Hi Guys,
Looking for some more sage advice, I have a little '91 SR125 that I'm doing up gradually but I think the battery is stuffed!
If I charge it on low using the car battery charger, it charges fine up to about 12.9v, then drops down to about 12.65v, which I believe is normal? However, it then dropped to 12.54v after a couple of days, and now (after about 5 days) it's at 12.32v; it has just been sat on the workbench during this time, so there's been no draw on it.
Does this mean the battery's completely stuffed, or would connecting it to a "smart" charger possibly bring it back to life? (I have an Oximiser on order as I needed a new one anyway)
I've tried looking around on the site and the web in general but can only find info about parasitic draws, which clearly isn't the issue unless the spiders have been using it overnight!
Oh, it's a Lead/Acid battery by the way, one of these:
https://www.tayna.co.uk/motorcycle-batte...de/eb7l-b/
Each of the 6 cells should be 2.1v MINIMUM, adding up to 12.6v. But normally once charged they'll sit around the 12.8v mark or above.
Lead acid batteries hold their charge quite well if they're in reasonable condition, but 12.5v or less will just drop right down once you try and crank a bike with it.
More people are born because of alcohol than will ever die from it.
09-04-20, 10:52 AM
(This post was last modified: 09-04-20, 10:53 AM by Gnasher.)
(09-04-20, 10:20 AM)Farmboy81 link Wrote: Does this mean the battery's completely stuffed.
Quite possibly yes. Using a car charger could well have caused it to buckle plates and or over heat, so they touch and discharge themselves. i.e. battery doesn't hold charge.
(09-04-20, 10:20 AM)Farmboy81 link Wrote: or would connecting it to a "smart" charger possibly bring it back to life? (I have an Oximiser on order as I needed a new one anyway)
Again possibly, it nothing else it will confirm if it's toast or not.
Later
Lead acid batteries will always discharge when idle due to their internal resistance. Dropping to 12.32 is not exceptional, but leave it for 10 to 14 days and see how low it drops
I replaced a battery in an RC8 recently owner was not too happy about having to replace the battery after a year, but it was dropping below 8v when cranking. I charged the old battery and left it on the bench for 10 days and it was down to 5.4 which convinced him it was for the bin.The only real test is how much it drops under heavy load like starting the engine.Take it to the local battery supplier and they will test it for you.That battery is a standard lead acid on and is ok to charge it with a car charger, but with the red cell caps off. A note of warning though when charging it, connect the leads with the charger off and only disconnect the leads when charged with the charged switch off for at least 30secs. This prevents sparks igniting the gasses given off by the charging process
Thanks guys, basically confirmed what I was thinking, I know that the car charger isn't ideal, but I did keep an eye on it and there was no overheating (would've quickly pulled the plug if there was!).
I nearly bought myself a new battery, but figured that connecting to the Oximiser was worth a shot; better that than order a battery and a charger, only to find out I've wasted 35 quid!
Off the top of my head, I think it drops to 9.5-10.5v when cranking so there may be hope for it yet!
(09-04-20, 11:12 AM)unfazed link Wrote: That battery is a standard lead acid on and is ok to charge it with a car charger, but with the red cell caps off.
No, if it's a intelligent charger, type that can detect the charge AMP/voltage and cycle charge like CTEK for example yes. Your standard low/high charge rate charger will bugger it. I lost count of the amount of owners who've buggered their batteries in this way, red caps off or not.
Later
(09-04-20, 11:22 AM)Farmboy81 link Wrote: I nearly bought myself a new battery, but figured that connecting to the Oximiser was worth a shot; better that than order a battery and a charger, only to find out I've wasted 35 quid!
A charger like that is a better option than a basic trickle charger, because it can detect when to stop charging.
Quote:Off the top of my head, I think it drops to 9.5-10.5v when cranking so there may be hope for it yet!
That, however, sounds a bit iffy.
What you need to do is get a Drop Tester put on it to check that it's still putting out enough amps to crank the engine.
Imagine you've got six full pint glasses, each glass being one "cell" on the battery. A volt meter will register they're all full and you'll be able to crank the engine without a problem.
Now imagine one of them is empty. The volt meter will still read "full", because at least one of them *is* full, but you'll be down on amps and it will be much harder to get the engine to turn over and fire.
Normally I'd suggest taking the battery around to a friendly local garage/ workshop and getting it checked, but that might be a bit more difficult at the moment 
(09-04-20, 12:15 PM)Gnasher link Wrote: [quote author=unfazed link=topic=26060.msg312157#msg312157 date=1586427128]
That battery is a standard lead acid on and is ok to charge it with a car charger, but with the red cell caps off.
No, if it's a intelligent charger, type that can detect the charge AMP/voltage and cycle charge like CTEK for example yes. Your standard low/high charge rate charger will bugger it. I lost count of the amount of owners who've buggered their batteries in this way, red caps off or not.
[/quote]my ctek charger (yam branded ) is supposed to restore batteries that you think are dead some sort of intelligent charging or something or other.
I don't do rain or threat there of. dry rider only with no shame.
(09-04-20, 07:47 PM)fazersharp link Wrote: my ctek charger (yam branded ) is supposed to restore batteries that you think are dead some sort of intelligent charging or something or other.
It sure does desulphation, basically it try's to remove sulphates from the lead plates of the battery restoring battery capacity. It does this with very cleaver charging programme, pulsing voltage I believe but only to a point, if the battery drops below something like 10v (don't quote me on this figure) the battery is shot. They also auto detect what type of battery you've got WET, MF, Ca/Ca, AGM and GEL, think that's all of the current types, all of which are charged slightly differently.
A quality well maintained battery will last for many years, I've got a 15yr work car it's still got the same battery from new. It's used regularly and charged twice a year, never allow a battery to become discharged for long. Some of these cheap Chinese gel batteries most stealers flog are crap, lasting no more than a couple years at best, if allowed to discharge this can be months, I kid you not.
Later
I brought my charger in January 2012 after flattening it trying to start the bike with knackered spark plugs. The battery was 14 years old at that point and never been on a charger. I think it took 24 hours whilst the charger did its thing through different cycles until it registered a fully charged battery. Ever since then I have kept the bike connected to the charger (optimiser) when the bike is not in use which could be 5 weeks at a time. Don't wish to chance fate but the battery is now 22 years old :eek
I don't do rain or threat there of. dry rider only with no shame.
10-04-20, 11:00 AM
(This post was last modified: 10-04-20, 11:01 AM by fazersharp.)
I don't do rain or threat there of. dry rider only with no shame.
(10-04-20, 11:00 AM)fazersharp link Wrote: Here it is
https://www.ctek.com/storage/ma/3f8cf349...-UK-EN.pdf
https://www.ctek.com/products/vehicle/mxs-5-0
Not cheap but in my opinion better the Opimate 
Later
(10-04-20, 11:09 AM)Gnasher link Wrote: [quote author=fazersharp link=topic=26060.msg312222#msg312222 date=1586512831]
Here it is
https://www.ctek.com/storage/ma/3f8cf349...-UK-EN.pdf
https://www.ctek.com/products/vehicle/mxs-5-0
Not cheap but in my opinion better the Opimate
[/quote]Are you saying the optimate is better or the ctek is better
I don't do rain or threat there of. dry rider only with no shame.
(10-04-20, 11:42 AM)fazersharp link Wrote: Are you saying the optimate is better or the ctek is better
As said mate, Ctek in my opinion
Later
(09-04-20, 12:15 PM)Gnasher link Wrote: [quote author=unfazed link=topic=26060.msg312157#msg312157 date=1586427128]
That battery is a standard lead acid on and is ok to charge it with a car charger, but with the red cell caps off.
No, if it's a intelligent charger, type that can detect the charge AMP/voltage and cycle charge like CTEK for example yes. Your standard low/high charge rate charger will bugger it. I lost count of the amount of owners who've buggered their batteries in this way, red caps off or not.
[/quote]
You are correct, however since Farmboy81 does not have either an Optimate or Ctek charger then the car charger can be used with care. The biggest issue with using car chargers on old style lead acid batteries is they were being left on for 24 hours or more mostly because a lack of understanding of how they and batteries worked. I have seen many garages leave them on for a few days to give the battery an extra boost which you and I know was totally false economy and destroyed many batteries.
If you use a voltmeter to measure the open circuit voltage of the battery (Open circuit voltage is the voltage of the battery with no load or disconnected from any circuit). It is important not to charge the battery before you test the open circuit voltage. In relation to Farmboy81 Battery, it is a 12v 8ampere hour
In simple terms it would take 8 hours at 1 amp to charge the battery plus about 15%, to allow for the internal resistance but I am not going to go into the full method of how to charge
If the voltmeter shows a voltage reading of 12.2 volts then the battery is approximately 50% charged.
I his case 12.32 volts does not mean the battery is dead.
Generaly a lead acid cell is:
Fully charger at 12.6 to 12.7 volts
75% charged at 12.40v
50% charged at 12.2v
25% charged at 12v
0% charged as 11.8v
Again Farmboy81 battery has a charge of around 60% and his charger would charge it fully in a few hours at a 2 amp rating.
It would be vital for Farmboy to user the charge set to its lowest charging rate which is normally 2amps
All the above of course is not relevant if you have an Optimate or Ctek intelligent charger
Sorry to be a pain Unfazed, but could you type a bit smaller please? I can still read it if I turn the screen up to 400% magnification :lol
11-04-20, 06:48 AM
(This post was last modified: 11-04-20, 06:51 AM by darrsi.)
(10-04-20, 07:17 PM)vinnyb link Wrote: Sorry to be a pain Unfazed, but could you type a bit smaller please? I can still read it if I turn the screen up to 400% magnification :lol
***UNFAZED
[size=1.35em] You are correct, however since Farmboy81 does not have either an Optimate or Ctek charger then the car charger can be used with care. The biggest issue with using car chargers on old style lead acid batteries is they were being left on for 24 hours or more mostly because a lack of understanding of how they and batteries worked. I have seen many garages leave them on for a few days to give the battery an extra boost which you and I know was totally false economy and destroyed many batteries.[/size] If you use a voltmeter to measure the open circuit voltage of the battery (Open circuit voltage is the voltage of the battery with no load or disconnected from any circuit). It is important not to charge the battery before you test the open circuit voltage. In relation to Farmboy81 Battery, it is a 12v 8ampere hourIn simple terms it would take 8 hours at 1 amp to charge the battery plus about 15%, to allow for the internal resistance but I am not going to go into the full method of how to chargeIf the voltmeter shows a voltage reading of 12.2 volts then the battery is approximately 50% charged.I his case 12.32 volts does not mean the battery is dead.Generaly a lead acid cell is:Fully charger at 12.6 to 12.7 volts75% charged at 12.40v50% charged at 12.2v25% charged at 12v0% charged as 11.8vAgain Farmboy81 battery has a charge of around 60% and his charger would charge it fully in a few hours at a 2 amp rating.It would be vital for Farmboy to user the charge set to its lowest charging rate which is normally 2ampsAll the above of course is not relevant if you have an Optimate or Ctek intelligent charger
More people are born because of alcohol than will ever die from it.
11-04-20, 07:16 AM
(This post was last modified: 11-04-20, 01:51 PM by darrsi.)
According to my Electronics fella at work, who builds and maintains our batteries (film industry, we handle A LOT every day) the "ideal" scenario to charging batteries is in multiples of 4.
So, although not set in stone, a 1amp charger would be "ideal" for a 4ah battery, or 3amp charger for a 12ah battery, and so on.
Obviously a 1amp charger with a 12ah battery does work absolutely fine, but will take 12hrs from flat in theory, if maths are to be believed, although you will never flatten a lead acid battery down to zero during usage, they don't work the same as Lithium batteries which will use up every drop of power. Low ampage chargers with big batteries are not really a viable option in our game due to not having time on our side while out filming.
For the record, when needed (once, maybe twice a year) i use a 4amp charger at work, and it normally charges my battery to full in less than an hour.
The chargers will boost them up to just past 80% then it will turn into a much lower trickle charge for the remainder, switching itself off once full, as i would presume all modern chargers should do these days.
More people are born because of alcohol than will ever die from it.
Thanks for all the feedback, here's the update.
Charger arrived yesterday, read the battery as ok and then topped it up to 12.6v, put it on the SR, fixed the brake lights, fitted a new relay for the indicators, and then tried to start the bike...
Turned over but not enthusiastically, checked the voltage, 12.17v, oh well, new battery needed after all!
One thing I did spot that I hadn't considered was that when buying the standard lead/acid battery, most places send them empty due to some law (which I can understand, but would have been a bit of a bugger), so I've got a shiny new Motobatt AGM battery on the way for less than the suggested L/A one!
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