With enough voltage (>15V) and enough heat (>120F) you might get a small reversal of soft sulfation, with the risk of some Northstar battery damage.
NorthStar AGM battery charging and sulfation woes with Optima® Digital 1200 Battery Charger.
- Thread starter jmegas
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With enough voltage (>15V) and enough heat (>120F) you might get a small reversal of soft sulfation, with the risk of some Northstar battery damage.
I've been trying to establish a few points regarding your Northstar batteries.
1: The smart charger deciding to never read above 75%, might mean absolutely nothing.
If it stalls at 75%, what is the amperage it is accepting at the voltage the charger is holding the battery at? This is highly revealing data, far more than a 75 number which never changes and likely has no basis in reality. I have seen voltage displays on chargers being as much as 0.4v off. The charger is reading voltage at the DC output at the circuit board of the charger, not at the battery terminals. The voltage at the battery terminals will be lower, and it will be lower the more amperage the battery is accepting from the charger, and will be lower the longer and thinner the wiring is, due to voltage drop on the DC output wiring.
Generally at high states of charge the battery is only accepting 1 amp or less, and the less amperage that is flowing through wires the less voltage drop on the wiring from source to load. A 25 amp charger should be using 10 AWG wiring. It likely uses 14 as 14awg is rated to carry 30 amps, but 14 awg will drop several tenths of a volt at 25 amps. The battery would accept slightly more amperage for longer and recharge slightly, but measurably faster if the cable from charger to alligator clamp at battery were 10awg instead of 14, or worse, 16 awg. My 25 amp schumacher used the worst quality 14 awg I've ever seen. I could not believe how hot it would get passing 25 amps. When i replaced it with 10AWG it worked better, and its max outptu was closer to 28 amps.
Some chargers get the voltage at circuit board to say 14.6v, then instantly drop to 14.2, though this tends to happen on the flooded/wet settings rather than AGM. With undersized wiring, the voltage at dc output at circuit board will read 14.6, but the voltage at battery terminals will be upto a few tenths of a volt lower. This in effect, potentially never gets the battery to absorption voltage at all, and this is a Big No No in deep cycle duty, especially AGMS, especially TPPL Agms like Northstar/Odyssey. My dekas once I get them to 14.4v, I can lower voltaqge to 14.1 and amps only go down by 0.5 or 0.9, but my Northstar if I get voltage to 14.7v then lower voltage to 14.4v, amps drop by no less than 5. This is just one example of the weird personalities that batteries will exhibit when one looks closely with the right tools to do so. The Northstars I bring to 14,7v and hold them there, the Dekas there is little benefit from holding them at their 14.4 spec once they have reached it, so I lower it to 14.1 or so, sometimes even 13.9v and wait for amps to taper to 0.3 before turning voltage down to 13.4, or just turning off the power supply entirely.
2.
The repair mode might to its magic crystal resonating pulse thing, or it might simply bring the battery to a high absorption voltage and hold it there for a few hours. Im not going to research to see what either noco or optimate says it does.
I've stated my opinion on the magic resonating sulfate crystal thing, but an additional 4 hours held at 14.8v stands a very good chance of charging a sulfated battery to a slightly less sulfated state.
3. A battery at 85% charged or higher, cannot accept high amperage. If it pumps out 25 amps continuous, it would quickly push the voltage well over 15, which is to be avoided, especially with AGMS. The charger is going to limit voltage to 14.8 or so, and will only produce enough amperage to maintain 14.8v. This amperage will taper farther and farther towards zero the more full the battery gets.
4. the high amp recharge from a well depleted state is the best way to potentially dissolve hardened sulfation and restore lost capacity and cranking amps.
HIgh amps recharging........ applied to battery.............. when it is well discharged. 80% charged is not well discharged.
You cant push high amps into a battery unless it is well depleted, no matter how high you set the pressure/voltage.
Even if the charger says 25 amps, and you set it to 25 amps, on an 85% charged group 34, it will accept 25 amps for less than a second, taper to about 15 amps in 5 to 10 seconds, and taper to about 10 amps in 30 seconds and then over the next 3+ hours taper towards zero amps, IF the charger even holds absorption voltage for that long, which is unlikely.
This is too little amperage, and too little time to heat the hardened sulfate and potentially dissolve it back into solution, opening up the clogged plate pores, restoring capacity and CCA.
To get high amperage into a battery it must be well depleted. The more depleted it is, the longer it can accept high amps, the more it can heat the hardened sulfate, and the better the chance it then redissolves into solution and restores capacity and CCA.
You can drive 6 hours, then put the charger on restore mode 10 times in a row and have it do nothing other than add to your electric bill.
you can drive 6 hours then turn engine off and leave headlights on until voltage falls to 11.2, then turn off headlights, plug in the charger set at 25 amps, and that WILL do something, or at least it stands the best chance of doing something. When it shuts down put on the charger which says it takes 4 hours to restore/recondition as this is likely just an extended absorption voltage stage cycle, but check to insure voltage does not exceed 15!
5, without knowing the voltage your vehicle holds as you drive, you have no idea of the state of charge of the battery, and it is unwise in the extreme to assume that it must be fully charged because you drove 6 hours. It could be doing the MPG thing where the voltage regulator sends no field current to the rotor and the alternator places no additional load on the engine when it is most advantageous to add 0.06mpg.
You could fully charge your battery on your charger, leave home at 99% charged, drive 6 hours to your cabin, and arrive with an 80% charged battery and perhaps burned a few less thimbles of fuel than if it had held 14.4v for 10 minutes then 13.8v for the final 5 hours and 50 minutes.
6.
Sticking a charger on a battery, and the charger declaring a % of charge, and believing what the charger says, is unwise in the extreme.
Voltage is ONLY indicative of state of charge on a well rested battery. well rested meansing a battery which has not seen either discharging loads, or charging sources applied for several hours. If you place a charger on a battery that has just been on another charging source, the voltage will likely be artificially high, as it has not had time to bleed off.
This surface charge voltage can and will stick around on a healthy AGM for DAYS when there is no loads applied to the battery. Place a smart charger on a battery that reads 13.4v surface voltage from another recent charging source, and it thinks it is already fully charged and will go right to float mode. This 13.4v artificially high surface charge does not indicate the battery is full, nor does it mean it is healthy. It could still be only 84% charged and 80% state of health, and need 3 hours or more being brought to and held at 14.7v before its anywhere near 99% charged.
But the smart charger saw 13.4 volts and assumed it was already full and went right to float voltage, so instead of 3 hours till full charge, it takes 4 days at 13.4v, or whatever the float voltage set point of the charger is. The old sulfated battery stands little chance of ever reaching full charge at float voltage. One could leave ithe old abused sulfated battery plugged in for weeks at float voltage, and never get it above 90%. Its like a balloon with a bunch of tiny pinholes letting the pressure escape.
So back to the first thing I typed in this thread. trying to determine state of charge, or state of health of a battery, by what some smart charger displays, or does not display is a frustrating, confusing lesson in futility and means nothing.
Perhaps just slightly more than nothing, when one generates enough experience with that charger and many other tools which actually can reveal data which corresponds to reality and has the gumption and aptitude to play battery detective/ battery whisperer.
So the suspected weak northstar, drain it to a low voltage, then high amp recharge it with no less than teh 25 amp charger, then press the 4 hour magic restore button and hope it holds absorption voltage for an additional 4 hours. There is no point in pressing the magic restore/recondition button over and over without first draining the battery to a low voltage/ low state of charge then immediately providing it with as much amperage as you can muster.
It is possible to put two chargers in parallel and combine their amperage, but one needs the battery to be well depleted and start both chargers quickly, so that one charger does not bring the battery above ~12.7v before the other charger gets started.
Also, whencombining charging sources in parallel, once they together gets the battery to around 75 to 85% charged, or the maximum voltage of one charger or the other, then that lower voltage charger will just stop, and can be removed. Their combined amperage is not needed at that point anyway.
A guy on an RV forum used to combine 4 older VEctor/ black and decker 35 and 40 amp chargers on 6 golf cart batteries, in order to reduce the time it took to get from 50%to 80% while running his noisy gas guzzling generator during limited genertor run hours.
He later just got a100 amp and a 55 amp adjustable voltage power supply put them in parallel, so he did not have to stuff/stack 4 sets of 14 awg weak alligator clamps on a battery bank.
I used to combine my 2/12/25 amp schumacher charger with my 40 amp meanwell power supply for 65 amps of charge current, before I got my 100 amp adjustable voltage power supply. One time pre 100 amp power supply, I also added a transformer based old school 2 and 10 amp transformer based charger to the smart charger and the power supply, but later determined the 10 amp setting this POS manual charger only makes 4.2 amps max on the 10 amp setting, and its not worth the effort to get 69.2 amps rather than 65.
If I can source two different 15 amp household circuits, I can, and have combined the output of the 40 and 100 amp power supplies, and managed 138 amps into my group 31 Northstar which was depleted 67 of its 103 amp hour rating. I can get 122 amps from one of my alternators and 116 from the other, though I've not tried to combine them both, yet.
While I cant say for sure, 65 amps seems to be the most rewarding amount of amperage to feed my G31 northstar when it gets lazy from too much floating, or when I have done a bunch of cycles either not getting to 100% charged, or a bunch of lower slower recharges to full at no more than 12 amps/~ 200 watts of solar panel.
The 100 amp adjustable voltage power supply, I set its voltage to 0.1v above battery voltage, then hook it to well depleted NS battery, then twist the voltage dial upwards until it delivers the amperage I desire, upto its 100 amp limit. I have not noticed 100 amps being more advantageous than 65 to smack the lazy northstar back to expected performance, so unless time is of the essence, I control amp flow with the voltage dial in order to not exceed 65 amps.
My adjustabe voltage power supply's voltage dial is kind of similar to a throttle pedal. The higher I turn it the more amperage is generated, at least on a well depleted battery that has not yet risen to absorption voltage. It's very enlightening.
1: The smart charger deciding to never read above 75%, might mean absolutely nothing.
If it stalls at 75%, what is the amperage it is accepting at the voltage the charger is holding the battery at? This is highly revealing data, far more than a 75 number which never changes and likely has no basis in reality. I have seen voltage displays on chargers being as much as 0.4v off. The charger is reading voltage at the DC output at the circuit board of the charger, not at the battery terminals. The voltage at the battery terminals will be lower, and it will be lower the more amperage the battery is accepting from the charger, and will be lower the longer and thinner the wiring is, due to voltage drop on the DC output wiring.
Generally at high states of charge the battery is only accepting 1 amp or less, and the less amperage that is flowing through wires the less voltage drop on the wiring from source to load. A 25 amp charger should be using 10 AWG wiring. It likely uses 14 as 14awg is rated to carry 30 amps, but 14 awg will drop several tenths of a volt at 25 amps. The battery would accept slightly more amperage for longer and recharge slightly, but measurably faster if the cable from charger to alligator clamp at battery were 10awg instead of 14, or worse, 16 awg. My 25 amp schumacher used the worst quality 14 awg I've ever seen. I could not believe how hot it would get passing 25 amps. When i replaced it with 10AWG it worked better, and its max outptu was closer to 28 amps.
Some chargers get the voltage at circuit board to say 14.6v, then instantly drop to 14.2, though this tends to happen on the flooded/wet settings rather than AGM. With undersized wiring, the voltage at dc output at circuit board will read 14.6, but the voltage at battery terminals will be upto a few tenths of a volt lower. This in effect, potentially never gets the battery to absorption voltage at all, and this is a Big No No in deep cycle duty, especially AGMS, especially TPPL Agms like Northstar/Odyssey. My dekas once I get them to 14.4v, I can lower voltaqge to 14.1 and amps only go down by 0.5 or 0.9, but my Northstar if I get voltage to 14.7v then lower voltage to 14.4v, amps drop by no less than 5. This is just one example of the weird personalities that batteries will exhibit when one looks closely with the right tools to do so. The Northstars I bring to 14,7v and hold them there, the Dekas there is little benefit from holding them at their 14.4 spec once they have reached it, so I lower it to 14.1 or so, sometimes even 13.9v and wait for amps to taper to 0.3 before turning voltage down to 13.4, or just turning off the power supply entirely.
2.
The repair mode might to its magic crystal resonating pulse thing, or it might simply bring the battery to a high absorption voltage and hold it there for a few hours. Im not going to research to see what either noco or optimate says it does.
I've stated my opinion on the magic resonating sulfate crystal thing, but an additional 4 hours held at 14.8v stands a very good chance of charging a sulfated battery to a slightly less sulfated state.
3. A battery at 85% charged or higher, cannot accept high amperage. If it pumps out 25 amps continuous, it would quickly push the voltage well over 15, which is to be avoided, especially with AGMS. The charger is going to limit voltage to 14.8 or so, and will only produce enough amperage to maintain 14.8v. This amperage will taper farther and farther towards zero the more full the battery gets.
4. the high amp recharge from a well depleted state is the best way to potentially dissolve hardened sulfation and restore lost capacity and cranking amps.
HIgh amps recharging........ applied to battery.............. when it is well discharged. 80% charged is not well discharged.
You cant push high amps into a battery unless it is well depleted, no matter how high you set the pressure/voltage.
Even if the charger says 25 amps, and you set it to 25 amps, on an 85% charged group 34, it will accept 25 amps for less than a second, taper to about 15 amps in 5 to 10 seconds, and taper to about 10 amps in 30 seconds and then over the next 3+ hours taper towards zero amps, IF the charger even holds absorption voltage for that long, which is unlikely.
This is too little amperage, and too little time to heat the hardened sulfate and potentially dissolve it back into solution, opening up the clogged plate pores, restoring capacity and CCA.
To get high amperage into a battery it must be well depleted. The more depleted it is, the longer it can accept high amps, the more it can heat the hardened sulfate, and the better the chance it then redissolves into solution and restores capacity and CCA.
You can drive 6 hours, then put the charger on restore mode 10 times in a row and have it do nothing other than add to your electric bill.
you can drive 6 hours then turn engine off and leave headlights on until voltage falls to 11.2, then turn off headlights, plug in the charger set at 25 amps, and that WILL do something, or at least it stands the best chance of doing something. When it shuts down put on the charger which says it takes 4 hours to restore/recondition as this is likely just an extended absorption voltage stage cycle, but check to insure voltage does not exceed 15!
5, without knowing the voltage your vehicle holds as you drive, you have no idea of the state of charge of the battery, and it is unwise in the extreme to assume that it must be fully charged because you drove 6 hours. It could be doing the MPG thing where the voltage regulator sends no field current to the rotor and the alternator places no additional load on the engine when it is most advantageous to add 0.06mpg.
You could fully charge your battery on your charger, leave home at 99% charged, drive 6 hours to your cabin, and arrive with an 80% charged battery and perhaps burned a few less thimbles of fuel than if it had held 14.4v for 10 minutes then 13.8v for the final 5 hours and 50 minutes.
6.
Sticking a charger on a battery, and the charger declaring a % of charge, and believing what the charger says, is unwise in the extreme.
Voltage is ONLY indicative of state of charge on a well rested battery. well rested meansing a battery which has not seen either discharging loads, or charging sources applied for several hours. If you place a charger on a battery that has just been on another charging source, the voltage will likely be artificially high, as it has not had time to bleed off.
This surface charge voltage can and will stick around on a healthy AGM for DAYS when there is no loads applied to the battery. Place a smart charger on a battery that reads 13.4v surface voltage from another recent charging source, and it thinks it is already fully charged and will go right to float mode. This 13.4v artificially high surface charge does not indicate the battery is full, nor does it mean it is healthy. It could still be only 84% charged and 80% state of health, and need 3 hours or more being brought to and held at 14.7v before its anywhere near 99% charged.
But the smart charger saw 13.4 volts and assumed it was already full and went right to float voltage, so instead of 3 hours till full charge, it takes 4 days at 13.4v, or whatever the float voltage set point of the charger is. The old sulfated battery stands little chance of ever reaching full charge at float voltage. One could leave ithe old abused sulfated battery plugged in for weeks at float voltage, and never get it above 90%. Its like a balloon with a bunch of tiny pinholes letting the pressure escape.
So back to the first thing I typed in this thread. trying to determine state of charge, or state of health of a battery, by what some smart charger displays, or does not display is a frustrating, confusing lesson in futility and means nothing.
Perhaps just slightly more than nothing, when one generates enough experience with that charger and many other tools which actually can reveal data which corresponds to reality and has the gumption and aptitude to play battery detective/ battery whisperer.
So the suspected weak northstar, drain it to a low voltage, then high amp recharge it with no less than teh 25 amp charger, then press the 4 hour magic restore button and hope it holds absorption voltage for an additional 4 hours. There is no point in pressing the magic restore/recondition button over and over without first draining the battery to a low voltage/ low state of charge then immediately providing it with as much amperage as you can muster.
It is possible to put two chargers in parallel and combine their amperage, but one needs the battery to be well depleted and start both chargers quickly, so that one charger does not bring the battery above ~12.7v before the other charger gets started.
Also, whencombining charging sources in parallel, once they together gets the battery to around 75 to 85% charged, or the maximum voltage of one charger or the other, then that lower voltage charger will just stop, and can be removed. Their combined amperage is not needed at that point anyway.
A guy on an RV forum used to combine 4 older VEctor/ black and decker 35 and 40 amp chargers on 6 golf cart batteries, in order to reduce the time it took to get from 50%to 80% while running his noisy gas guzzling generator during limited genertor run hours.
He later just got a100 amp and a 55 amp adjustable voltage power supply put them in parallel, so he did not have to stuff/stack 4 sets of 14 awg weak alligator clamps on a battery bank.
I used to combine my 2/12/25 amp schumacher charger with my 40 amp meanwell power supply for 65 amps of charge current, before I got my 100 amp adjustable voltage power supply. One time pre 100 amp power supply, I also added a transformer based old school 2 and 10 amp transformer based charger to the smart charger and the power supply, but later determined the 10 amp setting this POS manual charger only makes 4.2 amps max on the 10 amp setting, and its not worth the effort to get 69.2 amps rather than 65.
If I can source two different 15 amp household circuits, I can, and have combined the output of the 40 and 100 amp power supplies, and managed 138 amps into my group 31 Northstar which was depleted 67 of its 103 amp hour rating. I can get 122 amps from one of my alternators and 116 from the other, though I've not tried to combine them both, yet.
While I cant say for sure, 65 amps seems to be the most rewarding amount of amperage to feed my G31 northstar when it gets lazy from too much floating, or when I have done a bunch of cycles either not getting to 100% charged, or a bunch of lower slower recharges to full at no more than 12 amps/~ 200 watts of solar panel.
The 100 amp adjustable voltage power supply, I set its voltage to 0.1v above battery voltage, then hook it to well depleted NS battery, then twist the voltage dial upwards until it delivers the amperage I desire, upto its 100 amp limit. I have not noticed 100 amps being more advantageous than 65 to smack the lazy northstar back to expected performance, so unless time is of the essence, I control amp flow with the voltage dial in order to not exceed 65 amps.
My adjustabe voltage power supply's voltage dial is kind of similar to a throttle pedal. The higher I turn it the more amperage is generated, at least on a well depleted battery that has not yet risen to absorption voltage. It's very enlightening.
Somehow your answer ended up in my spam folder.Not really. There is a weak and non-linear correlation between CCA and capacity. You have to lose a lot of capacity from sulfating before it affects CCA.
BU-806: Tracking Battery Capacity and Resistance as part of Aging
BU meta description needed...batteryuniversity.com
I did not know this. It seems that you and I get a lot of our information from the same source, Battery University. They are the ones who seem to love AGM batteries. If CCA measurements won't help, then I will have to start taking some of the measurements wrcsixeight talks about. I do not have a carbon pile load tester, for example. I do have an excellent Fluke multimeter but I don't know how to use it. I guess the easiest next step would be to go to an auto parts store and to have them measure my battery. My Foxwell BT-715 isn't very sophisticated, which was why it appealed to me in the first place. I thought CCA would be the best sign of a battery's decline in performance. My guess is that my NorthStar tests OK but, for some reason, it is still confusing the Optima 1200.
The $217 8-amp charger from Battery Minder is guilty of undercharging during float when using its dedicated Odyssey setting. It floats at 13.2V @77F. I owned one for a short time, but returned it.
BatteryMINDer® Model 128CEC2: 12V 2/4/8 AMP Charger-Maintainer-Desulfator & Lithium Charger Maintainer
BatteryMINDers' desulfating battery charger maintainers fully charge without ever overcharging, no matter how long they are left connected. Visit our website to browse our available products.www.batteryminders.com
Maybe the BatteryMinder charger is why my odyssey's aren't impressing me because I'm only getting 6-7 years out of the odyssey's in my bikes.. I'm tempted to go back to lead acid and buy tenders for everything, but I'll admit I left one Odyssey hooked up to the DRZ which is known for parasitic draw and next spring the $220 PC310 has 3 volts. At one time I was under the impression trickle charging AGM's wasn't recommended..
In my situation where my bikes sit for months at a time, which type of battery and charger would you folks suggest? I need to replace the batteryminder, and don't mind paying for quality and features so it doesn't become obsolete in a year..
Thanks
I like the Optima chargers, although it appears they may have been discontinued. They are still available all sorts of places. They were specifically designed by Johnson Controls for AGM batteries, so they do a better job than most.
A "stored" battery can be damaged by too low a float voltage (leading to plate sulfating) or too high a float voltage (leading to excessive gassing).
In general, buy a temperature compensated charger that produces a float voltage that meets the requirements of your specific battery. For an Odyssey battery, the recommended float voltage at 77F is 13.5-13.8V. Use a volt meter to confirm that your charger is providing the correct float voltage.
The float on my battery minder was 13.3V and the charge was 14.5 charging a old PC680 that needs replaced. Considering I might be damaging my odyssey's with this charger because it also does not compensate for outside temperature.. Should I continue buying odyssey's and buy their OBC-20A Charger?
That's a viable and expensive option, but does the OBC-20A have temperature compensation?
The Odyssey tech manual has detailed charging instructions:
Actually that's in the same price range as the Optima 1200 charger and it is almost *twice* as powerful. From their website, however, it looks as if you might have trouble finding one.
Wrcsixeight mentioned he would switch to lithium if he didn't own all the AGM batteries that he has.. Maybe I should consider Shorai lithium batteries.. Great reviews and prices aren't bad. $90 for their proprietary charger.
Thing is with Odyssey's.. They build car batteries that their own 20 amp charger shouldn't be used on, following their own MINIMUM charge current rule of 4C(10Hr rate). But they list 20HR Nominal Capaity (AH) for their batteries now?? To make it even more confusing and they cant even spell capacity..
Are lithium's as touchy as AGM's for charge and float voltage, or do the good ones with BMS take care of all that, and what kind of charge amperage are we talking about with lithium's?
Sorry, didn't mean to hijack this discussion..
You're not hijacking this discussion at all *if* lithium batteries can work interchangeably with AGMs in all automotive applications. I think SubLGT and I got much of our information on AGMs from Battery University--at least I know I did--and some of it appears to be inaccurate. If lithium batteries can replace AGMs with even better properties, then they would be the way to go. I'm just not sure whether the charging system in my Ford F-150 would be fine with a new lithium battery instead. I don't understand the system all that well.
As stated in the latest tech manual, the minimum acceptable charge current for Odyssey AGM2 battery is 0.1C10, and the optimum current is 0.4C10. The optimum charge current is especially important when the battery is subjected to deep cycle use. Odyssey does create confusion with their tech manual by showing "0.4C10 min" on their charging graph.
quoted from the 2021 Odyssey tech manual:
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A lithium-ion upgrade for your car, but not the one you’re expecting
We try out a 12V lithium-ion battery upgrade for your car.
arstechnica.com
SubLGT,A lithium-ion upgrade for your car, but not the one you’re expecting
We try out a 12V lithium-ion battery upgrade for your car.
Thank you for posting this. For me, this would not be worth the cost, particularly if the entire charging system would have to be modified in any way. AGMs, which do seem to be worth it, are approximately twice what a FLA battery are. These lithiums would be at *least* three times as much and perhaps much more than that. I'd have to know more about exactly *how* they are better and how much.
Some good articles on lithium iron phosphate vs sealed lead acid batteries:
www.power-sonic.com
www.power-sonic.com
One shortcoming of lithium iron phosphate is that it has very poor charge acceptance at temperatures below 32F compared to lead acid. But there are specialized batteries from Relion for low temp use, down to -4F:
https://eepower.com/new-industry-pr...lem-of-li-battery-cold-temperature-charging/#
The Complete Guide to Lithium vs Lead Acid Batteries - Power Sonic
The complete guide to lithium vs lead acid batteries. Learn how a lithium battery compares to lead acid. Learn which battery is best for your application
www.power-sonic.com
How To Charge Lithium Iron Phosphate (LiFePO4) Batteries - Power Sonic
A complete guide on how to charge lithium iron phosphate (LiFePO4) batteries. Learn about the charging of a lithium battery from Power Sonic
www.power-sonic.com
One shortcoming of lithium iron phosphate is that it has very poor charge acceptance at temperatures below 32F compared to lead acid. But there are specialized batteries from Relion for low temp use, down to -4F:
https://eepower.com/new-industry-pr...lem-of-li-battery-cold-temperature-charging/#
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I would / will eventually switch to Lifepo4, as I intentionally deep cycle my Lead acid batteries, often.
Lead Acid batteries can only be recharged quickly to ~80% state of charge, the last 20% means many many hours held at absorption voltage, before reaching true 100% charged. Achieving True 100% charge, is absolutely vital for them to live a good cycle life in deep cycle applications.
The less depth of discharge that lead acid has to deal with (whether flooded/ AGM or GEL) , the less important the true 100% recharge becomes, even though Ideal = 100% state of charge.
A perfectly treated lead acid battery designed for deep cycling, in a laboratory, might accumulate 1000 deep cycles to exactly 50% depth of discharge, before its capacity drops to 80% of new.
Lithium likely goes 2500 cycles minimum, as long as they are not overcharged, nor overdepleted, and are kept within their happy temperature window when being cycled. If also kept in the 20% to 80% charged range they likely go 4000+ cycles. But, all it takes is one overcharge or overdischarge to ruin them, unlike lead acid which is remarkably tolerant of either overcharging and overdischarging events, as long as this abuse is seldom, and when overdepleted, returned to true full promptly.
I would never get a lithium battery just for engine starting duties, even though they obviously have the ability to perform such a task.
The BMS on lithium batteries will cut the battery off from the charging source when it is fully charged.
Removing the load from an alternator without also removing the field current to the rotor at same time or before, can fry the diodes within the alternator, and perhaps also cause a voltage spike which can damage other electronics.
The BMS will also cut off the loads from a battery before it is overdischarged. This might present issues to the discharging load(s), depending on what the load is.
Lithium batteries have a minimum temperature at which they can be safely charged. Some will say not to discharge at a high rate( like engine starting) when below a certain temperature.
It's good there are companies designing lithium starting batteries.
There's many considerations that they have to take into account to keep the salivating lawyers, and the ever increasingly idiotic indignant modern consumer at bay.
I doubt lead acid starting batteries are going to disappear as engine starting batteries anytime soon, but in deep cyclic applications their days are numbered.
But who knows what will really happen, as opposed to what could happen, regarding world events and existing and future supply chain issues.
Hopefully the BMS that is built into the LiFePO4 battery is designed to not just protect the battery, but also the alternator and vehicle electronics.. But I have to wonder how compatible or incompatible it would be with a modern vehicle BMS. A simple voltage regulator + alternator charging system would probably work better with the LiFePO4 battery BMS.
I have *fantastic,* but unexpected, news. I am at my cabin where I can leave the battery charged for days at a time without worrying that the charger will be stolen. After two days of attempted desulfating with the Optima 1200 charger the battery is at 100% and is fully desulfated!!! This means the Optima 1200 I have at home was reading the battery correctly and it *had* become far more deeply sulfated in just one week than I had imagined. (I had been able to desulfate it the week before.) I did not need the new 25 amp NOCO Genius Pro charger after all. :-( The Optima 1200 charger was fine--I just needed to be more patient. (A common problem for me, unfortunately.) I think this means I will have to desulfate my battery a couple of times a week during the long Minnesota winters. Thank you all for your advice!
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