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Thread: What lightweight race battery are you using?

  1. #26
    Join Date
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    Z3M, X5M
    Quote Originally Posted by jakermac View Post
    I've had no issues with the charging of my 9.2ah home made 3lb LiFePo using the 80amp Bosch alternator in my 93 325is. Discharging on the other hand has done in a couple of my packs. But that's on me entirely. I found the key to be picking the right model of cell. The A123 cells that I've been using are capable of accepting up to a 10C charge rate. That equates to 23 amps. And since my battery is configured as a 4S4P, that means the pack can take up to a 92amp charge rate.

    And the LiFePo batteries that I've been using get really really pissed off when you overcharge them, and they hiss at you and get hot, but they DON'T catch on fire.
    I'm not knowledgeable on electrical items but do have lipo batteries for an RC car. I have a smart type charger that figures out the battery specs and charges it accordingly. Could this battery be used strictly for track?
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    Last edited by Z-Thrizzle; 06-05-2019 at 03:35 PM.
    -Phil

  2. #27
    Join Date
    Aug 2009
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    CA
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    E36
    For anyone looking for a good middle of the road battery I have used the Deka ETX18L for years and it has worked great. I could let the car sit for about a month and it would still fire up no problem. If I let it sit for over a month it would crank slow but would still fire up and after a drive it was all charged back up.

    Deka
    ETX18L
    340CCA
    18 lbs
    20AH
    About $90

    Never used the battery below about 30F so if you live somewhere colder it might not work as well.

  3. #28
    Join Date
    Jun 2005
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    Charlotte
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    e46 M3
    Another vote for Deka. I use the ETX14 and have the under-drive pulley on the alternator. Happy with its performance but I am mindful to keep it on a tender. Wouldn't go any smaller myself.

  4. #29
    Join Date
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    E30 M3 Touring Car #10
    I used the Braille 6lb unit in my car when it was M3T. barely adequate. didnt like hot starts, and if t didnt start by the second try, SOL.

    Now I use a 90lb Marine deep cycle battery. I need the weight, so why not have all the power i could ever need? I can warm the car up on the battery for a half hour. I can run a dozen laps at speed on just the battery.

    That siad, I'm loking to rebalance the car now and have acquired a PC680. we'll see how that goes. But a 12:1 S14 race engine with dry sump is a little different than a track/street E36
    2010 BMW Club Racing E30 M3 Touring Car Champion, 2011 and 2013 SCCA National Championship Runoffs 3rd Place, STU, 2011 SCCA Jim Fitzgerald Rookie of the Year, 2012 SCCA Northeast Division STU Champion, 2015 SCCA Runoffs Pole Position Daytona/STU

  5. #30
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    Howell, MI
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    '97 m3/4/5, '95 M3
    Quote Originally Posted by dirtdiggler View Post
    For anyone looking for a good middle of the road battery I have used the Deka ETX18L for years and it has worked great. I could let the car sit for about a month and it would still fire up no problem. If I let it sit for over a month it would crank slow but would still fire up and after a drive it was all charged back up.

    Deka
    ETX18L
    340CCA
    18 lbs
    20AH
    About $90

    Never used the battery below about 30F so if you live somewhere colder it might not work as well.
    That’s what I have in mine. Www.battersharks.com has a Deka equivalent for $60 shipped.

    - - - Updated - - -

    Attachment 653327

  6. #31
    Join Date
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    3 - E30 M3s, '04 Ford F350, '06 Audi A3
    Quote Originally Posted by JS154 View Post
    I used the Braille 6lb unit in my car when it was M3T. barely adequate. didnt like hot starts, and if t didnt start by the second try, SOL.

    Now I use a 90lb Marine deep cycle battery. I need the weight, so why not have all the power i could ever need? I can warm the car up on the battery for a half hour. I can run a dozen laps at speed on just the battery.

    That siad, I'm loking to rebalance the car now and have acquired a PC680. we'll see how that goes. But a 12:1 S14 race engine with dry sump is a little different than a track/street E36
    LOL thats exactly what I put in my car for the one Majors I ran in STU at Pitt Race to make weight, I put my trailer deep cycle battery in there because I needed the weight.

    I usually run a small AGM 20AH wheelchair battery which is similar to the ones you guys are talking about. I think it equals about 230CCA in car terms when put on a tester and weighs around 8-9 lbs.
    I start the my S14 around the paddock with a larger jump battery to assist and just as Eric said I get 2 maybe 3 cracks at it if I need to start without the jump pack.
    My normal class has no minimum weight so I'm looking to save whatever I can.

    I want to try a LiPo battery but I dont know if they are 100% there yet, they are really expensive still in that 20-25AH range, that and the internet lore of them being potential fireballs has given me just enough pause in buying one,
    Last edited by jimmypet; 06-08-2019 at 02:16 AM.
    jimmy p.


    88 E30 M3 Zinnoberot - street
    88 E30 M3 Lachsilber - SCCA SPU
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  7. #32
    Join Date
    Aug 2012
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    Central, MD
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    Quote Originally Posted by jimmypet View Post
    LOL thats exactly what I put in my car for the one Majors I ran in STU at Pitt Race to make weight, I put my trailer deep cycle battery in there because I needed the weight.

    I usually run a small AGM 20AH wheelchair battery which is similar to the ones you guys are talking about. I think it equals about 230CCA in car terms when put on a tester and weighs around 8-9 lbs.
    I start the my S14 around the paddock with a larger jump battery to assist and just as Eric said I get 2 maybe 3 cracks at it if I need to start without the jump pack.
    My normal class has no minimum weight so I'm looking to save whatever I can.

    I want to try a LiPo battery but I dont know if they are 100% there yet, they are really expensive still in that 20-25AH range, that and the internet lore of them being potential fireballs has given me just enough pause in buying one,
    Yea, I burned 2 up. 25% my fault, 75% manufactures fault. (I'm sticking to those numbers. lol)
    The quick story; both were advertised to have internal over charge protection, thermal protection, and undercharge protection. Both were expensive batteries.
    Each had gone into "off" mode, where they turn themselves off at some discharge voltage.
    I followed the poorly written manufacturers instructions on how to wake them up and charge them. Neither would charge, and both went into thermal run away.
    It was a scary moment. One was IN a motorcycle. Unhooking everything does no good. That's why it's called thermal runaway. We quickly rolled the motorcycle out of the garage fully expecting to need to call the fire department when the bike caught fire. It took about 15 minutes for the battery to stop smoking, smelling and melting WHILE COMPLETELY UNHOOKED FROM ANYTHING.
    Same for the 2nd battery, but at least we'd learned our lesson and had it out of the motorcycle when we tried to wake it up and charge it. On both, we used chargers that we're on the manufacturers approved list.

    On followup, 2 problems were obvious.
    1) Due to very poorly written instructions, we were using the wrong procedure to wake up the battery.
    2) The over voltage and/or thermal protections did nothing to protect the battery, or us, or the motorcycle.

    I'm not in the mood to carefully watch the output voltage of my cars rebuilt alternator/regulator to insure it NEVER reaches over-voltage for the battery, or stand 30 feet away while the nasty smell of melting plastic and LiOn battery internals fills the air.

    Obviously, others either have better luck, or manage the batteries better.

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