Battery Life

Reading and searching the forms (which is alot ) I have read many topics on battery life.

We are using a 7.2 2000mah battery that comes with the classroom kits. With 4 293 driving the robot and 2 lifting the scissor lift it seems this battery (which is brand new This year) only last 1-2 mins before the light goes red. Is this normal with this battery?

We have the 7.2 3000mah one on order and are going to replace the 2 lift motors with 393s. But are worried since we are going to add 3 more motors later.

This is a rough design ont he robot in the video. Its made of steel so I’m guessing wieght has a big factor but seems odd it would die that fast.

This is our rookie year so we have alot to learn. So any tips or ideas the team would love.

That battery life is surprising but I have used every vex battery except the one you have so that is also a factor.
One huge thing I would suggest to remove the strain on the motors while turning is buy 1 pack of omni wheels
http://www.vexrobotics.com/276-2185.html

The more work a motor has to do the faster batteries are depleted.

My team’s battery only lasts about 5 minutes before going red, so I’d say it’s not uncommon. From my experiences, reducing the motor’s strain will make a huge difference, as a motor working hard takes up considerably more power then one that isn’t.

There was some discussion about this in a recent thread https://vexforum.com/t/power-expander-practical/22186/1

Thanks

I just placed the order for the other battery and the Omni wheels. They are also working on reducing weight ,That video was a few meetings ago.

Another question, What has teams found with charging the battery. We meet once a week and I wouldnt think leaving the battery othe charger for the week is good. We have the smart charger doesnt it matter?

If you look at the documentation (here : http://content.vexrobotics.com/docs/inventors-guide/276-1445-instr-1011.pdf) it says that the charger will shut off once the battery is charged, so I would assume it’s safe to leave them over a week.

Yea I looked at this before. Just wanted to see what teams was really seeing with their chargers.

From what I’m reading our battery is acting normal. I will pass it along to the team and then we can work on ideas to help prolong the life of them. We will also have to work on getting funds for a few more batteries to take to tournamants.

Thanks for helping us newbies out. The kids and I are learning alot in a quick time. We only meet about 2 hours a week so have alot to get done.

With batteries, we have 3 batteries … 2 of them are 3000mah and 1 of them is 2000mah … and we only use the 2000mah for practice, the 3000mah are cycled between matches, but i found the 3000mah battery seemed to work good for 4/5 matches then they dropped to yellow … but that is with all 10 motor ports in use … 8 269 and 2 393 …

If you are draining even the smaller 2000mAh battery in two minutes something is wrong. My guess is that you have a lot of friction in your drivetrain. It’s time to make sure everything moves freely when NOT plugged into a motor. The only other thing I can think of is that your battery is not really fully charged.

This question might be a bit off topic of this thread but here goes.

We have the old style battery chargers (2 ports) and 2000mah ni-cd batteries. My question is, will this charger work with the new 3000mah nimh batteries?

From the product info here: old charger + new battery --> very bad

From the info here: old battery + new charger --> acceptable

Update

The team went through their lift and made some adjustments. One big thing they noticed and even I over looked was they weren’t using the right gears to match the rack gears. We also replaced the wheels with OMNI wheels which turns alot better but all four makes the robot real easy to push so maybe just 2 omins or even try somethings they have read in other post

But the battery works better. The 3000mah works alot better. Least now they can run a whole match :rolleyes:

Thanks