No battery no matter what type it is will not last as long as it should if not recharged to true one hundred percent... A Northstar, Odyssey, Trojan or a Lifeline will not perform well as they should if not brought up 100 percent after a discharge happens. Bottom line.... If you are that worried about it buy the necessary equipment to do the job right.... A smart charger to bulk charge your battery, a manual charger to truly top your battery off at 100% and a ammeter to measure amps flowing into your battery has it near and gets to one hundred percent charge..
EFB and AGM batteries charge faster?
- Thread starter slybunda
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Originally Posted by wrcsixeight
... The issue with alternator recharging depleted batteries is not too much current. It is the voltage regulator rolling back voltage way too early.
That's probably true of my Prius (aside from the fact it's not actually an alternator). According to my ScanGauge, it holds about 14.6v immediately after boot-up, if the lights are on, or if the battery compartment is cold. Otherwise, it soon drops abruptly to about 13.6v. I'm considering moving the temperature sensor down from the top of the battery space to nearer the bottom, where the temperature might often be a little cooler, thus indirectly keeping the higher voltage longer.
Prius battery is AGM, not EFB, contrary to one post above.
... The issue with alternator recharging depleted batteries is not too much current. It is the voltage regulator rolling back voltage way too early.
That's probably true of my Prius (aside from the fact it's not actually an alternator). According to my ScanGauge, it holds about 14.6v immediately after boot-up, if the lights are on, or if the battery compartment is cold. Otherwise, it soon drops abruptly to about 13.6v. I'm considering moving the temperature sensor down from the top of the battery space to nearer the bottom, where the temperature might often be a little cooler, thus indirectly keeping the higher voltage longer.
Prius battery is AGM, not EFB, contrary to one post above.
Originally Posted by slybunda
i see most solar chargers are advertised at 18v. wont that destroy all batteries since the voltage is considerably too high?
The cheap one I bought from Harbor Freight puts out about 18v at zero current. However, the current it produces is far below the modest claimed output, even with near-optimum angle to the sun, especially after the panel heats up. Therefore it's useless, and its effective voltage is scarcely different from the car battery's open-circuit voltage. I'm sure some of them are better.
i see most solar chargers are advertised at 18v. wont that destroy all batteries since the voltage is considerably too high?
The cheap one I bought from Harbor Freight puts out about 18v at zero current. However, the current it produces is far below the modest claimed output, even with near-optimum angle to the sun, especially after the panel heats up. Therefore it's useless, and its effective voltage is scarcely different from the car battery's open-circuit voltage. I'm sure some of them are better.
Gel is different than AGM. AGM is absorbed glass mat, and Gel is well, Gel.
Originally Posted by CR94
Prius battery is AGM, not EFB, contrary to one post above.
When I replaced the OEM GS Yuasa, there was definitely electrolyte you can hear sloshing around, and the Gen 1-3 cars use the same JIS-post S46B24R battery.
Now, the Gen 4 Prius built on TNGA appears to use a DIN-sized battery in the engine bay and that is more than likely an AGM.
Prius battery is AGM, not EFB, contrary to one post above.
When I replaced the OEM GS Yuasa, there was definitely electrolyte you can hear sloshing around, and the Gen 1-3 cars use the same JIS-post S46B24R battery.
Now, the Gen 4 Prius built on TNGA appears to use a DIN-sized battery in the engine bay and that is more than likely an AGM.
Originally Posted by Colt45ws
Gel is different than AGM. AGM is absorbed glass mat, and Gel is well, Gel.
It used to be that simple but there are now Gel/AGM hybrid batteries. I've had one in my motorcycle for 5 years. Basically they have glass mat separators like an AGM with Gel instead of liquid electrolyte. They are said to combine the best of both types with in increased volume of electrolyte making them last longer than straight AGM's. Only downside is a slightly higher internal resistance than an AGM.
I don't know if there are Gel/AGM batteries being used in cars but they certainly used in marine applications.
Gel is different than AGM. AGM is absorbed glass mat, and Gel is well, Gel.
It used to be that simple but there are now Gel/AGM hybrid batteries. I've had one in my motorcycle for 5 years. Basically they have glass mat separators like an AGM with Gel instead of liquid electrolyte. They are said to combine the best of both types with in increased volume of electrolyte making them last longer than straight AGM's. Only downside is a slightly higher internal resistance than an AGM.
I don't know if there are Gel/AGM batteries being used in cars but they certainly used in marine applications.
JHZR2
Staff member
Originally Posted by slybunda
Originally Posted by wrcsixeight
The battery accepts as many amps as it wants at the system voltage reaching the battery terminals, upto the maximum output of the charging source.
i have read from here: https://www.impactbattery.com/blog/2017/05/how-fast-can-i-charge-my-car-battery/ and here: https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
that charging car battery with high ampage is not possible since battery can blow up.
so i dont get how for example a 70 amp alternator can dump all its current into a battery in one go, it would cause the battery to heat up considerably and blow up.
most of those websites i have checked say that charging lead acid batteries should be no more than 20% of the ah rating, most suggest 10%. so a 50ah battery should be charged at 5amp or so.
nthach's post above makes sense that the cars alternator/control module needs to be programmed to work with a battery that accepts a higher charge rate.
so what happens if you put an EFB or AGM battery in an older car that was designed to work with just a normal flooded battery? does it charge at the same rate as the flooded battery or will it actually charge up faster?
It comes down to resistance.
Vt=Voc+I*R
Vt (voltage @ terminals) = Voc (open circuit voltage, what the battery would measure if totally disconnected and left alone) + I (current) x R (resistance of the battery).
In other words, the voltage you observe is based upon the electrochemical potential, which varies with state of charge, and the resistance of the battery, for any current pushed in or out.
You can electrolyze water into hydrogen and oxygen if you apply the right voltage.
So remember above. If you give a certain voltage (Vt) from the alternator, the amount of current (I) that will flow is based upon the state of charge (Voc) and the resistance of the battery (R). The alternator is regulated so that the voltage doesn't go sufficiently high and electrolyze water into an explosive gas mixture (hydrogen and oxygen).
For a given Voc, and for a given R, both parameters you have no control over, the only way to charge faster/higher/harder (ie more I), is to up the voltage, Vt. Get it now? Push Vt too high to allow the current to flow, and then you'll electrolyze the water and make an explosive gas. Too much gas in a flooded (unsealed) battery, and it will flow out and away. Too much in an AGM and it will vent, which you dont want to happen.
Hope that makes sense...
Some claim that you should charge harder/higher. But recall also that P=I^2 R, so the battery will heat up with the square of current, times the resistance. Heat is what causes damaging side reactions and degrades batteries. Sometimes there is something to be said about charging with more over potential, even if limiting the current in. But in general, the more gentle and easy you charge a battery, the better off you are (assuming you do indeed fully charge it).
Originally Posted by wrcsixeight
The battery accepts as many amps as it wants at the system voltage reaching the battery terminals, upto the maximum output of the charging source.
i have read from here: https://www.impactbattery.com/blog/2017/05/how-fast-can-i-charge-my-car-battery/ and here: https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery
that charging car battery with high ampage is not possible since battery can blow up.
so i dont get how for example a 70 amp alternator can dump all its current into a battery in one go, it would cause the battery to heat up considerably and blow up.
most of those websites i have checked say that charging lead acid batteries should be no more than 20% of the ah rating, most suggest 10%. so a 50ah battery should be charged at 5amp or so.
nthach's post above makes sense that the cars alternator/control module needs to be programmed to work with a battery that accepts a higher charge rate.
so what happens if you put an EFB or AGM battery in an older car that was designed to work with just a normal flooded battery? does it charge at the same rate as the flooded battery or will it actually charge up faster?
It comes down to resistance.
Vt=Voc+I*R
Vt (voltage @ terminals) = Voc (open circuit voltage, what the battery would measure if totally disconnected and left alone) + I (current) x R (resistance of the battery).
In other words, the voltage you observe is based upon the electrochemical potential, which varies with state of charge, and the resistance of the battery, for any current pushed in or out.
You can electrolyze water into hydrogen and oxygen if you apply the right voltage.
So remember above. If you give a certain voltage (Vt) from the alternator, the amount of current (I) that will flow is based upon the state of charge (Voc) and the resistance of the battery (R). The alternator is regulated so that the voltage doesn't go sufficiently high and electrolyze water into an explosive gas mixture (hydrogen and oxygen).
For a given Voc, and for a given R, both parameters you have no control over, the only way to charge faster/higher/harder (ie more I), is to up the voltage, Vt. Get it now? Push Vt too high to allow the current to flow, and then you'll electrolyze the water and make an explosive gas. Too much gas in a flooded (unsealed) battery, and it will flow out and away. Too much in an AGM and it will vent, which you dont want to happen.
Hope that makes sense...
Some claim that you should charge harder/higher. But recall also that P=I^2 R, so the battery will heat up with the square of current, times the resistance. Heat is what causes damaging side reactions and degrades batteries. Sometimes there is something to be said about charging with more over potential, even if limiting the current in. But in general, the more gentle and easy you charge a battery, the better off you are (assuming you do indeed fully charge it).
JHZR2
Staff member
Originally Posted by slybunda
so the hotter the battery gets the higher its resistance so wont charge as quick when cold?
The hotter the battery gets the lower it's electrochemical impedance is, so the chemical reactions actually proceed faster/easier/better.
This offsets any positive resistive coefficient for the conductors, which are extremely short as well.
so the hotter the battery gets the higher its resistance so wont charge as quick when cold?
The hotter the battery gets the lower it's electrochemical impedance is, so the chemical reactions actually proceed faster/easier/better.
This offsets any positive resistive coefficient for the conductors, which are extremely short as well.
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