New NiMh 5100 Batteries Hissing

[masavy]

I received my new Speedpack 2 5100mAh NiMh batteries today and was told by the rep ate Horizon to charge them at 5.1a. The first tine they charge they said they were full at 3000mAh so I waited 30 minutes and charged them again and they added another 800mAh before the alarm went off saying they were done. When I went to get them they were hot and I could hear a light hissing from one of them. What I'm wondering is are these safe to use or did they fry? I charged them with the exact settings I was supposed to. I tried calling Horizon but you can't get through. Not sure if I should discharge them or if I shouldn't use them now at all.

*Update… chatted with Horizon, told me to discharge them and try again at 4amp instead of 5.

 

[KyleRC]

Nimh batteries hissing is very bad. Chances are one of the cells overheated and leaked.
the batteries probably came partially charged which would be the reason the mah reading was off. What kind of charger are you using and what settings? Pics help a lot.

 

[masavy]

Nimh batteries hissing is very bad. Chances are one of the cells overheated and leaked.
the batteries probably came partially charged which would be the reason the mah reading was off. What kind of charger are you using and what settings? Pics help a lot.

I'm using the dynamite passport ultra p2. I talked to Horizon, he said to discharge it and if it discharges with no error it's ok. I discharged them and they successfully discharged. I'm going to charge them again using the app and QR code and test them out in the cars. I had used the settings they told me to use: NiMh, Charge, 5.1a, 6 Cell.

 

[weave]

Massey, this is what happens when you over charge a battery. Although this is a Lipo, the same can happen to NiMh. It's best to charge one or two amps under the rated amperage. It may take a little longer too charge but it's safer and your batteries will last longer.