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Method to extend Hymotion Battery by 25%

Discussion in 'Gen 2 Prius Technical Discussion' started by rwyckoff, Jun 19, 2008.

  1. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    120 A123 M1 cells configured for 13.4V (about 1kwhr) could power a 12V inverter in your trunk, and then provide the 700 Watts required by the chargers in the Hymotion battery pack while you are driving the car. This would pump about 1 Kwhr into the Hymotion battery in the first hour, extending the usuable amount of kwhr from the present 3kwhr to 4kwhr.

    Can the Hymotion chargers work while while the pack is being used?

    Cost- Buying 36v Dewalt battery packs (10 cells per Pack) off of Ebay would cost between 960 and 1200$. So increasing the cost of the whole system by 10% would improve the overall system by 25%

    Charging- These cells require an inteligent charging system that load levels every cell at the end of each charging cycle. This charger would have to be designed for the 13.4v system. This by the way is why the Hymotion pack does not allow the hybrid system to charge this battery.

    Ron
     
  2. Bob64

    Bob64 Sapphire of the Blue Sky

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    Uhh... Why not just connect everything together without additional recharging/inverters...
     
  3. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    Good question. The Hymotion battery pack comes with it's own chargers, 3 of them. So if you wanted to add to the pack you would have to integrate another charger some how. Doing the 12v pack and going through an inverter allows you to disconnect the whole thing and take it out, Leaving the Hymotion system intact and uncompromised.

    Another way to do this would be too use a 36V UPS. Then you could just hook up DEwalt 36v battery packs to the UPS, so your packaging is taken care of sort of, and you can recharge the Dewalt packs with their own dewalt chargers (4 to 12 of them). Tahnks-

    Ron
     
  4. Cheap!

    Cheap! New Member

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    Hymotions system has a charge lockout so you can't drive the car while it is charging.
     
  5. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    Thanks for that info. Too bad, I can't think of any reason why that would be necessary. Guess you could charge the system whenever you are out of the car shopping or whatever.

    Ron
     
  6. szajac@advantagecap.com

    [email protected] New Member

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    I like the concept but can this be done with "off the rack" products or do I need to modify technology? If I buy the Dewalt Packs, the chargers and a 36 Volt UPS, how do I get the packs to power the inverter or UPS since they are structurally desinged for Dewalt tools? The ideal system for me would be set up to charge the Dewalt cells from the AC outlet and then have the subsystem charge the Hymotion system when the car is not running.
     
  7. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    Chargeing these batteries is not trivial. They require a sofisticated charger.

    Standard UPS's use female spade connectors to connect to gelcel lead acid batteries. You would have to change those to male spade connectors, probably 10 guage ones. You would have to package the Dewalt battery packs and make up a cable harness that would match the individually packaged battery packs. Just push the spade connectors into each battery pack. You may want to come up with some way to secure the spade connectors to the packaging structure (and this structure should restrain the battery packs also) so they don't try to back out of the battery packs. The whole package needs to disasemble quickly so the Packs can be taken out and charged individually in there own chargers. An interresting job for amature and expert alike!

    Ron
     
  8. Stefx

    Stefx Member

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    If those Dewalt batteries were deep-cycled at each use (from 100% to 0% back to 100%) how long will they last? 500-700 cycles?

    To make them last, wouldn't you have to find a way to use the 20-80% range like the Prius battery?
     
  9. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    If you believe A123 their M1 cells will last several thousand cycles in full cycle mode. Even then they will retain 80% of capacity. Keeping them above 20% charge will help them do even better. These cells have two great advantages over previous generation cells, the first being long life. The other is huge discharge/recharge capability. Their middling capacity and difficult recharge habits has made it difficult to use the latter advantage of huge current capabilities, except for the electric motorcycle dragster that uses these cells.

    A123 has promised their new cells being tested by GM for the Volt has far more capacity with the same low internal resistance (.01 ohm). We can only hope for that and some moderation in price!

    Ron
     
  10. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    I forgot to mention that Hymotion is using a 5KWR battery pack, but is only using 3KWH of that capacity. This means that they are leaving 40% of capacity on the low end. So figure 40%-100% use of capacity. Charging to 100% capacity will not shorten life because it is done very slowly and carrefully with internal charging circuits. This battery pack will be rediculously under stressed, as it is capable of putting out over 90KW but will never have to provide more than 22 KW. You could charge this pack to 90% of full charge in as little as 5 min. It will take over 6 hours to charge this pack. Hey Hymotion, how about adding a 220V charger so we can do a full charge in 1 hour at least! Thanks-

    Ron
     
  11. miscrms

    miscrms Plug Envious Member

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    Not a bad thought, but I think you will find that the complexity gets out of hand pretty quick. You will need a BMS to manage all of your batteries on charge and discharge and keep everything balanced and safe and within proper limits. I think you underestimate the effect of lifetime too. Lets say you get 1kWh of capacity (@100% DOD) for $1200 worth of batteries. If you get 1000 cycles out of them, and get about 4 miles EV range per cycle (Prius should be ~250Wh per mile) thats 4000 miles for $1200, or 30c per mile. To keep the cost of batteries + cost of electricity (~2c/mile) below the Prius' current ~8c/mile on gas you'd need to keep your battery cost to ~6c/mile. To do that you need 5000+ cycles out of the batteries, which I believe means you have to take pretty good care of them and treat them pretty gently.

    My question is, if you are going to go to all that trouble why bother with the Hymotion pack at all? You are going to have to design or buy a charger, charge controller, BMS, battery pack, battery box, cooling and ventilation system and a way to connect and disconnect the pack. Thats basically everything that the Hymotion pack does except the controller to decide when to connect and disconnect the pack. You can buy a CAN-View for $500 to do this, or soon the Cal-cars SOC spoofing CAN controller will be available for less.

    The Cal-Cars conversion, while mostly implemented in PbA currently, is mostly battery technology independent and people are working to implement it in Li-ion and NimH as well. Its still a work in progress (like most open source projects) but there is enough data out there at this point to put together a good working conversion.

    Some links:
    Good source of PHEV info:
    Main Page - EAA-PHEV
    Cal-Cars Prius Plus conversion:
    PriusPlus - EAA-PHEV
    PbA Cal Cars complete kit for $5k, working on Li-ion:
    Plug-In Supply Inc of Petaluma California
    Steve Woodruff is I believe working w/pluginsupply on Li-ion:
    Plug In Hybrid Electric Vehicle PHEV
    These guys are offering a cal-cars based conversion w/ nilar NimH:
    Home of Plug-In Conversions
    Can-View Prius CAN traffic reader & PHEV controller:
    CAN-view index
    Same guy is also now working on a BMS for NimH and Li-ion conversions:
    blank
    Maker of EV chargers, and a dc:dc converter based conversion:
    BLCD drive

    Very good maillist where most of the people working on Cal-cars development and some commercial converters hang out:
    Maillist - EAA-PHEV

    If I can every get the time and money together (Its amazing how quickly small children drain you of both :rolleyes: ) my plan is to do a PbA cal-cars conversion for about $3k, and then work on a NimH or Li-ion upgrade to be ready for when the lead pack needs replacing in 1-2 years.

    Rob
     
  12. misslexi

    misslexi Member

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    Not claiming to be an expert but, after looking into USING the Dewalt 36v packs for an eBike project, I bailed out for now. They are not easy to charge nor to use for anything other than their intended purpose. There are folks who have harnessed them but they've forgotten more about EE than I'll ever hope to know.
     
  13. donalmilligan089

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    To do this you will need to fool the computer into knowing where the power was coming frem as it rcognizes only the HV battery