Need Some Help Deciding on a Battery Please
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Originally Posted By: wrcsixeight
Battery longevity is more dependent on the average temperature it sees, and its average state of charge, than who put thier sticker on the casing, or who made it for those who did....
Lots of good info there.
While I don't agree 100% with the part of one make is no better than another (there are differences in construction and design between some makes, like plate thickness and count that make a difference), as well as AGM batteries being better overall (but a different tech the flooded batteries), most of the rest is pretty spot on.
One of the things I have found out is as said, heat is the killer of batteries, and high CCA is not a good thing if your in a hot area. The higher the CCA, the thinner the plates and shorter the life in the heat. Some models have a southern and northern version of batteries for this reason (S model will be lower CCA with thicker plates).
I decided the other day to try the Walmart ValuePower battery in my truck. The spec's of it are actually identical to the OEM, and decided I am going to try to do better maintenance on this battery. I have always checked the fluid level yearly on the batteries and kept terminals clean, but seldom, if ever, gave them top off charges.
With this one (and the one if my wife's car, a JCI made Autocraft Gold), I am doing as before, checking the water level and keeping terminals clean, but am now dong a monthly overnight charge (2 amps) to make sure they stay fully charged. Both of them get a lot of short trips, so I know they are not getting fully recharged with driving.
Battery longevity is more dependent on the average temperature it sees, and its average state of charge, than who put thier sticker on the casing, or who made it for those who did....
Lots of good info there.
While I don't agree 100% with the part of one make is no better than another (there are differences in construction and design between some makes, like plate thickness and count that make a difference), as well as AGM batteries being better overall (but a different tech the flooded batteries), most of the rest is pretty spot on.
One of the things I have found out is as said, heat is the killer of batteries, and high CCA is not a good thing if your in a hot area. The higher the CCA, the thinner the plates and shorter the life in the heat. Some models have a southern and northern version of batteries for this reason (S model will be lower CCA with thicker plates).
I decided the other day to try the Walmart ValuePower battery in my truck. The spec's of it are actually identical to the OEM, and decided I am going to try to do better maintenance on this battery. I have always checked the fluid level yearly on the batteries and kept terminals clean, but seldom, if ever, gave them top off charges.
With this one (and the one if my wife's car, a JCI made Autocraft Gold), I am doing as before, checking the water level and keeping terminals clean, but am now dong a monthly overnight charge (2 amps) to make sure they stay fully charged. Both of them get a lot of short trips, so I know they are not getting fully recharged with driving.
Walmart batteries in the the New York/New Jersey area are now East Penn built and you can't get much better than that.
Not all that cheap however, about $99 +tax for the Ever Stop version.
Sears DieHard are also mostly East Penn built.
Not all that cheap however, about $99 +tax for the Ever Stop version.
Sears DieHard are also mostly East Penn built.
My AGM battery, when stuffed full to the brim, well at 14.7v it accepts 0.0x amps, the X is because I have no Ammeter which can read below 0.05 of an Amp.
So with this absolutely fully chrged battery, I start my engine. When amps again taper to 0.0x amps, at 14.7v, the battery can again be considered fully charged.
So how long does it take for amps to taper back to 0.0x amps at 14.7v after starting my engine?
About 45 seconds.
I don;t buy the short trip driving as a killer of batteries. I think it it parasitic loads and the fact that it takes a long time for a 95% charged battery to get to 100% charged.
One can discharge a battery to 95% in a few minutes with the stereo on with engine off, but recharging 95% to 100%, you are basically looking at 2 hours when held at 14.5ish volts.
Plugging in a charger overnight is wise, as long as the charger does not exceed the high 14 volt range, and this could be excessive.
How to know if a batery is fully charged? Well voltage alone is not a good indicator, unless on has earlier verified what the fully charged resting voltage was when the battery was new at a certain temperature.
Get a hydrometer. OTC 4619 or similar, that has a thermometer on it for temp compensation.
For AGM batteries, when they can accept 0.5 amps or less per 100AH of capacity, when held at absorption voltage( generally 14.4 to 14.7v), then they can be considered fully charged.
Most AGM batteries will actually decline to very low levels of amperage to be held at just about any voltage under 14.8v, given enough time.
Some maintenance free batteries will also exhibit this behavior of accepting very little current when fully charged at high voltages, where as regular starting batteries will usually require 0.7 or more amps to be held at 14.5ish volts.
They will all vary on these numbers, they are not written in stone, but the Ammeter and hydrometer are great tools for establishing full charge. The green light full charge indicator on automatic charging sources, should be viewed with high suspicion when it first alights. They are just following an algorithm, they do not know the size of the battery or its 'numbers'.
They guess, and hopefully when they drop to float voltage, well they are eigher close to full charge, or there is enough time at float voltage to finish the task.
Abused batteries might never revert to maximum specific gravity at 'normal' charging voltages.
An Equalization charge is upto 16.2 volts at 77f, but there are some safety considerations to performing this procedure, and it might or might not restore lost capacity/performance of an abused battery.
So with this absolutely fully chrged battery, I start my engine. When amps again taper to 0.0x amps, at 14.7v, the battery can again be considered fully charged.
So how long does it take for amps to taper back to 0.0x amps at 14.7v after starting my engine?
About 45 seconds.
I don;t buy the short trip driving as a killer of batteries. I think it it parasitic loads and the fact that it takes a long time for a 95% charged battery to get to 100% charged.
One can discharge a battery to 95% in a few minutes with the stereo on with engine off, but recharging 95% to 100%, you are basically looking at 2 hours when held at 14.5ish volts.
Plugging in a charger overnight is wise, as long as the charger does not exceed the high 14 volt range, and this could be excessive.
How to know if a batery is fully charged? Well voltage alone is not a good indicator, unless on has earlier verified what the fully charged resting voltage was when the battery was new at a certain temperature.
Get a hydrometer. OTC 4619 or similar, that has a thermometer on it for temp compensation.
For AGM batteries, when they can accept 0.5 amps or less per 100AH of capacity, when held at absorption voltage( generally 14.4 to 14.7v), then they can be considered fully charged.
Most AGM batteries will actually decline to very low levels of amperage to be held at just about any voltage under 14.8v, given enough time.
Some maintenance free batteries will also exhibit this behavior of accepting very little current when fully charged at high voltages, where as regular starting batteries will usually require 0.7 or more amps to be held at 14.5ish volts.
They will all vary on these numbers, they are not written in stone, but the Ammeter and hydrometer are great tools for establishing full charge. The green light full charge indicator on automatic charging sources, should be viewed with high suspicion when it first alights. They are just following an algorithm, they do not know the size of the battery or its 'numbers'.
They guess, and hopefully when they drop to float voltage, well they are eigher close to full charge, or there is enough time at float voltage to finish the task.
Abused batteries might never revert to maximum specific gravity at 'normal' charging voltages.
An Equalization charge is upto 16.2 volts at 77f, but there are some safety considerations to performing this procedure, and it might or might not restore lost capacity/performance of an abused battery.
Pep Boys has 30% off on Bosch batteries with online code MMJ30 right now.
When the batteries in my wife's car and my truck crater I plan on replacing both with Bosch AGM's. With 48 month non-prorated warranty, the cost per warrantied year of service is tough to beat.
When the batteries in my wife's car and my truck crater I plan on replacing both with Bosch AGM's. With 48 month non-prorated warranty, the cost per warrantied year of service is tough to beat.
Originally Posted By: BISCUT
17 Subaru Outback 3.6H engine. The OEM batters was a major engineering malfunction/cost cutting decision that went WRONG! It's a major issues with them and pretty well known. I have 13k on mine so far and I did leave the tailgate and a door open for a few hours and IT DIED. Not sure why there is not (or why it didn't work if there is one) an auto turn off after XX minutes.
Not unusual for new car batteries to be in sad shape. Reason, they sit on car lots not being run for months at a time, then suddenly get a jump start and move right into daily service. Sitting at a low charge state is hard on any wet cell battery, it sulfates the plates, which decreases capacity and service life. Sometimes they recover after a full recharge, sometimes they have major permanent damage, usually something in between.
Getting a warranty replacement might be hard, if the battery can hold enough charge to start the vehicle, then not their problem. So, getting a new battery will probably be on you. I can recommend the East Penn/Deka batteries. There are other good choices. I would avoid Johnson Controls.
BTW I agree on the need for a timeout. My 2005 Pilot has a 15 minute timeout. It has probably saved us from countless dead battery mornings because of the combination of: kids, doors and overhead lights. Subaru needs to get their act together, everybody sells AWD vehicles now. Being a New England cult favorite from the 70's-80's is not a valid marketing plan.
17 Subaru Outback 3.6H engine. The OEM batters was a major engineering malfunction/cost cutting decision that went WRONG! It's a major issues with them and pretty well known. I have 13k on mine so far and I did leave the tailgate and a door open for a few hours and IT DIED. Not sure why there is not (or why it didn't work if there is one) an auto turn off after XX minutes.
Not unusual for new car batteries to be in sad shape. Reason, they sit on car lots not being run for months at a time, then suddenly get a jump start and move right into daily service. Sitting at a low charge state is hard on any wet cell battery, it sulfates the plates, which decreases capacity and service life. Sometimes they recover after a full recharge, sometimes they have major permanent damage, usually something in between.
Getting a warranty replacement might be hard, if the battery can hold enough charge to start the vehicle, then not their problem. So, getting a new battery will probably be on you. I can recommend the East Penn/Deka batteries. There are other good choices. I would avoid Johnson Controls.
BTW I agree on the need for a timeout. My 2005 Pilot has a 15 minute timeout. It has probably saved us from countless dead battery mornings because of the combination of: kids, doors and overhead lights. Subaru needs to get their act together, everybody sells AWD vehicles now. Being a New England cult favorite from the 70's-80's is not a valid marketing plan.
I think that you have to take the current based on the voltage difference of the charger and the battery. So say you have a 25% discharged battery (resting open circuit voltage of ~12.40V). Also assume the resistance is about the same, the the potential difference is as calculated below.
13.7-12.4 = 1.3V
14.7-12.4 = 2.2V
Take the voltage/resistance at the two points and I calculate the current to be 59% at 13.7V compared to 14.7V. Not quite the 33%, but closer! I'm sure there's more to it too.
13.7-12.4 = 1.3V
14.7-12.4 = 2.2V
Take the voltage/resistance at the two points and I calculate the current to be 59% at 13.7V compared to 14.7V. Not quite the 33%, but closer! I'm sure there's more to it too.
Originally Posted By: willbur
How did you come up with your figure that about 1/3 (33%) the amps flow at 13.7 volts than at 14.7 volts?
Ohms Law indicates about 93% amp flow at 13.7 volts, not 33%
Am I missing something?
My figures come from actual observation of an ammeter on my dashboard as I spin the voltage potentiometer I located there next to the digital voltmeters whose voltage sense lines are on battery terminals.
I also have an adjustable voltage power supply with an Ammeter on the output that I use as a battery charger and I deep cycle a battery pretty much each and every day. I have an amp hour counting battery monitor on it and usually know with about 90% accuracy the state of charge of my battery.
I regularly see how many amps are flowing into a battery at various states of charge, at what voltage, and it is very enlightening to twist a dial and see the changes.
The battery resistance changes with battery state of charge, health, temperature, how many cycles it has been since the last true full charge, and the last high amp recharge from a well depleted state.
My ~2/3 figure observation is on a group 27 Northstar AGM battery that had about 475 deep cycles on it at that time. It was after a drive. battery was aboit 75% charged. I had voltage set at 14.7 and the battery was accepting 29.x amps. I slowly lowered voltage to 13.7 and gave it a minute to stabilize and it was accepting around 8.6 amps. Goose voltage back upto 14.7 and amps went back up over 30 then lowered back to 29.x and stayed there until I shut off engine.
As this battery has aged, the amount of amps it accepts at any voltage has declined. It takes longer and longer to recharge to full, even at 14.7v. When depleted it used to gobble up 100+ alternator amps and took a long while at 65 to 100 amps before battery voltage would raise to 14.7. Now a steady 65 amps takes about 20 minutes to get it to 14.7v at which point the amps start tapering to maintain that voltage.
65 amps is the maximum my plug in chargers can supply when in parallel, and is also about the maximum my alternator is capable of when still cool and with engine under 1100 rpm. when hot this falls to the 50 range at hot idle. My engine consumes 8.2 to 12.2 amps of that output to run fuel pump, ignition. My depleted AGM battery will max out the alternator at most rpm I ever drive at, if I have voltage set to 14.7. If the cold wet belt starts squealing, I lower voltage until it does not.
Alternator temperature is another thread, but basically hot Idling maxed out at about 50 amps, temp skyrockets to the 200F zone, and at 65mph it is unlikely to get above 130f maxed out at 100 ish amps.
How did you come up with your figure that about 1/3 (33%) the amps flow at 13.7 volts than at 14.7 volts?
Ohms Law indicates about 93% amp flow at 13.7 volts, not 33%
Am I missing something?
My figures come from actual observation of an ammeter on my dashboard as I spin the voltage potentiometer I located there next to the digital voltmeters whose voltage sense lines are on battery terminals.
I also have an adjustable voltage power supply with an Ammeter on the output that I use as a battery charger and I deep cycle a battery pretty much each and every day. I have an amp hour counting battery monitor on it and usually know with about 90% accuracy the state of charge of my battery.
I regularly see how many amps are flowing into a battery at various states of charge, at what voltage, and it is very enlightening to twist a dial and see the changes.
The battery resistance changes with battery state of charge, health, temperature, how many cycles it has been since the last true full charge, and the last high amp recharge from a well depleted state.
My ~2/3 figure observation is on a group 27 Northstar AGM battery that had about 475 deep cycles on it at that time. It was after a drive. battery was aboit 75% charged. I had voltage set at 14.7 and the battery was accepting 29.x amps. I slowly lowered voltage to 13.7 and gave it a minute to stabilize and it was accepting around 8.6 amps. Goose voltage back upto 14.7 and amps went back up over 30 then lowered back to 29.x and stayed there until I shut off engine.
As this battery has aged, the amount of amps it accepts at any voltage has declined. It takes longer and longer to recharge to full, even at 14.7v. When depleted it used to gobble up 100+ alternator amps and took a long while at 65 to 100 amps before battery voltage would raise to 14.7. Now a steady 65 amps takes about 20 minutes to get it to 14.7v at which point the amps start tapering to maintain that voltage.
65 amps is the maximum my plug in chargers can supply when in parallel, and is also about the maximum my alternator is capable of when still cool and with engine under 1100 rpm. when hot this falls to the 50 range at hot idle. My engine consumes 8.2 to 12.2 amps of that output to run fuel pump, ignition. My depleted AGM battery will max out the alternator at most rpm I ever drive at, if I have voltage set to 14.7. If the cold wet belt starts squealing, I lower voltage until it does not.
Alternator temperature is another thread, but basically hot Idling maxed out at about 50 amps, temp skyrockets to the 200F zone, and at 65mph it is unlikely to get above 130f maxed out at 100 ish amps.
In the northern states, everyone seems to always recommend "bigger is better" regarding CCA. At the same time, it has been suggested that cramming more, thinner plates into a battery cases of equal size can result in a shorter lived battery. I.E. - Same group size case, 540CCA vs. 700CCA.
With all this talk about the alternator's limited ability to get or maintain batteries to full charge, what is the implication of installing a higher CCA rated battery vs. what came in a vehicle as OE? Will a higher CCA battery be even more difficult for the alternator to maintain the battery near full charge??
With all this talk about the alternator's limited ability to get or maintain batteries to full charge, what is the implication of installing a higher CCA rated battery vs. what came in a vehicle as OE? Will a higher CCA battery be even more difficult for the alternator to maintain the battery near full charge??
Interesting stuff WRC,
Your observations apply to the set up/circuit you employed, not in the general case. OHMS Law governs.The potentiometer placed in the circuit and the rest of the system together are functioning as a voltage divider circuit. Some of the current is shunted to ground (and some also lost as heat in the potentiometer) and you just are measuring the remainder.
Thank you for sharing your research
Your observations apply to the set up/circuit you employed, not in the general case. OHMS Law governs.The potentiometer placed in the circuit and the rest of the system together are functioning as a voltage divider circuit. Some of the current is shunted to ground (and some also lost as heat in the potentiometer) and you just are measuring the remainder.
Thank you for sharing your research
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Thanks for all the good posts...and really free education!
I don't short trip....it's my daily ride with an average of 2k miles a month. Short trip for me is 12-15 mile range. I don't run the battery to run radio often at all. I don't leave doors or gate open often. This is a well known Subby issue. The dealer who said it's because the key fob is withing 15ft?? He deserves a punch where the sun don't shine
With exception of a Nissan Armada (kids ran it dead multiple times) i've never gotten less than 4 years from a battery. I think more to do with good habits and no short trips.
I don't mean to sound negative on Subby. besides a few minor what the heck things I don't like, I find it hard to get a better ride for the price. It's early, 13k into it but it is as pleasing as vanilla can get. Happy with her so far.
Decisions, decisions.....
I don't short trip....it's my daily ride with an average of 2k miles a month. Short trip for me is 12-15 mile range. I don't run the battery to run radio often at all. I don't leave doors or gate open often. This is a well known Subby issue. The dealer who said it's because the key fob is withing 15ft?? He deserves a punch where the sun don't shine
I don't mean to sound negative on Subby. besides a few minor what the heck things I don't like, I find it hard to get a better ride for the price. It's early, 13k into it but it is as pleasing as vanilla can get. Happy with her so far.
Decisions, decisions.....
Originally Posted By: willbur
Interesting stuff WRC,
The potentiometer placed in the circuit and the rest of the system together are functioning as a voltage divider circuit.
My potentiometer is not in the circuit, it is a 2 watt 2k Ohm BOurns 10 turn potentiometer whose changing resistance tells the voltage regulator how to control the field current to the alternator in order to seek and or maintain a voltage with as many amps as required.
I know of no potentiometer which could act as a big enough precision resistor to limit alternator current to the battery i think that would be termed a rheostat and would have to be HUGE to bleed off that much heat.
My voltage regulator was internal to engine computer, and was batcrap crazy. I used a 50 watt 10 OHM resistor into tricking the computer that it was still connected to the alternator, and used an external adjustable voltgae regulator to enable me to choose anyoutput voltage i desire. the alternator makes whatever it has to, or can, in order to achieve or hold the voltage I have chosen.
While there will be differnences in circuit resistance between alternator and battery, and different resistances of differneet batteries at different states of charge/health/tmeperature, regarding how much a battery accepts at 13.7v vs 14.7v, I'll stand by my Data, and it does not contradict Ohm's law.
I do not think you are accounting for battery resistance or its variability.
Much more amperage will flow into a depleted battery when the voltage regulator is seeking 14.7 compared to 13.7v
Interesting stuff WRC,
The potentiometer placed in the circuit and the rest of the system together are functioning as a voltage divider circuit.
My potentiometer is not in the circuit, it is a 2 watt 2k Ohm BOurns 10 turn potentiometer whose changing resistance tells the voltage regulator how to control the field current to the alternator in order to seek and or maintain a voltage with as many amps as required.
I know of no potentiometer which could act as a big enough precision resistor to limit alternator current to the battery i think that would be termed a rheostat and would have to be HUGE to bleed off that much heat.
My voltage regulator was internal to engine computer, and was batcrap crazy. I used a 50 watt 10 OHM resistor into tricking the computer that it was still connected to the alternator, and used an external adjustable voltgae regulator to enable me to choose anyoutput voltage i desire. the alternator makes whatever it has to, or can, in order to achieve or hold the voltage I have chosen.
While there will be differnences in circuit resistance between alternator and battery, and different resistances of differneet batteries at different states of charge/health/tmeperature, regarding how much a battery accepts at 13.7v vs 14.7v, I'll stand by my Data, and it does not contradict Ohm's law.
I do not think you are accounting for battery resistance or its variability.
Much more amperage will flow into a depleted battery when the voltage regulator is seeking 14.7 compared to 13.7v
MAXX from Walmart. I purchased one in 09 and it is still going strong. Three year warranty and pro rated after that.
Originally Posted By: blupupher
wrcsixeight said:
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