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- Thread starter D-Man
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safe
1 GW
- Joined
- Dec 22, 2006
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- 5,681
Generally I would agree.
The only thing is that every motor has a "designed powerband" where a certain current flow situation is ideal. If your battery configuration matches your motor configuration and you are in the "sweet spot" then you get better overall performance. If you miss the "sweet spot" in either direction then... well... obviously your results will get worse.
Peukerts Effect is the biggest problem with SLA. Even a very "heavy" battery setup still tends to draw at a rate that produces a 50% "waste factor" due to the Peukerts Effect. Add a lousy motor powerband and you get into the range of 75% of the energy you have being lost to nothingness.
NiMh and Lithium avoid Peukerts Effect for the most part, so right off the bat you save about 50% in weight just on that alone.
I like SLA batteries, my bike uses them presently, but I'm pretty much at the limit already of what it can do. At 86lbs of batteries on a bike that weighs 140 lbs (and goes 40+ mph) you are running into all kinds of limits.
So my next machine will be NiMh or Lithium...
The only thing is that every motor has a "designed powerband" where a certain current flow situation is ideal. If your battery configuration matches your motor configuration and you are in the "sweet spot" then you get better overall performance. If you miss the "sweet spot" in either direction then... well... obviously your results will get worse.
Peukerts Effect is the biggest problem with SLA. Even a very "heavy" battery setup still tends to draw at a rate that produces a 50% "waste factor" due to the Peukerts Effect. Add a lousy motor powerband and you get into the range of 75% of the energy you have being lost to nothingness.
NiMh and Lithium avoid Peukerts Effect for the most part, so right off the bat you save about 50% in weight just on that alone.
I like SLA batteries, my bike uses them presently, but I'm pretty much at the limit already of what it can do. At 86lbs of batteries on a bike that weighs 140 lbs (and goes 40+ mph) you are running into all kinds of limits.
So my next machine will be NiMh or Lithium...
I understand the peukert effect. But what I don't get why Knightmb only got 1 extra mile on his test between nimh and sla on the 24 volt mongoose range test. I thought there would have been a bigger difference. So now I'm not so sure about what to believe.
xyster
10 MW
My scooter uses SLA. This past summer in warm weather (80F) I could squeeze 10 miles from its stock, 36v 10ah pack. One cold, 40F morning I went riding my normal, ~9 mile route only to have the pack poop out completely after only 7 miles. In cold weather my ebike's lithiums maintain the same range, but their current capacity drops a few amps.
safe
1 GW
- Joined
- Dec 22, 2006
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- 5,681
D-Man said:
Okay, went over and read it.
Something is wrong. Even in the best of circumstances you are going to see the Peukerts effect on SLA batteries. It's simply not avoidable. The lowest amp rate that you could run would still give you a waste factor of 35% (being generous) or more with SLA.
I simply reject those results...
xyster
10 MW
My bet is unbalanced pack -- one or more of knightmb's NiMH cells are not performing up to par, and may have come that way since these chinese batteries seem to have a high defective rate. (I did read his excellent reviews and might have missed it if he did test the cells individually.)
Hi
The best way to get good range with SLA is to take them out and put something else in instead. I never had any joy at all with lead acid batteries they are way too heavy, you can only get half the rated capacity from them, they are ok for the first 5 mins of hard use and thats all.
They are ok for light ev use on a low power bike but they are useless on an assist bike in all honesty, you can get away with them just on a motorbike as in safes application but for an assist they are a wast of time when you consider the other options.
NIMH is falling in price all the time and Lithium is in reach, you just need to condition your brain that you are an early adopter of the technology, the swap from Lead to NIMH on my bike was amazing it easily doubled my range and helped with the handling no end, by this time after 6 months I would have changed 2 sets of lead batteries (Im not kidding) these NIMH cells seem stronger than ever.
Leads Dead
For me at least, Cheers
Knoxie
The best way to get good range with SLA is to take them out and put something else in instead. I never had any joy at all with lead acid batteries they are way too heavy, you can only get half the rated capacity from them, they are ok for the first 5 mins of hard use and thats all.
They are ok for light ev use on a low power bike but they are useless on an assist bike in all honesty, you can get away with them just on a motorbike as in safes application but for an assist they are a wast of time when you consider the other options.
NIMH is falling in price all the time and Lithium is in reach, you just need to condition your brain that you are an early adopter of the technology, the swap from Lead to NIMH on my bike was amazing it easily doubled my range and helped with the handling no end, by this time after 6 months I would have changed 2 sets of lead batteries (Im not kidding) these NIMH cells seem stronger than ever.
Leads Dead
For me at least, Cheers
Knoxie
Lessss
1 MW
My SLA need to last just long enough for Firefly's new batteries to come on the market.
knightmb
100 kW
I've always thought of SLA as being cost effective. For current draw SLA kicks butt compared to everything else, but they just weigh so much. I do wish the easy of mass production and cheap SLA was more durable to deep discharge and lighter, but it's just a function of the technology I guess.
Hello
I tried expensive and cheap ones and they all sucked big time, good for about 5 mins of hard use and thats its, I can squeeze 15Ah measured! from my Nimh with careful use, ok I dont do this often for obvious reasons but it you treat NIMH well you can, 15Ah is 3 times what I got from a much heavier SLA pack.
It totally transformed my riding, I like to do 35 mile rides Before I could not use power for 2/3 of the ride using lightly on the last 10-12 miles with a lot of peddling, now I can peddle very lightly the whole 35 miles and use heavy on hills etc with power to spare at the end of the ride.
Until you swap to NIMH you will never know what you are missing, shop around and listen to user reports in order to get the best batteries or make your own pack if you are confident, either way NIMH or NICAD strip the ass out of lead, lead is 100 year old + technology, I understand Lipo has it price limit and people are worried about safety, this makes NIMH simply un missable for EV use.
Lead is fine for low power bikes and people that only want to pop to the local store and back when the weather is nice and its not windy, occasional use etc, If you are more serious then NIMH and Lipo or Lion are the must haves, I could never now go back to Lead in any form, I am spoilt as I have Lipo and Nimh packs in abundance now, Im an addict now you see!! ha ha
Happy Riding
Knoxie
I tried expensive and cheap ones and they all sucked big time, good for about 5 mins of hard use and thats its, I can squeeze 15Ah measured! from my Nimh with careful use, ok I dont do this often for obvious reasons but it you treat NIMH well you can, 15Ah is 3 times what I got from a much heavier SLA pack.
It totally transformed my riding, I like to do 35 mile rides Before I could not use power for 2/3 of the ride using lightly on the last 10-12 miles with a lot of peddling, now I can peddle very lightly the whole 35 miles and use heavy on hills etc with power to spare at the end of the ride.
Until you swap to NIMH you will never know what you are missing, shop around and listen to user reports in order to get the best batteries or make your own pack if you are confident, either way NIMH or NICAD strip the ass out of lead, lead is 100 year old + technology, I understand Lipo has it price limit and people are worried about safety, this makes NIMH simply un missable for EV use.
Lead is fine for low power bikes and people that only want to pop to the local store and back when the weather is nice and its not windy, occasional use etc, If you are more serious then NIMH and Lipo or Lion are the must haves, I could never now go back to Lead in any form, I am spoilt as I have Lipo and Nimh packs in abundance now, Im an addict now you see!! ha ha
Happy Riding
Knoxie
Reid Welch
1 MW
excerpted from a email from Justin of last November:
Hullo Knoxie and all
I would like to know what to expect in the way of voltage sag from NiMH in particular.
If I get the BatterySpace 24V pack (ideally, two of them for series/parallel running of my Currie bike), what will be the voltage sag say 15 amps from a single 24V pack? Will the series resistance of NiMH cells increase with age?
These are Nexcell brand. From Battery Space.com:
for instance, if I choose to try a single BS24V pack at first, I might have a seven volt drop under high loads? I don't have seven volts sag at present, even with two tired-out SLA bricks.
---
In emails of last December, Justin noted when I asked of his pack, vs, BS's pack above,
BS's own data for their NiCad cells seems to confirm that NiCad from them, at least, is not good for high-current work (over 15amps).
So--I dunno. I would love to learn (knightmb) what you see in voltage sag from you BS 12AH packs, at various current draws like 10, 15, 30A?
Is that data on hand?
Thanks for advice,
Reid
Hullo Knoxie and all
I would like to know what to expect in the way of voltage sag from NiMH in particular.
If I get the BatterySpace 24V pack (ideally, two of them for series/parallel running of my Currie bike), what will be the voltage sag say 15 amps from a single 24V pack? Will the series resistance of NiMH cells increase with age?
These are Nexcell brand. From Battery Space.com:
What they don't say is what the typical total series resistance may be. A quarter ohm at 30 amps = what? A seven volt loss,
Impedence of this battery pack is less than 250 mohm, and the Max discharging rate is 40Amp
for instance, if I choose to try a single BS24V pack at first, I might have a seven volt drop under high loads? I don't have seven volts sag at present, even with two tired-out SLA bricks.
---
In emails of last December, Justin noted when I asked of his pack, vs, BS's pack above,
BS's own data for their NiCad cells seems to confirm that NiCad from them, at least, is not good for high-current work (over 15amps).
So--I dunno. I would love to learn (knightmb) what you see in voltage sag from you BS 12AH packs, at various current draws like 10, 15, 30A?
Is that data on hand?
Thanks for advice,
Reid
knightmb
100 kW
I did a 2.5 A draw for an hour in my experiment. In theory, with the 4 fans I have, I could wire them into a (2.5 X 4 = ) 10 A draw and do some measurements. Just don't have enough devices around here to wire up, LOL.Reid Welch said:
I should get a bike dynamo with adjustable resistance, that would be a great way to measure all of this. I'll make a trip by a bike shop or two and see what they have, hopefully it will be cheap
If not, I'll scour e-bay for something like this.
knightmb
100 kW
Well, the selling point for me wasn't the power but really the lighter weight and ability to run completely dead without fear of quickly killing the batteries.
If you have 12 AH SLA and 12 AH NiMH, then in theory you should get about the same distance, save the less weight of the battery may improve range a little. I've tried testing of running down both sets in one hour and they are very close, when testing it out in the field, they came close again. 1 mile difference isn't too much considering where I was testing the bike was not a perfectly level 1 mile loop. It has a couple hills that the bike has to keep going up and over for each lap.
I wasn't completely sure of the NiMH either, but now that the batteries are getting old and still putting out good power, that for me made it worth the cost. I can't speak for all NiMH packs, but the ones I've used have been through a lot of years of abuse and riding. To this day, they are still going strong. That's not to say SLA won't have a good life if you take care of them too, but when you want a lot of power but not a lot of weight that's where the NiMH shines in my opinion. At least cost wise.
When I put the 24 volt NiMH pack in my Mongoose E-Bike, it didn't make much of a weight difference compared to the 2 SLA batteries. I do notice the difference though between (2) 24 volt packs and (4) 12 volt SLA batteries. The bike is so heavy, it's hard just to keep it standing up straight.
So, really it's a matter of need vs. want. I'm going to leave the SLA in my Mongoose because it's not much of a weight difference and once I get a good charge/discharge going on the SLA I'm sure it will easily match the NiMH for distance, maybe more since they are new. I want to keep the Mongoose as a stock e-bike, it's a good way to get friends into it. Mine that rockets around 700C rims and 48 volts, I keep to myself for fun. Of course after seeing some of the e-bikes posted here, mine feels more like a minivan now after seeing all the corvettes and porches that people have made their e-bikes into, LOL :lol: :lol:
If you have 12 AH SLA and 12 AH NiMH, then in theory you should get about the same distance, save the less weight of the battery may improve range a little. I've tried testing of running down both sets in one hour and they are very close, when testing it out in the field, they came close again. 1 mile difference isn't too much considering where I was testing the bike was not a perfectly level 1 mile loop. It has a couple hills that the bike has to keep going up and over for each lap.
I wasn't completely sure of the NiMH either, but now that the batteries are getting old and still putting out good power, that for me made it worth the cost. I can't speak for all NiMH packs, but the ones I've used have been through a lot of years of abuse and riding. To this day, they are still going strong. That's not to say SLA won't have a good life if you take care of them too, but when you want a lot of power but not a lot of weight that's where the NiMH shines in my opinion. At least cost wise.
When I put the 24 volt NiMH pack in my Mongoose E-Bike, it didn't make much of a weight difference compared to the 2 SLA batteries. I do notice the difference though between (2) 24 volt packs and (4) 12 volt SLA batteries. The bike is so heavy, it's hard just to keep it standing up straight.
So, really it's a matter of need vs. want. I'm going to leave the SLA in my Mongoose because it's not much of a weight difference and once I get a good charge/discharge going on the SLA I'm sure it will easily match the NiMH for distance, maybe more since they are new. I want to keep the Mongoose as a stock e-bike, it's a good way to get friends into it. Mine that rockets around 700C rims and 48 volts, I keep to myself for fun. Of course after seeing some of the e-bikes posted here, mine feels more like a minivan now after seeing all the corvettes and porches that people have made their e-bikes into, LOL :lol: :lol:
deerfencer
100 mW
I've had the same wretched experience as Knoxie with SLA's on several different rides, including a new Lashout a few years back that died about 2 1/2 miles up the first hill--and this was with the larger Ah batts! In all fairness some of that problem was controller related, but I upgraded the bike recently with a 48V Powerpack upgrade, threw some NIMHs aboard, and completely transformed the ride.
Separately, I have a 6-7 year old Denali e-dirt bike that runs on (3) 15Ah SLA Hawkers wired in series, which is great fun--for about 20 minutes. As Knoxie noted, you get an incredible surge out of lead acids fresh off the charger, but I never got squat for range from them--about 1/2 what I've gotten from other chemistries at double or triple the weight. There's a reason they're called lead, and IMO it's impossible to pack enough power on a bike without greatly affecting the ride--and not in a good way. Beyond a certain point it no longer handles or rides like a bicycle.
A year and a half ago I bought a Tidalforce S750X and last May upgraded to a double 15Ah lithium pack that enables me to sprint up most hills at close to 22-23 mph and put in an hour's hilly ride @ 24 mph average, all for a total payload of 22 lbs or so of battery weight. I weigh 230+ lbs, am 52 years old, and not in terribly great shape, but this is the kind of performance that gets me out there pedaling with a huge grin whatever chance I get.
larry
Separately, I have a 6-7 year old Denali e-dirt bike that runs on (3) 15Ah SLA Hawkers wired in series, which is great fun--for about 20 minutes. As Knoxie noted, you get an incredible surge out of lead acids fresh off the charger, but I never got squat for range from them--about 1/2 what I've gotten from other chemistries at double or triple the weight. There's a reason they're called lead, and IMO it's impossible to pack enough power on a bike without greatly affecting the ride--and not in a good way. Beyond a certain point it no longer handles or rides like a bicycle.
A year and a half ago I bought a Tidalforce S750X and last May upgraded to a double 15Ah lithium pack that enables me to sprint up most hills at close to 22-23 mph and put in an hour's hilly ride @ 24 mph average, all for a total payload of 22 lbs or so of battery weight. I weigh 230+ lbs, am 52 years old, and not in terribly great shape, but this is the kind of performance that gets me out there pedaling with a huge grin whatever chance I get.
larry
I can agree with that if your using the standard e-bike battery and you max amps all the time. Here's the stats for a standard e-bike 12v-12ah sla battery. (constant current)
36 amps = 9 minutes run time to D.B (Dead Battery).
24 amps = 14 minutes to D.B
12 amps = 35 minutes to D.B
7 amps = 70 minutes to D.B
5 amps = 120 minutes to D.B.
If your into "economy" and low amps, use them. If your into high amps, high speed, big hill climbing, don't use them. Prepare to use your wallet.
Edit: I know this chart makes sla's look bad but if you raise the voltage high enough, like at least 48 volts, or if you parallel 2 pairs of sla batteries and let them share the load,(24 volt system) you will be in the lower amp range and get good range. That is if you keep your speed 20 mph and under and don't have a big amp controller.
OR - use B&B EB series 20ah batteries- They have a 15ah 1 hour rate. Its a 15 lb battery but will have twice the capacity of the 12ah rated at 7.2 ah 1 hour rate. See, leads not dead. Just go bigger!
Also: Outside temp plays a huge role in sla performance:
Geebee
1 kW
D-man those figures are almost identical to my experience in the real world with SLA's.
It's just hard to justify the cost of the upgrade when you have loads of them around the house, but I sure would like to lose the extra weight.
It's just hard to justify the cost of the upgrade when you have loads of them around the house, but I sure would like to lose the extra weight.
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