Do deep cycle batteries have a memory?

[SeaEagle]

I was just told by a dealer that the deep cycle batteries have a memory. He said that the batteries have a certain number of recharging cycles built into them. So if you recharge when the battery is only 50% depleted, you use up one of those cycles the same as you would if it was 100% depleted. Is this true? He said it would be best to fully discharge the battery each time you use it before you recharge. Can I take this to mean that topping a battery off once a month while it is in storage in the winter would use up one of those cycles and "waste" it?<br /><br />He also said the gel cell batteries give you more power than the lead acid types. Any opinions on this? Are the gel cells worth the extra cost?<br /><br />Thanks.

 

[Paul Moir]

Re: Do deep cycle batteries have a memory?

No that's not true. There will be (far) more cycles if you only deplete the battery 50%. All lead acid batteries hate to be discharged as it shortens their life. The deep cycle ones just tolerate it a lot better than a car/starting battery. Actually, to maximize the life span of your deep cycle battery, it's best not to discharge them past about 50%, as damage gets exponentially worse past that.<br />So topping up the battery actually will extend it's life, not waste it.<br /><br />Gel does not give you any more power. It actually lessens the peak amount of current the battery can provide ('Cranking Amps'). Gels have certain conveniences but I don't think they're worth the extra cost. Today, I think the choice is between flooded (normal) batteries and AGMs. The flooded ones have the advantage that you can maintain them by adding water. <br />The AGMs have a number of advantages, but are expensive and particular about recharging. They can provide a lot of instantaneous current (cranking amp) so they can be used to crank an engine. They put up with discharging better than any other lead acid. But probably the biggest advantages is if you break one open, they will not leak acid.<br /><br />Hope that helps you!

 

[Dunaruna]

Re: Do deep cycle batteries have a memory?

Hi seaEagle, welcome to i-boats!!<br /><br />Just for a moment think of how a sacraficial anode (zinc) works, it slowly gets eaten away.<br /><br />The inside of your battery is the same (actually the very same electro/chemical process). With every discharge/re-charge cycle a little bit is eaten away off the plates. There is only a finite amount of times this can happen before the battery is toast, you could call this a 'memory'. Some brands don't last long, some do. The build quality of the dividing plates inside the battery vary from brand to brand. Generally speaking, the more you pay the longer it will last.<br /><br />Deepcycle batteries are built in such a way as to allow a deeper discharge (up to 50%) but still be recoverable. If it is constantly discharged below 50% it will not recover 100% - this could also be called a 'memory'. It is normal and acceptable for a good brand lead-acid deepcycle to last up to 2 or 3 thousand cycles before the plates are eaten away to a point where it will not hold a re-charge and/or a short between the cells occur.<br /><br />The very same thing can be said for a normal car battery - AKA shallow cycle. It should only be discharged to about 75% and then recharged. Hence the terms "deepcycle" & "shallowcycle".<br /><br />Gell batteries - in my opinion, have no place as a deepcycle, although the technology behind gells are improving almost daily.<br /><br />If the salesman said it should be FULLY discharged before recharging - he is an idiot.<br /><br />Aldo<br /><br />EDIT: you beat me to it Paul!

 

[amirm]

Re: Do deep cycle batteries have a memory?

Yup. The salesman is confusing cheap NiCad batteries with lead acid. They operate on completely different principals. If what he said was true, car batteries would die right away since they are being charged all the time. You want to keep lead acid batteries as full as you can and as mentioned, never below 50% if you can help it.<br /><br />Even when it comes to NiCads, the memory effect is exaggerated. NiCads die because they are cheap rechargeable chemistry. Deep cycling them helps a bit but not a whole lot.<br /><br />Amir

 

[Boatist]

Re: Do deep cycle batteries have a memory?

I agree with everyone else do not listen to this guy again as what he is telling you will shorted the life of your batteries. Starting battery should not be discharged below 80 pecent, (20 used, 80 left). Deep Cycle can go to 50 percent. Both should be charged as soon as possible to extend there life.

 

[18rabbit]

Re: Do deep cycle batteries have a memory?

Paul – gels, not AGMs, are particular about their charging routine. Current AGMs are flexible about recharging, maybe more so than flooded bats. As with all bats, there is a preference charging voltage. And yup, they are not cheap, but the advantages are such that I have all but totally moved away from flooded batteries. I agree with Aldo, I wouldn't touch a gel bat.

 

[Paul Moir]

Re: Do deep cycle batteries have a memory?

Ah, thanks 18rabbit. Perhaps the information I've got is a little dated or plain wrong. I'm mostly working off memory from when I built a charger for my first AGM batt, which was a surplus telco batt. Personally I think AGMs are the greatest thing since sliced bread and they're the only thing I have, but I see why people still get flooded batts for trolling motor setups and such.

 

[LubeDude]

Re: Do deep cycle batteries have a memory?

Originally posted by Dunaruna:<br />If the salesman said it should be FULLY discharged before recharging - he is an idiot.<br />

 

[Dunaruna]

Re: Do deep cycle batteries have a memory?

Originally posted by LubeDude:<br />

Originally posted by Dunaruna:<br />If the salesman said it should be FULLY discharged before recharging - he is an idiot.<br />

What, too harsh??

 

[18rabbit]

Re: Do deep cycle batteries have a memory?

Probably just the LubeDude playing with the flashing purple eyeball guy.<br />

 

[LubeDude]

Re: Do deep cycle batteries have a memory?

Originally posted by 18rabbit:<br /> Probably just the LubeDude playing with the flashing purple eyeball guy.<br />

I actually agree with you, and yes, just playing with the purple eyeball dude!

 

[Dunaruna]

Re: Do deep cycle batteries have a memory?

 

[FishyFun]

Re: Do deep cycle batteries have a memory?

If your going to invest in a good battery make sure you get a good onboard charger. They are a very big component to keeping a battery healthy. Automotive chargers are to hard on batteries, boiling them. A good onboard charger will keep your battery happy and healthy. Make sure you plug it in as soon as you can when you are done fishing.<br /><br />lee

 

[Realgun]

Re: Do deep cycle batteries have a memory?

So if you recharge when the battery is only 50% depleted, you use up one of those cycles the same as you would if it was 100% depleted.

Hes a battery Dealer what do you want him to say?<br /><br />Hes about as correct as a 3 dollar bill. Just use the battery till its about 50% then fully charge it up. Better yet if possible only discharge it 25% then charge it you will get to use it a lot longer that way.<br /><br />I was into solar electric a while ago and the battery packs, they use around 10-12 deep cycle batteries, were shown to last a lot longer at a 25% discharge. Also it is extremly important to be sure you fill up those batteries with distilled water. This does not apply to the gell batteries.