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Thread: Battery Choices

  1. #11
    Join Date
    Feb 2009
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    NYC
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    5,131

    Default Battery Choices

    For the Odyssey PC680 there are a couple of case options

    http://SRX_PC680_BattHoldDown / Vert..._A3ZlFbTGWAWVF

    or

    http://Odyssey Battery HK-PC680 Hold...bB9TJESE<br />


    If the Earthx is the same size as the PC680 then these cases should work.
    Mike
    2010 Caterham CSR with Cosworth 2.3 Duratec
    2018 Caterham 420R with 2L Duratec 210hp at Donington UK
    1975 BMW CSL Group 4 (restoration finished - track set up time)
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    1992 Ford Escort RS Cosworth WRC (dyno time)
    1990 Range Rover 2 door Classic
    and another project car coming....

  2. #12
    Join Date
    Jun 2013
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    N. California
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    127

  3. #13
    Join Date
    Jan 2020
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    177

    Default

    Quote Originally Posted by KnifeySpoony View Post
    What case do you use for the 680? Is there an aftermarket solution, or do you have to fab it up? I'd like to go with a light battery on my upcoming build but not sure what the best/easiest solution is.
    I'm using an inexpensive case EarthX sells, BB-MU, but there are a lot of choices that fit both the EarthX "E" size and the PC680. In many cases you will wind up shimming with foam supplied with the battery. The ETX680 needs about 3/16" on either side, and I believe that for the PC680 the shimming is front to back to account for the tapered shape of the battery. One thing to be mindful about is some cases allow battery removal only from the top, whereas others also allow removal from the front. The other option is to use one of the hold downs like Croc and Ashyers mention.

    For what it is worth, I personally would not have spent the extra money to save that much weight. I've used lithium batteries in off-road racing motorcycles and for that application the weight savings was important to me, but for me and the Seven the real benefit is (sadly) being able to leave the battery unattended for long periods. I just sold a motorcycle that sat for five years with no tender on the battery and it still cranked.
    Last edited by Pokey; 08-09-2020 at 10:15 AM.
    Greg

  4. #14
    Join Date
    Jan 2020
    Posts
    177

    Default

    Thought it might be helpful to post the dimensions of both the EarthX 'E' size case and the Odyssey PC680 case (information from the respective manufacturers' websites):

    EarthX 'E' 6.5 L x 3.1 W x 6.6 H
    PC680 7.15 L x 3.0 W x 6.65 H

    And the weight:

    EarthX ETX680 - 3.9 lb
    Odyssey PC680 - 15.4 lb

    If I remember correctly, EarthX has at least one other option that would work in this application that weighs less and has a smaller case, but I wanted to stay with a form factor that would allow for using the Odyssey too if needed.
    Greg

  5. #15
    Join Date
    Feb 2010
    Posts
    57

    Default

    Thanks for the feedback and suggestions. LiFePO4 appears to be a bit of a minefield. Despite being known as the safest lithium chemistry, I have seen examples of exploded cells and meltdowns which make me a bit nervous. I'm sure most of this is down to "operator error", but it makes you think.

    I'm trying to stay in the sub-$200 price range, so the Battery Tender/Deltran offering is interesting ($200, 8Ah, 4 lbs). How about Shorai? They have a unit on Amazon for $172 that weighs in at 3lbs and is also approx 8Ah: https://www.amazon.com/Shorai-Lithiu.../dp/B0088JGV2Q

    Also: is there a unified definition of "CCA"? For example, the Odyssey PC680 has a CCA of 170. The Deltran is 480. The Shorai is 315. Given the PC680 is the gold standard for lead acid, should I assume that these LiFePO4 choices are as good at starting in cold temps?

  6. #16
    Join Date
    Aug 2007
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    USA
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    587

    Default

    Quote Originally Posted by Ferrino View Post
    Given the PC680 is the gold standard for lead acid...
    It seems to be the most popular SLA choice, but I have always preferred the PC625 over the PC680.
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    Sean

  7. #17
    Join Date
    Jan 2020
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    177

    Default

    Quote Originally Posted by Ferrino View Post
    Thanks for the feedback and suggestions. LiFePO4 appears to be a bit of a minefield. Despite being known as the safest lithium chemistry, I have seen examples of exploded cells and meltdowns which make me a bit nervous. I'm sure most of this is down to "operator error", but it makes you think.

    I'm trying to stay in the sub-$200 price range, so the Battery Tender/Deltran offering is interesting ($200, 8Ah, 4 lbs). How about Shorai? They have a unit on Amazon for $172 that weighs in at 3lbs and is also approx 8Ah: https://www.amazon.com/Shorai-Lithiu.../dp/B0088JGV2Q

    Also: is there a unified definition of "CCA"? For example, the Odyssey PC680 has a CCA of 170. The Deltran is 480. The Shorai is 315. Given the PC680 is the gold standard for lead acid, should I assume that these LiFePO4 choices are as good at starting in cold temps?
    I can't recall ever having a problem with the Shorai brand, but my experience has been in motorcycles only.

    I'll let others more knowledgable compare and contrast CCA and PCA of lead acid to lithium, but my experience is that lithium doesn't crank as well when temperatures are cold, but rather than go from cranking slowly to dead battery they do the opposite - as you crank the battery warms and things get better not worse. Again, just experience and not theory, but lithium batteries can be had with an ample CCA/PCA that are quite small, the sacrifice being AH. But I wouldn't think we need AH so much in a Caterham because of the lack of accessories.

    The big differentiators between lead acid and lithium are price, weight and how long they hold a charge without load. And if you are willing to sacrifice AH you can also have a smaller form factor.
    Greg

  8. #18
    Join Date
    Jan 2006
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    Seattle-ish
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    Default

    Greg, one tip with cold starts on a Lithium battery: turn on the headlights for about 10 seconds before attempting the start. This puts some heat in the battery prior to engaging the starter motor and was recommended by the manufacturer of my battery. It seems to work well in mid 30F weather.

    When I researched Lithium batteries several years ago, it became apparent that you can't easily compare specs with SLA or AGM batteries. First, the discharge properties are very different. A SLA can be discharged about 30% before voltage starts to fall off, the AGM about 50%, and the Lithium about 80% (some claim up to 95%). This means that although a Lithium battery may have a lower AH rate than an AGM, the actual usable capacity could be higher. e.g. AGM rated 15 AH may have 7.5 AH available (15 x 0.5) whereas a Lithium rated at 10 AH may have 8 AH available. Second, the CCA test was developed for lead acid batteries and can't be safely completed by a Lithium. This page has a good explanation, but the short version is Lithium batteries can't discharging that fast without going bang. I've read that because of this, CCA ratings for Lithium batteries are either extrapolations or pure fabrication. PCA may be a different story since that is a 5 second test.


    -John
    '95 Westfield SEiW w/2.0L Duratec
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    Throttle Steer

  9. #19
    Join Date
    Feb 2010
    Posts
    57

    Default

    Thanks John. It's confusing because some lithium battery manufacturers have taken it upon themselves to list a "lead equivalent" Ah rating on their batteries. So it makes it hard to compare with, say, an AGM, which has a better discharge profile than SLA. Often they will list the actual capacity in terms of W/Hr, which you can then translate into the actual A/Hr.

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