Which Lasts Longer?

[Kankujoe]

I have a question about the charge longevity of different types of batteries. I'm not sure if I will phrase my questions correctly but here goes...

If the current draw, voltage & mAh are the same which technology will hold it's charge the longest under draw? Which technology will have the longest self life before self discharge? Which will have the longest functional life (charge cycles) before it fails permanently?

a) LSD NiMH
b) SLA
c) lithium ion
d) standard NiMH

 

[VidPro]

a) LSD NiMH - low self discharge, possible to get more than 300 cycles out of them, lifetime possible to be beyond 10 years. present low capacity designs are more robust than high capacity ni-mhy, so the cell is more likly to make it more cycles and more abuse than high capacity normal ones.

b) SLA - not comparable, med self discharge, doesnt like to be deep discharged, great for cars, and standby power, bad for repetion, taken care of well enough, might get 4 years in use , many short cycles very very FEW full cycles, in deep discharge can be as low as 20cycles, poorly treated can die in less than 2 years. extreeme weight, cheap price

c) lithium ion - lowest self discharge. possible to get more than 300 cycles, high energy per weight and size, lifetime can be limited from 2-3 years to 5-9 years depending on quality of original cell, total life is deemed to be expendable compared to ni-?? chemestries, but really good cells are lasting longer than thought possible.

d) standard NiMH - higher self discharge, possible to get more than 300 cycles, more likly to have peaked out capacity for size. lifetime possilbe to go beyond 10 years, high capacity versions were not robust at all, so those particular ones were shmuck and didnt make cycles or time or low self discharge well.

like everything completly depends on the way the cell was made, by whom, and what they give up on one thing, for the ramifications of another.

which one will have the most available juice for its size after time, the li-ion. so if the world ended tomorrow, the li-ion would have more stuff left in it, UNTIL it got to old
if the world ended tomorrow, and you have a solar charger, then a good LSD ni-mhy would probably be a better choice.

 

[mdocod]

Depending on the specific comparison, good ole NiCd cells and packs are proven performers in rugged situations where proper charging and discharging are not always adhered to. They are generally tolerant to rapid discharge/charge rates, extreme temperatures and hundreds of cycles. Though many of them suffer from rapid self-discharge problems after they have some use on em. I'd still take a LSD NIMH personally, but it's worth a mention, especially considering they are dirt cheap.

 

[Mugrunty]

Just to add some info:

I wouldn't say that Lithium ion has the lowest self-discharge rate. The protection circuitry normally draws about 3% of the cells capacity per month. Generally speaking, li-ion batterys are less than 10% per month.
SLA actually has a very low self-discharge per month if you keep them properly charged off (5%). the only bad thing is that lead based batteries do not perform well under heavy load. For example if you discharge a Lead-acid battery at 1C, it typically will only provide 30 minutes of service. Li-ion and nickel based chemistries are closer to 1 hour.

You don't have it listed, but NiCd batteries have a very long cycle life and are quite resistance to abuse. Unfortunatly the self discharge is highest immediately after charge, and then tapers off. The capacity loss of nickel-cadmium is 10% in the first 24h, then declines to about 10% for every 30 days thereafter. (average of 20%) High temp also increased self-discharge. I actually have some NiCd cells from 1984 that I used in my senior project for school. They suffer from higher internal resistance and only retain about 70% of their capacity. Blah. The standard NiMH actually have even worse self-discharge. about 30% per month, then tapers off. I really don't know much about the low self discharge NiMH. (About a year to 80%?)
oh yeah, like VidPro said...The li-ion cell starts degrading immediatly after its made at the factory. I believe its something about how they use Lithium ions and that it degrades the cell just from being there. Storing at 40% decreasing the aging effect. *sigh*, this got a little long.

 

[Mugrunty]

Not sure exactly how to quote, but YAY! mdocod! Didn't see your post before mine. Don't forget that NiCd cells can spank out huge amounts of current!! Yeah, charging NiCd cells is endothermic!

 

[Kankujoe]

Thanks for the replies!!

 

[lctorana]

If the current draw, voltage & mAh are the same which technology will hold it's charge the longest under draw?

Assuming the actual mAh in each battery is exactly equal, it would be a four-way dead heat.

Which technology will have the longest self life before self discharge?

LSD NiMH

Which will have the longest functional life (charge cycles) before it fails permanently?

NiCad.

NiCad Also wins in a fourth question you didn't ask - which chemistry can take the deepest regualr discharge and still bounce back for next time?

 

[VidPro]

I wouldn't say that Lithium ion has the lowest self-discharge rate. The protection circuitry normally draws about 3% of the cells capacity per month. Generally speaking, li-ion batterys are less than 10% per month.

yes, if the cell is protected it can make the difference for sure, as LSD ni-mhy isnt usually using protection.
but not all protection is alike, and because even when there is a draw via the protection, its the Same even if you parellel a huge stack together. so like on a few things i have one protection with a lot of parellel cells. and the discharge from the protection is a significantly reduced %.

then you take your cell phone battery, or digital camera battery, and there aint much power to begin with, any even minor draw from the protection is significant.

if were going to put protection into the mix (which it should be) and we include the beasty SLA , then we give a reprieve on the protection not being a big deal, because a SLA Sized li-ion , with protection drawing a bit of juice , aint nothing 4LBS of li-ion and one protection curcuit, will blow away LSD ni-mhy still in self discharge.

what we are always seeing with protection sucking away at li-ion, is because you guys aint using enough JUICE to begin with like nice FAt Dcells, which could be compared to ni-cd and ni-mhy . and were getting junk cells from china , but buying great LSD cells .

so now you have more factors than just the cell, the cell and the protection design. which would lead back to the entire question being dependant on WhatChaGonnaTryAndDoWithit

 

[mdocod]

in my experience, protection circuits on li-ion have the most significant effect on smaller cells. As VidPro was saying.

Here's a recent example in my experience with protected li-ion cells:
Charged a pair of AW brand button top (black label) protected 17500 size cells to 4.20V about 4 months ago. They have since sat at room temperature in a plastic storage bin doing nothing. Pulled them out the other day to test them out of curiosity, they were at 4.20V and 4.19V. Which means, they have lost practically nothing.

This coincides with other experiences on CPF from members who have large collections of li-ion cells. The *good* quality protected cells really don't discharge all that bad. It does vary a bit from brand to brand and depending on the particular circuit used, but the overall experience suggests that even with a protection circuit, li-ion will generally beat the pants off LSD NIMH in long term retention.

 

[VidPro]

also lots of devices using li-ion cells, are not "off" when you turn them off, like PDAs Cell phones, both sneak some power out to maintain Ram memory. pull the battery OUT of the device, to do the actual self-discharge testing.

and Bad li-ion cells, that i get from china (not that ALL bad cells come from china) have higher rates of self discharge in the cell reguardless of the protection.