Charging Deep Cycle Batteries

[huntandhook]

I recently bought a new charger for my deep cycle battery. The charger has 2 amp outputs 2A and 12A. Which one should I use for charging the battery? The battery is a regular lead-acid deep cycle. I don't care about the length of charge time, I want to know if the lower rate is better for the battery than the higher rate.

Thanks for the help

Jason

 

[Silvertip]

Re: Charging Deep Cycle Batteries

The battery doesn't care which setting you use. If you need the battery charged quickly use the 12A setting. If you want a "maintenance charge" use the 2A setting. If this is a smart charger, it doesn't matter which setting you use. The charger will taper off as the battery approaches full charge. Both settings do the same thing but the 2A setting will take six times longer to top off a battery to full charge.

 

[ZmOz]

Re: Charging Deep Cycle Batteries

The slower you charge a battery, the longer it will last. This is true for every rechargeable battery ever made. As you charge, the lead sulphate (crystals that form in your battery during use) dissolves. The slower you charge, the more it will dissolve. Faster charging can cause it to get hard, and it will eventually build up and kill your battery.

If you're not in a hurry, use the 2 amp setting.

 

[NBE]

Re: Charging Deep Cycle Batteries

The slower you charge a battery, the longer it will last. This is true for every rechargeable battery ever made. As you charge, the lead sulphate (crystals that form in your battery during use) dissolves. The slower you charge, the more it will dissolve. Faster charging can cause it to get hard, and it will eventually build up and kill your battery.

If you're not in a hurry, use the 2 amp setting.

Well, I guess I am going to open the proverbial can of worms but from my three years or so on here it seems the general consensus has been that you should always charge your batteries after you use them as FAST as you can. Meaning use the higher setting to recharge them quickly and then use the maintain mode to keep them topped off.

Numerous people on this site, including some who work for battery manufacturers, have said this is the way to go. That doing it this way will prolong the life of the batteries.

So, having said this, has something changed or have I just not understood what I have been reading in the past?

Thanks for your comments!

 

[ZmOz]

Re: Charging Deep Cycle Batteries

Numerous people on this site, including some who work for battery manufacturers, have said this is the way to go. That doing it this way will prolong the life of the batteries.

You must have read wrong. There have been numerous posts on this subject, and there is almost always an arguement ending in agreement with me. Read any battery manufacturers website, and they will tell you exactly what I did. If somebody works for a battery manufacturer, and told you fast charging is better, they need to quit their job.

You can charge your battery at a fast rate if you really want, a time or two, but if you do that every time your battery WILL die an early death, no question about it.

There is nothing to debate. Every rechargeable battery ever made - whether it's a 100AH lead acid, or a little double A battery - will last longer with a slower charge. That's just how batteries work.

 

[divo]

Re: Charging Deep Cycle Batteries

From the Interstate battery site:

What's the best way to charge deep cycle batteries? The maximum charger rate in amps should be 20% of the amp hour rating of the battery.

Normally, deep cycle batteries do not require special charging procedures. However, we recommended that you use a charger designed specifically for deep cycle batteries. It is best to slow charge all batteries, especially deep cycle. The 20% rule should be used when charging a deep cycle battery. That means to choose a charger where the maximum current (in amps) is less than 20% of the Ah rating. For example, an Interstate SRM-27 is rated at approximately 100 Ah, so a 20-amp charger should be the maximum. Also, it is best to use a charger that is adequate to recharge the battery within 10-12 hours (see next question).
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How long should I charge my battery and at what current? Generally, we recommend that you use a low amp charge, i.e. as low as the battery will accept, over a longer period of time. A 10-20 amp charger can charge most automotive batteries. Fully charging a completely discharged automotive battery, for example, with a 10-amp charger may take approximately 6-10 hours at a temperature of 80°F. Lower ambient temperatures require a longer charge time.

Some chargers automatically adjust the current and length of charge according to the battery's state of charge and then shut off when the battery is fully charged. If the charger requires manual adjustment for current or shut-off, check the charger's instructions to determine the proper current and length of charge based on your battery's rating.

 

[95yj]

Re: Charging Deep Cycle Batteries

NBE, what you read is that you should discharge your battery as little as possible before you recharging it. The farther you run the battery down the more it "hurts" it. Therefore you should charge your battery as fast as you can as in not discharging it and not letting it sit uncharged. This does not mean charge it quickly during the charging process. Charging it fast causes it to get hot, change chemical characteristics, warp plates, etc. etc.

That's what smart chargers do for you as Silvertip said. It will bring the battery up from a low charge safely and then lower the input amperage as the battery hits 75% and finally bring it to full charge on a pulse. This will help do their best to keep from damaging the batteries when charging.

 

[NBE]

Re: Charging Deep Cycle Batteries

OK , seems like great advice. I will say that I was generally speaking about using 10 amp charge versus 2 amp charge when getting back to the house after a fishing trip.

I looked back at several posts and all recommended using the 10 amp and hook up as soon as possible when back at the house. To begin charging as soon as possible and as fast as possible......fast being 10A rather than the 2A.

All of this is while using an external smart charger, not an onboard charger, and no doubt that it would lower the amperage as the battery gets closer to full charge.

My onboard charger is a three bank 15 amp charger. So I am thinking that it starts out with 15 amps or close to that and eventually reduces itself and reaches the point that it goes into the maintain mode. I do start recharging as soon as I can once back at the house and as I have no control over the amperage I can only hope that the charger is doing as it is supposed to.

I haven't ruined any batteries yet so I guess things are ok with the charger.

Thanks for all of the good input. I apologize for the unintentional hijacking. Not wanting to start a debate but simply make sure that the original poster got correct information.

Thanks again! Great input!

 

[Boatist]

Re: Charging Deep Cycle Batteries

Many times a 3 bank 15 amp charger is Actually 5 amps per bank. I do not think I have ever seen a Onboard charger that was not a smart charger.

I will say this about charging any battery. Starting batteries discharged more that 20 percent will do damage and the longer it is discharged the more damage is done. Cars today have 60 to 100 amp alternators with a regulator. Smart chargers also charge as fast as they can and regulate the voltage.

Deep cycles batteries discharged more than 50 percent also do damage. Again the faster you get it above 50 percent the better. Key in My book is always use a smart charger that will not over charge.

Only time I would the low 2 amp setting is if the boat is sitting out in the sun and covered with an inside temperature of 140 degrees.

My boat I charge my starting and My Deep cycle with my 60 amp alternator thru a battery isolator. Never had a battery that did not last 6 years. However I use the deep cycle for my house battery and do not have a electric trolling motor.

 

[I/O WALDO]

Re: Charging Deep Cycle Batteries

U can charge a flooded battery as fast as you want as long as it does nott get too hot.Most inverter/3stage charger combos come with a temp sensor that is mechanically connected to the neg. term. on the battery and lowers the voltage when too high a temp is detected.These babys can put out over 100 amps into a flooded bank untill the absorption voltage is reached and them back to a trickle.Most of them have an equalizing mode to be manually activated about once a month that runs them up to as much as 16 volts at full amps to cook off sulpherization and equilize the cell voltages. Low amps is old school!

 

[ZmOz]

Re: Charging Deep Cycle Batteries

This thread is not about whether charging a battery fast will make it explode or not. Sure it works, but it is not a good way to recharge your battery. The original question was:

I don't care about the length of charge time, I want to know if the lower rate is better for the battery than the higher rate.

And the answer is, without a doubt, use the slower setting when you are not in a hurry. There isn't a single reason to charge your battery at more than 2 amps if you're not going to need it for a few days. And there are a lot of good reasons not to charge your battery at any high rate of amps. Heat is not the only concern.

 

[ZmOz]

Re: Charging Deep Cycle Batteries

Most of them have an equalizing mode to be manually activated about once a month that runs them up to as much as 16 volts at full amps to cook off sulpherization and equilize the cell voltages. Low amps is old school!

This is totally wrong. You cannot "cook off" battery sulphation. (not sulpherization

) The only way to remove it is to slowly dissolve it with a slow charger, or even better a battery desulphator which uses pulses of electricity to SLOWLY remove the sulphation. Charging a battery at 16 volts serves no purpose other than cooking the water out of it and ruining the battery. It does not in any way desulphate it, nor is that how you equilize a battery.

 

[bruceb58]

Re: Charging Deep Cycle Batteries

There are a lot of claims, that know one has proven works, regarding battery desulphation.

Pulsing and the higher voltage are both methods that have been discussed regarding it.

Bottom line is prevent it in the first place by keeping you battery topped off with a float charger and you minimize it in the first place. If I had a battery that was in need of a "desulphation", I would be replacing said battery.

 

[I/O WALDO]

Re: Charging Deep Cycle Batteries

(nor is that how you equilize a battery) So how do you equilize a battery bank,I guess these chargers with equilization modes are all F.O.S.?

 

[Dunaruna]

Re: Charging Deep Cycle Batteries

[colour=blue]

(nor is that how you equilize a battery) So how do you equilize a battery bank,I guess these chargers with equilization modes are all F.O.S.?

If you are talking about a 'bank' of batteries, they are already equalised.

 

[I/O WALDO]

Re: Charging Deep Cycle Batteries

eq. is about cells,knott batterys.

 

[Dunaruna]

Re: Charging Deep Cycle Batteries

[colour=blue]Equalising chargers simply continue the charge for a few hours after the battery is full - AKA, topping off. They do this at a greatly reduced amperage (and monitored low temps).