Re: [EVDL] suspicious of a bad calb cell?
Bill Dube via EV wrote: Probably the best plating to use would be Alodine (AKA Bonderite). Not terribly difficult to do. A bit pricey, but you would only have to coat a tiny area. Alodine is the conductive, gold/brown plating used on aluminum aircraft parts. Great for corrosion prevention. Conducts very well (unlike anodizing.) Abrasively clean the aluminum surface, slightly etch with AlumiPrep, rinse with distilled water, dip in Alondine, (or brush on,) rinse with distilled water. You could do it yourself, actually. I have done it myself with aircraft parts. Unfortunately, Alodine is a chromate solution, which must be carefully contained. (Erin Brokovich became famous for suing on behalf of chromate pollution victims.) As I understand it, they make non-chromate Alodine-like plating solutions. Might be worth looking into. You buy Bonderite from Aircraft Spruce: http://www.aircraftspruce.com/categories/building_materials/bm/menus/cs/metalprepsupplies.html https://en.wikipedia.org/wiki/Chromate_conversion_coating Thanks, Bill! I've seen alodyne coatings, but never checked its electrical conductivity. I'll dig around in my midden heap, and if I can find an aluminum part with Alodyne, I'll try a connection and see what kind of resistivity I get. As it happens, I just got a set of used CALB cells to put in my LeCar, so the timing is excellent. :-) -- It is vanity to do with more that which can be done with less. -- William of Ockham -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
Probably the best plating to use would be Alodine (AKA Bonderite). Not terribly difficult to do. A bit pricey, but you would only have to coat a tiny area. Alodine is the conductive, gold/brown plating used on aluminum aircraft parts. Great for corrosion prevention. Conducts very well (unlike anodizing.) Abrasively clean the aluminum surface, slightly etch with AlumiPrep, rinse with distilled water, dip in Alondine, (or brush on,) rinse with distilled water. You could do it yourself, actually. I have done it myself with aircraft parts. Unfortunately, Alodine is a chromate solution, which must be carefully contained. (Erin Brokovich became famous for suing on behalf of chromate pollution victims.) As I understand it, they make non-chromate Alodine-like plating solutions. Might be worth looking into. You buy Bonderite from Aircraft Spruce: http://www.aircraftspruce.com/categories/building_materials/bm/menus/cs/metalprepsupplies.html https://en.wikipedia.org/wiki/Chromate_conversion_coating Bill D. On 2/6/2018 11:44 AM, Lee Hart via EV wrote: Bill Dube via EV wrote: Did you lightly sand (or Scotchbite) each terminal and apply a thin coating of NoAlOx before connecting? No? Then you have to redo all the connections. They will give you no end of grief. (Ask me how I know. :-) ) If you don't do this connection treatment, the dissimilar metals will corrode, over heat, and behave badly in general. Often, the cell terminals arrive with a lot of corrosion formed during shipping. Bill has it right! I've had Thundersky, CALB, and GBS cells, and *all of them have at least one aluminum terminal. It is devilishly difficult to make reliable low-resistance connections to aluminum. I've even wondered if there is some way to plate them with copper or nickel; or spot-weld some easier-to-connect metal tab to the terminals. ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
Bill Dube via EV wrote: Did you lightly sand (or Scotchbite) each terminal and apply a thin coating of NoAlOx before connecting? No? Then you have to redo all the connections. They will give you no end of grief. (Ask me how I know. :-) ) If you don't do this connection treatment, the dissimilar metals will corrode, over heat, and behave badly in general. Often, the cell terminals arrive with a lot of corrosion formed during shipping. Bill has it right! I've had Thundersky, CALB, and GBS cells, and *all of them have at least one aluminum terminal. It is devilishly difficult to make reliable low-resistance connections to aluminum. I've even wondered if there is some way to plate them with copper or nickel; or spot-weld some easier-to-connect metal tab to the terminals. -- It is vanity to do with more that which can be done with less. -- William of Ockham -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
You are aware that 3.00V resting is considered dead right? Also, the 3C current rating is very optimistic. Drawing 216A for more than a few seconds is not good for life. Even drawing 1C (72A) on a continuous basis will lead to a short life. Since you are running a low voltage pack, I'm guessing you are drawing relatively high current. Low voltage packs should use at least 100Ah cells and preferably 180Ah cells or higher. Al On 2/5/2018 10:20 PM, rash via EV wrote: Hello, I recently upgraded my lead-acid EV conversion to lithium, specifically 46 CALB 72Ah cells. I've been conservative in my bms settings, not allowing any cell to go above 3.55V or below 2.6V (hopefully "conservative" limits with calb-published limits of 3.65 and 2.5 ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
Thanks for the suggestions - I've definitely got some things to try - I'm running a cycle on the suspect cell on the PowerLab8 tonight; will do a "good" cell after that. I also need to redo the connections, as Bill suggested. I'll report back in a while after I know more; thanks again! -- Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com/ ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
Did you lightly sand (or Scotchbite) each terminal and apply a thin coating of NoAlOx before connecting? No? Then you have to redo all the connections. They will give you no end of grief. (Ask me how I know. :-) ) If you don't do this connection treatment, the dissimilar metals will corrode, over heat, and behave badly in general. Often, the cell terminals arrive with a lot of corrosion formed during shipping. Bill D. On 2/5/2018 8:34 PM, Cor van de Water via EV wrote: Philip, Another problem may be a bad connection between the cells, so that a cell voltage is seen including the drop in the wire. But yeah, you can have a bad cell as well, a quick way to check is to watch what the BMS says during driving - does the bad cell also drop quickly? Another way to check if the BMS or the cell is a problem is to swap two cells and re-connect the wires and BMS in the same way so the cell is in a different spot according the BMS. Success! Cor. -Original Message- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of rash via EV Sent: Monday, February 05, 2018 7:21 PM To: ev@lists.evdl.org Cc: rash Subject: [EVDL] suspicious of a bad calb cell? Hello, I recently upgraded my lead-acid EV conversion to lithium, specifically 46 CALB 72Ah cells. I've been conservative in my bms settings, not allowing any cell to go above 3.55V or below 2.6V (hopefully "conservative" limits with calb-published limits of 3.65 and 2.5 respectively). I took care when I got the batteries to balance them; I've also been careful to not charge when the temp is below 0C. I've been driving with them for about a month now and have been really happy with the results so far (especially after shedding over a kilopound of battery weight!) But just this week I've become suspicious of one particular cell: now during charging its voltage rises significantly faster than the other cells, and of course once it reaches 3.55V, my charger pauses/ turns off, meaning the other cells don't get as much charge as intended. Then all the cells find a "resting voltage" nearly equal to each other (including the suspect cell). But of course once charging resumes, the one cell still rises faster than the rest. Today I've had some luck turning down the current on the charger enough so that the shunting in the BMS can (mostly) keep up, allowing the remaining cells to charge. (Though this means of course that charging is taking much longer.) Is this a sign I got a bad cell? I also have a PowerLab8 (that I haven't used in a long time), so I may experiment with it when I get some time later in the week... These cells should still be under warranty, so I can explore that route, but thought I'd get some feedback here first; thanks! Philip Rash http://www.evalbum.com/3381 -- Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com/ ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at 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 Please discuss EV drag racing at 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 Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
I would individually test the suspect cell's actual amp-hour capacity, and compare it with factory specs, AND also compare it witth with the actual capacity of one or more other cells in your battery. If it's substantially lower than either, I'd say a warranty claim is justified. Good luck! David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] suspicious of a bad calb cell?
Philip, Another problem may be a bad connection between the cells, so that a cell voltage is seen including the drop in the wire. But yeah, you can have a bad cell as well, a quick way to check is to watch what the BMS says during driving - does the bad cell also drop quickly? Another way to check if the BMS or the cell is a problem is to swap two cells and re-connect the wires and BMS in the same way so the cell is in a different spot according the BMS. Success! Cor. -Original Message- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of rash via EV Sent: Monday, February 05, 2018 7:21 PM To: ev@lists.evdl.org Cc: rash Subject: [EVDL] suspicious of a bad calb cell? Hello, I recently upgraded my lead-acid EV conversion to lithium, specifically 46 CALB 72Ah cells. I've been conservative in my bms settings, not allowing any cell to go above 3.55V or below 2.6V (hopefully "conservative" limits with calb-published limits of 3.65 and 2.5 respectively). I took care when I got the batteries to balance them; I've also been careful to not charge when the temp is below 0C. I've been driving with them for about a month now and have been really happy with the results so far (especially after shedding over a kilopound of battery weight!) But just this week I've become suspicious of one particular cell: now during charging its voltage rises significantly faster than the other cells, and of course once it reaches 3.55V, my charger pauses/ turns off, meaning the other cells don't get as much charge as intended. Then all the cells find a "resting voltage" nearly equal to each other (including the suspect cell). But of course once charging resumes, the one cell still rises faster than the rest. Today I've had some luck turning down the current on the charger enough so that the shunting in the BMS can (mostly) keep up, allowing the remaining cells to charge. (Though this means of course that charging is taking much longer.) Is this a sign I got a bad cell? I also have a PowerLab8 (that I haven't used in a long time), so I may experiment with it when I get some time later in the week... These cells should still be under warranty, so I can explore that route, but thought I'd get some feedback here first; thanks! Philip Rash http://www.evalbum.com/3381 -- Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com/ ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at 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 Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
