That's not the slippery slope, it's the smart way to go. Just be careful when calculating the max charge voltage.
That's not the slippery slope, it's the smart way to go. Just be careful when calculating the max charge voltage.p.s. am I heading down the slippery slope to bottom balancing and no bms? argh! ~< :|
Not THAT smart. Actually, I would call it "dumb" in the sense of smart-bomb vs dumb-bomb. You wouldn't remove the thermostat on an ICE and hope it was running the correct temp. Electronics have proven themselves very reliable IF properly designed, manufactured, and installed. Thats a big IF.That's not the slippery slope, it's the smart way to go. Just be careful when calculating the max charge voltage.
You have options regarding final output voltage for your Elcon charger.The only solution is to reduce the max charge voltage, which is pre-set and unadjustable at 3.65v on this charger.
Is the method of adjustment to send it off to be reprogrammed? From what I gather, the factory installed several charge "profiles" indicated by the number of blinks on startup. Selecting a different profile just changes the amp-rate, not the voltage. To do that I have to get a new set of profiles?You have options regarding final output voltage for your Elcon charger.![]()
I don't believe they have. I think they're designed for 2-5 year lifespan and need to be greatly overdesigned to last the lifetime of the vehicle, which makes them really expensive. The batteries can last 10 years. We have BMS's failing all over the place right now. Do you really believe a shunting resistor will last 10 years and over 3000 charges?Not THAT smart. Actually, I would call it "dumb" in the sense of smart-bomb vs dumb-bomb. You wouldn't remove the thermostat on an ICE and hope it was running the correct temp. Electronics have proven themselves very reliable IF properly designed, manufactured, and installed. Thats a big IF.![]()
With batteries which have over 3000 cycle life, the change in capacity between two batteries which finish at 3.65 and 3.60 will be negligible for 1500+ cycles. If you have a battery packs getting 100 miles range, then those batteries will stay together in capacity for 150000 miles. And even then, all you'd have to do is change the lowest capacity battery, costing you $250 bucks?If I bottom balance and cell capacities vary by much then the weaker ones will be going to higher voltages, further reducing their capacity and making the problem worse over time.
That's so they have something else to blame when a battery fails.but there is no DATA... only probably..
It is no coincidence that the battery companies who make and test these batteries recommend bms or install them at the factory. They should know.
Seriously? My house heating circuit died about a month ago, had to spend $150 to change it (it was a 24vac relay). Two of my friends just complained their computers died, and I built one of those so I know it had a good air circulation. And if you don't think the battery BMS's will get gunk and will be exposed to high temps (especially the shunting resistor) after 10 years of driving, then I guess you would put your batteries in boxes with no ventilation or cooling.I AGREE wholeheartedly that the current crop of bms has me concerned enough to question the installation.
However, when was the last time you had a blinker circuit go bad? Or a failed relay? Or even a blown fuse? Only bulbs and sensors subjected to extremes of heat and gunk go bad these days.
I'm going to stop then...Auto electronics are generally VERY reliable. My Subaru has 200,000+ miles with no issues. Only failures to date are water pump and battery cable. I last changed the oil 45,000 miles ago.![]()
except that they are still to blame since it is their bms, so obviously they think the risk of failure using bms is less than without. Everything is an odds calculation.That's so they have something else to blame when a battery fails.
Right. Everything fails (it's called entropy). Again, it's a numbers game. Let's compare the likelihood of a house to burn down from a wood stove vs. an electronically controlled heater. I think you will agree the electronics are MUCH more reliable than humans.Seriously? My house heating circuit died about a month ago, had to spend $150 to change it (it was a 24vac relay).
Here is what I did.... I had to get my 6kw 192 volt lead-acid Elcon re-programmed for lifepo. I also wanted final voltage output adjustability. So, I have Greg setting my curve # 5 to the voltage I want (3.5 * 65 = 227.5) Curve 4 will be 1 cell less (-3.5v) Curve 6 will be 1 cell count more (+3.5v). . . and so on. 1 - 10.Is the method of adjustment to send it off to be reprogrammed? From what I gather, the factory installed several charge "profiles" indicated by the number of blinks on startup. Selecting a different profile just changes the amp-rate, not the voltage. To do that I have to get a new set of profiles?
It's only 10ma... so, as long as you aren't leaving it for days on end... not a big deal.I should mention I have the "Chinoz" stickered Elcon. Later they went by Chennic. It has the tiny 5v wire which activates it that nobody has heard of. I haven't quite figured out how to get that switched with the evpower bms. I can use the aux bat and drop 12v to 6v, but that will drain the 12v while charging and I don't necessarily want the dc-dc on all the time, so I may need a small 12v charger to keep the aux bat happy.
The rest I'm not touching...been hashed every which way so far...I must say that I am a bit skeptical of bottom balancing since it allows variation at "average" full charge, a place you are going to be A LOT. Top balancing creates issues at full discharge, which can be easily avoided by not running the car down. Am I not getting something?
Also, damage from over-charging seems worse (swelling and venting) than pulling a cell too low from which they seem better able to recover. (from what I have heard)
Cheers
Or just do what I did. Add an extra cell or two. I had my Zivan programmed for 19 cells for 3.65vpc and then I installed 20 cells so my ending voltage is 3.485vpc (I adjusted the calibration pot up a little).Is the method of adjustment to send it off to be reprogrammed?
I wish that was possible, but I think the cells I have are pretty much it. I am not sure there are many 260ah in the country. I have only seen them in one other build, and nobody seems to carry anything bigger than the 200ah.Or just do what I did. Add an extra cell or two. I had my Zivan programmed for 19 cells for 3.65vpc and then I installed 20 cells so my ending voltage is 3.485vpc (I adjusted the calibration pot up a little).
You might check with Willie McKemmie (sp?) on EVDL, he has been using them for a couple years I think. Also might send Dave Kois at currenttechev an email, since he used them on his earlier conversions for a while - should be 4 or 5 years or so on them now. Supposed to be pretty good. Overall design is similar to the minibms - I think Dimitri said that their design discussion on an aussie forum is where he got his inspiration. But the devil is in the details, I don't know how they differ and what issues that might leave them exposed to. I believe Rod Dilks was the, or one of the, designers, so might email him at evpower also. Seems like a straight-up guy, and a LOT more experienced than most of the talking heads here.Can others report in with success/failure stories for this system?