I keep reading on here that both car and leisure batteries are ruined by running them flat, and that leisure batteries are ruined by running them half flat.
Has anyone had any practical experience of ruining batteries by running them flat.?
I do it all the time and never had a problem.I Just give it a good thrutch at 6 to 8 amps and they recover fine.
PLEASE just don't quote what you've read or been told, what would be interesting is if anyone has actually ruined a battery this way.
PS Don't forget that my battery supplier gets many batteries back which are supposedly dead, and recharges them at high amperage and they recover OK.
Yes. Don't run a leisure battery flat. You cannot fully re-charge them & they will eventually die completely. Trust me, I kanckered one a couple of years ago. Here is the Caravan & Camping Clubs data sheet on the matter. They do not reccoment discharging less than 80% of fully charged. I am sure others will add to this!
Hello, I have EHU. No I didn't try a high power charge. I used to work with batteries, the plates can be cleaned, but they can also buckle with these types of charger. They may last a little longer, but you are really only putting of the inevitable.
Quote: Originally posted by Steve McV on 10/7/2008
Yes. Don't run a leisure battery flat. You cannot fully re-charge them & they will eventually die completely. Trust me, I kanckered one a couple of years ago. Here is the Caravan & Camping Clubs data sheet on the matter. They do not reccoment discharging less than 80% of fully charged. I am sure others will add to this!
Steve.
"Don't run a leisure battery flat" -I did a couple of years ago when I accidentally left the TV booster on over winter/. 110ah battery was completely discharged. The van charger would not touch it neither would my standard battery charger. In the end I bought a Sealey Smartcharge inverter charger. After about 30 hours it completed the precharge and then started charging normally. Battery has been fine for last 2 years and will hold a full charge. Note this charger has a special feature to charge discharged batteries. Saved its cost with the first use.
High frequency switching inverter with microprocessor control gives fully automatic charging and subsequent maintenance-charging to optimize battery life and performance. Gradually increasing start-up voltage protects discharged batteries from high-current damage. Suitable for standard SLI (Starting-Lighting-Ignition), Gel, AGM (Absorbed Glass Mat) and VRLA (Valve Regulated Lead Acid) batteries. Fully protected against short circuit, reversed polarity, faulty battery, incorrect battery voltage, current overload, thermal overload and low supply voltage. Aluminium case with handle and storage for clamps and clamp cables. Suitable for 12V 25-300Ah batteries.
high amps wont recover a battery if the plates are coated it will just buckle and short them even more ,very high volts but at a few milliamps will recover them but as the battery starts to respond the volts go down whilst the milliamps go up until the correct voltage/ampage is used.
we recovered both flooded and gel types using a psu that supplied 500v and had a regulated output controlled by a computer (who wants to watch a meter for days?).
you can also batter them back to life with high frequency as battery reconditioner type chargers do.we were probably doing what smart chargers do today without the risk!!!
i would notrecommend anyone doing so though the equipment used was not available over the counter (the psu we used certainly isnt but "smart" chargers are now) and certainly not for those who just like big bangs when you get it wrong.
never try and charge coin cells they always go bang however you try.
so called "sealed" batteries are not actually sealed but are liquid retaining! (recovery) boiling a battery using high amps will just shorten their life if there was a glimmer left by turning the acid into vapour which will be vented by the battery (as its designed to in use)until the liquid has gone or the gravity rises making the charging process impossible.
repeated charging also kills batteries even if its done by the book as each time the lead salts slighly change until its useless ,looking carefully into the small print generally the more you pay the more charges you get its usually about 200 for the cheap leisure batteries and twice that for the expensive (from a "low" state not a "dead" state)unfortunately physics has a nasty way of not changing for anyone
even batteries with shorted plates will take a charge but you can tell ones short when the battery gets hot and gasses easily ,take the charger off and put a meter on if the 12v drops over an hour then you have shorted plates if the voltage is over 13 and drops slowly you have coated plates which a reconditioning charger can help prolong the life of .
a battery is about 13.2 volts a battery with less than 12.5 volts needs a charge one with just 12v is in need of emergency TLC if its 10v you probably have a very sick battery thats fit for the dump (sorry recycling)
the desperate (myself included) can recover really dead batteries by draining them unshorting the cells and refilling with fresh acid but its only a small % that recover enough to be of any use ,now most are "sealed" its nigh impossible (got one in bits in my garden awaiting a dump run at the moment)
the chemistry in batteries is rather complicated and once out of balance the battery starts to decline until the resistance in the plates themselves stops them being charged ,trying to charge a leisure battery with a car charger will i'm afraid not charge the battery to its full charge nor will trickle chargers stop the plates getting coated luckily the new smart chargers will keep a battery topped up by checking the voltage and only charging when its needed
all you have to do is check the charger is suitable for the battery you have the one in the earlier post sounds excellent mines a 16 amp ring charger ,the 8 amp version is ok for up to 110 amp i have a 120 amp battery
whilst ceratinly no way connected to any smart charger company they are an ideal investment as batteries get more expensive ,not just for your leisure batteries but they will recondition your car ones as well ,my car battery was getting annoying by occasionally not starting my car in the winter ,a bit of reconditioning and its fine!! i bet plenty of car batteries are replaced when in reality they are just sick but not dead
talking to someone that sells car batteries about the problem you can bet for vested interests the answer will be "your batteries 'ad it mate ,you need a new one" but i expect a good % just need a bit of tlc
I have a professional sealy smart charger which after using many cheap ones decided to pay £120 for, it has a seperate system for leisure batterys, it'll also slow/fast charge car batterys and regulate to charge properly from flat. it'ill also start a diesel frontera with a dead flat battery using a boost start facility great piece of kit and well worth the extra money.
I never take my battery off the caravan over winter i just disconnect it so it stands for approx 4 months and it's always been fine the following year and i've done this for the last 5 years.
------------- Doing as little as possible for as much as possible...
this is a great subject for a thread.
Like you, I hear and see conflicting advice all the time about batteries.
Judging by the excellent replies so far.....there will be no definitive answer.
I do remember killing a car battery once by treating it like a NiCad battery. I rigged up a bulb and a couple of wires to completley discharge it...that worked alright, but I never got it charged up again.
Interesting to see how much some folks are prepared to pay for trick chargers, I wonder if there is much payback for the average Joe Bloggs user?
Thanks Crypto, and to those who have contributed so far, they have been very constructive.
I think I'm learning that recovering a flat battery isn't impossible, but it's not easy (and best avoided), and best recovered with something like a sealy smart charger
The one thing I haven't got my head around is that many people empty their batteries from time to time, but (like me) just put the car battery charger on it, and bob's your uncle.
I'm off to Wales tomorrow for a month, and there's a pretty good chance I'll empty my battery. I've only got my car charger, so that might make an interesting experiment.
I'll be at Cae Du at Towyn for the middle 2 weeks, so if you see someone kicking a battery around the beach, say hello
PS I think I know what I'll be getting for my Birthday!!
There is a silver lining in all this - of sorts. In order to completely discharge the battery you will have to leave something comnnected to it for a long time. As you will be in your van at the time, you will notice when it is getting low, lights will start to dim, the TV will not work, or at least the picture will reduce in size etc. It is highly improbable that you will completely discharge it under these circumstances (unless you fall aspleep with the TV screen getting smaller and smaller, and the lights reduced to a dim yellow glow, hence it will still charge readily from your car charger. The only time you flatten a reasonably healthy car battery is when you leave the car with the lights on all night.
lights will dim when the voltage drops but the battery itself will recover slightly back up to near 12v if you remove the drain on the battery but ofcourse its the capacity in amps that have been drained ,put the lamp back on and it will dim almost instantly.
the voltage of a battery is just and indicator its the amps that count ,a small charger will put in the amps but over a long period perhaps longer than you wait so your battery may not be fully charged when you use it but on a meter its in the green but for a shorter time when you use it.a small charger may not charge at all if the plates are coated as it hasn't the umph to get the electrons moving
gassing as well isnt an indicator it could have shorted plates in each cell ,the only way is to work out roughly how many amps youve used then put it on charge for the correct number of hours your charger needs to pump in the amps ,its not easy to work out by any means and perhaps its this that shortens their lives.
the smart chargers do this to an extent and measure the volts until they cease to drop (the battery will try and share the amps between the plates until theres a balance as it does so theres a voltage drop)
once the volts dont drop then the battery is fully charged ,it them monitors the battery and tops up as needed rather than trickle charging constantly.
putting more amps in quickens charging but can damage the plates so bits break off and lodge between them causing shorts ,its still the same voltage at the end but because theres now less plates (two become one etc due to the short) theres less capacity.
its interesting how something seemingly so simple is a balance of several things that make it work ,i'l get me anorack
probably the worst thing for a battery is leaving it in a discharged state ,batteries slowly lose their charge so regular maintainance lengthens their lives or rather doesn't shorten them
I take it we're on about re-chargeable batteries here?
Most re-chargeable batteries suffer from something called "battery memory" which means if you don't fully charge them, they lose a percentage of their capacity. Obviously all re-chargeable batteries have a maximum number of times they can be re-charged, a rule of thumb is, the more expensive, the more charges you'll get from them.
Being an electrical engineer, I've always been taught that you're supposed to run a battery as flat as possible before you re-charge it, I'm not sure why, I'd have to dig out some old theory books to find out that
I think battery memory applies to NiCads only. I don't think it applies to lead acid batteries.
Also modern NiMh batteries can be topped up at will.
I remember an early laptop computer that had a NiCad battery and there was actually some software in it to "exercise" the battery to extend its life. It would cycle the battery by draining and recharging a few times. This was to prevent battery "memory".
I think battery memory applies to NiCads only. I don't think it applies to lead acid batteries.
Also modern NiMh batteries can be topped up at will.
I remember an early laptop computer that had a NiCad battery and there was actually some software in it to "exercise" the battery to extend its life. It would cycle the battery by draining and recharging a few times. This was to prevent battery "memory".
Thanks for that *makes notes in old college books*
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.
Topic: Running batteries Flat- fact or fable
