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  1. #1
    RC Qualifier NitroBugg's Avatar
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    Exclamation Charger\batter Issue?

    I have (2) 5000mah 35C batteries, and as always, I charge them to 4.2 per cell. After running, I always discharge them to 3.7v per cell if I'm done running for the day, or the next at the latest, but never stored charged, or partial charge for more than 2 days tops.

    I am using a dual charger so I can charge\discharge both at the same time.

    The issue I need some advice about is the resistance per cell\battery. Have the packs labeled PACK1, and PACK2 so I can rotate them out and get equal run time for each battery.

    Hooked up PACK1 to the left side, and PACK2 on the right side.

    PACK1 Reststance:
    Total: 24M
    Cell1: 7.9
    Cell2: 7.9
    Cell3: 7.0

    PACK2 Resistance:
    Total: 27M
    Cell1: 9.1
    Cell2: 9.3
    Cell3: 8.8


    Now this is where things change, and am suspecting it may be the charger(?), but needed an opinion.

    I switch batteries, and put PACK1 on the RIGHT side, and PACK2 on the LEFT side, and I get this...

    PACK1 Resiatance:
    Total: 44M
    Cell1: 15.4
    Cell2: 14.1
    Cell3: 14.2

    PACK2 resistance:
    Total: 14M
    Cell1: 4.1
    Cell2: 4.2
    Cell3: 4.2

    I don't have a stand alone resistance checker, and also noticed PACK2 is just "slightly swelled"...not much, but not flat like PACK1.

    Any thoughts or suggestions? I've even changed out the balance boards only and all values stay the same no matter which side I use them on. If its a defective charger, I need to get it repaired\replaced. And if its the batteries, I need to see if they are under warranty and have them replaced, or dispose of them and get new batteries as I don't want the horror of a Lipo house fire, or have one catch fire and melt down my rig.

    As soon as I get time, I will include some pics of the charger screen.

  2. #2
    RC Qualifier GotNoRice's Avatar
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    Quote Originally Posted by NitroBugg View Post
    After running, I always discharge them to 3.7v per cell if I'm done running for the day, or the next at the latest, but never stored charged, or partial charge for more than 2 days tops.
    Why would you not storage charge them after you use them? Storage charge is usually between 3.80-3.85 per cell. 3.7 is too low IMO. I have batteries from 2011 that still work great, likely at least partially because I am meticulous about storage charging them each time.

    Quote Originally Posted by NitroBugg View Post
    The issue I need some advice about is the resistance per cell\battery. Have the packs labeled PACK1, and PACK2 so I can rotate them out and get equal run time for each battery.
    I wouldn't get too worked up about these sorts of details really. Just balance charge them each time, use them, and then storage charge them when you are done. If you are curious about the voltage being reported correctly, then get a LVA to connect to the balance cable. Something like this:

    https://www.ebay.com/itm/222533108820

    Quote Originally Posted by NitroBugg View Post
    I don't want the horror of a Lipo house fire, or have one catch fire and melt down my rig.
    These sorts of fears are largely overblown. LiPos don't just catch fire in a rig unless there is some sort of short circuit. If you are worried about them while in your house, it's good practice to store them, and possibly charge them also, while inside a metal ammo box or similar. I've been through a lot of LiPos over the years and I've never had one catch fire and explode. A few packs that had puffed, my friend and I couldn't get anything exciting to happen even after we did things like intentionally puncturing the pack, short-circuiting the pack, and even tossing one in a fire pit.

  3. #3
    RC Champion nickruger's Avatar
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    Those are some extremely high IR readings, even the pack in the 4's is really high. I would see if you can borrow a healthy battery to eliminate your charger. Those little lipo checkers are good for ball parking voltage but they dont read IR as far as I know. Some of my SMC packs that are three years old have IR readings of 1.0 to 1.3 ohms. The only time I've seen readings that high were in batteries I either didn't take care of properly or that couldn't handle the system they were powering.
    As far as the gentleman above who kind of dismissed the hazards of lipos, I know he has a right to his opinion, but I wouldn't dismiss safety just because it hasn't happened to him, lots of people drive drunk, but have never got a DUI or killed someone.
    What charger are you running?
    Sent from my SM-N960U using Tapatalk
    Last edited by nickruger; 10-24-2019 at 06:20 PM.

  4. #4
    RC Qualifier NitroBugg's Avatar
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    Quote Originally Posted by GotNoRice View Post
    Why would you not storage charge them after you use them? Storage charge is usually between 3.80-3.85 per cell. 3.7 is too low IMO. I have batteries from 2011 that still work great, likely at least partially because I am meticulous about storage charging them each time.
    Because they set up less than 24 hours, and don't see a need. If I don't plan to run within 24 hours, then yes, I storage charge them.

    Quote Originally Posted by nickruger View Post
    Those are some extremely high IR readings, even the pack in the 4's is really high. I would see if you can borrow a healthy battery to eliminate your charger. Those little lipo checkers are good for ball parking voltage but they dont read IR as far as I know. Some of my SMC packs that are three years old have IR readings of 1.0 to 1.3 ohms. The only time I've seen readings that high were in batteries I either didn't take care of properly or that couldn't handle the system they were powering.
    As far as the gentleman above who kind of dismissed the hazards of lipos, I know he has a right to his opinion, but I wouldn't dismiss safety just because it hasn't happened to him, lots of people drive drunk, but have never got a DUI or killed someone.
    What charger are you running?
    Sent from my SM-N960U using Tapatalk
    The batteries I use (purchased from LHS) are Venom. And they both were in the 4 ohm range from day 1.

    The Charger is the Prodigy 625. And as stated above, the ohms change when I change sides with the battery, so that has me concerned a little. I got the charger in December 2018, so its still under warranty if I need to send it in.

    I do have 2 SMC batteries that I haven't used yet, but the wrong plugs were installed, so i will need to change those before I use them. Will try and get that done this weekend and see what they read. I usually charge\discharge a new battery 2-3 times before I actually use it to (for the lack of a better word) "Settle In".

  5. #5
    RC Qualifier NitroBugg's Avatar
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    Oh...I also bumped up the storage charge to 3.8. Was told initially 3.7-3.85. (year and a half ago) But most recommend 3.8 so going with that.

  6. #6
    RC Champion nickruger's Avatar
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    Yeah, not a fan of venom batteries. Venom was the first Lipos I bought when I first got into the hobby a few years back. I didn't take care of them the way you are supposed to so they died prematurely and I over taxed them running 35c batteries on a 6s system with high gearing. I did give them another try once I knew what I was doing and still got similar poor results. Get the charger figured out first. Run those SMCs before too long, it's also not good to leave lipos un-cycled for too long as well. Ever since I got religious about battery care my packs are really healthy and longevity has been multiplied times over. I know it doesn't seem like much of a difference leaving them at 3.70 or 3.80, but I would play it safe and just storage charge them as soon as you are done running them. It is important because not only are you putting them to the proper voltage you are also balancing out the cells. Say in your 3s lipo after you run, cell 1 is 3.65, cell 2 is 3.70, and cell 3 is 3.75. After you leave them like that until you charge them again, after 20 times doing that those numbers are likely to get more and more out of whack. My charger wont finish until every cell is within a hundredth of each other. Not doing so could be a problem over time.

    Sent from my SM-N960U using Tapatalk

  7. #7
    RC Qualifier NitroBugg's Avatar
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    Thanks. After what I've seen with them...I'm not a fan any more either. I will get the SMC's out in the morning and cycle them a few times, then change the plugs out. I ordered them with XT60, but they put Traxxas plugs on them. Easy fix though.

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