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Myers Motors NMG 2007 # 6 Yellow

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  • bschmid8721
    This is my first post to the group. I have NMG 2007 # 6. I have used it in almost all my daily commuting for 2 1/2 years, except when ice or snow is on the
    Message 1 of 4 , Mar 6, 2010
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      This is my first post to the group. I have NMG 2007 # 6. I have used it in almost all my daily commuting for 2 1/2 years, except when ice or snow is on the roads. I have 8500 miles driven in that time. I have opportunities to charge at my stops at work, so seldom stress the batteries below 65% state of charge.
      Recently I had a sudden loss of power, which came back on when I turned the switch on again. It hapened many times in a short trip, so I knew something wasn't right. After driving home slowly and checking the batteries, I found two were quite low, 11.5 volts, and several slightly low. I put a load tester on them and also this showed they were no longer good batteries. So I resigned myself that I have to replace all the batteries. I wonder if 8500 miles and 2 1/2 years is about average for battery pack life? I was somewhat disappointed with this battery life, as I previously had a converted Ford Escort with 18 six-volt flooded lead-acid batteries, and with meticulous care they gave me about 15000 miles and 3 1/2 or 4 years of life. I realize the Optima batteries are probably more "touchy" than the flooded lead acid batteries.
      So now I have to decide if I want to tackle the job of replacing the pack. I don't need more range, so upgrading to lithium ion would not be necessary for me at present.
      Any comments about other's experience with mileage on a set of batteries would be welcome.
      Thank you.
      Ben Schmid
    • John G. Lussmyer
      ... From my experiences with a Sparrow, that is actually pretty good. Have you tried individually charging the low batteries? Sparrow packs tend to get
      Message 2 of 4 , Mar 7, 2010
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        On 3/6/2010 7:02 PM, bschmid8721 wrote:
        > Recently I had a sudden loss of power, which came back on when I turned the switch on again. It hapened many times in a short trip, so I knew something wasn't right. After driving home slowly and checking the batteries, I found two were quite low, 11.5 volts, and several slightly low. I put a load tester on them and also this showed they were no longer good batteries. So I resigned myself that I have to replace all the batteries. I wonder if 8500 miles and 2 1/2 years is about average for battery pack life? I was somewhat disappointed with this battery life, as I previously had a converted Ford Escort with 18 six-volt flooded lead-acid batteries, and with meticulous care they gave me about 15000 miles and 3 1/2 or 4 years of life. I realize the Optima batteries are probably more "touchy" than the flooded lead acid batteries.
        >

        From my experiences with a Sparrow, that is actually pretty good.
        Have you tried individually charging the low batteries? Sparrow packs
        tend to get unbalanced over time.

        --
        --
        John G. Lussmyer mailto:Cougar@...
        Electric Vehicle Battery Monitoring Systems, http://www.CasaDelGato.com
      • Eino Lindfors
        Hi Ben, Based on driving my sparrow about 27000 miles now over more than 5 years, I would say that a battery gets weak every 3 to 4 months, even if they are
        Message 3 of 4 , Mar 7, 2010
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          Hi Ben,

          Based on driving my sparrow about 27000 miles now over more than 5 years, I would say that a battery gets weak every 3 to 4 months, even if they are new. My sparrow runs a V10 Zivan charger, and I use PowerPulse units on them (one across a 4 battery group, and the other 3 across a 3 battery group). I use a homebrew microcontroller on each battery with an isolated I2C bus. It measures negative terminal temperature and records battery voltage each second. I believe that the monitoring is necessary. I think many sparrow owners are driving around with weak or dying batteries and they do not know it. With my monitoring circuit, I can change out the weak one before it fails. My main concern is once a cell goes really weak in an optima, I think it will generate a lot of heat and can explain some of the battery fires that have occurred. I cannot say how long a pack lasts, since I have changed out batteries so often. Again, I would estimate 4 batteries have to be replaced each year. Since I change them out early, I can sell them as used starting batteries. I use my sparrow regularly for a 15 mile each way commute. I also charge it at both ends of the commute.

          General recomendations:

          Always recharge the batteries after a drive. Do not let the batteries sit discharged for long. Use the latest V10 chip on the charger. Add desulphators (ie- PowerPulse). I do not know if dissipative balancers will help, since I have not used them. My next project is to finish adding the cooling/heating system to maintain the battery temperatures around ambient. I think most of the damage occurs during summer when the battery temperatures go above 50C.

          Eino #233

          [Non-text portions of this message have been removed]
        • Jacob Oshins
          Ben, as the others have said, you’re actually doing quite well. Optima batteries, or almost any other AGM battery for that matter, are much more fragile
          Message 4 of 4 , Mar 7, 2010
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            Ben, as the others have said, you’re actually doing quite well. Optima
            batteries, or almost any other AGM battery for that matter, are much more
            fragile than flooded lead-acid batteries.



            Anecdotally, I think that most Sparrow owners see less than 3000 miles per
            pack, due to a combination of issues; over-charging with old charger
            profiles, over-discharging – particularly when “you just need to get home”
            from a trip that was a little too far, letting the batteries sit for long
            periods and then driving without breaking the pack back in, lack of battery
            management, very warm conditions, very cold conditions, etc.



            I experimented for several years and got my average up to around 9000 miles
            per pack by installing a battery management system and being pretty careful.
            In the end, though, I got fed up with dealing with them and switched to
            lithium.



            Others have switched to more durable lead-acid batteries, either flooded,
            gel, or “silicone.” That’s worked for some of them, but mostly when they
            were happy to give up a lot of freeway-speed power in the trade. My own
            commute involves a lot of long hills on freeways, so I wouldn’t consider
            that.



            The bottom line is that AGM batteries are really good at short bursts of
            really high power and relatively bad at long-term durability.



            - Jake Oshins

            #220





            From: bschmid8721 [mailto:schmidb@...]
            Sent: Saturday, March 06, 2010 7:03 PM
            To: sparrow_ev@yahoogroups.com
            Subject: [sparrow_ev] Myers Motors NMG 2007 # 6 Yellow





            This is my first post to the group. I have NMG 2007 # 6. I have used it in
            almost all my daily commuting for 2 1/2 years, except when ice or snow is on
            the roads. I have 8500 miles driven in that time. I have opportunities to
            charge at my stops at work, so seldom stress the batteries below 65% state
            of charge.
            Recently I had a sudden loss of power, which came back on when I turned the
            switch on again. It hapened many times in a short trip, so I knew something
            wasn't right. After driving home slowly and checking the batteries, I found
            two were quite low, 11.5 volts, and several slightly low. I put a load
            tester on them and also this showed they were no longer good batteries. So I
            resigned myself that I have to replace all the batteries. I wonder if 8500
            miles and 2 1/2 years is about average for battery pack life? I was somewhat
            disappointed with this battery life, as I previously had a converted Ford
            Escort with 18 six-volt flooded lead-acid batteries, and with meticulous
            care they gave me about 15000 miles and 3 1/2 or 4 years of life. I realize
            the Optima batteries are probably more "touchy" than the flooded lead acid
            batteries.
            So now I have to decide if I want to tackle the job of replacing the pack. I
            don't need more range, so upgrading to lithium ion would not be necessary
            for me at present.
            Any comments about other's experience with mileage on a set of batteries
            would be welcome.
            Thank you.
            Ben Schmid





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