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Thread: 6 Pound Battery

  1. #1
    Sport Button On - DSC Off Robert Linton's Avatar
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    6 Pound Battery

    Has anyone tried this http://www.voltphreaks.com/home.html -- 12V battery (VPHR18) that weighs 6 lbs. For the price, $675, on a per pound basis, better weight savings for a Z8 than many other things.

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    Administrator thegunguy's Avatar
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    These batteries are building a following in the Lotus community, and I've read good reports. Certainly, the price is pretty high, but the net gain is pretty massive considering the weight savings, not to mention the size!
    thegunguy

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    Team Z8 RRZ8's Avatar
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    Quote Originally Posted by Robert Linton View Post
    Has anyone tried this http://www.voltphreaks.com/home.html -- 12V battery (VPHR18) that weighs 6 lbs. For the price, $675, on a per pound basis, better weight savings for a Z8 than many other things.
    Robert, did you see the (18ah) capacity ? Versus 'our' 90ah, this means the batery is dead within no time (....)

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    I used the Odyssey dry cell PC680 battery in my Z8 for a number of years with no problems. It is a 16 lb., 16ah capacity battery with 680 CA (cranking amps), 210 CCA (cold cranking amps), and a 28 minute reserve (25 amp load). The weight savings was terrific and the battery had more than enough power to start the Z8. If you have a very high-powered stereo installed or are in the habit of leaving your lights on without the engine running, or unwilling to use a Battery Tender when the car sits for long periods, this might not be a good choice. I have recently switched to the VPHR18 battery Robert referred to earlier and I must say I am very impressed! This battery weighs only 6 lbs. yet it is rated at 18ah capacity with 850 CA, 675 CCA, and a 40 minute reserve. So it's 10 lbs. lighter than the Odyssey with significantly more power output! The battery uses state-of-the-art nano-lithium technology which does not have the thermal problems experienced with other lithium based batteries. Installation is a little tricky depending on how clean you want the finished product to be, but not complicated. For comparison sake, the OE battery is rated at 90ah, with 850 CCA, and weighs 50 lbs.

  5. #5
    Wow, that is a wonderfully easy way of shedding over 40lbs! If this new battery works well over the next few months maybe we could see if one of the good fabricators could make up a custom base and clamp for this unit. I use that under(trunk)floor compartment to stow runflat-goo, puncture plugs, tools, manuals etc, so the space saving could be handy too. Do you have a snap of it installed by chance?
    Andrew Macpherson

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    I'm not sure pics would be of much value since I have gutted my Z8's battery compartment to eliminate all the old battery paraphernalia, including relocating the auxiliary power panel. Assuming most owners would prefer to simply replace their OE battery with the light weight one, retaining as much of the stock set-up as possible would be important so the car could be returned to original configuration in the future. With that in mind, you should know that the VPHR18 battery is so light, it can easily be strapped in place with large tie wraps (supplied with the battery) or held in place with industrial strength velcro. Also, its case has flanges on the sides with pre-drilled holes for more permanent mounting (screws, bolts, pop rivets). I'm sure a hold-down bracket could be designed which would utilize the attachment points of the OE set-up and this might be worth pursuing, however, installing the battery is actually the easy part; it's rearranging the wiring that takes some creativity. The VPHR18 has eye loops for cable attachment which means you must adapt your cabling to connect. The company can supply 1.5 foot long properly terminated cables which makes things much easier, albeit a bit untidy looking with all the extra wiring involved. I will take a look at my other Z8's battery compartment and try to assess what would be involved in installing a VPHR18 in a stock Z8. Since the battery has already demonstrated more than enough power to start the Z8, I don't anticipate any issues in the future which would make it unsuitable. Remember, once the car is running, the alternator supplies all of the power the car requires and the battery is simply maintained in a charged up state. The only time this isn't true is when you have a very high powered stereo system which requires more amps on peaks than the alternator can supply, in which case, the battery acts like a capacitor and supplements the alternator's output. Since the VPHR18 should prove adequate even under those circumstances (unless you've turned it into one of those boomboxmobiles which shake the earth at traffic lights), the only drawback to its lower ah rating is a significantly reduced reserve capacity when the engine is not running. If you had to crank the engine for a very long time, or left the lights on for a while, or let the car sit for weeks at a time without a battery charger attached, that low reserve would certainly be an issue compared to the very potent reserve of the OE battery.

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    Some thoughts on weight savings in a Z8: For some of us, removing as much weight as possible from the Z8 without ruining its sumptuous character, is a never-ending quest. The benefits include more responsive handling and faster acceleration due to the reduced mass. However, it takes a lot of shaved pounds to provide a noticeable benefit on a street car. It's a very different case on a race car where a few pounds difference may show up as an improved lap time. In a street car, the benefits are much harder to appreciate. Consider the 44 lbs. of weight which can be removed by switching to the VPHR18 on a Z8. The weight reduction takes place in the rear of the car. Where you really want to reduce weight on a Z8 is up front. Weight over the rear axle in a rear drive car is often advantageous. Assuming most spirited driving is done solo, you also want to reduce weight on the driver's side of the car. Unfortunately, the battery is located on the passenger side in the Z8. Remember, too, that a 40 pound weight reduction is roughly equivalent to an increase of 4 HP, which would be very hard to detect in a car as powerful as the Z8. Also, the difference in weight among different drivers can be considerably more than 40 pounds, not to mention adding a passenger to the mix. My point is this: switching batteries as part of an overall effort to substantially reduce weight in a street car makes sense, but until you get over 100 lbs. and preferably more like 200 lbs., don't expect to feel much of a difference. If you are only going to do the battery, I'm not sure I would bother since the performance difference will be minimal and the weight bias change is less than ideal. If you really want to feel a difference, go to lighter weight wheels, tires, and brakes. These all represent a reduction in unsprung weight which has a far more noticeable effect on the car's handling.

  8. #8
    Good thoughts indeed, I hadn't really thought about the left/right weight bias in the Z8, though I've sent a lot of time with the Lotus (and I) on the scales getting the corner balancing to within a couple of pounds all round. This make me wonder how much does a tank of gas weight in the Z8, and what is its lateral inertia like when full, and does it have inbuilt baffle plates?
    Andrew Macpherson

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  9. #9
    Sport Button On - DSC Off Robert Linton's Avatar
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    We are running an evaluation and tests of the Voltphreaks unit and I am not sure I would jump to replace your current battery until more information is available.

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    The following numbers represent a completely stock Z8 with all accessories on board and a full tank of gas. Numbers are rounded off to nearest lb. for convenience sake. Curb weight: 3685 lbs. With a 162 lb. driver added and the top down, the left front tire has 964 lbs. on it, right front has 925, left rear has 996, right rear has 962. That yields a left side weight of 50.9% and right side 49.1%. Ideal is 50/50. Front weight is 49.1% and rear is 50.9%. Ideal varies but 50/50 is great on a front engined car and a little rear weight bias is just fine. Cross weights are 49.9% left rear to right front and 50.1% right rear to left front. Anything higher than 49.5% and lower than 50.5% is great with 50/50 ideal, except in racing where it may be advantageous to alter cross weights to better suit a particular track. Front to rear bias and left to right bias are normally changed by moving weight. Cross weights are adjusted by changing ride height at the corners. If you add a 125 lb. passenger, the left front tire has 968 lbs. on it, right front has 969, left rear has 1022 and right rear has 1012. Front weight is 48.8% and rear weight is 51.2%. Left weight is 50.1% and right weight is 49.9%. Left rear to right front cross weight is 50.1% and 49.8% right rear to left front. As you can see, BMW has done a great job of balancing the Z8's weight distribution and for street use, you really can't ask for much better.

    I believe all modern cars have baffles built into their gas tanks to keep the fuel from sloshing around in response to g-forces. I don't know what is used in the Z8. Anybody want to cut one open to find out? Race cars use foam filled gas tanks to prevent fuel movement. There is no doubt the amount of gas on board will affect weight bias but for street use, not really an issue. On a race car, the minimum amount of fuel required to finish the race is all that would be onboard. Since the Z8's tank is in the rear, and the above measurements were taken with a full tank, the front to rear weight bias will shift forward slightly as the fuel tank empties. Hope this helps.

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    Found another interesting option for people to consider at tekbattery.com. These guys offer essentially the same battery technology as VoltPhreaks (supplier of the VPHR18) but they can build one with the same dimensions and terminal hook-ups as your OE battery, with a weight savings of app. 80%. That would mean their battery would weigh only 10 lbs. They just build a box to match your supplied dimensions, put terminals where your original ones were located and then insert their lightweight battery materials leaving lots of empty space which they fill with foam. This would mean a direct replacement of your OE battery with no modifications required whatsoever. I think the cost will be high but an alternative approach for the faint of heart. By the way, the VoltPhreaks batteries are being used in a number of OE applications now and the M5Board and Elise community have had excellent results with them. There's also a very informative explanation of the technology involved on Wikipedia which confirms their inherent safety.

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    Sport Button On - DSC Off Robert Linton's Avatar
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    I have three of the TekBettery units on order and we will begin testing as soon as they are received. The cell technology is similar to that of the Voltphreaks but the peripherals and execution are somewhat different. The questions that arise therefrom are also similar, e.g., (1) are these batteries at the present stage of their development appropriate for certain vehicles including, but not limited to, the care and feeding required versus other options, (2) is their cost justified vs. an "ordinary" battery and (3) is the quality of assembly sufficient for prolonged use in a variety of conditions. Finally, as to Voltphreaks, (1) there appears to have been some use by M5 owners and Elise owners, but I would opine that this falls quite far short short of qualifying for the type and sufficiency of testing under multiple conditions required before I would discard one's conventional battery and (2) I know of no instance where a Voltphreaks unit is being included by a main line automotive manufacturer as original equipment.
    Last edited by Robert Linton; November 9th 2007 at 03:07.

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    Hey Robert, you began this thread by asking if anyone had experience with the Voltphreaks battery. I've had experience with it and it has all been positive. It easily starts the Z8, doesn't overheat, is compatible with a Battery Tender, and shows no signs of inadequate build quality. There are also a number of M3, M5, and Elise owners who are using the Voltphreaks battery in their cars and their experience seems to be the same as mine. As should be clear from my previous postings, I am not advocating a switch to the Voltphreaks battery for everyone who owns a Z8; just those who want to push the envelope a bit. If that means we will be acting as guinea pigs, so be it. I did my due diligence before installing the battery and am comfortable that it will not harm my Z8. Of course, there are always risks when modifying a vehicle but waiting until something becomes mainstream is not a way forward, just a way to follow. If people are unwilling to accept those risks, then they should not be modifying their vehicles. Your thorough testing approach is laudable and I look forward to hearing about your results, but I doubt anyone else is in a position to undertake such a project, so we must rely on our own judgement when making choices. Mine is based on years of race car building experience and I am comfortable with my choice. I assume you will not be crash testing your Alpina before you drive it with all of the new parts you had built for it, so perhaps our approaches are not so different after all. Also, I meant to say that the TECHNOLOGY used in the Voltphreaks batteries is being used in a number of OE applications. Thanks for pointing out the error.

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    Mac, I did check out the install of the VPHR18 in a stock Z8 trunk and it looks pretty straight forward. I would probably use industrial grade velcro to avoid having to drill any holes and attach the OE battery cables to it by using the 1.5 foot long cables Voltphreaks sells as accessories. Just attach them to the accessory mounting points on the cable ends and then bolt them to the VPHR18. Don't be concerned that the attachment cables are a slightly smaller gauge than the OE cables. They are more than adequate for the amps drawn.

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    In the past, Voltphreaks issued warnings about safety issues involved in charging or jumpstarting their batteries but the knowledge base is continuing to expand and the company has recently issued updated operating instructions which go into more detail concerning safety procedures for their use. Apparently, the big problem is the potential for the battery to overheat if improperly charged or jumped and the liquid contents are flammable so there is potential for fire. Of course, a lead-acid battery has the potential to explode if improperly charged so these concerns are not new in automotive use, but the procedures for safely charging or jumpstarting a Voltphreaks battery are somewhat different than what most people are used to.

    Unlike a lead-acid battery which can be charged at a relatively high amp rate, the maximum charge rate on a Voltphreaks battery is 25 amps and this only applies to a partially charged battery measuring over 12.8V (still able to power the headlights). If the Voltphreaks battery has been drained to below 12.8V, it can only be safely charged at 750mA or less, i.e., using something like a Battery Tender. So if the battery is dead, you cannot throw a high amp charger on and restore its charge without risking overheating and the possibility of a fire. Also, with newer cars that have a lot of advanced electronics, you must disconnect both terminals from the battery before attempting to charge it. At home, these requirements shouldn't be an issue since you can use a trickle charger like the Battery Tender to restore the battery's charge and disconnecting a battery's terminals while charging is always a good idea, but on the road, jumpstarting may be your only recourse. Fortunately, jumpstarting a dishcharged Voltphreaks battery will allow you to start your car and then the alternator will safely bring the battery up to full capacity. However, the procedure is somewhat different than the typical one used with lead-acid batteries and once again, to avoid overheating and the potential for fire, it must be followed precisely. The primary difference when jumpstarting a Voltphreaks battery is that you never start the ignition of the assisting car. The ignitions on both cars must be off and the headlights on the assisting car must be on before you connect their batteries with jumper cables. Then you wait a few minutes for the Voltphreaks battery to gain sufficient charge to start the car. Of further note, if you are providing a jumpstart to another car, you can use the normal procedure and have your car running while the batteries are connected.

    While following these procedures will protect your Voltphreaks battery from overheating and the potential for fire, they are somewhat less convenient than the procedures associated with lead-acid batteries and you run the risk of someone else using an improper procedure under the assumption that you have a lead-acid battery installed in your car. Voltphreaks does provide warning stickers you can place near the battery or charging terminals which give specific instructions on how to jump or charge the battery, so this shouldn't be a major concern. Still, there is risk involved.

    The Voltphreaks battery in my Z8 continues to work without a hitch and despite the aforementioned caveats, I see no reason to abandon its use. However, I have figured out a way to modify my set-up to eliminate most safety issues and make it more practical. Since the primary problem with these ultra lightweight batteries is their lower storage capacity and thus higher potential to become discharged, I am going to install a second Voltphreaks battery as a back-up and because its only use would be to start the car if the primary battery is dead, I can use the 4.5 lb. Voltphreaks battery for this purpose. That means my total battery weight will rise to app. 11 pounds but that is still less than any comparable lead-acid battery plus now I will have a built-in emergency starting system. If my main battery gets drained for any reaqson, I can just swap cables in the trunk and I'm back on the road with no safety issues to worry about and no need for outside assistance. In many ways, this is a better system than even the OE set-up. Once I get to my destination, I can simply recharge the main battery with a Battery Tender and be good to go. Because these batteries are so small in size, there is plenty of space for the second battery and because it is so light in weight, it can simply be strapped to the main battery with tie-wraps. The Voltphreaks batteries will hold their charge for app. 1 year so with a minimum of maintenance, the set-up should be close to bullet-proof.

    We're definitely playing in the lunatic fringe here, but for me, the weight savings are more than worth it. In fact, since most of my driving consists of day jaunts, I may only strap the back-up battery in place when I plan to keep the car out overnight! Voltphreaks has posted complete details on how to use their batteries safely on their website (voltphreaks.com) and I urge anyone interested in this technology to read them carefully.

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    For anyone wishing to maintain the OE battery layout in their Z8, an intriguing possibility would be to have the guys at tekbattery.com build one of their batteries in an OE sized case but add a second battery in the unused internal space. They could put two sets of battery terminals on top and all you would have to do if your primary battery died would be to swap cables on top or just use short jumpers to recharge the main battery using the spare. Weight would be somewhat higher than the voltphreaks set-up but it would still provide a substantial savings over the OE battery and you would never have to worry about a dead battery again.

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    Sport Button On - DSC Off Robert Linton's Avatar
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    How do you put out a lithium fire?

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    With care!

    Fire Fighting: Lithium fires are very hot and difficult to extinguish unless they are caught early. Lith-X is recommended for lithium fires. It acts by smothering the lithium. Because much heat is retained under the Lith-X, re-ignition can easily occur if the Lith-X blanket is disturbed before ambient temperatures are again reached. Dense white clouds of caustic and choking lithium oxide are formed when lithium burns. A self-contained breathing apparatus must, therefore, be worn when fighting lithium fires. If a lithium fire reaches large proportions, nothing can be done but to let it burn. In a sealed room such as a dry room, remember that the supply of oxygen is quickly consumed in feeding a lithium fire.

    Source......http://www.espi-metals.com/tech/Tech...20Handling.htm
    Andrew Macpherson

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  19. #19

    Has one of this brand of batteries actually caught fire in a car?

    I'm not sure if this affects this particular brand or not, but upon further investigation there have been reports of this type of unit catching fire in cars.

    Since the battery compartment is in very close proximity to the fuel tank on our Z8 I would advise being very cautious about using these batteries.

    Here is an NTSB bulletin.
    http://www.ntsb.gov/events/2006/Phil...its/350561.pdf

    FAA bulletin here.
    http://www.fire.tc.faa.gov/pdf/syste...y_04112006.pdf

    Please note that the cells tested by both the NTSB and the FAA are the same type used in this kind of automotive battery.
    Andrew Macpherson

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    WHOA THERE PARDNER! The lithium used in Voltphreaks' batteries is lithium iron phosphate which is much safer than the standard lithium cobalt commonly used in laptops and cell phones. Unlike a standard lithium fire which requires complicated measures to extinguish, a fire involving lithium iron phosphate can be extinguished with plain water or any standard fire extinguisher and there is no danger of uncontrollable combustion. Remember, too, that while the electrolyte solution in a voltphreaks battery is potentially flammable, it requires a meltdown of the internal battery casings (it will not explode) to create the potential for a fire. The same level of abuse involving a lead-acid battery would cause it to explode resulting in highly corrosive sulphuric acid being spewed everywhere, which, by the way, is also flammable not to mention toxic. Under normal use, the Voltphreaks batteries present no safety issues whatsoever. It is only if misused or abused that they have the potential to catch on fire. The lead-acid battery in your Z8 presents a far greater risk if misused or abused, but because it is a common technology, we have become inured to those risks. Lithium battery technology is currently being used in numerous prototype automobiles as a primary power source and the next few years will see the release of many of these as production cars. In the not too distant future, the heavy, inefficient, lead-acid battery with its toxic ingredients will be relegated to the dustpile of history, most likely replaced by some sort of lithium battery, and I say good riddance!

  21. #21
    Phew - I was more than a bit worried reading all that stuff - the last thing I wanted to hear was that something crazy happened to that amazing car of yours!!!
    Andrew Macpherson

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  22. #22
    Team Z8 riverflyer's Avatar
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    Good thread. Did not see the final results of your test Robert, do you mind posting them?
    GM, did you double up the batteries? Happy with the results?
    thanks

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    I did not end up adding the second Voltphreaks battery to my Z8 since it was headed to Dinan's for more massaging of the powerplant. In the mean time, Voltphreaks has upgraded their batteries to eliminate virtually all of the safety concerns mentioned above and added some with higher capacities. The new batteries have built-in overcharge cut-off circuits, built-in undercharge cut-off circuits, and built-in fault detection circuits. They also feature on/off switching, internal venting, and optional undercharge cut-off level settings which allow you to have the battery shut down before its charge is depleted to a point where it won't start the car, so if you leave the lights on too long, you won't return to a dead battery. Very slick. They also offer models with extreme vibration protection and completely waterproof cases for difficult environments. These new Voltphreaks batteries can now be considered direct replacements for OE lead/acid batteries since they operate in virtually the same way and are compatible with all vehicle charging systems as well as most auxiliary chargers. The only drawback is their pricing: not for the faint of heart!

  24. #24
    Administrator thegunguy's Avatar
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    Thanks for the great info as always, GM. Battery technology is really advancing for all applications these days as almost everything thing we use in our lives has a battery in it. It's great to see that the Voltphreaks products are becoming mainstream capable. Although, I doubt we'll see one in a GM or Ford any time soon...

    For the Z8, I love my Odyssey PC1200, but I'm tempted to try one of these in the Lotus (currently a Odyssey PC625).
    thegunguy

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    Team Z8 riverflyer's Avatar
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    So do you guys have built in chargers that you just plug a power cord into or do you charge to the terminals or cigarette lighter? I have all kinds in my various cars, some coming build in, just not sure about the best way to charge the Z8. thanks.

    GM, the voltfreaks batteries sound great with the upgrades. I will check their site. Are they still $600?

  26. #26
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    I wired in a direct plug behind the rear license plate.
    thegunguy