OK, my EV truck came with a flooded pack (20 high quality 6V "golf cart" style batteries) as well as 2 spares who together make up the 12V aux battery. Early in its life, a bad terminal clamp caused so much heat that a terminal post completely melted and run across the battery, leaving only a "ground zero" behind that a local battery salesman did not dare to cast a new post onto, so I promoted that battery to one of the "spares" and I have been using it with a stainless bolt tapped into the sunken post, since the aux load is never more than 20-30A for headlights and wipers and such. In the past weeks I have had quite some difficulty with sag as well as never quite charging to the old finishing voltage but the finish charge level had been dropping for a while and the sag I blamed on the cold weather, I am familiar to losing range due to cold batteries. Last Thursday I came home and wanted to plug in to charge when I heard a sound different than what I was used to. Normally batteries can burp a little and under charge they might bubble, but this was a sizzling sound as if something was steaming hot... So I opened the hood and located the sound... hm, the vents on that cell had brown residue sitting on the white speedcaps, not a good sign and whisps of steam coming from it, so I carefully opened the speedcap and a short hiss came from that cell (I had not started charging yet, so this was not good news). It was the middle cell of one of the batteries under the hood. I peeked inside the steaming cell and saw... bone dry plates. After the cell had cooled (we were immediately leaving for dinner, so I had no choice than to wait anyway) I poured some distilled water in the cell and started the charger. Some time later it appeared as if the water had disappeared, but I now think that the fluid was so clean that I could not see it with the flashlight, so I added a little more water and saw a bubble float, so I knew there was some water till halfway between plates and top of the cell. I charged more and all other cells were bubbling by now, but not this one and the fluid stayed pristinely clear, which I am not used to see. So, I charged some more and eventually decided to take a voltage reading. Aha! only 4V so the bad cell is really a short now... That explains a lot. My next step will likely be to purchase a (used) 12V car battery as the aux battery and rotate the other spare battery into service instead of the 4V one, because I doubt that I should continue to run this guy, I expect more steam and/or worse. One other alternative would be to buy another 6V battery to replace the bad one. Just wanted to share the experience and the surprise to see a battery with one cell staying pristinely clear and the other cells have somewhat mudded electrolyte from old age and other near-end-of-life issues (this pack has seen over 15k miles and about 4 years of driving). Soon I will have to decide if I am going to spend the time to install my Lithium in this truck or not, but that will definitely need to wait till better weather, so I can commute by bike while the truck is out of commission.
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 http://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. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160109/2223110b/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
