(Another?) Question about batteries (and the sabertooth)

Hi again fellow roboteers,

I’ve looked up the forums and the dimension engineerings documentations and did not find a clear enough answer to my question.

They say, for the sabertooth 2x5 at the least, that there’s a function called “lithium cutoff” which prevents a lithium battery from discharging below 3V since it damages the battery and at some point it won’t be able to be recharged ever.

But on the Tri-Track page, you (Lynxmotion) suggest these batteries and charger:

batt: lynxmotion.com/p-727-120-volt-ni-mh-2800mah-battery-pack.aspx
Charger: lynxmotion.com/p-602-60-12vdc-ni-cd-ni-mh-universal-smart-charger.aspx

They look neat for the price and all. I will most probably use that since I’m not verse in batteries except for their nominal values (Volts/mAh). So I don’t know which “chemestry” is more damageable or whatever… So here I go:

First: I guess not, but can I use the sabertooth “lithium cut-off” with the Ni-mh batteries? (maybe they react the same or something?)
If I can, is there some adaptation to be made?

If not, I guess I should read the voltage all the time with an ADC on my MCU and below a certain point cut the power or raise an alarm.

Now, sorry for the dumb question, but the battery and charger is the last thing I need to buy to make start using it. I do have a recycled DC power supply, but it seems it’s not good to use that without a battery in parallel.

Thank you very much,

Alex

We recommend NiMH because it is a safe and proven reliable chemistry. NiMH do not have the dangerous thermal runaway characteristics of LiPo. There is nothing wrong with using liPo, I am just not interested in selling them. For the rover you can use a 3s which will provide 11.1vdc, and the battery protection will work. LiPo batteries have 3.7vdc per cell. So by connecting them in series you can get, 7.4, 11.1, etc. NiMH cells are 1.2vdc each. So there is no way to exactly duplicate the voltage of a LiPo so the battery protection will not work. Hope this helps.