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Dec 27, 2017, 11:32 PM
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Gt500 Duo charging/discharging/cycle below 3.8v

Could any of you help me. I'm having an issue with my gt500 duo when discharging and charging typically below 3.8 volts per cell. On every one of my packs, whether it be my 3s or 4s 1300s or my 5200 6s packs, cell 1 when discharging will always drop substantially lower than the others and when charging, cell 1 will read higher than all the others on every single pack I own. The internal resistance also reads much higher than the others. Once the voltage goes above 3.8 per cell when charging they seem to all even out and when discharging, once the pack goes below 3.8 per cell is when cell 1 plunges. Any ideas?
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Dec 28, 2017, 08:01 PM
Registered User
This is normal if you had set or left the balancing start voltage at default of 3.80V. Below this voltage, the balancing is switched off and the weaker cells will typically drop or rise faster than the others. Above this voltage, when the balancing is active, the cell readings will track each other more closely.

You can change the balancing start voltage at the Advanced Settings -> Balance menu.
Jan 07, 2018, 01:54 AM
Registered User
I had another issue come up. I powered the charger with a small 12v car battery and attempted to do a regenerative discharge of a 6s 5Ah lipo but 15 seconds into the discharge the charger said "dc supply detected". I did have the charger set to automotive battery in the supply settings and had regenerative discharging on. I then tried the 12v deep cycle option but the same result. Any ideas ?
Jan 07, 2018, 08:06 PM
Registered User
It looks like the charger is having problems regenerating the deep cycle battery. Make sure you have a good connection from the deep cycle battery to the charger. If you are using crocodile clips on the terminals, I would suggest changing them. When discharging 5Amps from the 6s 5Ah pack, the deep cycle battery could receive as much as 10Amps.
Jan 08, 2018, 02:04 PM
Registered User
If the battery isn't a deep cycle, it's a smaller lawn mower battery, could that be to cause? Would the charger somehow recognize the battery couldn't take the amperage? I was using alligator clamps but I had a good connection. Or if the battery was mostly charged would that cause the issue?
Jan 09, 2018, 02:48 AM
Registered User
If the battery couldn't take the amperage, then yes, its terminal voltage would rise quickly and cause the issue.
Jan 14, 2018, 01:50 AM
Registered User
I charged the lead acid battery I mentioned on the gt500 and it said it finished. I didn't have a capacity cut off and it didn't go past my time set for safety, but I threw the battery on my hitec X4 ac plus and it currently has put an additional 3Ah into the battery. Why would the gt 500 have said it was full if it was not?
Jan 14, 2018, 08:07 PM
Registered User
Please post more information about your setup e.g.
- charge current and lead acid battery capacity,
- terminal voltage (read by the GT500) of the lead acid battery when finished,
- finished terminal voltage using the Hitec X4 AC charger.
- program used, SLA/Gel or AGM?
- is float mode turned on, etc.

Mar 14, 2018, 01:36 PM
Registered User
Just curious if there is an officially released software patch for this issue. The charger charges the cells to the proper voltage but the cell voltage initially in the screen says in this case 25.25V, but when added up, the voltage adds up to 25.195V. Thanks.

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