Best way to charge and maintain a battery?

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Hello everyone, I am wondering what the best way to charge and maintain a battery is. I have a couple of questions: 1. There are a bunch of high end chargers like my Noco G7200 that analyzes the battery and charges it in pulses rather than with a steady current and I am wondering if there is actually a benefit to this. They say it helps reduce sulfation and a bunch of other wonderful things and I am wondering if anyone has an opinion on this. 2. What is the best way to maintain a battery and keep it charged? Some chargers like my Battery Tender Plus (which I love by the way) go into a float mode and hold the battery's voltage at 13.2 volts or so to keep the battery topped off while others completely shut off when fully charged and turn back on and recharge the battery when the voltage drops below a certain level and then turns back off once recharged. Which method is better for the battery's longevity? I would think the more proactive approach of consistently float charging the battery at a low voltage would be a better method than the reactive approach of waiting for the battery to run down to recharge it, but any opinions on this would be appreciated. All opinions are appreciated as always smile
 
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Is this for a daily driver or something that sits for extended periods of time? ???
 
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Pretty much any computer controlled battery charger is going to work fine. I have a Schumacher because it's what the hardware store had available, and it works great. Just plug it in, tell it what sort of battery it is and don't worry, the charger will take care of the rest. You can leave it hooked up for a long time and the charger will just scale back to prevent overcharging the battery. I have left it on my boat battery for weeks at time because I forgot to take it off and everything is just fine. It automatically detects sulfated batteries, too, and seems to be fairly effective in treating them. FWIW they're probably all made in a handful of factories these days, so a lot of the difference is going to be sticker packages. Just get the one you can afford with the features you need and dont worry.
 

Avery4

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Originally Posted by littlehulkster
Pretty much any computer controlled battery charger is going to work fine. I have a Schumacher because it's what the hardware store had available, and it works great. Just plug it in, tell it what sort of battery it is and don't worry, the charger will take care of the rest. You can leave it hooked up for a long time and the charger will just scale back to prevent overcharging the battery. I have left it on my boat battery for weeks at time because I forgot to take it off and everything is just fine. It automatically detects sulfated batteries, too, and seems to be fairly effective in treating them. FWIW they're probably all made in a handful of factories these days, so a lot of the difference is going to be sticker packages. Just get the one you can afford with the features you need and dont worry.
Thank you. I have a Noco G7200, Battery Tender Plus, a Harbor Freight battery maintainer, and a Schumacher 1.5 amp maintainer. My favorite charger is the Battery Tender Plus, it is designed the best out of all the chargers I have in my opinion. My complaints about the Noco G7200: It says the battery is fully charged before it actually is, it doesn't fully charge the battery until a couple hours after it says 100%. It also doesn't actually charge at the 7.2 amps it claims to, it charges at a significantly lower amperage most of the time. I contacted Noco about this and they said it is designed to charge in stages and its normal. Not sure how much benefit there is to this? It also causes interference with my car's radio. My complaints about the Schumacher 1.5A maintainer: It charges up to 15.7-15.8V before switching to maintenance mode. On a regular battery with caps this may not be too bad, but on maintenance free and AGM batteries (which it claims to work with) this is not good because it boils water out and there is no way to add that water back into a sealed battery without caps. The high voltage may damage some modern vehicle's electrical system too, not sure. It doesn't recharge the battery until after it drops down below 12.5V either, which is a bit low. It will charge at 1.6A continuously, marginally above its 1.5A rating. This charger also causes interference with my car's radio. My complaints about the Harbor Freight Deluxe Battery Maintainer: Not much. My only complaint is it is a bit underpowered for charging a car battery at 0.75A. It will get it done, but it can take a few days to fully charge a large battery that is run down. Unlike the Noco it will charge at its rated current continuously and it is plenty powerful to keep a battery charged. Good maintainer for the price. My complaints about the Battery Tender Plus: Not much. Similar to the Harbor Freight maintainer, it is also a bit underpowered for charging a significantly run down car battery since it is only rated at 1.25A. It will get it done, but it can take a couple days to fully charge a large battery that is run down. This isn't a big deal for me because of how I use it. It will consistently charge at 1.3A though, so unlike the Noco it marginally exceeds its rating. I have had this charger for the longest (5 years) and has been used the most and it has never given me any trouble. It will not cause interference with my car's radio.
 
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Mine is a 15a max unit with a 3A slow charge so I can't really speak on the smaller models. My boat is all electric so I want something that can charge the 100AH battery up fast. It will maintain the battery too, when it's fully charged. Unit works well, only complaint is that it can get a little hot sometimes but the onboard fans seem to keep it under control.
 

Avery4

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Originally Posted by littlehulkster
Mine is a 15a max unit with a 3A slow charge so I can't really speak on the smaller models. My boat is all electric so I want something that can charge the 100AH battery up fast. It will maintain the battery too, when it's fully charged. Unit works well, only complaint is that it can get a little hot sometimes but the onboard fans seem to keep it under control.
All my chargers will heat up significantly under load too, none of them have fans since they are smaller units though. Does your charger actually charge at its rated current?
 
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Originally Posted by Avery4
Originally Posted by littlehulkster
Mine is a 15a max unit with a 3A slow charge so I can't really speak on the smaller models. My boat is all electric so I want something that can charge the 100AH battery up fast. It will maintain the battery too, when it's fully charged. Unit works well, only complaint is that it can get a little hot sometimes but the onboard fans seem to keep it under control.
All my chargers will heat up significantly under load too, none of them have fans since they are smaller units though. Does your charger actually charge at its rated current?
Can't say I've ever tested it, but it seems to have some guts. It can charge my 100AH battery after a day of fishing in a matter of hours.
 
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My favorite charger is an adjustable 5 amp power supply. I have complete control over what it does. Just set it to ~14V (depending on temperature) and charge until the current stops tapering off. Then set to ~16V for 30 minutes if I want to "equalize". It's also useful for charging other types of batteries/cells and countless electronic projects on my workbench. Similar to this: https://www.amazon.com/Eventek-KPS3...justable+power+supply&qid=1591545367 Since I park on a city street and running a cord to a battery maintainer is impractical I sit a 10 watt solar panel on the dashboard. On a sunny day it brings the battery up to ~13.5V to keep it full.
 

Avery4

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Originally Posted by circuitsmith
My favorite charger is an adjustable 5 amp power supply. I have complete control over what it does. Just set it to ~14V (depending on temperature) and charge until the current stops tapering off. Then set to ~16V for 30 minutes if I want to "equalize". It's also useful for charging other types of batteries/cells and countless electronic projects on my workbench. Similar to this: https://www.amazon.com/Eventek-KPS3...justable+power+supply&qid=1591545367 Since I park on a city street and running a cord to a battery maintainer is impractical I sit a 10 watt solar panel on the dashboard. On a sunny day it brings the battery up to ~13.5V to keep it full.
That is certainly one way to do it. Do you have some type of charge controller on that solar panel to keep from overcharging the battery? I did the same thing with a solar panel from Harbor Freight. I set it on my trunk deck and ran the wires into the trunk (where I put my battery). I was seeing 15V+ with the sun on the panel and a fully charged battery, which surprised me since the solar panel was only 5 watts if I remember correctly.
 
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Originally Posted by Avery4
Originally Posted by littlehulkster
Mine is a 15a max unit with a 3A slow charge so I can't really speak on the smaller models. My boat is all electric so I want something that can charge the 100AH battery up fast. It will maintain the battery too, when it's fully charged. Unit works well, only complaint is that it can get a little hot sometimes but the onboard fans seem to keep it under control.
All my chargers will heat up significantly under load too, none of them have fans since they are smaller units though. Does your charger actually charge at its rated current?
Look up IUoU charge cycle. Charging at a fixed 7.5A no matter what is sure to kill batteries quicker
 

Avery4

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Originally Posted by Jetronic
Originally Posted by Avery4
Originally Posted by littlehulkster
Mine is a 15a max unit with a 3A slow charge so I can't really speak on the smaller models. My boat is all electric so I want something that can charge the 100AH battery up fast. It will maintain the battery too, when it's fully charged. Unit works well, only complaint is that it can get a little hot sometimes but the onboard fans seem to keep it under control.
All my chargers will heat up significantly under load too, none of them have fans since they are smaller units though. Does your charger actually charge at its rated current?
Look up IUoU charge cycle. Charging at a fixed 7.5A no matter what is sure to kill batteries quicker
I don't know Noco's logic with the way they designed the charger, they likely have a very good reason for it. Charging slower is also better if someone has the time since it doesn't heat the battery up as much. However, 7.2 amps is not a whole lot for a decent size automotive battery, the alternator regularly charges at a higher current than that without a problem. In a perfect world would the battery last longer if the alternator's charge current was limited to a lower amperage, say 3 amps? Who knows, that would likely create other problems such as sulfation. My point is that when a battery charger says 7.2 amps, it should be able to charge at that rate. I am going to do more testing. However, I have not seen this Noco charger go over 3.5 amps when connected to a significantly discharged battery and it regularly charged at an even lower current than that, 1.6 amps isn't uncommon. Is that better for the battery? Presuming the the battery is not going to be charged at a much higher rate by the alternator when the person runs out of time waiting for it to charge or stored partially discharged because the person didn't have time to charge it, probably. However, if someone wanted to charge the battery slower, they would have bought one of their smaller chargers such as the G3500 and saved the money. I am partially discharging an extra battery right now as I type and I am going to see what the maximum current I can get out of this charger is, I will report the results as soon as I have them.
 
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7.2 amps is a lot if you have to crank the voltage past 14.8v to get it... They charge at that rate as long as the overvoltage isn't going past 14.8v... that's the I in IUoU. Then they keep the voltage constant at 14.8v (or less for Gel batteries) until the charge current drops low enough to go from Uo to the float voltage U. Car alternators shouldn't output 14.8v anyway, and most of what they actually supply is used directly by the car, rather than charging the battery. Can't speak for the Noco charger, but my chargers have no issue to deliver their rated output. I don't rate the noco products we have at work...
 

Avery4

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Originally Posted by Jetronic
7.2 amps is a lot if you have to crank the voltage past 14.8v to get it... They charge at that rate as long as the overvoltage isn't going past 14.8v... that's the I in IUoU. Then they keep the voltage constant at 14.8v (or less for Gel batteries) until the charge current drops low enough to go from Uo to the float voltage U. Car alternators shouldn't output 14.8v anyway, and most of what they actually supply is used directly by the car, rather than charging the battery. Can't speak for the Noco charger, but my chargers have no issue to deliver their rated output. I don't rate the noco products we have at work...
Good points, high voltage certainly can damage a battery. Most car alternators typically don't output 14.8 volts, but are capable of charging at very high currents if the battery is run down. I have not seen a vehicle that regulates the battery's charge current in any way. On every vehicle that I have seen the battery is directly connected to the alternator, which is more or less a constant voltage charger that is capable of charging the battery at extremely high currents, possibly 100+ amps.
 
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Originally Posted by Avery4
That is certainly one way to do it. Do you have some type of charge controller on that solar panel to keep from overcharging the battery? I did the same thing with a solar panel from Harbor Freight. I set it on my trunk deck and ran the wires into the trunk (where I put my battery). I was seeing 15V+ with the sun on the panel and a fully charged battery, which surprised me since the solar panel was only 5 watts if I remember correctly.
No charge controller. Between my not driving every day, and the car's "smart" charging system, I haven't seen excessive voltage (13.6V max at the end of a sunny summer day). OCV of the panel in direct sunlight is ~18V, so there is tapering of the current. I've never connected the panel to a freshly charged battery. I bought it to avoid doing that. Before I got the panel I used to remove the battery every 3 months, bring it in my cool basement, and charge overnight. The original battery in my previous car (Toyota Matrix) was going strong at 10 y.o. when I replaced it on principle.
 

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Originally Posted by circuitsmith
Originally Posted by Avery4
That is certainly one way to do it. Do you have some type of charge controller on that solar panel to keep from overcharging the battery? I did the same thing with a solar panel from Harbor Freight. I set it on my trunk deck and ran the wires into the trunk (where I put my battery). I was seeing 15V+ with the sun on the panel and a fully charged battery, which surprised me since the solar panel was only 5 watts if I remember correctly.
No charge controller. Between my not driving every day, and the car's "smart" charging system, I haven't seen excessive voltage (13.6V max at the end of a sunny summer day). OCV of the panel in direct sunlight is ~18V, so there is tapering of the current. I've never connected the panel to a freshly charged battery. I bought it to avoid doing that. Before I got the panel I used to remove the battery every 3 months, bring it in my cool basement, and charge overnight. The original battery in my previous car (Toyota Matrix) was going strong at 10 y.o. when I replaced it on principle.
Cool, thanks! 13.6V max is fine. My panel would produce 23V+ open circuit. Sounds like the solar panel is working quite well for you
 
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I find solar panel works well. Just pop it in the window and let it maintain the battery
 
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Some actual Data. I have a 100 watt 'flexible' Sunpower panel which can fit on my dashboard when parked facing south, a few hours either side of noon, unshaded. https://documents.wholesalesolar.co...83196947.1591816585-659526708.1591816585 I measured 87 watts from it On top of the windshield near noon, and then placed it behind windshield at the same exact angle.....43 watts....... and this decreased as it heated up. No shadows, as even a small one can knock out a considerable portion of a panel's output. I have no data on other windshields, mine is old and pretty heavily pitted. Newer thinner unpitted windshields could be much better, I don't know. So Expect an approximate 50% reduction in amperage output behind windshield glass. Note that the panels open circuit voltage might read the same or very close, behind glass as without it. As far as whether a solar charge controller is needed for a small wattage panel behind a windshield/glass , that depends on the battery state of health, its size, state of charge, and parasitic draw as well as temperature where the panel is, and the hours of direct sun it sees per day as well as the open circuit voltage of the panel itself. Many variables to consider. An aging battery will require more and more amperage, to be held at the same voltage when fully charged, or in that range A relatively healthy battery with little or no parasitic draw on it, can easily be overvolted by even a small panel, and cause increased water usage and unnecessary positive plate shedding. How much hotter does any specific battery get, than ambient temps in the afternoon? Ideal float/maintenance voltage is directly proportional to battery temperature. All battery manufacturer charge voltage specs are at 77f / 25c. Hotter requires lesser voltage, colder, more. https://marinehowto.com/do-i-need-a-solar-controller/ Some can get away with it, some cannot. DO NOT assume you and your battery are fine, without confirming that the battery is not being brought to and held at too high a voltage every sunny day. Basic PWM Charge controllers ( voltage limiters) can be had for cheap. There is not a really good reason to not employ one.
 

Avery4

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Originally Posted by wrcsixeight
Some actual Data. I have a 100 watt 'flexible' Sunpower panel which can fit on my dashboard when parked facing south, a few hours either side of noon, unshaded. https://documents.wholesalesolar.co...83196947.1591816585-659526708.1591816585 I measured 87 watts from it On top of the windshield near noon, and then placed it behind windshield at the same exact angle.....43 watts....... and this decreased as it heated up. No shadows, as even a small one can knock out a considerable portion of a panel's output. I have no data on other windshields, mine is old and pretty heavily pitted. Newer thinner unpitted windshields could be much better, I don't know. So Expect an approximate 50% reduction in amperage output behind windshield glass. Note that the panels open circuit voltage might read the same or very close, behind glass as without it. As far as whether a solar charge controller is needed for a small wattage panel behind a windshield/glass , that depends on the battery state of health, its size, state of charge, and parasitic draw as well as temperature where the panel is, and the hours of direct sun it sees per day as well as the open circuit voltage of the panel itself. Many variables to consider. An aging battery will require more and more amperage, to be held at the same voltage when fully charged, or in that range A relatively healthy battery with little or no parasitic draw on it, can easily be overvolted by even a small panel, and cause increased water usage and unnecessary positive plate shedding. How much hotter does any specific battery get, than ambient temps in the afternoon? Ideal float/maintenance voltage is directly proportional to battery temperature. All battery manufacturer charge voltage specs are at 77f / 25c. Hotter requires lesser voltage, colder, more. https://marinehowto.com/do-i-need-a-solar-controller/ Some can get away with it, some cannot. DO NOT assume you and your battery are fine, without confirming that the battery is not being brought to and held at too high a voltage every sunny day. Basic PWM Charge controllers ( voltage limiters) can be had for cheap. There is not a really good reason to not employ one.
Great info. I noticed little change in OCV when the panel was directly in the sun compared to in the shade. You are correct that putting the panel behind glass significantly cuts its output, which is why I put my panel on my trunk deck instead. Checking the voltage with the sun on the panel with a fully charged battery is definitely a good idea, my then 6 year old Optima Yellowtop D34 battery was easily overvolted by the I think 2.5W panel, an older or lower quality battery may not be. The problem with using a charge controller with a small panel is that the charge controller could add enough inefficiency to use up a significant amount of the power that a small panel could produce. If someone has a 2.5W panel like I did and they put it behind their windshield, it may produce 1.5W of power. Even if the charge controller only uses 1W of power, and most probably use more than that, that's 2/3 of the total power the panel is producing and you only have 1/2W available to charge the battery. Not good. This will only get worse if the panel isn't in direct sunlight. If someone has a larger panel that produces 10W of power or more this probably isn't a big deal, but it's something to consider.
 
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Originally Posted by Avery4
The problem with using a charge controller with a small panel is that the charge controller could add enough inefficiency to use up a significant amount of the power that a small panel could produce.
An adjustable low dropout linear regulator and a blocking diode could do it with simplicity and low losses. Just set it to top out at 13.8V Something I might play with while hiding from COVID.
 
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I employ a 50 amp rated 'ideal diode' on my 40 amp adjustable voltage power supply, so I can leave it connected to the battery when I remove the AC cord, and the additional fans and ammeter/voltmeter/amp hour counter do not stay running/ illuminated with the DC conncetor still hooked to the battery. It drops only 0.04v at 40 amps. A pretty neat recently introduced product many are not familiar with. 13.6v applied forever, on a sulfated battery, will not be able to return it to its potential, maximum remaining capacity. This is easily provable with a good hydrometer on a flooded battery, which no one ever bothers with. 13.6v can and will fully charge a new healthy battery, it will not be able to fully charge ( to maximum remaining potential capacity) an old sulfated one. 14.8v might not, 16v might not, but they stand a heck lot of a better chance. Breaking my own rule about joining battery threads here...... I just wanted to share actual solar panel data behind windshield glass.
 
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