Plz. advice, which lead acid battery charger would U recommend to buy
Regards / Groetnis. ...........
-- Which lead acid battery charger?. ----
-- Which lead acid battery charger?. ----
Hallo All,
Plz. advice, which lead acid battery charger would U recommend to buy
Regards / Groetnis. ...........
Plz. advice, which lead acid battery charger would U recommend to buy
Regards / Groetnis. ...........
Last edited by Frootbat on Wed Apr 09, 2008 1:23 pm, edited 1 time in total.
Hannes.
Bantam B22J (ZU-DUX)
Luff your aerie.
Bantam B22J (ZU-DUX)
Luff your aerie.
-
Duck Rogers
- Toooooo Thousand
- Posts: 2318
- Joined: Tue Nov 29, 2005 9:49 pm
- Location: West Rand
Eish Morph.......now you've put me on the spot 
Asking a question like "what charger to buy" is like opening Pandora's Box
The obvious question is "what size of battery and for which application"
Rather than attempt to answer the question I decided to just post the following extract from Hawkins Manufacturing datasheets. They're a South African company and make excellent stuff. Not the cheapest, but you'll get a good idea of what to look for.
How to choose an automotive lead acid battery charger
Apart from the obvious relationship between the power of a charger and its cost, a charger should be chosen in relation to the battery capacity, the time available for charging and any extra features that may be required.
1 The simple rule relating charger size and battery capacity (C ) is a recommended current not exceeding 1/10th of the battery size measured in amp hours; C/10. For example, a 50amp-hour battery should be charged at no more than 5 amps. A lower charge rate will do the battery no harm but a higher rate, particularly at the completion of the charge, will lead to excessive gassing and progressive damage of the battery's internal plates. Fortunately most of the ordinary or unregulated chargers that are on offer will show a decline in current as full charge is approached and this should be seen as a desirable feature. The 1/10th of battery capacity in amp rating of the charger is generally a good rule to follow.
2 If the time available for charging is short, the battery is expected to bear the brunt of this impatience. A recently discharged automotive battery can safely accept very high initial currents (C/4 or more) but by 60% of recharge this should be reduced to C/10. A Hawkins Commercial charger that will provide adjustment of currents between 10 and 20 amps could be used.
3 Chargers that can get a flat battery to start a vehicle with a minimum of delay are generally labeled power boosters or engine starters. They work on the principle that the battery will safely accept a short high charge and then together with the assistance of the charger, this charge will swing the engine for a start. Specially designed circuitry is required to cope with the high currents incurred during engine starting. The size of the vehicle and its battery will then dictate the rating of the charger. The Hawkins 6/60G and GX will start most heavy vehicles.
4 Special batteries need special chargers. The new generations of sealed lead acid batteries need careful charging and this generally involves electronic control of the charge. Batteries with gell cells and recombination lead acid batteries used in golf carts and wheel chairs fall into this category and must never be overcharged. In addition most of these batteries need to be fully charged to perform satisfactorily and this is a compelling reason to buy the correct charger for the job. Serious damage to these batteries will occur if a simple charger is left to run with the battery beyond its voltage limit. Automatic or "smart" chargers will also treat a standard automotive battery to an ideal charge cycle.
How long should it take to charge a battery?
The recommended current C/10, mentioned in paragraph 1 above, uses 10 hours as the theoretical time for charging lead acid batteries. It would however be useful to look at the variations that can occur in real life and calculate the effects on time.
Batteries are seldom totally flat and a 10% residual charge would cut the time by at least 1 hour. It is sometimes difficult to achieve the rated charge on a used battery and 90% is a good aiming point and this can cut the time by another hour.
A car battery with a 50% charge will start any engine, particularly if it has been recently on charge and is still warm. In this case the battery would need four hours of charge.
Example 1
A gel cell battery for a golf cart needs to be recharged overnight. Assume a 36 ah Sonnenschien with 10% capacity remaining. A Hawkins Gel 3 amp charger is used providing a smoothed and steady 3 amps from start to finish. It should be close to the 90% charge within 10 hours. The charger will however continue to charge at a constant voltage and very low current to achieve a maximum charge. In total 11 hours are needed to provide the golfer with a charge close to the maximum.
Example 2
A heavy truck battery of capacity 130 ah has been fully discharged in providing lighting for a bush camp. The only charger available is a Power 4 amp Domestic charger that will start the cycle at 4 amps but will only deliver about 1.5 amps at completion. Assuming an average of about 2 amps from start to finish the charging time that should be expected is 130/2 = 65 hours.
A Power 8 charger from the top of the Hawkins Domestic range would have done the same job in 130/6 = 22 hours. A Power 15 charger from the bottom of the Hawkins Commercial range would be able to provide 10 amps from start to finish and therefore take 13 hours. The smallest charger capable of providing 13 amps would be the Power 30 and the time taken would be 10 hours or less if the advantage of the higher current was used at the beginning of the charge.
Why is it difficult to charge a very flat battery?
The chemistry of a flat battery is such that the sulphuric acid it contains is consumed in producing lead sulphate on both the negative and positive plates. The strength of the remaining acid can be so low that it presents a high resistance to the current flow within the battery. The result is often a very low current that may not even indicate on the meter.
Under these conditions it is worth leaving the charger connected doing apparently very little and sometimes, after days of this treatment, the current will start to flow and a charge may be restored. The older the sulphate, the harder it is to recharge and this is the reason why lead acid batteries need to be kept in a charged condition.
It is worth mentioning that the battery may never fully recover from a state of deep and long discharge so please don't blame the charger without checking it on a good battery.
Can more than one battery be charged on one charger?
Any charger offering voltages that are multiples of 12 can be used for batteries arranged in series. The current flows through all of the batteries and they all receive the same benefit. 12 volt batteries arranged in parallel on a 12 volt source will share the current available unless the batteries are unequally charged in which case the lowest charged battery will take the largest share of the power until it matches the others.
Problems that arise from multiple charging originate mostly from the condition of the batteries. A battery with a short circuit fault in a parallel arrangement can draw all of the current all of the time and prevent the others from getting charged. A battery with a poor internal connection or in a very flat condition, will prevent a series chain from receiving the expected current from the charger
The Power 15, Power 30, Power 615, Power 324, and Power 625 are capable of charging more than one battery at a time.
Can the larger chargers be used for welding?
No and it will cost you some expensive components!
Can I run a 12-volt DC appliance off the charger?
With few exceptions chargers usually rely on the battery to smooth out their rectified output voltage and some DC equipment would not run well on the output from a charger. A battery permanently installed between the charger and the appliance may solve the problem.
Care is needed with this sort of arrangement to ensure that the charger can provide more current than that needed for the appliance.
Why the concern about overcharging?
As the battery approaches its point of full charge, the chemistry of formation of lead oxide and lead on the positive and negative plates reaches completion. Any further rise in voltage across the cell at this point will result in an electrolytic decomposition of the acid and bubbles of oxygen and hydrogen will be evident. Some of the oxygen is used to make additional lead oxide and in doing so, some lead from the plate is permanently consumed. The result is a weakening of the positive plate that will eventually cause it to fall apart. The excess hydrogen and oxygen will leave the cell and the level of the acid will drop. This can and should be topped up with pure water in the wet cell batteries found in most cars.
In the case of a gel cell or recombination battery, gases that are unable to recombine will eventually be released through a one-way valve and when the plates get too dry, the battery will cease to operate.
Bubbling is often seen long before a total full charge is reached and this is usually due to some points on the plate reaching a high voltage before the rest. High current flows and tight packing within the battery that prevents circulation of the acid aggravate this situation. The reason for moderate charging rates at the end point should now be more apparent. In the case of the gel cells, reduced voltage ripple is used together with voltage regulation to minimise gas loss. Modern cars use sophisticated voltage control of the alternator for the same purpose.
High temperatures will make the problem worse by altering the same chemistry in the wrong direction and if the heat is coming from high current and gas recombination, there is a possibility of warping the plates that will hasten the collapse of the battery.
An AutoMate unit can be used to provide voltage control for a standard charger but a range of Hawkins regulated chargers are now available for improved control of charging.
Stand-by charging
There are some misconceptions about stand-by charging that could be damaging to your battery's health. If the stand-by charge is provided by a regulated charger, you should be able to leave the charger connected indefinitely. The regulation will keep the supply voltage below the point at which the battery gasses and the continuous but slight internal discharge present in most batteries is compensated by the charger.
This is not the case with a so-called trickle charger that turns out to be nothing more than a small and usually cheap charger. Despite its size it can continue charging to a voltage well into the gassing zone and given time, will most certainly dry out the battery. Its output must match the internal discharge to do the job correctly but this is a matter of chance and a poor one at that.
Hope this helps. If it doesn't....don't call us, we'll call you
Just kidding! You're welcome to ask specifics after you've read this.
Asking a question like "what charger to buy" is like opening Pandora's Box
The obvious question is "what size of battery and for which application"
Rather than attempt to answer the question I decided to just post the following extract from Hawkins Manufacturing datasheets. They're a South African company and make excellent stuff. Not the cheapest, but you'll get a good idea of what to look for.
How to choose an automotive lead acid battery charger
Apart from the obvious relationship between the power of a charger and its cost, a charger should be chosen in relation to the battery capacity, the time available for charging and any extra features that may be required.
1 The simple rule relating charger size and battery capacity (C ) is a recommended current not exceeding 1/10th of the battery size measured in amp hours; C/10. For example, a 50amp-hour battery should be charged at no more than 5 amps. A lower charge rate will do the battery no harm but a higher rate, particularly at the completion of the charge, will lead to excessive gassing and progressive damage of the battery's internal plates. Fortunately most of the ordinary or unregulated chargers that are on offer will show a decline in current as full charge is approached and this should be seen as a desirable feature. The 1/10th of battery capacity in amp rating of the charger is generally a good rule to follow.
2 If the time available for charging is short, the battery is expected to bear the brunt of this impatience. A recently discharged automotive battery can safely accept very high initial currents (C/4 or more) but by 60% of recharge this should be reduced to C/10. A Hawkins Commercial charger that will provide adjustment of currents between 10 and 20 amps could be used.
3 Chargers that can get a flat battery to start a vehicle with a minimum of delay are generally labeled power boosters or engine starters. They work on the principle that the battery will safely accept a short high charge and then together with the assistance of the charger, this charge will swing the engine for a start. Specially designed circuitry is required to cope with the high currents incurred during engine starting. The size of the vehicle and its battery will then dictate the rating of the charger. The Hawkins 6/60G and GX will start most heavy vehicles.
4 Special batteries need special chargers. The new generations of sealed lead acid batteries need careful charging and this generally involves electronic control of the charge. Batteries with gell cells and recombination lead acid batteries used in golf carts and wheel chairs fall into this category and must never be overcharged. In addition most of these batteries need to be fully charged to perform satisfactorily and this is a compelling reason to buy the correct charger for the job. Serious damage to these batteries will occur if a simple charger is left to run with the battery beyond its voltage limit. Automatic or "smart" chargers will also treat a standard automotive battery to an ideal charge cycle.
How long should it take to charge a battery?
The recommended current C/10, mentioned in paragraph 1 above, uses 10 hours as the theoretical time for charging lead acid batteries. It would however be useful to look at the variations that can occur in real life and calculate the effects on time.
Batteries are seldom totally flat and a 10% residual charge would cut the time by at least 1 hour. It is sometimes difficult to achieve the rated charge on a used battery and 90% is a good aiming point and this can cut the time by another hour.
A car battery with a 50% charge will start any engine, particularly if it has been recently on charge and is still warm. In this case the battery would need four hours of charge.
Example 1
A gel cell battery for a golf cart needs to be recharged overnight. Assume a 36 ah Sonnenschien with 10% capacity remaining. A Hawkins Gel 3 amp charger is used providing a smoothed and steady 3 amps from start to finish. It should be close to the 90% charge within 10 hours. The charger will however continue to charge at a constant voltage and very low current to achieve a maximum charge. In total 11 hours are needed to provide the golfer with a charge close to the maximum.
Example 2
A heavy truck battery of capacity 130 ah has been fully discharged in providing lighting for a bush camp. The only charger available is a Power 4 amp Domestic charger that will start the cycle at 4 amps but will only deliver about 1.5 amps at completion. Assuming an average of about 2 amps from start to finish the charging time that should be expected is 130/2 = 65 hours.
A Power 8 charger from the top of the Hawkins Domestic range would have done the same job in 130/6 = 22 hours. A Power 15 charger from the bottom of the Hawkins Commercial range would be able to provide 10 amps from start to finish and therefore take 13 hours. The smallest charger capable of providing 13 amps would be the Power 30 and the time taken would be 10 hours or less if the advantage of the higher current was used at the beginning of the charge.
Why is it difficult to charge a very flat battery?
The chemistry of a flat battery is such that the sulphuric acid it contains is consumed in producing lead sulphate on both the negative and positive plates. The strength of the remaining acid can be so low that it presents a high resistance to the current flow within the battery. The result is often a very low current that may not even indicate on the meter.
Under these conditions it is worth leaving the charger connected doing apparently very little and sometimes, after days of this treatment, the current will start to flow and a charge may be restored. The older the sulphate, the harder it is to recharge and this is the reason why lead acid batteries need to be kept in a charged condition.
It is worth mentioning that the battery may never fully recover from a state of deep and long discharge so please don't blame the charger without checking it on a good battery.
Can more than one battery be charged on one charger?
Any charger offering voltages that are multiples of 12 can be used for batteries arranged in series. The current flows through all of the batteries and they all receive the same benefit. 12 volt batteries arranged in parallel on a 12 volt source will share the current available unless the batteries are unequally charged in which case the lowest charged battery will take the largest share of the power until it matches the others.
Problems that arise from multiple charging originate mostly from the condition of the batteries. A battery with a short circuit fault in a parallel arrangement can draw all of the current all of the time and prevent the others from getting charged. A battery with a poor internal connection or in a very flat condition, will prevent a series chain from receiving the expected current from the charger
The Power 15, Power 30, Power 615, Power 324, and Power 625 are capable of charging more than one battery at a time.
Can the larger chargers be used for welding?
No and it will cost you some expensive components!
Can I run a 12-volt DC appliance off the charger?
With few exceptions chargers usually rely on the battery to smooth out their rectified output voltage and some DC equipment would not run well on the output from a charger. A battery permanently installed between the charger and the appliance may solve the problem.
Care is needed with this sort of arrangement to ensure that the charger can provide more current than that needed for the appliance.
Why the concern about overcharging?
As the battery approaches its point of full charge, the chemistry of formation of lead oxide and lead on the positive and negative plates reaches completion. Any further rise in voltage across the cell at this point will result in an electrolytic decomposition of the acid and bubbles of oxygen and hydrogen will be evident. Some of the oxygen is used to make additional lead oxide and in doing so, some lead from the plate is permanently consumed. The result is a weakening of the positive plate that will eventually cause it to fall apart. The excess hydrogen and oxygen will leave the cell and the level of the acid will drop. This can and should be topped up with pure water in the wet cell batteries found in most cars.
In the case of a gel cell or recombination battery, gases that are unable to recombine will eventually be released through a one-way valve and when the plates get too dry, the battery will cease to operate.
Bubbling is often seen long before a total full charge is reached and this is usually due to some points on the plate reaching a high voltage before the rest. High current flows and tight packing within the battery that prevents circulation of the acid aggravate this situation. The reason for moderate charging rates at the end point should now be more apparent. In the case of the gel cells, reduced voltage ripple is used together with voltage regulation to minimise gas loss. Modern cars use sophisticated voltage control of the alternator for the same purpose.
High temperatures will make the problem worse by altering the same chemistry in the wrong direction and if the heat is coming from high current and gas recombination, there is a possibility of warping the plates that will hasten the collapse of the battery.
An AutoMate unit can be used to provide voltage control for a standard charger but a range of Hawkins regulated chargers are now available for improved control of charging.
Stand-by charging
There are some misconceptions about stand-by charging that could be damaging to your battery's health. If the stand-by charge is provided by a regulated charger, you should be able to leave the charger connected indefinitely. The regulation will keep the supply voltage below the point at which the battery gasses and the continuous but slight internal discharge present in most batteries is compensated by the charger.
This is not the case with a so-called trickle charger that turns out to be nothing more than a small and usually cheap charger. Despite its size it can continue charging to a voltage well into the gassing zone and given time, will most certainly dry out the battery. Its output must match the internal discharge to do the job correctly but this is a matter of chance and a poor one at that.
Hope this helps. If it doesn't....don't call us, we'll call you
Just kidding! You're welcome to ask specifics after you've read this.
Airspeed, altitude, or brains....you always need at least two
Knowledge base.....
Dankie banja Oom Dakkie,
This is really much, much moore than what I've asked for.....but this is what the forum is known for....people with a wealth of knowledge/information are a few key strokes away. 024
Thkz. 4 the offer, I will knock on your door 4 more advice, when needed.
Regards,
This is really much, much moore than what I've asked for.....but this is what the forum is known for....people with a wealth of knowledge/information are a few key strokes away. 024
Thkz. 4 the offer, I will knock on your door 4 more advice, when needed.
Regards,
Hannes.
Bantam B22J (ZU-DUX)
Luff your aerie.
Bantam B22J (ZU-DUX)
Luff your aerie.
-
James Bentley
- Almost a pilot
- Posts: 165
- Joined: Tue Apr 24, 2007 8:36 am
- Location: Hilton, KZN
-
Duck Rogers
- Toooooo Thousand
- Posts: 2318
- Joined: Tue Nov 29, 2005 9:49 pm
- Location: West Rand
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John Boucher
- The Big Four K
- Posts: 4330
- Joined: Mon Jan 29, 2007 5:23 pm
- Location: Dana Bay, Western Cape South Africa
- Contact:
Hi there Duckie.... Gee whiz, still on the crutches?
What about a product such as the CTEK XS 800 (12V, 10W) charger?
Would it also "cook" the cells?
ps. VSI ETA?
What about a product such as the CTEK XS 800 (12V, 10W) charger?
Would it also "cook" the cells?
ps. VSI ETA?
John Boucher
MISASA Chairman 2023
jb.brokers@gmail.com
chairman@misasa.org
A Bushcat is Born - CH 211 C "Super Excited"
MISASA Chairman 2023
jb.brokers@gmail.com
chairman@misasa.org
A Bushcat is Born - CH 211 C "Super Excited"
-
Duck Rogers
- Toooooo Thousand
- Posts: 2318
- Joined: Tue Nov 29, 2005 9:49 pm
- Location: West Rand
Yip, still on the sticks. Can't put any weight on the foot and half the foot is "dead'. Looks like nerve damageBAD NAV wrote:Hi there Duckie.... Gee whiz, still on the crutches?
What about a product such as the CTEK XS 800 (12V, 10W) charger?
Would it also "cook" the cells?
ps. VSI ETA?
The CTEK XS 800 probably won't even "cook" a cuppa water! With only 0.8A output current it also probably takes very long to charge a battery. More like a "trickle" charger. A lot of hype and bullsh*&t in the advertising material that means very little. But it probably works, otherwise they won't be selling any! More of a maintenance charger, it seems. It does appear to look after the battery very carefully during the final stages of charging as the battery nears full charge, which is a good thing.
ETA for VSI is probably in the next 10 days
if nothing unforseen happens at our brilliant Postal Organisation Airspeed, altitude, or brains....you always need at least two
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