friedwires
100 W
is regenerative braking safe to use with sla batteries? are there any potential problems that i need to be aware of?
sla's and regen.
- Thread starter friedwires
- Start date
Ykick
1 GW
friedwires said:
Not a great idea IMO. SLA's don't like being charged at high rates. 9-12Ah SLA's probably best to keep under 2-3A. That's not gonna do much for regen braking. And the risk of too much current throwed at the battery is probably not a good thing.
dogman dan
1 PW
I sorta disagree within certain limits. I doubt most setups put out more than 5-10 amps of regen, and then for just a short time before it drops dramaticly as you slow. Might even be good for sulphite crystal softening. But you would want to avoid any regen for long periods, like coasting down a hill 5 miles long or something like that. Then you would be looking at a fairly long period of recharging at too high a current, and possibly shorten it's cycle life. The benefit of even slightly less dod using regen, may offset any other harm when it's used on normal stopping.
Can't prove it though, I'm just opinonating dog science.
Can't prove it though, I'm just opinonating dog science.
icecube57
10 MW
Man my motor and controller can put out over 30A of regen current. The controller would pop something trying to shove that much current in a SLA batter. Maybe regen is limited by chemistry. My LIPO can accept 30A regen but SLA is limited by its high IR and chemical process in the battery
friedwires
100 W
you know dogman,you may be right.these sla's are over a year old and are starting to show their age.but it seems like my range has gotten better in the past week since i started using the regen.i should have kept log from the get go.and no i dont regen downhill,we dont have any hills here in sw florida.
Ykick
1 GW
I do agree with Dogman while better understanding your experience in this case. It's just that in general, you try not to ignore electrical specifications like max charging currents and such. Apparently, this application is mild enough so that regen may work well and perhaps derive some conditioning benefits but I wouldn't go so far as to say it's fine to regen the hell outta SLA without observing certain parameters. And Dogman wasn't saying that either. Now, just make sure to regularly check your spokes, LOL...
friedwires
100 W
i'm not sure about the rated charge current on these 12ah sla's, but they're staying cooland performing fine.
today i'll check to see what kind of amperage the regen is dumping into the batts.
today i'll check to see what kind of amperage the regen is dumping into the batts.
rgody
100 mW
Sirs :
For your information :
(Can AGM VRLA lead acid batteries be fast charged?)
http://www.powerstream.com/SLA.htm
Regards
Rodrigo
Viña del Mar
Chile
For your information :
(Can AGM VRLA lead acid batteries be fast charged?)
http://www.powerstream.com/SLA.htm
Regards
Rodrigo
Viña del Mar
Chile
dogman dan
1 PW
Ok, 30 amps is a lot of regen. I'd want to be cautious if that much current flowed for long.
But is that a measue of an amp spike? Or a reading you see on the meter for a longer period. I would think most chemistries might tolerate a 1 second spike of 30 amps, and maybe several more of 15.
But in a normal stop, the entire braking period might be less than 5 seconds. Sounds to this idiot like a nice desuphinating pulse. But I will say again, riding that regen down a substantial hill at amps over the recomended charging rate would be a whole different story. I'd not want to try that.
The only regen I've ever tried was a pretty lame 5 amps, and it dropped to only 1 or 2 amps after about 1 second. So that sort of regen would be unlikely to be a problem.
Showing my ignorance but willing to learn, isn't regen usually only about 20% of what got used to get up a hill, or get up to speed? So for a 30 amp regen, does that mean you are running a 150 amp controller? Or is it the same amps your controller can put in, but just for less time?
But is that a measue of an amp spike? Or a reading you see on the meter for a longer period. I would think most chemistries might tolerate a 1 second spike of 30 amps, and maybe several more of 15.
But in a normal stop, the entire braking period might be less than 5 seconds. Sounds to this idiot like a nice desuphinating pulse. But I will say again, riding that regen down a substantial hill at amps over the recomended charging rate would be a whole different story. I'd not want to try that.
The only regen I've ever tried was a pretty lame 5 amps, and it dropped to only 1 or 2 amps after about 1 second. So that sort of regen would be unlikely to be a problem.
Showing my ignorance but willing to learn, isn't regen usually only about 20% of what got used to get up a hill, or get up to speed? So for a 30 amp regen, does that mean you are running a 150 amp controller? Or is it the same amps your controller can put in, but just for less time?
friedwires
100 W
i just went for as ride with my panel meter hooked up in reverse.when braking its putting out 11 amps,and like you said dogman,its only for about 5 seconds at a time.but now i have a problem.with the meter on i a made a few test stops.and on the last stop the regen went out.i rode it back home with no problem.i disconnected the meter and now it wont run.i hit the throttle,the motor spins for a second and shuts almost all the way offto maybe 40 rpm's.sometimes when i throttle it it does nothing.it seems to depend on wheel position so i tested the sensors and they check out fine.the voltage on the phase wires.spikes and then drops to next to nothing.i also bypassed the throttle,and the same shit happens.i opened the controller to get a look see.and the only thing i can see is some melted solder on one of the two shunts that was'nt there when i opened it up apon delivery.both shunts looked like clean straight bars.maybe some solder rolled down on them,i dont know?this is an e-city power controller,1500 watt 48 volt.also the three large resistors got pretty hot while i was checking things out
friedwires
100 W
there is also an led on the pcb that blinks when the controller is turned on .normal?
dogman dan
1 PW
OUCH! Unfortunately my electronics consists mostly of buying new stuff when that sort of thing happens to me. But I'll take a guess and say that controller was not perfect, and just cooked off. Not related to anything you were doing.
friedwires
100 W
i just checked the fets,there are no shorts.and i evened out that blob of solder on the one shunt.still no improvement.i made a typo earlier in the post.this is a 1000 wat controller.not 1500 watts.
friedwires
100 W
damned chinese horseshit is what it is
icecube57
10 MW
I have alot of steep hills and I know i can sustain 15 -20+A going down them for atleast 10-15 seconds. Friedwires... sounds like SLA and regen dont mix. Something went pop. I think controllers dont like it when they have regen current and there is no place for the current to go or the battery cant accept it fast enough. There has been instances where people have BMS that doesnt accept regen current and it can take out the controller. My Ebay Ductape pack did that.
friedwires
100 W
shit i hope not ,its only two weeks old.
If the regen current is high enough, and the internal battery resistance high enough, the voltage generated across the battery could end up pretty high. It could easily exceed the controller's max voltage, if the controller not smart enough to stop regen if voltage goes that high.
Also possible is that there are spikes of current or voltage much higher than what your meter reads, but too short for the meter to catch them (or it may have something built into it that filters out short enough spikes as "noise" in the data, and ignores them, never displaying them even if they are "real"). If true, either could damage the controller.
It's also possible that the controller simply got so hot inside from normal use that it melted solder on the shunt or on some other component, the solder ran onto other things and provided paths for voltage and/or current that damaged other parts, leaving it in the state it is now. Or that there is still another tiny bit of solder floating around somewhere, bridging across something. Could be a tiny tiny ball between two SMT pins on a chip, or between pads on SMT resistors/caps, etc.
Also possible is that there are spikes of current or voltage much higher than what your meter reads, but too short for the meter to catch them (or it may have something built into it that filters out short enough spikes as "noise" in the data, and ignores them, never displaying them even if they are "real"). If true, either could damage the controller.
It's also possible that the controller simply got so hot inside from normal use that it melted solder on the shunt or on some other component, the solder ran onto other things and provided paths for voltage and/or current that damaged other parts, leaving it in the state it is now. Or that there is still another tiny bit of solder floating around somewhere, bridging across something. Could be a tiny tiny ball between two SMT pins on a chip, or between pads on SMT resistors/caps, etc.
friedwires
100 W
thanks AW.today im gonna get a good look at things under magnification,my eyes arent that great.well so much for using regen on these small sla's.they,re just not equiped to handle the high current.the fact that they were hot off the charger probably did'nt help matters any.
you guys have any suggestions on a 48v 30-40a controller.i have a feeling that i'll be in the market for one soon.
you guys have any suggestions on a 48v 30-40a controller.i have a feeling that i'll be in the market for one soon.
That's one of hte issues with regen, is that if you need it to work even at the start, you can't charge your batteries full, or there is nowhere for the regen power to go, without overcharging the batteries (regardless of chemistry). If you use enough power at startup to leave room for the regen power during first braking, then that would still be ok, as long as you ensure that the regen currents delivered aren't higher than the chemistry can take.
With your 12Ah SLA, probably 3A is their max charge rate (it is often printed on the side of the battery). That's not much stopping power, if you could somehow limit your regen current to that (I'm certainly not an expert on them, but I don't know of any of the controllers that do regen that have a settable limit like that; rather they seem to have a *voltage* limit, settable by changing components on the PCB rather than programming--seems like an obvious hole in the design to me).
With your 12Ah SLA, probably 3A is their max charge rate (it is often printed on the side of the battery). That's not much stopping power, if you could somehow limit your regen current to that (I'm certainly not an expert on them, but I don't know of any of the controllers that do regen that have a settable limit like that; rather they seem to have a *voltage* limit, settable by changing components on the PCB rather than programming--seems like an obvious hole in the design to me).
friedwires
100 W
so i guess,with fully charged batteries the regen current has nowhere to go but to the controller,which then overheats,melts solder,fries components,etc.i'll chalk this one up on the list of lessons learned the hard way. 
oh shit! the list is full,i'll have to start on another page i gave the board a good visual with a loop,and could'nt find any stray solder or bad joints,i also gave it a thorough blow with 120psi.then gave it another try on the scooter and the same thing happens.im gonna use the controller from my kids e-bike to make sure everything else checks out before ordering a new one.im thinking a 12 fet infineon,if i can scrounge up the dough.i wonder if lien has any set up for 48v?
oh shit! the list is full,i'll have to start on another page i gave the board a good visual with a loop,and could'nt find any stray solder or bad joints,i also gave it a thorough blow with 120psi.then gave it another try on the scooter and the same thing happens.im gonna use the controller from my kids e-bike to make sure everything else checks out before ordering a new one.im thinking a 12 fet infineon,if i can scrounge up the dough.i wonder if lien has any set up for 48v?
Not exactly, but sort of; in that if the batteries are already charged to full voltage, more current thru them simply increases that voltage (and they are less and less able to pull down the regen voltage to their max voltage), and if that's more than the controller can handle....poof!friedwires said:
I stopped making the list; it was discouragingly longer than the first three Dune books. :lol:i'll chalk this one up on the list of lessons learned the hard way.
Well, hold onto the carcass for parts/etc., later on you may start learning to fix them and want some spares.
Or someone else will want such a carcass for something. [/quote]
AFAIK all of Lyen's current models are good for up to at least 60V without modification.
friedwires
100 W
the other controller works fine on it, so its time to order a new one,i was'nt planning on upgrading this soon,but more power would be nice. 
friedwires
100 W
I just bit the bullet and bought a lyen 12 fet controller with regen.Hes setting the lvc for my 48v pack and adding the milti volt option for up to 100v.Im totaly stoked and cant wait for it to show up.maybe i can kill the sla's by christmas.so i can put lipos on my santa list.
hey AW. do you think my ecitypower controller is repairable? i have a curry style bmc 600w i'd like to try on 48v.the fets arent shorted,and if its just a matter of caps,it should'nt be a problem,im pretty handy with as soldering iron..........
hey AW. do you think my ecitypower controller is repairable? i have a curry style bmc 600w i'd like to try on 48v.the fets arent shorted,and if its just a matter of caps,it should'nt be a problem,im pretty handy with as soldering iron..........
itchynackers
100 kW
fried...I was under the impression that the 12fet Lyen (in stock form) should only be run at 84V max. Doesn't he have 100V caps in there? Do you have any experience (or links) with running it at 100V? I'd certainly like to do that in the future, if it will handle it.
friedwires
100 W
whats up itchy! its nice to see one of my M.E.S. bros. here on the sphere all i know is its an add on option,maybe he swaps out the 100v caps for something else.the lyen controller is new to me,i still need to do some homework on it.im sure i'll know more when it gets here.
all i know is its an add on option,maybe he swaps out the 100v caps for something else.the lyen controller is new to me,i still need to do some homework on it.im sure i'll know more when it gets here.
