Adding the LiPO4 battery settings


#1

Hi,

We are using the LiPO4 batteries on our unit. We just completed the build. What min and max voltage settings do I use so that the battery gauge reads correctly ? Right now I am only getting 2 bars with a full charge.

Thanks !

jon


#2

Yep. We will need to add a preset for those. If you get the latest release candidate (https://github.com/OpenROV/openrov-software/releases/tag/v2.5.1-rc5%2Bb95), you can adjust the setting through the UI: https://www.youtube.com/watch?v=zAqkamgW7PA&list=UUm-sjVIC9Bg_KCSPVws0Rgw


#3

Thanks Brian,

Can you tell me what the min and max voltage should be ?

jon


#4

Hi,

The LiFePO4 batteries oare 3.2v each. We have three in series for a total voltage of 9.6. The two packs are in parallel.

I have set the max voltage at 9.6 and the minimum at 8.0

Does that make sense ?

jon


#5

You can charge the LiFePO4 until 3.45-3.55V - stop charging at this point.

The cell will settle down afterwards to 3.2 to 3.3V

LVC (Low Voltage Cut) should be at 3.0V and the cells should never see a voltage < 2.5V.

If you are charging the cells in parallel - 3 in a time for example - make sure that they are at the same voltage level after charging. That the set is "balanced". If one gets higher than the rest you can discharge it using a resistor (or a light bulb) until it is at the same level as the rest. Then charge again until you are reaching the HVC (High Voltage Cut) point.

This is not an issue (normally) for low discharge currents, but in our case the current drawn by the motors is not small in relation to the cell size.

Hubert


#6

I have this chargers:
http://www.ebay.com/itm/161229036095?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

It have the 3.0v option. Just wonder if it will automatically stop charging at the right level...or I have to be ware and follow it all the time?


Tom-Vidar


#7

We have a couple of those chargers in the lab at OpenROV and they work great. The 3.0V setting is indeed for LiFePO4 batteries, and it will properly charge the batteries to ~3.5V. I have no idea why the switch says 3.0V.