Homebuilt ROVs Forum

To summarize the general internet opinion about Lipos in once sentence: "Do it wrong and burn down your house".

Since that isn't my intention I wonder if anyone would share their parallel lipo setup. How are you connecting them, are you using any fuses to protect the batteries, wiring and components. How have you solved the charging?

I read that it is a good idea to keep track of the voltage on the cells during operation so detect if any cell fails that could possible cause other cells to overcharge. So do you put the balancing cables in parallel as well and monitor the voltage on each row of cells? No monitoring at all? Or some other way?

Hi, I use a balanced charger and I never leave it alone while charging. But a fuse in the cable will help to protect it from draining to much to quick. So far I do not have any experience with that.

I have two in parallel sharing an auto reset breaker. I plan to do field charging in parallel with just the two conductors and then balance when the housing is opened after use.

My "crazy" plan is to have six 5000mah 4s batteries in parallel. all the time.
I will have access to the balance plug and charge plug from the outside.
Also I will be using a temperature probe connected to my charger to stop the charging if temp rises. Many lipo capable chargers has support for this.

fryslan76 wrote:But a fuse in the cable will help to protect it from draining to much to quick.

Would i be correct in thinking a "slow burn" fuse would be best for this? I am just thinking that with a quick burn, running electric motors, you might go through LOTS of fuses...

Slow burning would allow you to have a short peak above the max value, depending on the rest of your hardware that is oke or it is toasted.

I've thought it would be better to see how to connect your (4S=14,8V) lipolys cause I was previously uncertain, too. If you use a equalizer (not a balancer) inside the ROV you don't need to bring out balancer-outputs.

There is no need for main fuse because you need a fuse for every circuit.

Don't worry, a short-circuit (without fuse) burns until all lines before it harms the lipolys fatal. I've seen AWG 12 cable melting down and the lipoly-pack just "smile"... so you can be sure all cables gone before your lipoly will burst.

the greatest danger for lipos is (cell)undervoltage (under 3,2V). It will fatal damage and blow out your pack.

EDIT: BE CAREFUL before connecting Lipos - load them to ~3.85V per cell. If there is a high difference between connected cell they balance(load the weaker one) with HIGH CURRENT. So be aware that cells are +/- 0.10V before connecting.

Interesting. Could you post a link to what this equalizer actually is?

Robbe #8543 - 6Cell Mini Equalizer 130mah Link to description PDF(international)
http://www.robbe.de/media/download//i/n ... zer-6s.pdf

Really tiny and logical module. An equailizer starts balancing cells if top-voltage exceeds 4,2V (while loading) with 130mah. LEDs show you status and balancing-mode of each channel. You cannot use it parallel to charger still have balancer (connected) Only use LIPO (not LIION) Battery charger(mode). With an equalizer it could be the charger will find no end in loading. This is caused by equalizer starts at 4,2V and if all cells at 4,2V its burns the rest of loading current to protect cells from overload. This module will get warm (not hot) but should not be used packed side by side with lipopacks.

There are only germany sellers, but will get it into my shop if youre interested.

* a balancer (which has no need to "start" manually) still working if connected will only need power all the time. Equalizer have no stand-by power-consumption.

BOTH, equalizer and balancer do not prevent cells from undervoltage!

When charging your batteries do you have to disconnect them from your system? I am just trying to figure out a easy way to charge the batteries without opening their compartment.