Posted: Wed Nov 16, 2005 3:35 pm Post subject: Re: Increase battery life 3X ?
I suspect that those stats are unrealistically optimistic but devices like that do help battery life - I think its some kind of desulfator like this....
Joined: Nov 01, 2005 Posts: 796 Location: Euro high horse bastard on the run
Posted: Wed Nov 16, 2005 5:55 pm Post subject: Re: Increase battery life 3X ?
Single battery (ex. sealed lead acid agm/gel) => 450 deep cycles to 80%
However the same batteries connected in series (EVs, radio, solar etc) => only 150 deep cycles !@!
..
.
That's the bad magic of batteries connected in series and a major shortcomming which killed the lovely concept of electromobile prematurely. Did we know it prior WWI (the first major oil-drug trip of our species) perhaps there will be no dirty ICE cars today only EVs! Therefore what you need is called battery management system (BMS). They come in many designs cheap shunt regulators, advanced shunts..
But the most advanced BMS (for lead) is DC/DC bidirectional equalizers controled by small processor with smart alghoritm.. This can increase battery life by factor of 3x But that only means that you can get the original life span of 450 deep cycles of single battery nothing more.. the batteries are then almost 100% reliable and predictable in their functioning.. (don't forget thermal management too!) Google products such as Powercheq, Battcheq etc for details..
You can build yourself one pretty easily too, patents with diagrams and independent detailed papers on the subject are out there on the net.. _________________ DOOMerotron: at all-time high [8.1] out of 10..
Joined: Nov 01, 2005 Posts: 796 Location: Euro high horse bastard on the run
Posted: Wed Nov 16, 2005 6:25 pm Post subject: Re: Increase battery life 3X ?
? Please clarify your question..
Several batteries connected in series +- +- +- +- +- are discharged differently under load this is pretty significant in traction applications like EVs..
If you use BMS you can equalize individual batteries immediately and thus reducing aging/deformation processes within.
Basically if you allow having an unattanded battery bank consisting of individual voltages i.e. 10.4 11.5 12.3 11.6 V your bank is probably shot and won't cycle more than 150 cycles plus you will experience occasional nasty performance situations during that time..
If you don't believe me ask any elementary/highschool kid competing in EVs..
_________________ DOOMerotron: at all-time high [8.1] out of 10..
Posted: Fri Nov 18, 2005 5:07 am Post subject: Re: Increase battery life 3X ?
I guess I don't understand the unequal discharge of batteries connected in series. This can happen if batteries connected in parallel aren't equally loaded, but everything in series sees the same load.
Joined: Jan 03, 2005 Posts: 1159 Location: western Wisconsin
Posted: Fri Nov 18, 2005 9:48 am Post subject: Re: Increase battery life 3X ?
If series connection of cells was a major concern, we would need to run everything on single 2 volt lead acid cells (if using lead acid batteries). I don't think that there is a problem with series connection of batteries, as long as they are subject to the same temperature and other conditions. Parallel connection is a different story, and much care needs to be taken for large numbers of parallel connected batteries.
Back to the subject of battery desulfators: I think that there is a discussion group somewhere online whose subject is desulfators, and the arguments get pretty esoteric (to me at least). Many of the companies that install PV systems that I know of, recommend or require the use of desulfators along with a good quality charge controller in the systems that they sell and install. I think that only time will tell if they are doing what they are advertised to do. I did spend the $100 or so to install one on my new set of batteries but it has only been 6 or 7 years that they have been in use, so it is too early to tell if the desulfator has made a difference. Ask me in 10 years or so. I have, in the past, gotten 12+ years of use out of used batteries that were 5 to 10 years old when I got them from the telephone company, and back then I didn't have a good charge controller on the PVs or wind generator. I figured that the money spent on the desulfator was cheap insurance, as I decided it might help and most likely would do no harm.
I'd like to hear from anyone with more experience with them, or any bad experience.
Joined: Nov 01, 2005 Posts: 796 Location: Euro high horse bastard on the run
Posted: Fri Nov 18, 2005 1:32 pm Post subject: Re: Increase battery life 3X ?
Lonewolf> If you haven't noticed I made my point around SEALED agm/gel batteries and I stressed traction (EV) application with likely deep discharges.. Your 20% DoD shallow discharges are not the case in the EV World.
I made only one 'mistake' that I included solar application in the list which are mostly based on floodies and not so often on more expensive gel/agm batteries. Although the ratio is changing towards more sealed/recombination batteries used in solar lately..
Your trojans T105 are flooded Lead Acid that's a different kind of battery..
Floodies usually don't have BMS installed! With the exception of industrial ultra fast 15minut chargers..
We are basically debating about completely different stuff here..
If you don't believe me that's ok but please in reply read others post first before you react.. I'm trying to inform people here about basic EV related battery constrains so pls. don't post confusing info around..
Connection between low cycle life of sealed lead acid battery in series and missing temp/over/under current management is well proven fact in traction applications and it was #1 culprit for problems in early lead acid based electromobiles. This has been now largely mitigated thanks to usage of advanced BMS and it is both scientifically and empirically proven fact over the last decade.. End of debate.. _________________ DOOMerotron: at all-time high [8.1] out of 10..
Joined: Nov 01, 2005 Posts: 796 Location: Euro high horse bastard on the run
Posted: Fri Nov 18, 2005 3:06 pm Post subject: Re: Increase battery life 3X ?
I didn't want to hijack your thread. My experience is that people are usually unaware about simple strategies how to increase life of their battery pack in series by factor of 2-3x by using simple BMS. I encounter these people very often and the sealed lead acid is now mainstream so it was on target here.. No flames _________________ DOOMerotron: at all-time high [8.1] out of 10..
There are more additional papers on the topic available from the National insititute for renewables or what's the name of that gov. scientific body of yours.. _________________ DOOMerotron: at all-time high [8.1] out of 10..
Joined: Jan 03, 2005 Posts: 1159 Location: western Wisconsin
Posted: Sat Nov 19, 2005 11:39 am Post subject: Re: Increase battery life 3X ?
Lonewolf,
The desulfator that I have (can't recall the brand name) is available in different models for different battery voltages, and connects across the entire battery (as a load), rather than being a charging device, and was recommended for a wide range of battery sizes. Our current battery is a string of 12 cells, 2 volts and 1500 amp-hours each. As I mentioned before, I can't make any claims of the desulfator's usefulness so far, as it was installed on a new battery that is very carefully maintained and is less than 7 years old.
There is a battery additive that I have seen advertised in the classifieds in Home Power magazine over the years, and there have been articles written about it, that I tried in an old battery in an electric lawn mower. This was a small 12 volt battery powering an old Toro 16" cut electric mower that I got cheap at a garage sale. It sat for years, I tried to charge it with no great results, then added the additive per instructions, slow charge it for a couple of days, and used the mower occassionally throughout the summer. The next summer it was deader than a doornail. I would hesitate to use the additive on an expensive battery except as a last resort, but might try it on a friends batteries that he bought new 5 or 6 years ago, and have been sitting unused and uncharged since then. That could be a useful experiment.
If interested, I can look up the chemical and the source, and the issue of Home Power that the article was in. (The info isn't handy at the moment.)
Posted: Wed Jan 25, 2006 10:13 pm Post subject: Re: Increase battery life 3X ?
Here is a post
I had a desulfator for every two 6 volt battery and ran it across the twelve volt series, and it seemed to work our batteries didnt seem to age in the motor home after that, but since it takes the same time to desulfate and it dose to sulfate, I just left it hooked up all the time (it takes very little power)
here is something I found.
Excerpt: ... battery sulfation has been with us for a very long time. The problem is that in a typical wet (sulfuric acid) battery, the lead plates want to be exercised. That is, they want to be charged and discharged on a regular basis. If they just sit there, the acid slowly, slowly builds up a film of sulfide that eventually causes the battery to "go weak".
This "weak" has everything to do with the fact that lead sulfide is a fairly good insulator, and as the sulfide layer builds and builds over weeks and months of disuse, the internal resistance of the battery goes up and up.
Finally it gets to the point where most of the voltage of the battery is dropped in the internal resistance of the battery and darned little gets to the point of intended use…like the starter motor. ...
4. There are going to be some batteries that are so far gone that leaving the desulfator on charge for a month will only get you four weeks and change. In my experience with these circuits, if you get the battery right when you notice that it is laboring to turn the starter, you have half a chance to make the desulfation process work. If it is so far gone that it won't even pull in the master switch relay, the odds of being able to save it are slim to none at all. See photo #6 for an example of a battery that will probably never be able to be brought back to life.
5. The sulfation process took weeks or months to develop. The desulfation process will take the same order of magnitude of time. Don't expect to put the battery on desulfate today and back in the airplane tomorrow. I've left batteries on this system for a month before I was happy with the end result.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
News
Discussions
Resources
Members
Forum FAQ
Search
Usergroups
Profile
Log in to check your private messages
Log in
