Lead acid battery charging
AustralianMade
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An interesting discussion occurred at work today, and prompted this post, it went along the lines of the dangers posed by gases released by a lead acid battery being charged, and one of the boys watching his aunt, yes, his maiden aunt, have a look into a battery by the light of a match, resulting in a bit of a 'woof' sound and some quite un lady like expressions. Explosion, however, is not the only reason to charge a battery in a well ventilated area (& please, don't strike a match nearby!) I have seen good sets of tools/instruments and even an entire work table ruined by the escaping gases and aerosolized acid released during charging.
In the end I always placed batteries being charged inside a large shallow plastic tub on a table just inside the doorway of the workshop and prevented a lot of the damage that might otherwise have happened.
Had to have a bit of a laugh at Simmo's poor old aunt though...
... she was fine, only her pride - and Simmo's impression of her - was hurt.
In the end I always placed batteries being charged inside a large shallow plastic tub on a table just inside the doorway of the workshop and prevented a lot of the damage that might otherwise have happened.
Had to have a bit of a laugh at Simmo's poor old aunt though...
... she was fine, only her pride - and Simmo's impression of her - was hurt.
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Originally Posted by ABX
... whereas NMH & L-Ion batteries can be 'topped up' when only partially discharged without a problem.
My old camcorder came with a nifty gadget to fully discharge the NiCad battery before charging; unfortunately I haven't found the same thing for AA size NiCads.
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Though not subject to "memory blocking" as Ncads, Ihave seen advice that suggests the other types (lap-top batteries included) be fully discharged regularly, perhaps monthly, to "extend battery life"
We use a lot of lap-tops at work and after a year or so some of the batteries are totalled by being on near permanent charge in vans
We use a lot of lap-tops at work and after a year or so some of the batteries are totalled by being on near permanent charge in vans
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Quite right westy, it seems to be okay to leave your laptop battery on charge quite a lot, but they do appreciate being 'worked'.
I leave my laptop plugged into the mains all the time I am not using it elsewhere, however, I quite regularly discharge mine until the battery warning dialog box pops up (97% discharged) before putting it back on the charger. This seems to keep the battery reasonably healthy.
I leave my laptop plugged into the mains all the time I am not using it elsewhere, however, I quite regularly discharge mine until the battery warning dialog box pops up (97% discharged) before putting it back on the charger. This seems to keep the battery reasonably healthy.
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ABX You do realise that you have become the Forum battery Agony Aunt; and thank you.
We mentioned gel batteries earlier. Am I right in thinking that you can't mix "wets" with "gels", even if they are of the same capacity?
We mentioned gel batteries earlier. Am I right in thinking that you can't mix "wets" with "gels", even if they are of the same capacity?
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GBZ
It depends on application, I would IMO suggest that is designed for same duty & of similar capacities no problem.
As I have a lot of additional lighting on my vehicle (floodlighting, beacons etc) I have used a split charge system for years. In the early days, cos of space constraints I used a gel as the "lighting" battery, though not designed for the job it lasted about 6 years.
I now use a leisure battery (nearly 9 yrs old) for same job. Loads on it can reach 15 - 20A.
It depends on application, I would IMO suggest that is designed for same duty & of similar capacities no problem.
As I have a lot of additional lighting on my vehicle (floodlighting, beacons etc) I have used a split charge system for years. In the early days, cos of space constraints I used a gel as the "lighting" battery, though not designed for the job it lasted about 6 years.
I now use a leisure battery (nearly 9 yrs old) for same job. Loads on it can reach 15 - 20A.
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GBZ, I don't mind being the battery 'Agony Aunt', I have asked many questions here in these fora and many nice people have been kind enough to answer them, some in great detail. I am simply returning the favour.
Anyway, I basically agree with westy on this.
Gel and acid should mix reasonably well together as long as normal parameters are maintained i.e., mixing a gel and a lead acid battery in a car system shouldn't be a problem at all - as in west lake's experience.
Interestingly you can also mix batteries of differing capacities together if need be, the theory being that as the combined batteries work together (as opposed to individually). The different sized batteries simply add up to one larger unit and charge/discharge together.
Or to put it another way, if you have three 12V batteries, lets say:
1 x 75 Ah;
1 x 95 Ah;
1 x 130 Ah;
and join them all together in parallel, they will then act like one big 12V battery of (75+95+130) 300 Amp hours.
Or, if joined together, when battery A is at 77%, then battery B and battery C will also be at 77%.
As I said in my post above, the main concern with a gel battery is that you don't exceed its charge/discharge capacity.
An interesting case in point is a product we have here, known as a "Thumper Pack", marketed by Waeco. These are sold as a high capacity battery unit for jump starting, or deep cycle applications. They are a very capable product and can jump start a car or truck or run a fridge for a couple of days. Most folks assume that they are a gigantic battery inside, however in reality they are simply 4 modest SLA batteries of approx 65 Ah, all wired up together and packaged inside a tamper proof box. (So the punters can't see all the "trade secrets" inside!)
Cheers,
ABX
Anyway, I basically agree with westy on this.
Gel and acid should mix reasonably well together as long as normal parameters are maintained i.e., mixing a gel and a lead acid battery in a car system shouldn't be a problem at all - as in west lake's experience.
Interestingly you can also mix batteries of differing capacities together if need be, the theory being that as the combined batteries work together (as opposed to individually). The different sized batteries simply add up to one larger unit and charge/discharge together.
Or to put it another way, if you have three 12V batteries, lets say:
1 x 75 Ah;
1 x 95 Ah;
1 x 130 Ah;
and join them all together in parallel, they will then act like one big 12V battery of (75+95+130) 300 Amp hours.
Or, if joined together, when battery A is at 77%, then battery B and battery C will also be at 77%.
As I said in my post above, the main concern with a gel battery is that you don't exceed its charge/discharge capacity.
An interesting case in point is a product we have here, known as a "Thumper Pack", marketed by Waeco. These are sold as a high capacity battery unit for jump starting, or deep cycle applications. They are a very capable product and can jump start a car or truck or run a fridge for a couple of days. Most folks assume that they are a gigantic battery inside, however in reality they are simply 4 modest SLA batteries of approx 65 Ah, all wired up together and packaged inside a tamper proof box. (So the punters can't see all the "trade secrets" inside!)
Cheers,
ABX
Last edited by ABX; 27th Jul 2007 at 07:59. Reason: To fix a mistake, thanks balsa!
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The other type of battery to give troubles are the ones fitted to intruder alarms, though lead acid they do need to be changed & checked regularly if not all sorts of problems start.
1/ If your mains supply goes off the system seems to activate, often as the sounder (siren etc.) has its own battery, sees the loss of power as the back up in the control panel is knacked and can't be reset.
2/ And this is possiblt the worst (funniest) is all is OK until power is restored, lost count of the number of times I've restored power late at night/early hours for half the alarms in an area to go off - usually followed by us staging a strategic withdrawl
Had a look at one last year that did this (old lady on her own) the battery was a/ without any electrolite b/ had a hole in it & c/was deformed through heat.
So take the time to check yours and re[place every few years.
Can be seen in many locations in the UK, don't be tempted to buy a cheap one, I got given one and no way will it start my car (1.9l diesel). Go to a car parts specialist and get a decent one.
ABX maybe we should set up as consultants
1/ If your mains supply goes off the system seems to activate, often as the sounder (siren etc.) has its own battery, sees the loss of power as the back up in the control panel is knacked and can't be reset.
2/ And this is possiblt the worst (funniest) is all is OK until power is restored, lost count of the number of times I've restored power late at night/early hours for half the alarms in an area to go off - usually followed by us staging a strategic withdrawl
Had a look at one last year that did this (old lady on her own) the battery was a/ without any electrolite b/ had a hole in it & c/was deformed through heat.So take the time to check yours and re[place every few years.
These are sold as a high capacity battery unit for jump starting, or deep cycle applications.
ABX maybe we should set up as consultants
parallel batteries correction
If you have three 12V batteries:
1 x 75 Ah;
1 x 95 Ah;
1 x 130 Ah;
in parallel, they will act as one 12V unit of 300 Ah. No need to devide by 3.
In series, they could act as one 36V unit of 75Ah (smallest capacity) but only if you know what you are doing and are very careful in use. Not a practical setup.
If you must connect in series (to obtain higher voltage like 24V), then use identical batteries (manufacturer, model, and age) and connect them when they are flat. Then charge. Since discharging lead-acids to flat state costs you in battery life, you can use plan B: charge them separately fully, connect them briefly in parallel to further equalize the charge, and only then connect them in series. If the two batteries are identical it should be safe enough. Periodically you should check whether the voltage across all batteries is about the same.
I hope this helps someone.
bm.
1 x 75 Ah;
1 x 95 Ah;
1 x 130 Ah;
in parallel, they will act as one 12V unit of 300 Ah. No need to devide by 3.
In series, they could act as one 36V unit of 75Ah (smallest capacity) but only if you know what you are doing and are very careful in use. Not a practical setup.
If you must connect in series (to obtain higher voltage like 24V), then use identical batteries (manufacturer, model, and age) and connect them when they are flat. Then charge. Since discharging lead-acids to flat state costs you in battery life, you can use plan B: charge them separately fully, connect them briefly in parallel to further equalize the charge, and only then connect them in series. If the two batteries are identical it should be safe enough. Periodically you should check whether the voltage across all batteries is about the same.
I hope this helps someone.
bm.
Last edited by balsa model; 26th Jul 2007 at 18:39.
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balsa model,
You are quite right and I have edited my post above to fix the error. I can't type as fast as I think apparently!
I defo agree that when connecting batteries in series it is possible to connect batteries of unequal capacity however it is best to use batteries of equal capacity. Also it is best practice to use the same battery type from the same manufacturer and all of the same age.
Dozens of times I have said to a truckie, "When you change one you should change them all" only to ignored and accused of trying to make another sale!
Cheers.
You are quite right and I have edited my post above to fix the error. I can't type as fast as I think apparently!
I defo agree that when connecting batteries in series it is possible to connect batteries of unequal capacity however it is best to use batteries of equal capacity. Also it is best practice to use the same battery type from the same manufacturer and all of the same age.
Dozens of times I have said to a truckie, "When you change one you should change them all" only to ignored and accused of trying to make another sale!
Cheers.
