What a load of rubbish. Concrete makes not difference to any other material. If you look at big battery instalations you will find that they sit on concrete tubs designed to contain any acid spills if a case splits.Originally Posted by Spaniard_King
fnq,
did you know its bad for a lead acid battery to sit on the ground.. especially concrete, a residual voltage of over 12V is acceptable. Your voltage is the what I find most batteries hang at
I suppose your an expert on Batteries hey Andy
Garry
Retired Honda Master Tech
Quote:
Originally Posted by Spaniard_King
fnq,
did you know its bad for a lead acid battery to sit on the ground.. especially concrete,
Why is this?
Can I ask WHY???
I have heard this before and can find NO evidence to support the theory?? It seems that (from my research) it may well be better for the battery?
This is from Rainbow Power Company
All lead-acid batteries will naturally self discharge. The rate of self discharge is most influenced by the temperature of the battery's electrolyte and the chemistry of the plates. Some experts believe that storing car or deep cycle batteries on a colder concrete floor might actually slow down the self discharge (leakage) rate because the floor acts as a heat sink and cools the battery.
In the early 1900s, when battery cases were made of porous materials such as tar-lined wood boxes, storing batteries on concrete floor would accelerate their natural self discharge. Modern battery cases are made of polypropylene or hard rubber. These cases are sealed better, so external leakage-causing discharge is no longer a problem, provided the top of the battery is clean and free from wet or dried electrolyte and the same temperature as the floor.
Large differences in temperature could cause electrolyte stratification within very large batteries (>250 AH) which could accelerate it's internal "leakage" or self discharge if the battery is sitting on an extremely cold concrete, stone or steel floor in a warm room, boat or submarine. Stirrers or bubblers are often used on these types of large batteries to keep the electrolyte from stratifying.
In practical terms the batteries on the ground causing discharge it rubbish.
As Mr rainbow says it might have been a problem with very old battery case materials that we havnt seen for many decades.
It may be a problem in very cold locations & then not truly a discharge problem rather a temperature/performance problem.
And it may be a problem in very large cells that we are unlikly to encounter in recreational boating.
Putting battery on the ground or on the cement in our situations particularly in our climate (the frozen south excluded) is not going to make a blind bit of difference.....it may even marginaly help by keeping the battery cool.
There are a lot more significant and proven things you can do to look after your battery.
Back on the subject
One of the most commonly ignored and not considered facts is that ALL rechargable batteries self discharge at a significant rate....and the older they get the worse it gets......unless the battery is mismanaged, damaged or of faulty manufacture, this increase with age of self discharge will be the cause of the battery being not servicable.
There are all sorts of figures published concerning voltages and other stuff about batteries..........It must be understood that batteries are not a close tolerance device.....characteristics will vary from one battery to another and in the same battery over its life..... even from cell to cell within the same battery.
It is not unreasonable to have one or more cells charge faster & therefore gass more or earlier than others.
this is why hydrometer is best ( if you can be bothered) and never rely on the reading of one cell for an indication of condition.
It is unreasonable to expect an accurate "measurement" of the energy stored in a given battery at a given time..... because it will vary from battery to battery, with temperature (especilay) and over the life of the battery.
there are several ways of testing the APPROXIMATE condition of a battery, problay the most convienient is a tong tester....(they generaly have clips not tongs these days)....that loads the battery and gives an indication of its ability to deliver under load.....this gives a one time reasonable assessment of battery condition.... because along with the increase in self discharge the internal resistance will increase with age.
tong testers are a lot cheaper than they once were......the poor mans version is to measure the voltage then turn on the headlights( or whatever) and measure again....or even measure voltage while cranking....... but you have to know waht a similar good new battery would look like in the same situation.
To the inexperienced the voltages in the above tests may seem terminal as the voltages may drop considerably.
enough for now.
cheers
Too it back and they say it tested good then I made them justify why they thought that(I can be like that) anyway made him go get the special temperature compensated hydrometer even then they put it on the special machin that winds the volts up and reads a costant load in real time think it was sitting happily at 25amps after 5 min...anyway I believe them, we came to the conclusion that my charger is usually charging the same size but older batterys and they due to age take less work and the charger is struggling a little with this new battery to get it topped off...works for me.
Interesting stuff and I now have faith in the battery good enough to go in the boat.
Thanks for the help above esp s-r with that .doc was a great tool for understanding this stuff better.
cheers fnq
Had a bit to do with them over the years!I suppose your an expert on Batteries hey Andy
Hi FNQCairns, somewhere in this thread it was mentioned that the charger was putting out 13 volts, if this is the case then your battery is never going to be charged much over 12 volts.
All automotive type batteries require a charging voltage of around 1 full volt more than the batteries full charge voltage, in other words, as an automotive battery is fully charged at 12.7 to 12.8 volts, the minimum voltage that can achieve a full charge is 13.8 volt.
Put crudely, all automotive batteries are charge by causing a chemical reaction to take place inside the battery. This chemical reaction only occurs at full strength when there is a charge voltage of at least one volt higher than the batteries State of Charge ( the battery’s internal voltage level).
If your charger is only putting out 13 volts, this is why your battery is at 12.1 and as your battery is holding 12.1 volts then your battery is doing very well.
The problem is that at 12.1 volts, your battery is only just over 50% charged.
If I were in your position, I would try borrowing someone else's charger and seeing if this gets the battery to full charge.
By the way, State of Charge ( SoC ) voltages are as follows
100% = 12.7
90% = 12.5
80% = 12.42
70% = 12.32
60% = 12.2
50% = 12.06
40% = 11.9
30% = 11.75
20% = 11.58
10% = 11.31
0% = 10.5
IT could be 13volts if its in a constant current mode.
He actulay states that the battery "measured 13 volts tsraight off the charger"....... and that the battery was gassing prior to being disconnected.
sound like it was fully charged or close to.
I've seen a number of different state of charge figures....... it has to be understood that they are an approximate guide to condition.
not an absolute and accurate measurement of condition.
the figure that drive on quotes sound to me to be very close to the money for unladen figures. with the expectation that the battery isn't unusulay hot or cold and that it has been rested before measurement.
cheers
It must also be said that lead acid batteries do not like being deep cycled...... even the so called deep cycle batteries mearly tolerate being deep cycled better.
most manufacturers and writers will recomend not cycling below 50% charge as a regular thing for normal batteries.
most clever electronics with battery protection will cut out at 10.5 volts or higher..... bear in mind that cut out will be under load so the resting voltage will be higher.
cheers
Hi TheRealAndy, Yes it could as with a multi stage charger, the charge voltage will drop to something like 13 volts once the battery has reached around a 95% State of Charge ( SoC ) and the lower voltage will keep the battery from self discharging but unless the battery’s SoC is below 12 volts in the first place, this maintenance voltage ( 13v ) will not be capable of raising the battery’s SoC much above about 12 volts.
Cheers.
Last edited by driveon; 12-02-2008 at 02:11 PM.
As he stated that the voltage quoted was taken with the battery disconnected from the charger.......... it is purely academic.
however if the battery was in the early stages of a current limited/ constant voltage charge, from a low state of charge...... the charger terminal voltage of the charger may be reduced by the current limiting feature.....in that situation the charger will be delivering maximum charging current and will be charging effectivly.....
it is unlikly that a multistage charger would reduce its terminal voltage at the end of charge as float charge is considered somewhere between 13.5 & 14 volts...typiclay 13.8 volts.
but all this is purely hypothectical.
cheers
Hi folks, the link bellow is to a fairly useful battery info site.
Most of the data is a generalised nature but it is a good reference site
http://www.windsun.com/Batteries/Bat...ery%20Charging
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