V, the ones that don’t have the technology to assess the battery and stop.

Personally I worry more that the battery goes “pop”, the other casing cracks and spits the acid out into my eyes. Likelihood of it happening is probably minimal, but the severity of it if it does happen is what worries me.

Huddy84 said:

It could be a pop and dribble of acid, could be a fireball. I just had a quick look on google and found this; https://mechanics.stackexchange.com...-what-are-the-reasons-a-battery-would-explode

I had a feeling it was relating to risk of sparks, and this says it’s the hydrogen given off by lead acid batteries that ignites. So primary thing is to avoid doing anything to create a spark whilst charging.

The other thing is if your plates in the battery are warped or damaged and you force charge into the battery, the spark could occur inside with same effect. I think this is why some chargers require 11V, the ones that don’t have the technology to assess the battery and stop.

Personally I worry more that the battery goes “pop”, the other casing cracks and spits the acid out into my eyes. Likelihood of it happening is probably minimal, but the severity of it if it does happen is what worries me.

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Ok, cheers. Think I'll try and pull the Landy up the drive to a position where I can jump it from the mondeo. If i can get it started I'll take it for a long run and see if the charger works after that

Cool. If it does run after being jump started it should be a good sign, and you’ll get a very short window as the voltage drops to get your charger on it.

If in doubt I’d just bite the bullet and either get a new battery or find someone with a better spec charger. The more expensive ones will either recondition the battery or tell you it’s dead.

I upgraded to a Ctek MXS 5.0 and it’s an amazing bit of kit. Around £65 I think.

I second the Ctek chargers, have resurrected several "dead" batteries with mine. A properly designed charger should never cause the battery to release significant hydrogen. The Ctek has a recondition mode that will briefly raise the voltage to release hydrogen and promote mixing of the electrolyte in batteries that have been stationary for extended periods.

Huddy84 said:

It could be a pop and dribble of acid, could be a fireball. I just had a quick look on google and found this; https://mechanics.stackexchange.com...-what-are-the-reasons-a-battery-would-explode

I had a feeling it was relating to risk of sparks, and this says it’s the hydrogen given off by lead acid batteries that ignites. So primary thing is to avoid doing anything to create a spark whilst charging.

The other thing is if your plates in the battery are warped or damaged and you force charge into the battery, the spark could occur inside with same effect. I think this is why some chargers require 11V, the ones that don’t have the technology to assess the battery and stop.

Personally I worry more that the battery goes “pop”, the other casing cracks and spits the acid out into my eyes. Likelihood of it happening is probably minimal, but the severity of it if it does happen is what worries me.

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In that link I would suspect that the truck would be 24 v and the bike will be 12 v. You can jump a 12 v vehicle from a 24 v one as long as you get the leads correct and just connect to one battery on the truck (it will have 2 x 12 v batteries in series). That incident could just be down to stupidity / lack of knowledge.
With normal batteries they should have vent system to allow any excessive pressure out before it get to the point of trying to split the case so that shouldn't be an issue. Modern chargers (ctek all the way!) will also prevent excessive off-gassing as they limit the charge current depending upon battery voltage. Where you may get issues is where you have a damaged battery and just parallel connect a good one and leave it like that, there is no current control / monitoring so potentially 100s of amps could flow and this can then damage the flat battery and cause all kind of overheat / off-gassing issues.
If you do need to fool a slightly naff 'modern charger' by using a second battery, just connect them for a few seconds to let the charger get started then disconnect the good battery and let the charger get on with the rest.

A lead acid battery produces a small amount of hydrogen. Even if it's called a sealed lead acid or value regulated lead acid it will still have the vent to vent oft hydrogen. The hydrogen builds up int side and the vent opens if the pressure is high enough, the hydrogen escapes out the vent and the vent closes when the pressure drops. The is normal for valve regulated lead acid batteries. Hydrogen is created by the chemical charge process and not caused by the charger itself. A slower charge reduces the amount of hydrogen produced over a certain time period.

The topic of charger size.. it's true a lower current charger will still charge a battery bigger than what the charger is rated for, and take longer. But some chargers will struggle. Also the amps of charge dictates the quality of charge. As batteries get bigger they need a larger ideal current to charge then. Using the correct current gives them a better quality of charge. When lead acid batteries charge they saturate so limit the current passed through them anyway.

The average motorist doesn't know the size of their battery. So the rule of thumb was to use the engine size as a reference. Bigger engines, diesels and 4x4's have bigger batteries so you would point owners of these vehicles towards the larger battery chargers.

Huddy84 said:

Cool. If it does run after being jump started it should be a good sign, and you’ll get a very short window as the voltage drops to get your charger on it.

If in doubt I’d just bite the bullet and either get a new battery or find someone with a better spec charger. The more expensive ones will either recondition the battery or tell you it’s dead.

I upgraded to a Ctek MXS 5.0 and it’s an amazing bit of kit. Around £65 I think.

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Right, had dog out for a long walk then come back and put the charger on the Citroen C1 Charging LED came on for 10 seconds then it switched to the charging/maintaining LED, so the charger is obviously ok. I just need to somehow jump the Landy. Problem is the landy is at the bottom of a sloping drive and it's a tad heavy to push to the top What systems will I cock up on the Mondeo if I take the battery off it?