DaveInDenver
Rising Sun Ham Guru
Batteries and charging are something I've got quite a bit of professional experience, so a dreaded long form...
I like to see temperature compensation as a feature. It's not something you see very often, which makes options somewhat limited. As an alternative having the ability to adjust the voltage can work. Lead-acid is pretty tolerant so down to the 0.001V precision isn't necessary. Just that if the perfect voltage is 13.6V you want to be able to dial it up to perhaps 14.2V in the dead of winter and down to 13.3V in the middle of summer.
I like to see temperature compensation as a feature. It's not something you see very often, which makes options somewhat limited. As an alternative having the ability to adjust the voltage can work. Lead-acid is pretty tolerant so down to the 0.001V precision isn't necessary. Just that if the perfect voltage is 13.6V you want to be able to dial it up to perhaps 14.2V in the dead of winter and down to 13.3V in the middle of summer.
Strictly speaking there's no benefit to leaving a battery on a float indefinitely. You do need to charge a battery regularly. How often depends on the self discharge or any parasitic load on it.
If you disconnect the battery like Ige does on Annie it might only be necessary to put a battery on a charger a couple of times a year to minimize aging. You have to check with your specific manufacturer but most times the recommendation is to run a full charge first and at ~75°F you can store it for a year or two. How long it can sit will depend on temperature, though. Warmer shortens storage, colder increases it. Think about it. A battery is made, the factory fills and charges it then ships it to a warehouse and eventually to a store. It's not maintained ever and it could be many months or years before it's put into service. Better distribution might track dates but that's very rare outside military and aerospace. Usually a warranty clock only starts ticking when you buy it and put it into service.
Most of the time when you don't disconnect it from the load and the parasitic draw isn't excessive then once a month is usually fine. That's what I do. First of the month I put all my batteries on a "good" charger. BTW, that includes my daily driven vehicles since charging system in cars is not ideal and so your starter battery will last longer if you top it up with a good charge regularly. I'll leave a daily driver on a charge overnight so it takes a weekend to get all of our cars conditioned.
So answer the question directly my favorite off the shelf normal charger is the BatteryMinder 128CEC. This can charge a dead battery, albeit not super fast since it's only 8 amps maximum. A large battery might take 10 to 12 hours to fully bulk charge. I do have a massive bulk charger capable of 45 amps, specifically an Iota DLS-45. But the controller on it can't do temp compensation so I don't use it for routine maintance.
But the 128CEC does a 3 step charge and is temperature compensated. It can do the right voltages for gel (or lithium in newer models), regular lead-acid and Odyssey/X2 AGM (the so-called pure lead EnerSys/Northstar need a slightly higher voltage). It's one of the few commercial chargers I've found that follows Odyssey's spec for both voltage and temperature. It's plug and forget. If the battery needs more than a quik top it can handle it. Otherwise it just tests, can then sit idle overnight and do nothing. They make versions of these models that are FAA-certified for the aviation industry. An aircraft owner might just plug it in and let it sit a day or a month and it's certified not to ruin the battery, so there's that.
www.batteryminders.com
If you really want just a winter maintainer I like using industrial power supplies. I'll put my motorcycle on something like this for about a week once a month. The problem with a single voltage charger is it can't do constant high current bulk or a higher constant voltage absorption, so if it needs more than a float it would take a loooong time to get to 100% charge.
Many battery tenders are just that, a constant voltage power supply. They aren't usually particularly high quality, though. So for the money a charger designed to be integrated into equipment is usually pretty decent without a bunch of marketing fluff.
For that I've used a Mean Well SCP series power supplies, specifically I use a SCP-50-12. This is 13.8V nominally, adjustable (I tweak it down usually), 50W max (so can provide 3.6A maximum), very low ripple (meaning high quality DC output), well protected against over voltage and will automatically temperature compensate if you add an NTC 100K termistor. The supply is about $20, a thermistor is a few cents and a case if you really want to be fancy.
The design intended use for this particular supply is to maintain a battery like you'd find in mobile medical equipment, for example, so it's not junk but also doesn't have the overhead trying to market to be #olaf.
If you disconnect the battery like Ige does on Annie it might only be necessary to put a battery on a charger a couple of times a year to minimize aging. You have to check with your specific manufacturer but most times the recommendation is to run a full charge first and at ~75°F you can store it for a year or two. How long it can sit will depend on temperature, though. Warmer shortens storage, colder increases it. Think about it. A battery is made, the factory fills and charges it then ships it to a warehouse and eventually to a store. It's not maintained ever and it could be many months or years before it's put into service. Better distribution might track dates but that's very rare outside military and aerospace. Usually a warranty clock only starts ticking when you buy it and put it into service.
Most of the time when you don't disconnect it from the load and the parasitic draw isn't excessive then once a month is usually fine. That's what I do. First of the month I put all my batteries on a "good" charger. BTW, that includes my daily driven vehicles since charging system in cars is not ideal and so your starter battery will last longer if you top it up with a good charge regularly. I'll leave a daily driver on a charge overnight so it takes a weekend to get all of our cars conditioned.
So answer the question directly my favorite off the shelf normal charger is the BatteryMinder 128CEC. This can charge a dead battery, albeit not super fast since it's only 8 amps maximum. A large battery might take 10 to 12 hours to fully bulk charge. I do have a massive bulk charger capable of 45 amps, specifically an Iota DLS-45. But the controller on it can't do temp compensation so I don't use it for routine maintance.
But the 128CEC does a 3 step charge and is temperature compensated. It can do the right voltages for gel (or lithium in newer models), regular lead-acid and Odyssey/X2 AGM (the so-called pure lead EnerSys/Northstar need a slightly higher voltage). It's one of the few commercial chargers I've found that follows Odyssey's spec for both voltage and temperature. It's plug and forget. If the battery needs more than a quik top it can handle it. Otherwise it just tests, can then sit idle overnight and do nothing. They make versions of these models that are FAA-certified for the aviation industry. An aircraft owner might just plug it in and let it sit a day or a month and it's certified not to ruin the battery, so there's that.
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
If you really want just a winter maintainer I like using industrial power supplies. I'll put my motorcycle on something like this for about a week once a month. The problem with a single voltage charger is it can't do constant high current bulk or a higher constant voltage absorption, so if it needs more than a float it would take a loooong time to get to 100% charge.
Many battery tenders are just that, a constant voltage power supply. They aren't usually particularly high quality, though. So for the money a charger designed to be integrated into equipment is usually pretty decent without a bunch of marketing fluff.
For that I've used a Mean Well SCP series power supplies, specifically I use a SCP-50-12. This is 13.8V nominally, adjustable (I tweak it down usually), 50W max (so can provide 3.6A maximum), very low ripple (meaning high quality DC output), well protected against over voltage and will automatically temperature compensate if you add an NTC 100K termistor. The supply is about $20, a thermistor is a few cents and a case if you really want to be fancy.
The design intended use for this particular supply is to maintain a battery like you'd find in mobile medical equipment, for example, so it's not junk but also doesn't have the overhead trying to market to be #olaf.
SCP-50-MEAN WELL Switching Power Supply Manufacturer
MEAN WELL is one of the world's few standard power supply mainly professional manufacturers, covering 0.5 to 25,600W products are widely used in industrial control, medical and other fields, in line with international safety certification, short delivery of spot inventory.
www.meanwell.com
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