Interesting and modular approach, I like it! While on the subject - please *never* put eBike batteries in series. Wiring them in parallel to share the current is fine and depending on their quality (internal resistance) they may or may not share current very evenly, although that tends to even out especially for the battery types that have a good relation between SoC and voltage, such as the Li-poly type cells that are typical in eBike batteries, at least that was when I was looking at them.
If batteries have a low level discharge shutoff (a pair of anti-series MOSFETs) to disable the battery when a cell gets low, those transistor are sized to carry the open voltage of *this* pack. If you add a pack in series, they may or may not be able to open the circuit - or blow up. Just FYI in case you did not realize this limitation, so you are doing it right by only using packs in parallel. Regards, Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of Willie2 via EV Sent: Tuesday, July 21, 2015 12:30 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] more on ebike batteries in golf carts On 07/21/2015 11:51 AM, EVDL Administrator via EV wrote: > I'll be following this effort with interest. I'm especially keen to > see how long they last for you. The cheap Chinese bike batteries > don't seem to have a very good reputation on the ebike forums such as > Endless Sphere. However, I think most riders there work them pretty > hard, demanding high power from them. Your use may stress them less. Please > keep us updated. I imagine you are correct on reliability. The MAJOR attraction for me in doing things this way is maintainability. If a battery goes out, the vehicle can keep going and the battery can easily be swapped out. The golf cart I have running has given me no trouble in several charge cycles. It is surprisingly sprightly considering the minimal batteries. The pair of 20ah batteries are only supposed to supply 60 amps; with a "regular" battery, I've seen as much a 100 amps. I was expecting to have to put in 3 or 4 20ah batteries. I do not have an ah counter on it but expect to soon. So I can guess at my state of charge and know the discharge rates. > I also wonder where you found a 60 amp-hour ebike battery! I haven't > seen any that big. Isn't it pretty heavy for a bike? Or is that more > of a moped or ecycle battery? One of the ebike battery suppliers I've been talking to offers to build bigger batteries: http://www.aliexpress.com/store/208817 I have two 72v 30ah batteries coming from them for my Zap. If those work ok, I'm thinking of putting 4 or 5 120v or 144v 20ah batteries from that source in my Ranger. 20ah to keep the weight of each battery down to a manageable amount. The ~20 ah batteries seem to come with 12ga discharge wire. I've used SB50s to connect to my 10ga wire. 5 pair of 10ga wires soldered into two copper lugs to support up to 5 batteries. I think those gauges and configurations may work for all three of my applications: 36v golf carts, 72v Zap, 120v or 144v Ranger conversion with a 9" motor. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
