maillemaker

The battery in my Hovo 510 robotic vaccum is not holding a charge anymore for very long.

I thought maybe I could run in through the discharge/charge cycle a few times on my Venom PR2 charger.

Here is a picture of it:



It measures 16V across the red and black terminals and 2.5 volts across the white and red terminals.

The RC2 does not have a plug that matches this, so I would have to rig something (stick sewing pins in the sockets and use alligator clips?

But, I don't know which terminals to hook up where. Anyone have any idea?

Thanks,
Steve

init4fun

Hi Steve ,

Were this a "mission critical" battery , like one for an RC airplane's transmitter or receiver I'd be telling you to trash it before it trashes your plane . But where this is a robotic vacuum ("Roomba" type I assume ?) and the only danger is a crunchy floor , sure I'll share what I'd do ;

Disclaimer , if you , your bot , or the room it's to clean goes up in smoke remember free advice is worth every penny ya paid for it .

Id set up my charger outside , on a cement patio in case of fire (super tiny , almost non existent risk with Ni-Mh) and use the red and black wires disregarding the white . Red to + , Black to - , set your charger to cycle a 2200MAH battery (the stated rating on your battery's packaging) and let the charger have at it . It's my belief that the white is likely just a lower voltage "tap" that takes from one of the cells away from the full voltage ends of the battery . Oh , and as how to physically connect the battery to the charger ? The alligator clips and pins method would work provided you made darned sure to keep them from touching (shorting) , course on many occasions I've cannibalized different plugs to fit just such situations .

maillemaker

OK, I've got it hooked up and on a 5-time charge/discharge cycle. We'll see if this wakes it up.

Steve

maillemaker

Well, it finished it's 5-cycle charge/discharge, and then I gave it a charge. Now the robot has been running around the room for at least 20 minutes, and before it would not even go 5, so I think she may be back in action! This is great news, as a replacement battery pack is about $70 on Amazon!

Thanks for the help!

Steve

tntpooof

ok this is a 12 cell looks like a C size batter 2200mah so build on wont be 70$..might be around $15 .id use a nimh battery of same size and build my own..id even build one outa a LIfe A123 cell 5 cells.Unlikely the wakeup will last b4 ur at 5 mins runs again.

maillemaker

Thanks, TNT, I might try building my own.

Steve

maillemaker

Welp, you're right, this time it only ran for about 5 minutes again. Could be the base stand charger isn't as good as hooking it up to the Venom charger, too.

These cells seem smaller than C-cell batteries. Any idea what they could be so I can build my own?

Steve

maillemaker

The cells are .871" in diameter and 1.66" long

Steve

maillemaker

I believe these are "Sub C" batteries, size RR. They are 23mm in diameter and 42.2mm in length, which is about what these are.

STeve

maillemaker

I think I need something like this:

https://www.ebay.com/itm/12-pcs-Sub-...oAAOSwNuxXX9AG

or this

https://www.ebay.com/itm/12-pcs-Sub-...YAAOSwc-tY7ed6

Question: These batteries have tabs that appear spot-welded to one another. How is that done? Can I do it with a normal soldering iron and simply solder them down using solder?

Also I believe the white wire goes to a thermal sensor which is glued to the side of one of the batteries in the stack. There is also a white thing, now sticking up, that I don't know what it is. A fuse?

RustyUs

The batteries you linked have tabs already on them. Half the job is done for you. A good soldering iron with a good chisel tip will do fine for making you own pack.

I never seen that white piece on anything before. My guess is it's some type of thermal fuse...it gets too hot...battery connection will be disrupted.

tntpooof

white rectangle with 2 white wires is a thermal interrupter and yes subC are the size..dont think you really need thermal guard.

maillemaker

I have purchased some the 3300 mAh sub-c batteries linked above. I will try my hand at making my own battery pack. It looks pretty easy. I will preserve the thermal sensor and the thermal fuse.

Steve

tntpooof

great but what charger you using?..

maillemaker

The robot has its own docking station for charging. When it detects it is low on power, it seeks out the docking station and docks with it to recharge.

Steve

maillemaker

So my batteries came in and after a little soldering I have my new battery pack. Robot vaccum is back in service!

Thanks for the idea to just build my own battery pack. Waaaay cheaper than buying a replacement.

Steve

tntpooof

good going steve .been building my own for 30 years.