12-23-2017, 02:58 PM
The ammeter in combination with a voltmeter is a wonderful learning tool, and is pretty much a requirement to determine when an AGM is full.
All batteries flooded gel or AGM, will accept less and less amperage at a given voltage the more charged they are, so with some experience one can fairly accurately guestimate state of charge simply by how many amps the battery is accepting at a given voltage, and amperage flowing at absorption voltages give much better indications than any lesser charging voltage.
Many of the less expensice AGMS available will claim dual purpose/marine/deep cycle, but really they are thinner plate starting batteries that can also handle the occassional deeper cycle. AGMs have less resistance and thus generally have higher CCA figures and can be recharged to 80% faster, but ~85% to 100% is not much, if any, faster than a flooded. Many of the less expensive AGMS sold in NOrth America are relabelled Deka intimidators, and these are reported to do badly in deep cycle duty. But as a starting battery they do have increased CCA and they will not have terminal corrosion issues. So good starting battery, not so good as a deep cycle AGM.
The higher end AGMs like Northstar, odyssey and Lifeline are excellent performers in deep cycle duty when recharged properly, but not worth the high price, if not recharged properly.
The 'AGM's need higher voltage' is also a bit of horse hockey repeated by those who read it from someone else that did not know any better. Ideal absorption voltages are largely recommended by manufacturers when they are trying to guess how the battery will be used in average use by the most people, to minimize warranty returns.
One recent example of this is trojan revised their equalization charge to 16.2 volts from 15.5v. This was done because when equalized, 16.2 volts will require shorter durations to complete the task of achieving maximum specific gravity, than 15.5v, and the duration at which these intentional overchrging voltages are held, well it was determined higher voltage for lesser time would ultimately lead to less warranty returns. And, it will take many years of feedback and warranty returns before they would say, well perhaps 15.85v will reduce waraanty returns by 0.06%, and that means more executive bonus because baby has cut me off, and needs another diamond.
Generally 14.4 to 14.7 absorption voltage applied upto 100% state of charge and no longer, is not going to hurt any Lead acid battery not above 80F.
As far as your minivan, the voltages sought and held are an unknown. You can get one of those voltmeters which plug into a ciggy plug, and while these will not be truly accurate as to voltage at the battery terminals, they will give a good indication of what the vehicles voltage regulator will allow, and for how long as one drives. The longer it holds higher voltages the more effective it will be in recharging a depleted battery as one drives, and one can guess how effective, or not, it will be when trying to recharge a depleted battery.
There is also a possibility that some vehicles will see that a lot of field current ( to alternator)is being required to maintain a voltage and think something is wrong, and perhaps throw a check engine light, and perhaps cause a limp home mode, which might or might not cause the engine computer to revert to a set air fuel ratio and spark timing, rather than reading the sensors and adjusting for maximum fuel efficiency.
If my modified '89 Dodge sees 30 seconds of 1 volt higher than its tricked and bypassed voltage regulator is trying for and expecting, it will illuminate the check engine light and MPG and power takes a nosedive. I need to reset engine computer if I allow this to occur, but all I have to do to prevent this is not allow more than 14.7v.
Many people will put a voltmeter on their battery right after engine starting and see 14.4v and think that is the voltage always allowed. it is not. usually vehicles will allow 14's for a few minutes after starting, then drop to the 13.8v range, and 13.8v on a 50% depleted battery will have about 1/3 the amount of amps flow compared to 14.7v. But that figure will vary with the particular battery, its health, State of charge, temperature, and the thickness of the circuit between alternator and battery.
The wally world 29 is a decent battery and one free replacement is likely. While this is a bit amoral, it is a valid strategy for some. Just have jumper cables or a jumper pack and one can get away with a cheap marine battery as their house battery.
Also Do not idle parked to recharge for longer than 10 minutes . A maxed out alternator idling parked( it likely will be maxed out recharging a depleted battery), will get very hot and heat is what kills alternators. Driving has a lot more underhood airflow and will keep the alternator much cooler and thus it will last much longer and be more reliable. This is also highly variable vehicle to vehicle. My alternator temperature data collected is likely valid for most full size vans, but a Minivan?? I can't say for sure.
It is also wise to have a plug in charger and an extension cord, for when grid power is available. Automatic chargers generally suck at fully charging a regularly deeply cycled battery, but they are wy better than not being able to recharge at all when plugging in is an available option.
The Prologix 20 amp model sold on Amazon seems to get some good reviews as a garage charger. I have not used one. I hate recommending products I have not personally used. so consider the following link to be an option, that some gearheads seem to think works well..
https://www.amazon.com/Pro-Logix-PL2520-...B009RXYU4I
If one is willing to spend a bit more the Progressive dynamics PD9245 converter allows manual control of absorption voltage, and 45 amps are avaialable to seek and hold 14.4v. They also have a PD9245-14.8v model which wil charge faster. COnverters one must provide their own DC connection from converter to battery.
There are not many garage chargers above 20 amps, and a van dweller should have at least 20 amps available.
Regarding these garage chargers, if one is really trying to insure a full charge, after the green light flashes and indicates a full charge, assume the battery is about 92 to 95% charged. Unplug charger from grid and the battery, then turn on the headlights or other large amperage load, until voltage falls below 12.7 or so, then restart chrger on next lowest amperage setting.
lather rinse repeat in an attempt to get to the very desirable 100% state of charge. Smart chargers basically need to be tricked into doing what their marketers claim it can do.
One other trick, of one is to use the AGM setting on a flooded battery. These will float a battery at 13.6v, and when plugged in overnight, the 13.6v held battery has a much better chance than 13.2v of the flooded/regular setting, to get fully recharged.
The AGM setting might also allow for a longer absorption voltage stage which is almost always significantly better for a regularly deeply cycled battery, flooded or AGM.
All batteries flooded gel or AGM, will accept less and less amperage at a given voltage the more charged they are, so with some experience one can fairly accurately guestimate state of charge simply by how many amps the battery is accepting at a given voltage, and amperage flowing at absorption voltages give much better indications than any lesser charging voltage.
Many of the less expensice AGMS available will claim dual purpose/marine/deep cycle, but really they are thinner plate starting batteries that can also handle the occassional deeper cycle. AGMs have less resistance and thus generally have higher CCA figures and can be recharged to 80% faster, but ~85% to 100% is not much, if any, faster than a flooded. Many of the less expensive AGMS sold in NOrth America are relabelled Deka intimidators, and these are reported to do badly in deep cycle duty. But as a starting battery they do have increased CCA and they will not have terminal corrosion issues. So good starting battery, not so good as a deep cycle AGM.
The higher end AGMs like Northstar, odyssey and Lifeline are excellent performers in deep cycle duty when recharged properly, but not worth the high price, if not recharged properly.
The 'AGM's need higher voltage' is also a bit of horse hockey repeated by those who read it from someone else that did not know any better. Ideal absorption voltages are largely recommended by manufacturers when they are trying to guess how the battery will be used in average use by the most people, to minimize warranty returns.
One recent example of this is trojan revised their equalization charge to 16.2 volts from 15.5v. This was done because when equalized, 16.2 volts will require shorter durations to complete the task of achieving maximum specific gravity, than 15.5v, and the duration at which these intentional overchrging voltages are held, well it was determined higher voltage for lesser time would ultimately lead to less warranty returns. And, it will take many years of feedback and warranty returns before they would say, well perhaps 15.85v will reduce waraanty returns by 0.06%, and that means more executive bonus because baby has cut me off, and needs another diamond.
Generally 14.4 to 14.7 absorption voltage applied upto 100% state of charge and no longer, is not going to hurt any Lead acid battery not above 80F.
As far as your minivan, the voltages sought and held are an unknown. You can get one of those voltmeters which plug into a ciggy plug, and while these will not be truly accurate as to voltage at the battery terminals, they will give a good indication of what the vehicles voltage regulator will allow, and for how long as one drives. The longer it holds higher voltages the more effective it will be in recharging a depleted battery as one drives, and one can guess how effective, or not, it will be when trying to recharge a depleted battery.
There is also a possibility that some vehicles will see that a lot of field current ( to alternator)is being required to maintain a voltage and think something is wrong, and perhaps throw a check engine light, and perhaps cause a limp home mode, which might or might not cause the engine computer to revert to a set air fuel ratio and spark timing, rather than reading the sensors and adjusting for maximum fuel efficiency.
If my modified '89 Dodge sees 30 seconds of 1 volt higher than its tricked and bypassed voltage regulator is trying for and expecting, it will illuminate the check engine light and MPG and power takes a nosedive. I need to reset engine computer if I allow this to occur, but all I have to do to prevent this is not allow more than 14.7v.
Many people will put a voltmeter on their battery right after engine starting and see 14.4v and think that is the voltage always allowed. it is not. usually vehicles will allow 14's for a few minutes after starting, then drop to the 13.8v range, and 13.8v on a 50% depleted battery will have about 1/3 the amount of amps flow compared to 14.7v. But that figure will vary with the particular battery, its health, State of charge, temperature, and the thickness of the circuit between alternator and battery.
The wally world 29 is a decent battery and one free replacement is likely. While this is a bit amoral, it is a valid strategy for some. Just have jumper cables or a jumper pack and one can get away with a cheap marine battery as their house battery.
Also Do not idle parked to recharge for longer than 10 minutes . A maxed out alternator idling parked( it likely will be maxed out recharging a depleted battery), will get very hot and heat is what kills alternators. Driving has a lot more underhood airflow and will keep the alternator much cooler and thus it will last much longer and be more reliable. This is also highly variable vehicle to vehicle. My alternator temperature data collected is likely valid for most full size vans, but a Minivan?? I can't say for sure.
It is also wise to have a plug in charger and an extension cord, for when grid power is available. Automatic chargers generally suck at fully charging a regularly deeply cycled battery, but they are wy better than not being able to recharge at all when plugging in is an available option.
The Prologix 20 amp model sold on Amazon seems to get some good reviews as a garage charger. I have not used one. I hate recommending products I have not personally used. so consider the following link to be an option, that some gearheads seem to think works well..
https://www.amazon.com/Pro-Logix-PL2520-...B009RXYU4I
If one is willing to spend a bit more the Progressive dynamics PD9245 converter allows manual control of absorption voltage, and 45 amps are avaialable to seek and hold 14.4v. They also have a PD9245-14.8v model which wil charge faster. COnverters one must provide their own DC connection from converter to battery.
There are not many garage chargers above 20 amps, and a van dweller should have at least 20 amps available.
Regarding these garage chargers, if one is really trying to insure a full charge, after the green light flashes and indicates a full charge, assume the battery is about 92 to 95% charged. Unplug charger from grid and the battery, then turn on the headlights or other large amperage load, until voltage falls below 12.7 or so, then restart chrger on next lowest amperage setting.
lather rinse repeat in an attempt to get to the very desirable 100% state of charge. Smart chargers basically need to be tricked into doing what their marketers claim it can do.
One other trick, of one is to use the AGM setting on a flooded battery. These will float a battery at 13.6v, and when plugged in overnight, the 13.6v held battery has a much better chance than 13.2v of the flooded/regular setting, to get fully recharged.
The AGM setting might also allow for a longer absorption voltage stage which is almost always significantly better for a regularly deeply cycled battery, flooded or AGM.
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