I completed the 5-amp discharge testing of my e-max pack. The scooter had about 4750 km on it. Range was down to 12 miles and falling rapidly.
Here are the results, with a test on one of my new BB EB20-12's included for comparison:
The ampere-hours for the silicone batteries when discharged down to 9.5 volts under load, ranged from 6.1 to 15.4. The new BB battery got 17.6 AH - exactly what the manufacturer data sheet reports for for a 5 amp rate.
As you can see, the performance of the silicone batteries was _very_ inconsistent. The best silicone battery is down to about 85% of the new BB battery capacity at about 200 cycles. The BB battery data sheet, if it is to believed, shows that the BB battery will still be at 100% (down from 104% after break-in) at 200 cycles.
Besides the two batteries that were pretty much completely shot, a premature, continuous, voltage sag is characteristic of the rest of the silicone batteries. A hint to what is going on is apparent from my measurements of the voltage the battery recovers to when the load is removed - the worst battery (3A) recovered to 12.7 volts, the best (1A, 1B and 2B) to 11.9 to 12.0 volts, and the new BB to 11.3 volts. There was a lot of energy still left in the silicone batteries, but internal resistance rises too high, as the battery is discharged, for it to be usable.
I believe I have the highest mileage on my (first) e-max (2950 miles/4760 km) than any other owner who participates in this forum, and this mediocre performance represents the best performance of any e-max battery pack among these e-max owners. Most new e-max's were delivered new with at least a couple bad batteries. And most of the rest encountered battery problems within the first 1000 km of use.
In conclusion, the Guineng "silicone" batteries appear to be just another bottle of Chinese snake oil. Their performance is no better, and possibly worse, than good quality, but still considerably cheaper VRLA batteries.
Considering the best mileage I ever got on the silicone batteries was 28 miles, I look forward to getting record mileage (better than 35?) on my new BB battery pack - as soon as winter lets up a bit.
I welcome any comments!
Wanted to say I admire the thoroughness with which you analyzed the pack.
Were you above charging cycle 250?? I wonder if the silicones can be charged better (with a less "abusive" charger than we received)
Can't wait to get your report once you hit your first 1000 + miles with the BB's!
What does a pack of BB's go for these days??
I would so love to see someone configure a pack of lithiums (which don't have this sagging effect you're describing - at least to a sales manager at GAIA in germany....) of course, that'll have to be someone who is filthy rich... and has got a couple of 2000W spare motors in the shop...
Not sure, probably at least 200 cycles, 250 at most. My chargers don't seem to be abusing the pack. Mine follow the charge protocol pretty well - 59.5 volts (14.8 volts per battery) max at end of the charge. This is normal.
Your problems with overcharging may be due to a one or two batteries with excessive resistance, this causes the charging voltage to be unevenly distributed along the battery string. The high resistance batteries getting 16 volts, causing gassing, others getting 13 volts and are undercharged.
You may want to check voltages of individual batteries during charging to check what is going on.
Unless you build the pack with batteries matched-up from a large stock, I am convinced that battery equalizers (powercheq or smartspark) are practically mandatory.
This is really interesting and important work. Do you or anyone else have any data about real world battery performance vs temperature? I have three electric scooters, and they all seem to suffer from significant range degradation as the temperature drops.
Yes, it seems the Silicone batteries are no better than standard SLA. I suspect the lifespan would have been considerably better with some kind of balancing.
My silicone pack was rearranged into parallel pairs with powerceqs about halfway through their life. But perhaps some damage was already done.
While purely anecdotal, several other e-max owners including myself, reported only small degradation of range at lower (0C or below) temperatures. This may be the one advantage of silicone batteries. I forgot to mention that my tests were run my poorly-heated garage at probably about 50F/10C or so rather than the standard 20C.
Where I live, when it's cold, it also usually also snowing at least a bit. Between the temperature and dealing with snow, ice and dirty salt and cinders spread on the streets, I don't do alot of cold weather riding myself so this isn't much an advantage for me.
Since I have a dying set of silicone batteries, I look forward to hearing what kind of range you get with your new BB's (I will have to order some soon)... thanks for the research!
It probably will be a while - we're in a long cold spell, and my first cycles will be shallow - maybe I'll have some results in March.
Noticed you live in LA.
Craig/Deafscooter is reportedly giving scooter parts away this weekend. Must be picked up in person. Any chance you could get by his place (Palmdale) and see if he has any e-max parts?
Thanks for the post, and the careful documentation.
Let's hope you get better life out of the next pack!
So, since my batteries were dying again, I finally just bought and installed 8 new bb eb20-12's in my e-max, which was already rewired with buddy pairs, and has powercheq's. Went for one ride, and performance seems the same as when the silicone's were new. I will report back once I have put some more miles on these batteries (haven't tested total rnage yet). The powercheq's seem to be activating very little now, as opposed to the hard work they were doing balancing the messed up guinengs.
Is anyone sure whether or not the e-max chargers will damage these VRLA batteries? If anyone thinks I should not use the old chargers with these batteries, any links to a new 48v charger I could buy?
I think the e-max chargers should do fine - I have measured their charging voltages many times and they are right at those specified on the EB20-12 data sheet.
The only caveat is that, if one battery (or battery pair in the case of the e-max) has higher resistance, It can receive too high a charging voltage. This is always a potential problem with any kind of bulk charging. But the powercheqs should prevent this problem.
I’ve had Powercheqs on my batteries since cycle #2 and I’m now approaching 1500 miles (I’m expecting to hit 3k this summer) with no sign of them letting up yet, so I hope that balancing was the only issue with them.
2006 E-Max sport @ 60v
2006 E-Max sport @ 60v
OK - thanks for the thoughts about the chargers, PJD.
So, to be sure my new batteries are not being overcharged, what voltage should the pack be at when charging is complete? I am just trying to be diligent so that these batteries don't get destroyed in case my problem was a bad charger all along. I just read the voltage, and it is 52.5v, one day after a full charge, which would be 13.125v per battery - that seems a little high based on what I have read online about charging VRLA batteries, but I'm not sure.
The voltage you read is not high at all. The potential per cell for lead-acid chemistry is 2.20 volts per cell, so actually your 13.12 volt reading is a bit low.
The recommended charging charging voltage depends on temperature. The e-max charger's voltage during the absorbtion (CV) stage is 59.5 to 59.8 volts, or about 2.48 volts per cell, or 14.8 to 14.9 volts per battery. This is the recommended charging voltage for room temperature. Float voltage is about 54.5-55 volts or 2.27 to 2.29 volts - also about right (i'e you can keep it on float - flickering green light- indefinitely). Go to BB's web site and download the data sheet.
You may want to check individual battery voltages during charging. An imbalanced pack without powercheqs can result in voltages to individual batteries of more than 16 volts - which IS too high - but it isn't the fault of the charger, but an inherent problem with bulk (multi-battery) charging.
I finally have a qualitative assessment of the new battery packs performance.
Based on about 25 miles of hilly riding with a 1 hr "opportunity charge" at the midpoint, it appears that the BB EB-20-12 battery pack is providing comparable range performance to new silicones - while shaving about 4-5 pounds off the weight.
So, e-max owners should simply replace their silicone pack with good quality VRLA's when the time comes.
Have found that most degradation in batteries performance regardless of chemistry is related in improper charging , most charger have very poor temperature compensation, if the batteries and charger are done at room temperature ( 25 C) the degradation will significancly decrease .The NiMH pack are very difficult to charge at high temperature , charging efficiency rapidly dropped , have tested at 50 C with
charging efficiency as low as 20% and at a significance rate C/3 no less .
HEAT & LOSS & INEFFICIENCY RELATED DIRECTLY to IMPEDANCE
I've got two scooters and a motorcycle / scooter at the moment. The Lepton has AGM batteries, and prudent riding and recharging (but no balancing aside from what the charger provides) have let me get through 9 years with it on the original batteries, with about 60% of the range I originally had. I can still go 14 miles in Eco mode (and maybe 9 in Sprint mode) and not quite be into the Red.
I'm in my second season riding an Extreme XM-3000, with silicone batteries. I've ridden it about 1000km (adjusted for speedo error) and have noticed no decrease in range yet. It's too hard to get at the batteries for me to measure voltages, but I also rely on the charger to balance them, by leaving it connected for 3-8 hours after it shows Green. So far, so good.
I just bought a ZEV 5000LA that got damaged in shipping and is turning into a real Nightmare. It came with silicone batteries, and until I saw this thread my only concern was that the charger is, for some bizarre reason, programmed to only activate if the charge falls to 50%. Now I have yet another thing to worry about with that bike...