Re: [EVDL] Lead GC battery capacity
Well, I'd go by the test data, though there will be some variability in results. May also be some variability in what different websites give for the 20 and 5 hr rates. -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Lead-GC-battery-capacity-tp4676904p4676981.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. ___ 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)
Re: [EVDL] Lead GC battery capacity
tomw via EV wrote: I used the standard method of applying the Peukert equation to calculate the exponent based on the manufacturers published 20hr and 5hr rates for the Trojans. If the 20hr rate is A, the 5 hr rate is B, the capacity at rate A is CA, and the capacity at rate B is CB then: exponent = [log (B/A)/log (CA/A)] - log (CB/B) Which gives these exponents: T145: 1.159 T125: 1.176 T105: 1.164 T1275: 1.192 T890: 1.172 OK; that's the correct way to figure it (given the manufacturer's data). I've just found the numbers to be a little higher from my own tests. I measured the Trojan T105 at 1.18, and the Sam's Club at 1.21, for example. -- A truly excellent politician will tell you everything you want to hear. A truly excellent engineer will tell you the truth. -- D.C. Weber -- 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Lead GC battery capacity
I used the standard method of applying the Peukert equation to calculate the exponent based on the manufacturers published 20hr and 5hr rates for the Trojans. If the 20hr rate is A, the 5 hr rate is B, the capacity at rate A is CA, and the capacity at rate B is CB then: exponent = [log (B/A)/log (CA/A)] - log (CB/B) Which gives these exponents: T145: 1.159 T125: 1.176 T105: 1.164 T1275: 1.192 T890: 1.172 -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Lead-GC-battery-capacity-tp4676904p4676971.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. ___ 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)
Re: [EVDL] Lead GC battery capacity
tomw via EV wrote: I did a graph of gc battery capacity versus discharge current using the Peukert equation a number of years ago using the 20 hr and 10 or 5 hr rates. It gave these capacities at 100A discharge current: T145 (6V, 260Ah): 188Ah T125 (6V, 240Ah): 165Ah T105 (6V, 225Ah): 164Ah T1275 (12V, 150Ah): 91Ah T890 (8V, 190Ah): 127Ah Seems a little high. What did you use for the Peukert exponent? For golf cart batteries, it's usually somewhere around 1.2. -- A truly excellent politician will tell you everything you want to hear. A truly excellent engineer will tell you the truth. -- D.C. Weber -- 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Lead GC battery capacity
I did a graph of gc battery capacity versus discharge current using the Peukert equation a number of years ago using the 20 hr and 10 or 5 hr rates. It gave these capacities at 100A discharge current: T145 (6V, 260Ah): 188Ah T125 (6V, 240Ah): 165Ah T105 (6V, 225Ah): 164Ah T1275 (12V, 150Ah): 91Ah T890 (8V, 190Ah): 127Ah -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Lead-GC-battery-capacity-tp4676904p4676969.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. ___ 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)
Re: [EVDL] Lead GC battery capacity
On 28 Jul 2015 at 6:30, Willie2 via EV wrote: The longevity of ebike batteries is a BIG unknown here. One thing to watch out for is that (according to what I read on Endless Sphere) some of the really cheap Chinese bike batteries are made with recycled (used) laptop cells. I don't know how you'd check for that, though. The other issue is the quality and reliability of the BMS. 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Lead GC battery capacity
You're comparing apples and oranges. - six T105s would be about $900. - 12 TS-LPF100s: about $1500 + $300 BMS - five 20ah ebike batteries @ $285. Total: $1425. - Experience... indicates two 20ah ebike batteries can do ($570.) Then also instead of six Trojans, 3 deep cycle 12v Lead batteries at a cost of $300 will also do the job. Bob ___ 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)
Re: [EVDL] Lead GC battery capacity
On 07/27/2015 06:08 PM, Lee Hart via EV wrote: Willie2 via EV wrote: Thanks! Bottom line, take away: 50-90 ah on a fresh lead pack. It's not quite that bad. The Peukert effect does not change the ACTUAL capacity; it only describes the APPARENT capacity due to high currents. If you have a 200ah battery and discharge it at 100 amps so it appears dead after removing 100ah, it is in fact at the 50% discharged point. That's a safe discharge level -- you can do that every day for 600+ cycles. The other 100ah is still there -- you just can't use it with a 100 amp draw. If you draw a lower current, then it will be there. :-) Somewhat against my will, I just did some lead battery shopping. T105s are about $150. The minutes at 75 amps rating seems most appropriate. That would be just under 100 ah. From what you say, it appears those are usable amphours. SAMs batteries, with presumably less capacity and longevity, are about $90. So, a pack of six T105s would be about $900. Negatives: corrosion, watering, lower performance as SOC decreases, perhaps 1/3 the life of lithium, all or nothing major replacement. Compare to 12 TS-LPF100s: about $1500 plus about $300 worth of BMS stuff. Negative: nightmare of wiring maintenance, all or nothing major replacement. Compare to 5 20ah ebike batteries @ $285. Total: $1425. Experience so far indicates as few as 2 20ah ebike batteries can be used at a cost of $570. The longevity of ebike batteries is a BIG unknown here. I believe it is likely that the above can be scaled to larger vehicles. If the golf cart projects are successful, I will be exploring higher voltages and capacities on larger vehicles. The same 50% capacity limit applies to lithiums, too. If you discharge them to 80-100% on every cycle, you won't get as long a life. (How long the life will be depends drastically on the type and quality of the cells). I will not accept the contention that lithium batteries should be limited to 50%. ___ 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)
Re: [EVDL] Lead GC battery capacity
On 07/28/2015 06:30 AM, Willie2 wrote: Compare to 5 20ah ebike batteries @ $285. Total: $1425. Experience so far indicates as few as 2 20ah ebike batteries can be used at a cost of $570. Just checked Ping batteries, with an established good reputation: http://www.pingbattery.com/servlet/the-10/36V-20AH-LiFePO4-lithium/Detail $627 for 20ah. $3135 for five. ___ 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)
Re: [EVDL] Lead GC battery capacity
Willie2 via EV wrote: Somewhat against my will, I just did some lead battery shopping. T105s are about $150. The minutes at 75 amps rating seems most appropriate. That would be just under 100 ah. From what you say, it appears those are usable amphours. SAMs batteries, with presumably less capacity and longevity, are about $90. So, a pack of six T105s would be about $900. So the T105 is $150/(6v x 75a x 1.75hr) = $0.19/wh. The Sam's Club is $80/(6v x 75a x 1.75hr) = $0.10/wh. Negatives: corrosion, watering, lower performance as SOC decreases, perhaps 1/3 the life of lithium, all or nothing major replacement. Life would be about 800 cycles for the Trojans, and about half that for the Sam's Club batteries (with a 75a load, discharged to 1.75v/cell, barring any abuse from over-charging, over-discharging, or incorrect watering). I'm not sure what your all or nothing replacement means. You can replace individual batteries if they fail early. Compare to 12 TS-LPF100s: about $1500 plus about $300 worth of BMS stuff. $1800/(12 x 3.2v x 100ah) = $0.47/wh. About 2.5 times the cost/watthour of the Trojans, or 5 times the price of the Sam's Club. They would have to last 2.5-5 times longer to reach the same cost/mile. I used 100ah; but I doubt you can get even 75ah out of them with a 75a load before the voltage falls under 2.5v/cell. I don't know how these particular Thunderskys would test; but the older 90ah Thunderskys I tested had significantly higher internal resistance than 6v golf cart batteries. They weren't good for 75a continuous / 500a peaks; but more like 25a continuous / 100a peaks. Negative: nightmare of wiring maintenance, all or nothing major replacement. If you have a good BMS you should be able to replace individual cells. Whether the BMS wiring is a nightmare depends on the situation. Compare to 5 20ah ebike batteries @ $285. Total: $1425. Experience so far indicates as few as 2 20ah ebike batteries can be used at a cost of $570. $1425/(5 x 36v x 20ah) = $0.40/wh. That's barely any cheaper than the Thunderskys. The longevity of ebike batteries is a BIG unknown here. Yes; you'd have to test to know for sure. I believe it is likely that the above can be scaled to larger vehicles. If the golf cart projects are successful, I will be exploring higher voltages and capacities on larger vehicles. One unknown is the internal resistance of these small cell packs. Some may be good; some horrible. Ebikes don't draw much current, but a golf cart does! I will not accept the contention that lithium batteries should be limited to 50%. OK; so that's your hypothesis. Now do the testing, and see if it's correct. As you say, these Ebike batteries aren't all that expensive. Buy one, and rig up a life tester. It would: - Discharge the battery with a load representative of what your actual load will be, until it reaches your desired dead cutoff voltage. - For lead-acids, 1.75v per cell under load is usually used. - For lithiums, there are no standards. Try 2.5v/cell as the cutoff. Or go lower if you think life won't be reduced by deeper discharges. - Charge the battery to whatever fully-charged criteria you expect to use in your application. - For lead-acids, full is typically when the current falls to 4% of its amphour rating at 2.5v/cell. - For lithiums, again there are no standards. Maybe use the free charger/BMS that comes with the Ping cells? Or for LiFePO4 cells, try 3.7v until the current falls under 4% of its rated AC capacity. - Let it cycle, until the capacity falls to some reasonable fraction of its original capacity. - For lead-acid, 80% of original capacity is usually used. You can obviously use them longer; but without a BMS, the capacity usually falls fast once some cell starts getting weak. - For lithiums, you can use the same 80% limit, or keep testing to see what happens if you use them longer. -- A truly excellent politician will tell you everything you want to hear. A truly excellent engineer will tell you the truth. -- D.C. Weber -- 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Lead GC battery capacity
You're comparing apples and oranges. Well, Robert, how so? I presented three golf cart packs, each offering about 100ah of usable capacity. Where did I go astray? The apples were 100 Ah comparisons. Then you changed to 40 Ah oranges, without going back and putting the apples on the same 40 Ah basis. - six T105s would be about $900. - 12 TS-LPF100s: about $1500 + $300 BMS - five 20ah ebike batteries @ $285. Total: $1425. - Experience... indicates two 20ah ebike batteries can do ($570.) Then also instead of six Trojans, 3 deep cycle 12v Lead batteries at a cost of $300 will also do the job. Will 3 12v supply 100ah? I would guess not. No, but three would provide 40 Ah which is what I thought was the comparison... Bob ___ 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)
Re: [EVDL] Lead GC battery capacity
On 07/28/2015 12:00 PM, Lee Hart via EV wrote: So the T105 is $150/(6v x 75a x 1.75hr) = $0.19/wh. The Sam's Club is $80/(6v x 75a x 1.75hr) = $0.10/wh. I didn't check SAMs' battery claims. I had assumed less capacity than T105s. I'm not sure what your all or nothing replacement means. You can replace individual batteries if they fail early. It is pretty tedious to identify and change either a single lithium cell or a lead battery. Also, if you have a bad lead battery or lithium cell, you are likely to be near the end of it's mates. I am impressed by how easy it is to add or replace ebike batteries. It is mainly a matter of dealing with parallel rather than serial connections. With serial, you break your pack to repair and you are down until you are finished with your repair. You must have an entire working pack to be functional. With parallel, you can likely make do with a single bad battery and do the replacement much faster. Plug and un-plug SB50s or similar. Compare to 12 TS-LPF100s: about $1500 plus about $300 worth of BMS stuff. $1800/(12 x 3.2v x 100ah) = $0.47/wh. About 2.5 times the cost/watthour of the Trojans, or 5 times the price of the Sam's Club. They would have to last 2.5-5 times longer to reach the same cost/mile. I used 100ah; but I doubt you can get even 75ah out of them with a 75a load before the voltage falls under 2.5v/cell. I don't know how these particular Thunderskys would test; but the older 90ah Thunderskys I tested had significantly higher internal resistance than 6v golf cart batteries. They weren't good for 75a continuous / 500a peaks; but more like 25a continuous / 100a peaks. I think you will find that more modern TSs are good for at least 2C. Negative: nightmare of wiring maintenance, all or nothing major replacement. If you have a good BMS you should be able to replace individual cells. Whether the BMS wiring is a nightmare depends on the situation. I've been dealing with TS-LFP packs with miniBMS modules for many years. I judge the whole thing to be a nightmare compared to the integrated BMS/protection of an ebike battery. $1425/(5 x 36v x 20ah) = $0.40/wh. That's barely any cheaper than the Thunderskys. The ebike batteries include integrated BMS/protection. Therefore, have the possibility of being far more reliable/maintainable. One unknown is the internal resistance of these small cell packs. Some may be good; some horrible. Ebikes don't draw much current, but a golf cart does! The 20ah ebike batteries are SUPPOSED to be good for 30 amps. I expected to need to use 3-5 in parallel. I was surprised to discover a golf cart seems to run fine with 2. With the 12xTS-LFP100 pack, I've observed a maximum 100-120 amps with non-alarming voltage sag. As mentioned, I do not yet have an amphour counter on a ebike battery golf cart. I will not accept the contention that lithium batteries should be limited to 50%. OK; so that's your hypothesis. Now do the testing, and see if it's correct. That is outside my job description. If you wish to test, I am willing to send you an ebike battery and one or two semi-good TS-LFP100s and/or TS-LFP260s. ___ 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)
Re: [EVDL] Lead GC battery capacity
On 07/28/2015 07:41 AM, Robert Bruninga via EV wrote: You're comparing apples and oranges. Well, Robert, how so? I presented three golf cart packs, each offering about 100ah of usable capacity. Where did I go astray? - six T105s would be about $900. - 12 TS-LPF100s: about $1500 + $300 BMS - five 20ah ebike batteries @ $285. Total: $1425. - Experience... indicates two 20ah ebike batteries can do ($570.) Then also instead of six Trojans, 3 deep cycle 12v Lead batteries at a cost of $300 will also do the job. Will 3 12v supply 100ah? I would guess not. ___ 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)
Re: [EVDL] Lead GC battery capacity
The following data is from my inverter manual for my inverter that is use at a remote cabin here in Montana which uses the old EV battery from my EV which ran 8.5 years in the EV and another 10 years at the cabin. The T-105's 200 AH battery has a usable AH of 100 AH at 50% SOC at the 20 hour rating or 200 AH / 20 hrs = 10 amps. 50% SOC = 200 AH/2 = 100 AH. We normally do not drive a EV at battery ampere of 10 amps unless it a bike which has two 20 ah 12 volt batteries in my bike. They were on twenty something dollars for them. The Reserved Minutes of the T-105's is listed at 115 RS @ 75 Amps, therefore: The Formula: 115 Reserved Minutes / 60 minutes = 1.916 hours 75 amps x 1.916 hrs = 143.7 ah 50% SOC = 143.7 / 2 = 71.35 ah When I was using these batteries back in the 80's with a battery pack voltage of 216 volts, my EV would use about 3 ah per mile using about 70 ah. Roland - Original Message - From: Lee Hart via EVmailto:ev@lists.evdl.org To: Electric Vehicle Discussion Listmailto:ev@lists.evdl.org Sent: Tuesday, July 28, 2015 11:00 AM Subject: Re: [EVDL] Lead GC battery capacity Willie2 via EV wrote: Somewhat against my will, I just did some lead battery shopping. T105s are about $150. The minutes at 75 amps rating seems most appropriate. That would be just under 100 ah. From what you say, it appears those are usable amphours. SAMs batteries, with presumably less capacity and longevity, are about $90. So, a pack of six T105s would be about $900. So the T105 is $150/(6v x 75a x 1.75hr) = $0.19/wh. The Sam's Club is $80/(6v x 75a x 1.75hr) = $0.10/wh. Negatives: corrosion, watering, lower performance as SOC decreases, perhaps 1/3 the life of lithium, all or nothing major replacement. Life would be about 800 cycles for the Trojans, and about half that for the Sam's Club batteries (with a 75a load, discharged to 1.75v/cell, barring any abuse from over-charging, over-discharging, or incorrect watering). I'm not sure what your all or nothing replacement means. You can replace individual batteries if they fail early. Compare to 12 TS-LPF100s: about $1500 plus about $300 worth of BMS stuff. $1800/(12 x 3.2v x 100ah) = $0.47/wh. About 2.5 times the cost/watthour of the Trojans, or 5 times the price of the Sam's Club. They would have to last 2.5-5 times longer to reach the same cost/mile. I used 100ah; but I doubt you can get even 75ah out of them with a 75a load before the voltage falls under 2.5v/cell. I don't know how these particular Thunderskys would test; but the older 90ah Thunderskys I tested had significantly higher internal resistance than 6v golf cart batteries. They weren't good for 75a continuous / 500a peaks; but more like 25a continuous / 100a peaks. Negative: nightmare of wiring maintenance, all or nothing major replacement. If you have a good BMS you should be able to replace individual cells. Whether the BMS wiring is a nightmare depends on the situation. Compare to 5 20ah ebike batteries @ $285. Total: $1425. Experience so far indicates as few as 2 20ah ebike batteries can be used at a cost of $570. $1425/(5 x 36v x 20ah) = $0.40/wh. That's barely any cheaper than the Thunderskys. The longevity of ebike batteries is a BIG unknown here. Yes; you'd have to test to know for sure. I believe it is likely that the above can be scaled to larger vehicles. If the golf cart projects are successful, I will be exploring higher voltages and capacities on larger vehicles. One unknown is the internal resistance of these small cell packs. Some may be good; some horrible. Ebikes don't draw much current, but a golf cart does! I will not accept the contention that lithium batteries should be limited to 50%. OK; so that's your hypothesis. Now do the testing, and see if it's correct. As you say, these Ebike batteries aren't all that expensive. Buy one, and rig up a life tester. It would: - Discharge the battery with a load representative of what your actual load will be, until it reaches your desired dead cutoff voltage. - For lead-acids, 1.75v per cell under load is usually used. - For lithiums, there are no standards. Try 2.5v/cell as the cutoff. Or go lower if you think life won't be reduced by deeper discharges. - Charge the battery to whatever fully-charged criteria you expect to use in your application. - For lead-acids, full is typically when the current falls to 4% of its amphour rating at 2.5v/cell. - For lithiums, again there are no standards. Maybe use the free charger/BMS that comes with the Ping cells? Or for LiFePO4 cells, try 3.7v until the current falls under 4% of its rated AC capacity. - Let it cycle, until the capacity falls to some reasonable fraction of its original capacity. - For lead-acid, 80% of original
Re: [EVDL] Lead GC battery capacity
Willie2 via EV wrote: Thanks! Bottom line, take away: 50-90 ah on a fresh lead pack. It's not quite that bad. The Peukert effect does not change the ACTUAL capacity; it only describes the APPARENT capacity due to high currents. If you have a 200ah battery and discharge it at 100 amps so it appears dead after removing 100ah, it is in fact at the 50% discharged point. That's a safe discharge level -- you can do that every day for 600+ cycles. The other 100ah is still there -- you just can't use it with a 100 amp draw. If you draw a lower current, then it will be there. :-) That pretty well matches my gut feel that my 40ah of ebike batteries is around half of a good lead pack. I believe, in general, 80% or more of a lithium pack can be used. The same 50% capacity limit applies to lithiums, too. If you discharge them to 80-100% on every cycle, you won't get as long a life. (How long the life will be depends drastically on the type and quality of the cells). I recall that using lead, you got very little time with good performance since the voltage declines ~linearly. With lithium, you can't guess the SOC from performance; the carts are sprightly most of the time. It is indeed tricky to compare the two. Lead-acids have an internal resistance that is often lower when fully charged; but it goes up as they discharge. In a high-amp application, you can't use more than maybe half their rated amphour capacity. Lithium internal resistance doesn't change until they are almost dead. This is good for high-amp loads -- you can get more of the rated capacity. *But*, nothing is free -- you also get less than rated life due to the high currents and deeper discharges. -- Pollution is nothing but the resources we are not harvesting. We allow them to disperse because we've been ignorant of their value. -- R. Buckminster Fuller -- 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] Lead GC battery capacity
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 If you are using GC2 style 6 volt golf cart batteries, they are usually rated in minutes of 75 amp draw (Mine are 107 minutes). They are rated at 208 AH (if you draw them down over 20 hourswhich is unrealistic) and can probably deliver 110 or so AH when used at high amperages. My S10 pickup truck will regularly draw 300 amps while accelerating from a stop (for short periods of time) and average 75 amps just driving down the level road. They have lasted me 2-3 years at a time with this type of use/abuse on almost a daily basis. So if you never pulled more than 100 ah from them, I think they would live for more than 3 years, especially if you were not using them every day. Jay On 07/25/2015 09:11 PM, Willie2 via EV wrote: Continuing to cogitate on ebike batteries: can anyone give me a good estimate of the number of ah one can pull from a lead golf cart battery? I'm thinking my 2 20ah ebike batteries are a pretty good fraction of a lead pack. Can you keep a lead GC battery alive if you pull 100ah from it? ___ 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) -BEGIN PGP SIGNATURE- Version: GnuPG v1 iEYEARECAAYFAlWz7/UACgkQSWJjSgPNbM+K3wCfZK0PxVbUQhrN7B8/9C10grGR 9eAAoIb74fdGVA+og9iVQqN4vBjomH5m =LRGj -END PGP SIGNATURE- ___ 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)
Re: [EVDL] Lead GC battery capacity
Golf Cart batteries are not very well defined, there is quite a spread in capacity with quality and price as well. I have pretty good ones and IIRC they are spec'ed at 260 Ah in a 20-hour discharge (13A continuous) but in typical EV (truck) driving practice, I am happy if I get more than about 100Ah in half an hour discharge since I draw about 200A continuous while driving on the Freeway. So, specify your discharge rate and Peukert will tell you how much you can expect... Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.comPrivate: http://www.cvandewater.info Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626Tel: +91 (040)23117400 x203 -Original Message- From: EV on behalf of Willie2 via EV Sent: Sat 7/25/2015 12:11 PM To: Electric Vehicle Discussion List Subject: [EVDL] Lead GC battery capacity Continuing to cogitate on ebike batteries: can anyone give me a good estimate of the number of ah one can pull from a lead golf cart battery? I'm thinking my 2 20ah ebike batteries are a pretty good fraction of a lead pack. Can you keep a lead GC battery alive if you pull 100ah from it? ___ 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) -- next part -- A non-text attachment was scrubbed... Name: not available Type: application/ms-tnef Size: 3240 bytes Desc: not available URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150725/bfb08b60/attachment.bin ___ 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)
Re: [EVDL] Lead GC battery capacity
On 07/25/2015 03:25 PM, Lee Hart wrote: From: Willie2 via EV ev@lists.evdl.org Continuing to cogitate on ebike batteries: can anyone give me a good estimate of the number of ah one can pull from a lead golf cart battery? I'm thinking my 2 20ah ebike batteries are a pretty good fraction of a lead pack. Can you keep a lead GC battery alive if you pull 100ah from it? 6v golf cart batteries are generally 220-240 amphours at the 20-hour rate (about 5 amps), and 100-180 amphours at the 100-amp rate. (The change in amphour capacity depending on current is the Peukert effect that people talk about.) Golf cart batteries are designed for continuous loads of 75 amps, and will happily supply 200-500 amps peak for up to a minute. But life will suffer if you draw high currents for more than a minute or so. For best life, you also want to limit depth of discharge to about 50% or so. This is true for most types of batteries; not just lead-acids. The deeper the discharge, the worse the life. Thanks! Bottom line, take away: 50-90 ah on a fresh lead pack. That pretty well matches my gut feel that my 40ah of ebike batteries is around half of a good lead pack. I believe, in general, 80% or more of a lithium pack can be used. I'm working on my second golf cart ebike conversion. Just took out the 12 100ah ThunderSkys. When they were functional, I judged they had more capacity than the best lead I have used. They weigh about 100 pounds. The 20 ah ebike batteries are supposed to weigh right at 10 pounds each. The ebike batteries appear to have greater energy density than the TS-LFPs though I don't think they can have twice the density of LFP. I recall that using lead, you got very little time with good performance since the voltage declines ~linearly. With lithium, you can't guess the SOC from performance; the carts are sprightly most of the time. I'm eager to get a meter working so I can measure capacity. ___ 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)
Re: [EVDL] Lead GC battery capacity
From: Willie2 via EV ev@lists.evdl.org Continuing to cogitate on ebike batteries: can anyone give me a good estimate of the number of ah one can pull from a lead golf cart battery? I'm thinking my 2 20ah ebike batteries are a pretty good fraction of a lead pack. Can you keep a lead GC battery alive if you pull 100ah from it? 6v golf cart batteries are generally 220-240 amphours at the 20-hour rate (about 5 amps), and 100-180 amphours at the 100-amp rate. (The change in amphour capacity depending on current is the Peukert effect that people talk about.) Golf cart batteries are designed for continuous loads of 75 amps, and will happily supply 200-500 amps peak for up to a minute. But life will suffer if you draw high currents for more than a minute or so. For best life, you also want to limit depth of discharge to about 50% or so. This is true for most types of batteries; not just lead-acids. The deeper the discharge, the worse the life. -- Excellence does not require perfection. -- Henry James -- Lee A. Hart http://www.sunrise-ev.com/controllers.htm now includes the GE EV-1 ___ 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)
Re: [EVDL] Lead GC battery capacity
On 25 Jul 2015 at 14:11, Willie2 via EV wrote: can anyone give me a good estimate of the number of ah one can pull from a lead golf cart battery? It depends on current, but usually the reserve capacity is a good rough estimate in normal golf car use. For example, a T105 type battery with a 115 minute RC will deliver about 115ah. Here is how this works. At the standard RC current of 75 amps, 115 minutes is 1.92 hours. Then 1.92h * 75a == about 144 amp-hours. Then take 80% of that for decent cycle life, or about 115ah. With your bike packs, the golf car will be much lighter, and therefore will use less energy per unit of distance. This will partly offset the lower battery capacity, though 40ah (32ah at 80%) is a long way from 115ah. If you're using LiFePO4, its voltage curve stays high longer than lead's, so your golf car will seem peppier right up to the point where you should have stopped discharging it already. As I'm sure you know, taking it right down to where the protector cuts off is not recommended for long cycle life. I have 24v (actually 25.6v nominal) and 36v (38.4v) LiFePO4 batteries by Ping. I have never hit the overdischarge protection. I stop using the 24v when they hit 21 volts (about 2.6 vpc) under load, and the 36v when they fall to 31v under load. Or, when I've used 80% of their rated capacity, whichever comes first. 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 For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
