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Whats up with my battery?

nick_the_fish

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Discharged my battery last week by leaving the winch on for a few days by accident. When I say discharged I mean fully discharged - dash lights didn't come on and couldn't even turn on my voltmeter which only draws 15mA.

Put it onto the CTEK for 24 hours which recovered it, but now it seems to be holding a higher than usual charge - 14.5v when running at 1000 revs (usually more like 14.2v) and after 24 hours disconnected from the CTEK its still at 12.9v (usually more like 12.6v). I know that these voltages are in the acceptable range of a battery, but because they are higher than usual I have pause for thought - the last thing I need is the battery blowing up in the engine bay.

Any thoughts anyone? Should this ring alarm bells, or do I just run it for the next few months?

ps. I will be buying a new battery, but I want to wait until closer to the trip so I go away with a new battery rather than one that has been sat around on a CTEK for months on end.
 
Nick, not sure how old your battery is, but putting in the CTEK, it's likely that it's run the full recovery and recon programme which includes desulpherisation of the plates. It rather sounds as though it's done you a favour. Those new figure that you quote look like what I'd expect from a new battery. The old figures actually look a bit low. If you park up and put your head lights on for a few minutes, you probably see that float / standing charge drop off. Measuring voltages on a freshly charged standing battery will always give you a falsely high reading.
 
If it's gone below 10.5 V it will have permanently lost some of it's capacity to hold charge.As Chris said trying a load will give you some idea of what's going on.in a similar situation the CTEK seemed to work wonders but a cold evening & some short journeys round town led to mine giving up the ghost spectacularly , not even a jump start from the breakdown wagon could breath life into them .
 
Batteries are weird! Iv had my 24v on the Ramp for over 2 weeks while i chucked a load of new stuff at it.. Never started it in that 2 weeks, Started it today for the first time, It fired in to action straight away, Drove it off the ramp, Parked it up while i shifted stuff about... Got back in it..... Flat as a witches Tit... Weird!!!
 
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short journeys round town led to mine giving up the ghost spectacularly , not even a jump start from the breakdown wagon could breath life into them .

Given the situation at the moment this is what I am trying to avoid.

Just out of interest what kind of Ctek is it? Did you recondition it or just fully charge it?

It's a CTEK MXS 7.0. Its been on the CTEK almost constantly for the last few years, and TBH I thought it had been on the Recond setting for most of that time, but i'm starting to wonder if it was only on the charge setting, and it somehow switched automatically onto the Recond setting when it sensed the battery had no charge on it at all. I had thought that the default setting was Recond but maybe I was wrong.

Thanks for the input all. As David says 7 years is a good innings so I'll get a new battery tomorrow.
 
So whats the best way with the recon mode? When I leave batteries on, I dont leave them on recon, just charge. I only recon them manually if theyve been totally drained, or maybe once a year just to give them a kick.

What does everyone else do?
 
Personally I'd replace it, but if you hardly use it then just leave as is until your long trip. Won't matter if it dies whilst parked up but you just know it'll die on the most inconvenient part of your trip. :)
 
I have never had a car lead-acid battery die totally or get discharged to empty, but I have had smaller camping (low 10'sAh) lead acid batteries die, and I've never had luck reviving them, they just end up never holding charge.
 
I just leave it on charge.The reconditioning setting is the same as an equalization charge for deep cycle batteries used in P.V. systems.At home I do an EQ charge once a month but then top up with distilled water.Once a year? Dunno.
 
one last thing chaps, can I charge an AGM battery from the standard alternator? There are lots of confusing things all over the internet saying that you can, or can't do this.
 
Not sure about Toyota, but I put an AGM in another car of mine to replace a standard battery. It sort of worked OK, but the battery was never fully charged when I checked it. I think AGM's need about 14.7 volts to charge them happily, and if the vehicle isnt designed for that the alternator will put out nearer to 14.4...

See what everyone else thinks..
 
any particular reason why you're going for AGM Nick ? the charging V will vary depending on the manufacturer but according to my solar PV charger manual between 14.3 & 14.8 V .For a starter battery i would stick to ordinary lead acid...
 
I'm with G.O.B and Karl on this. I have tried AGM under the bonnet. And it suffered from direct charge from the alternator. Now there are as many opinions in his as there are trees in a forest, but I have posted this story before. AGM under the bonnet, 6 months in it just wasn't performing. I swapped to a trad battery and put the AGM in the back with a DC charger and it's still there over 5 years later. There is some pretty string evidence that says AGMs (not all, but most) demand a higher input and the alternator wants to ramp down once it thinks that the battery is charged. And it's not. If you get 7 years out of a std battery what benefit are you going to get from an AGM?
 
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