What is the trick to replacing rechargeable batteries please?

The connections are welded. Maybe several thousand degrees will take it off. Normally you bend them off.

Soldering to batteries can be risky both safety and damage. To solder, Dremel scratches in the metal. Use a very hot iron at about 750 degrees F. Time is the important part. You want to heat it up quickly and solder so it has time to cool. Metal strips can be replaced with ordinary wire.

greg

I often wonder why people don't call the manufacturer first. Is it that difficult?

I would contact iRobot and ask them what the recommended procedure is.

On the assumption that iRobot is not stupid, and knows that the batteries will eventually have to be replaced, it seems reasonable that the wires from the batteries connect to a push-on terminal on the main board. If this is so, you'll have to get the iRobot batteries.

Thanks for that everyone: I will try it.

Obviously no one calls iRobot for this question. they just want to sell their expensive batteries. The last thing hhey want is to advise on how to take the battery compartment apart. They even go to the length of putting special screws on it to prevent anyone taking it apart (using a triangular headed screwdriver: Has ANYONE ever come across that on any other unit of any type whatsoever?)

You sure they're not sub-C? They're spot welded. DO NOT SOLDER TO THE NEW BATTERIES. GET BATTERIES WITH TABS AND SOLDER TO THE TABS. Replace 'em ALL at once. Weak ones will be killed by the new ones. "Not exactly, but that's the result." I am pretty sure they aren't lithium!) If you're gonna replace cells, shouldn't you be CERTAIN what they are? Last thing you want is a robot running around your floors ON FIRE! always

Yes, it will.

If you're gonna solder on batteries, Wear safety glasses. Put 911 on speed dial. Order up a whole set of tabbed cells to replace the ones (actually ALL of them) you ruin by overheating. Make sure you understand the charging regimen so you can order the correct type of cells.

Now you're ready to ruin some new cells. Have at it.

OR, you can take it back where you bought it and say, "fix it!"

please or am i supposed to use a

Yes, it's common to prevent people who don't know what they're doing from hurting themselves and suing the company. Certification agencies like UL make a distinction between things that require a tool to open and relax requirements in those areas. But people are idiots, so vendors use fasteners that require uncommon tools to protect them from themselves. Your post suggests that you need that protection, but you're insisting on learning the hard way.

REMEMBER THE SAFETY GLASSES.

I'd send you a picture of the battery pack that exploded after I "fixed it" but it exploded so violently that I never found most of it. The hot electrolyte spots on my glasses was my learning experience.

Hi Amanda, You might want to look at this link, it details what to expect.

Theres a good link to thread of advice on which cells to buy etc

Good luck, I'm about to try the same on my Roomba, JC

The easiest - but more expensive way is to buy 'tagged' cells. These can them be soldered without damage to the cell - a very real possibility if you solder to them direct. But since they're less common on the retail market the prices tend to be high. You might find somewhere local that can weld tags to batteries for you. If you're lucky like me. ;-)

Hi JC

Yes, I had seen that and have two batteries to do: So my problem is probably in getting enough good cells in one of them if I can figure out how (as Mike would put it) to join up two separate tabbed cells without having a spot welder

It is noteworthy that the on line 'experience based' instructions say that you can solder where there was spot welding beforehand. (They dont tell how to get the tabs off in the instructions which I saw, which is why I posted here)

Amanda Ripanykhazova

In general, you don't want to remove the tabs unless absolutely necessary. Use them as "attachment points" to which you *can* solder. Trying to make a connection to the battery (cell) itself is an exercise in frustration and danger (batteries don't like heat; soldering irons are hot -- do the math)

If you *must* remove the tabs, you can usually just wiggle them back and forth repeatedly until metal fatigue causes them to fail. You will end up with a small cluster of "bumps" on the battery case as the "welds" usually stay behind (i.e., you will find an equivalent number of *holes* in the removed tab)

Hi Amanda, I haven't checked out the construction of the Roomba battery as yet but I'm guessing your problem is the original links between the batteries is not an easily solderable metal, maybe stainless steel?. In the link I gave you they are replacing all the batteries so soldering to the original batteries was not a required. The metal case of the batteries can usually be soldered to but its not recommended as others have stated. You may need a special flux and a high wattage iron to make decent connection to the original welded tags. JC

Just to add, it's sometimes cheaper to buy a different make of battery that may be on offer and rob it of its cells to fix another.

--

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW To e-mail, change noise into sound.

This is not generally a good idea. Replacing the bad cells in one battery with new, good cells, is likely to cause cell reversal during operation. You should generally replace all the cells.

It's also useful to have some way of measuring each cell's capacity while discharging it, so you can roughly match the cells' capacities.

Amanda, Lark Battery

Send them an email describing what you need and get a quote from them. They will sell you individual cells with tabs so you can build the battery yourself, or if you wish, they will construct the battery for you (at no additional charge). I have done business with them before, and I can attest to their quality. You will have to describe the battery construction or send a picture so they can construct it. From the web link posted above, it looks to be 12 sub-C cells in series, arranged in a 6x2 pack. There appears to be some additional wiring attached to the pack, so you'll have to attach it to the new pack. Lark Battery are good folks. No affiliation; just a satisfied customer.

Cheers,

I think that's what he means. Rob one (unusable brand) battery to replace the cells of your (wanted brand) battery. As long as the cells themselves are the same, it's all good.

The cells are sometimes stamped, if not, you can get a clue from the label of the battery case (the outside plastic case). They may not give you too much information other than the brand and model, but they usually do state the Ampere/hour capacity.

Two cautions: if this is a battery of multiple cells in series, you must replace ALL cells at once. It is important that all the cells have the same batch number and age if they are charged and discharged in series.

Second caution, the contents of these (NiCd or NiMH) is a caustic liquid, buy tabbed cells rather than trying to get the case up to soldering temperature. The tab ends can take solder temperature or spotwelding without hazard.

"William Sommerwerck" wrote in news:hlmo5e$4d8$ snipped-for-privacy@news.eternal-september.org:

Or take the pack to a Batteries Plus store or other rebuilder and have a new pack built. Usually at a lower cost than a new OEM pack.

"William Sommerwerck" wrote in news:hlnd8g$ctl$ snipped-for-privacy@news.eternal-september.org:

You also have OLD cells with lots of charge cycles mixed with new cells,and the old cells will fail sooner.

Agreed.

agreed.

l$ snipped-for-privacy@news.eternal-september.org:

nd

You can solder to the tabs or to the remains of the tabs where you have pulled them off. Scratch the metal before you solder to get them to take the solder. Use flux also. Replace all batteries, using NMH rather than NiCad, as they have larger capacity. they are sub-C, I have had to replace my wife's roomba batteries, so know first-hand

Sure, but surplus battery packs would more then likely be very similar, if not a little on the depreciated side.