How battery manufacturers mislead consumers

[willprowse]

Hey guys, I haven't posted in a while but I think you will like a new video I created. I have had to explain this reasoning to people in message boards for years, and thought there needs to be a video on it. Has to do with the true usable capacity of a battery, and how to measure it. I hope you like this video and I would love to hear what questions you have

[video=youtube]

 

[XERTYX]

Interesting video. Definitely food for thought. I was unfamiliar with Puekert effect. I'll be using flooded lead acid batteries in my build but only occasionally using such a high discharge load so I think I'll be ok in my application. I've used SLA batteries in the past and at a high rate of discharge but had no significant noticable drop in rated AH especially given that they were old salvaged batteries. Not disagreeing with the science behind it. That just wasnt my experience per se. Then again maybe my loss in efficiency wasnt due to the age of the batteries in my bank but rather Puekert effect. Thanks for the information.

 

[frater secessus]

AGM sealed types have less of a peukert effect due to lower (sometimes MUCH) lower internal resistance. The values are published for each chemistry and somtimes for particular batteries. Dunno if your sealed ones were AGM or similar but that might fit into your real world experience.

 

[Seminole Wind]

very misleading video. couldt even watch the whole thing. to claim you CAN'T use more than 50% of a flooded lead acid battery is a very poor interpretation of the situation.

50% discharge is and has been a general guideline to long life of fla batteries. but can most certainly use them beyond that. even the manufacture provides specs showing the expected life time cycle at discharge depths of more than 50%. for instance, the trojan sc150 a group 24 deep cycle is rated for 600 cycles when discharged to 50% and 500 cycles if you discharge it a bit deeper to 60% used up.

sure you get fewer cycles, but you extract more power in each cycle and get more available power for less weight/size. these benifits can out weight the possible shortened life time.

 

[ssminnow]

I've been watching some video's on the Tesla batteries and they look almost irresistible although it might take me some time to put that together.
I will definitely make sure I have every possible reason for failure covered before I venture into the purchase of one of those batteries!
The whole system will be built and tested before I ever put a Tesla battery in it!!
I see that there is a Tesla charging site right in Quartzite. I don't know if it would be possible to charge the house battery there but somebody will figure it out.
That Battery is almost science fiction like! They are going to power semi's with them and get 600 miles with 80,000 LBs per charge! HUH! More than 1 battery of course but still!!

 

[future_vandweller]

very misleading video. couldt even watch the whole thing. to claim you CAN'T use more than 50% of a flooded lead acid battery is a very poor interpretation of the situation.

I agree with Seminole Wind - his comments on depth of discharge is misleading.  His comments on Peukert's are also misleading & further muddles up a topic that is already misunderstood & misapplied.

 

[future_vandweller]

Interesting video. Definitely food for thought. I was unfamiliar with Puekert effect. I'll be using flooded lead acid batteries in my build but only occasionally using such a high discharge load so I think I'll be ok in my application. I've used SLA batteries in the past and at a high rate of discharge but had no significant noticable drop in rated AH especially given that they were old salvaged batteries. Not disagreeing with the science behind it. That just wasnt my experience per se. Then again maybe my loss in efficiency wasnt due to the age of the batteries in my bank but rather Puekert effect. Thanks for the information.

Peukert's law is *not* a basic law that was derived from first principles.  It is an empirical law - a mathematical description that fits what was observed in the early days (100+ yrs ago) of lead acid batteries.  We now know why these batteries behave in this manner, but there are still a few holes in our understanding.  To use Peukert's law to predict battery capacity, the rate of discharge and internal temperature must be kept constant.  This is hardly the case in real world applications where the battery internals heat up during discharge and compensate for the apparent capacity loss.

 

[RVTravel]

Batteries are so dynamic in their function that one must choose something to compare them...and that usually is the 20 hr discharge rates.

 

[Wabbit]

Keep on keepin' on Will! Didn't watch the video, so I have no opinion of my own on who's right or wrong or if it's more complicated than that. Prob the latter. No matter, keep doing what you love! Keep on posting your video links here, creativity and discussion are great ways to expand the mind!