battery info

I've never used Werker brand. I have used greensaver silicon batteries. They are a newer and slightly different kind of SLA that seems to last longer and tolerate deeper discharges.
I've also used powertron brand (ebay). Panasonic, too
Honestly, there isn't much of a difference between brand and generic SLAs. It's probably more important that you make sure to quickly recharge after each use and keep them fully charged. it's all similar China stuff.
make sure you buy deep discharge batts and not the alarm standby type

In my experience, Werker is a poor battery marketed mainly by price. Now, if you have a matched set and maintain them well, they may last, but my experience has not been good.

mark

B&B has a good rep, as do a couple of others. Frankly, the stock batteries from X-Treme are doing very well (knock wood). They are listed on the Green Max parts site.

true, B&B does have a good reputation. But the price is probably higher. Greensaver Silcone are a bit heavy and pricey. lifepo4 is better and it's possible to pick up a used pack at a low price. I did it.

I have a couple of quick responses: Saying that ANY Lead-acid battery is "a bit heavy" is a bit funny. They're ALL heavy! That's the lead!

B&B has a reputation and they probably do cost a bit more. I bought two via internet and they arrived damaged in shipping. My local supplier specialized in PowerSonic. They were better than the Werker's, but I wasn't thrilled. The "Shortage Batteries" from X-Treme spec 20 AH rather than 18AH; I was surprised that they did in fact seem to have a bit more capacity, and have seemed (so far) to last.

I have trouble with the Greensaver "Silicone" secret sauce; I suspect they are just standard SLA's with a sooper dooper name.

I have stayed away from lithium for two main reasons:

1. My understanding of the technology and its needs; my current charger(s) would not work with a new chemistry, and my monitoring instruments would largely be useless. I've
2. The need for BMS circuitry at the per cell level; From what I've read, a BMS is absolutely necessary for achieving the 1000-cycle life that is bragged about. While electronics at this scale CAN be reliable and effective (Tesla and Toyota), the quality of the components to go in my 700W scooter is nowhere near that level, and the payoff if the BMS fails is a puddle of melted plastic. I'm talking about vehicle fires; I've heard of more than one that started with the BMS boards as they are rarely fused.

Its advantages are:

1. Weight !!!!!!!!!!!
2. Resistance to Peukert: Heavy draws don't immediately reduce the storage capacity, AFIK.

Mark

The disadvantages of lithium are also the cost, but if you calculate the distance you can travel on a set of lithium xx batteries over their whole life and compare it to what you can get out of 3 or more sets of sla, there is not such a big difference. Most lithium's advertise 1000 cycles, some even more depending on the xx, i.e. the chemical that they are combined with. The straight lithium batteries are finicky - can actually be unstable and leave you with a flaming bike - hopefully, with you not on it. The lithium xx are much more stable. As a set of sla batteries age, each charge will provide significantly less range, whereas a lithium xx set will provide less of a decrease in usage with time. For example, my first ebike had a 36v 10 amp battery that gave me about 20 km on a charge. After about the 100th recharge, I was only getting about 16 km from it. The battery was still "good" but not good for me because I needed 20 km range, so I had to replace it, even though it still had 200 or so cycles left based on the mfg info.

I also have never had a "fake" full charge from a lithium set of batteries. With my sla's, from time to time the charger would say that the batteries were "full" so I would head out, only to find that, halfway through the ride, the batteries were only slightly more than half charged....well, ok, I know that some of you will say half discharged...point is, I had to pedal that heavy bike a lonnnnng way.