TM MP7 problem

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TM MP7 problem

Post  SiSedan08 on Mon Apr 16, 2012 1:21 pm

Hey guys,
So for the longest time my TM MP7 has been my back up choice for years. It was one of the early MP7's that hit the states. The gun has never given me a problem until as of late. Before this past Christmas the gun just wouldn't shoot. I assumed it was the battery so I bought a new one and the gun worked fine again. I have only used my MP7 three times since buying a new battery in Christmas; I used it at Ballahack, cqb, and once with you guys. The last time I used my MP7 with you guys it was acting a little funky (shooting wise). It was having feeding problems and consistency issues. It wouldn't shoot every bb and some would just trickle out the barrel.; however after a little while it free'd up and shoot good as new. I thought this may have been due to the high cap mag I have since it always has feeding issues and my standards don't. Anyways I took my gun back to ballahack around March 17th. I charged the battery all night and when I took the battery out in the morning it wasn't even warm. I popped it in my MP7 and surprise nothing, no cycle, nothing. I tried to be optimistic and think maybe it was a bad outlet so when i got back I plugged it in to an outlet that I knew worked. Waiting 2-3 hours to find the battery cool to the touch and again no cycling in the gun. I was wondering if I could receive some help on this. I am not that tech savvy with airsoft guns and I am not sure if the battery died again...find it hard to believe after 3 games a new battery died. Maybe its the contacts? If so what do I do? Maybe the charger? The charger for my MP7 is a two prong wall wort. It has a red light to let you know its charging, last time i looked the red light came on for 4-5 seconds then off and stayed off. So any help is appreciated, as of right not I have a 200+ dollar paper weight.

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Re: TM MP7 problem

Post  Bad Decision on Mon Apr 16, 2012 1:44 pm

Well, first off, you never want to charge a battery over night. That is how you kill a battery with overcharge.
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Re: TM MP7 problem

Post  SiSedan08 on Mon Apr 16, 2012 2:03 pm

It was in there for 6 hours, so I'm guessing you guys think I need a new battery. For the record with the old battery I did this on numerous occasions and it lasted a couple years

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Re: TM MP7 problem

Post  Bad Decision on Mon Apr 16, 2012 2:21 pm

Still not good to charge batteries for more than 3-4 hours, tops.
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Re: TM MP7 problem

Post  Slice on Mon Apr 16, 2012 2:46 pm

Shifter23 wrote:Still not good to charge batteries for more than 3-4 hours, tops.

Not necessarily. Depends on the mAH of the battery versus the mAH of the charger. With a non-smart charger, there's a simple equation to calculate how long to charge:

Charge time = mAH in battery / mAH charge rate.

Example 1: Let's assume your battery is 400mAH and your charger charges at a rate of 100mAH. 400/100 is 4, which means if you charge your battery for 4 hours it should be full assuming it was completely discharged previously.

Example 2: Let's now assume your battery is 1000mAH and your charger still charges at a rate of 100mAH. 1000/100 is 10, which means you need to charge your battery for 10 hours to reach a full charge.

These are just example numbers but with a large enough battery and a slow enough charger, charge times beyond 4 hours are indeed possible. Some chargers have a "fast charge" setting that increases the charge rate, but it is BETTER to charge at a SLOWER rate. In the end the easiest thing is to get a smart charger.
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Re: TM MP7 problem

Post  Cleaver on Mon Apr 16, 2012 7:09 pm

Is the new battery official tokyo marui? When I had an mp7 I had 2 batteries, an official TM and some off brand. The off brand was noticeably a bit shorter. If it's an off brand you may not be making good contact. Take the front of the gun off, push the battery all the way in, and see if it fires.
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Re: TM MP7 problem

Post  Oden on Tue Apr 17, 2012 11:48 am

my old NiMHs would take 8~10 hours to charge due to being 4Ah. but to me it sounds like a shot charger. I've seen batteries explode due to wall chargers overcharging them, so I'd imagine there not being any auto cut off system even if there's a red LED. try checking the voltage on your battery, if it's low then your charger is definitely shot, if not then try someone else's to check. Even if it isn't then a smart charger is always a good investment.
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Re: TM MP7 problem

Post  SiSedan08 on Tue Apr 17, 2012 2:17 pm

OdenFX wrote:my old NiMHs would take 8~10 hours to charge due to being 4Ah. but to me it sounds like a shot charger. I've seen batteries explode due to wall chargers overcharging them, so I'd imagine there not being any auto cut off system even if there's a red LED. try checking the voltage on your battery, if it's low then your charger is definitely shot, if not then try someone else's to check. Even if it isn't then a smart charger is always a good investment.

Its an official TM battery 7.2v. I have taken the front off the gun and put the battery all the way in and nothing. I think it may be the charger. The red led comes on to let you know its charging then turns off when its done. Un-fortunetly I can't test this as I am the only person I know that has a TM MP7. Not sure if i should buy a new battery or charger? both? Input?

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