For over a decade, we've been rebuilding various Currie VRLA (valve regulated lead acid "gel cell" aka SLA or AGM) Battery packs for our stable of Currie ebikes. The Currie 12ah and 10ah batteries can be replaced with lighter, lower AH batteries, of course you get less range. We now have 3 of the Currie RMB packs and have replaced the 10ah (12v) VRLA with "9ah" and 8ah VRLA batteries that are 25% lighter, over 35% less cost per battery (as low as $35 for a new pair) and of course give about 2/3 to 3/4 of the original range of the 10ah batteries. For the 12Ah frame mount packs we have substituted 10ah or less. In each case, we have added non-flammable, corrosion resistant insulated rubber padding.
We also test periodically with the Elk battery life tester (BLT) There are others such as West Mountain Radio on the market which have external software controlled charging. We have used the Elk BLT for almost 8 years and put a sticker on every VRLA/AGM battery to track the charging state over time. The main thing for us has been to match the batteries so that they have very similar mhos readings (using an Elk VRLA/Gel/AGM tester). For us, CSB and PowerSonic have been very reliable; the locally available Werker brand not so much. We are now avoiding the rebranded batteries from some sellers as we have no idea who the actual manufacturer and model number is in order to track reliability. A battery tester is an essential tool for rebuilding battery packs, but hard to justify for individuals with only one e-bike!
The only things you absolutely need are some long phillips #2 screwdrivers for the "newer" RMB plastic packs, a volt-ohmeter, a soldering iron, desoldering pump or wick, and solder and a 12v desulphating charger. All the VRLA packs we have worked with have soldered tabs, and it is a really good idea to solder them back in. We have run them without solder and using some of the expensive contact enhancing compounds such as deoxit, but whenever we get any degradation in performance from the pack we see some discoloration at one or more terminals and clean and solder the F2 tabs in place. By the way always get F2 tabs on the batteries to match the F2 connectors in the pack though F1 tabs are more readily available and the adapters are cheap. Just another point of failure and additional length of conductor to shield. We have had good results with the Schauer CM6 charger and BatteryMINDer 1A charger to rejuvenate and rebalance a pack where one of the two batteries may have failed and the other is good enough to match with a new battery.
Now we have worked on a NiMh pack for a Giant which we took an old pack case and transformed it into a connector and disconnect switch for a 24V rack mount Currie VRLA pack. Sign, would have loved to rebuild the NiMH or the Currie Li pack, but we don't have ready access to direct replacement batteries as with the VRLA/SLA/AGM batteries.
Best, Mark
