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  1. #1
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    NiMh battery care questions

    We've got the Slash VXL. So I just bought a new 8.4v 5000 mah NiMh battery. I don't think my previous ones lasted that long. Maybe 1 to 1.5 years. Not sure of the number of uses but I'll be tracking that with my new one. How many year(s) or uses can I expect out of a NiMh battery?

    What are some things to be aware of to get the most longevity out of the NiMh batteries?

    Questions:

    For a 5000 mah NiMh battery, what amp should I charge it at? I have the HiTec charger. 4? 4.5? 5?

    If we don't use the battery for a week or so, should I leave the battery charged or discharged?

    When the plastic wrap starts to break away, should I leave it as is or wrap a little with electrical tape?

    Thanks.

  2. #2
    Marshal Double G's Avatar
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    The wrap should say what the recommended charge is, though you can't go wrong with 1C or 5 amps.

    Charge it 100%. When I put my nitro Revo in for storage my receiver and glow ignitor batteries are charged to 100% and I occasionally take them out and top them off. Maybe cycle them. The 20-40 garage temp in the middle of winter probably helps preserve them.

    If the wrap wears away then cover it with electrical tape. If it melts away, then you've got other issues.
    The Super Derecho

  3. #3
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    It's good to leave those batteries fully charged.

  4. #4
    RC Qualifier zedorda's Avatar
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    If you google "NiMH battery storage voltage" you get this.

    To keep NiMh cells vibrant, you store them discharged and perform a charge/discharge cycle on them every 30 days. To discharge your cell, you apply a 1C load and stop when the voltage under load hits 1.0 volts. With a battery pack you stop when the voltage hits 1.0 volts per cell.

  5. #5
    RC Turnbuckle Jr. Greatscott's Avatar
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    Quote Originally Posted by 55Chevy View Post
    We've got the Slash VXL. So I just bought a new 8.4v 5000 mah NiMh battery. I don't think my previous ones lasted that long. Maybe 1 to 1.5 years. Not sure of the number of uses but I'll be tracking that with my new one. How many year(s) or uses can I expect out of a NiMh battery?

    What are some things to be aware of to get the most longevity out of the NiMh batteries?

    Questions:

    For a 5000 mah NiMh battery, what amp should I charge it at? I have the HiTec charger. 4? 4.5? 5?

    If we don't use the battery for a week or so, should I leave the battery charged or discharged?

    When the plastic wrap starts to break away, should I leave it as is or wrap a little with electrical tape?

    Thanks.
    Until I made the complete switch over to lipo, I had NiMH that were pushing 10 years old. They didn't have the punch they once did, but still did a good job at powering my trucks.

    For charging, recommend charging at 1C, you can go higher, but there is no real need to stress your packs.

    Honestly, I am horrible with my battery maintenance, any will typically just leave them in a discharged state until I go to run them again. NiMH are a bit more tolerant of this than lipos.

    The biggest thing that kills NiMH packs is over discharging them, this causes heat stress in the pack, which breaks down the chemicals that store the charge. If you heat shrink is cracking, then you are liking over discharging. Typically over discharging comes from running the pack until the RC can no longer move, and your packs will likely be almost too hot to touch. To prevent over discharging, stop running the RC when the pack dumps. Aside from the heat shrink being cracked, you will also see the results of heat damage due to over discharging when you charge your packs. A 5000mha pack mathematically should take about an hour to charge at 5A, but because it already has a charge in the pack, it normally take around 45 minutes, a damaged pack will take less and less time for the charger to say its full and end the charge cycle; conversely, you will see your run times decrease to the point to where your charger says they are charged but the truck will barely move. Static voltage readings here don't really help, but with no load on the pack it will say the pack is charged. Only when you put a load on the pack will you see what the pack is really doing and if it is healthy or not.

    HiMH Dump: While running your RC you will notice a point where suddenly the RC will only go about half its normal max speed at full throttle, this is the point where the pack has dumped. And, this is when you should stop running it. I ruined over 10 packs the first six months I had my E-Maxx because of not running when the packs have dumped.
    Submarine Qualified, Chief Inducted, Navy Retired

  6. #6
    Marshal Double G's Avatar
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    Quote Originally Posted by zedorda View Post
    If you google "NiMH battery storage voltage" you get this.

    To keep NiMh cells vibrant, you store them discharged and perform a charge/discharge cycle on them every 30 days. To discharge your cell, you apply a 1C load and stop when the voltage under load hits 1.0 volts. With a battery pack you stop when the voltage hits 1.0 volts per cell.
    You could search online and it will tell you to keep them fully charged. Best to go with what the manual or the manufacturer says on how to store. One of mine says before storage it should be charged to at least 50% and when taken out of storage to discharge and then fully charge. Others say that since it does not have the memory effect of nicd that you don't need to discharge it before recharging. Again, one of the manuals says to discharge prior to charging.
    The Super Derecho

  7. #7
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    What is charging at 1C? My HiTec charger has amps such as 4 amps, 4.5 amps, 5.0 amps, etc.

  8. #8
    RC Qualifier Sp2deSummit's Avatar
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    1C means charge at the mAh / 1000, so for your 5000 mAh battery, charge it at 5 amps and you should be good!
    I like free stuff!

  9. #9
    RC Qualifier zedorda's Avatar
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    Quote Originally Posted by Double G View Post
    You could search online and it will tell you to keep them fully charged. Best to go with what the manual or the manufacturer says on how to store. One of mine says before storage it should be charged to at least 50% and when taken out of storage to discharge and then fully charge. Others say that since it does not have the memory effect of nicd that you don't need to discharge it before recharging. Again, one of the manuals says to discharge prior to charging.
    Two things to remember when doing research in how to maintain batteries. 1) The manufacturer has a vested interest in misinformation. 2) Heat is the only real enemy to NiMH batteries.

    In theory NiMH batteries can be stored at any charge level without the memory affect that NiCaD batteries suffer. I have found Tested.com pretty reliable and unbiased in most cases.

    https://www.tested.com/tech/1245-how...ble-batteries/

    Quote from link.

    "In talking about rechargeable batteries, there are two terms that get debated endlessly: “memory effect” and “voltage depression.” With even a quick search, you’ll find all sorts of conflicting information on both phenomena, but few scientific tests to confirm them."

  10. #10
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    Thanks everyone.

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