I have a huge arsenal of Roombas. I think the count is up to 3 400 series Roombas
Looking to gain more run time and a longer cell life, I’ve tried out several Lithium Ion battery packs. If you’ve shopped for these, you’ll know that they are substantially more expensive than the plain NiMH batteries. I’m here to tell you that they are NOT worth the extra money. If I could buy a Lithium Ion pack for a 400 series Discovery for the same price as a NiMH, I might do that but otherwise I would advise against it. There are specifics for each robot as to why they are not well suited for use with a Lithium Ion pack. I will detail that below but the long and short of it is that the Roomba charging circuits are NOT designed to optimally charge a Lithium Ion pack. Most of the time the cells are being charged to 4.3v or maybe even higher. If you drop the peak charging voltage down to 4.2v, you gain substantially more charge/discharge cycles. I would say 4.2v versus 4.3v would result in a 100% increase in charge/discharge cycles.
The other problem is protection circuitry. Most(all?) of the Lithium Ion packs commercially available for the Roombas and Scooba do not have separate balancing/charging circuit boards. They all rely on “protected” cells. The protected cells have a circuit built in to protect them from catastrophic over charging and/or over discharging. These protection circuits are set at the absolute upper and lower limits of the cell’s operational ranges. They are set to protect against explosion and cell instability, not for cell longevity. Here are more specific problems present in each of the iRobot platforms:
500 series – The charging circuit is very touchy and is expecting specific characteristics. If those aren’t met, you will likely get an “error 5” on the screen. Much more likely than you would with a NiMH pack. The internal charger also will consistently charge this pack over-voltage. It’s supposed to be 22.5v on the input side but mine puts out 22.97v even in circuit. I’m taking a wild guess that mine is not the only one that has this problem. By the time you trace the voltage to the battery pack, it calculates out to over 4.3v per cell which is too high.
400 series – The 400 series is probably the best candidate for a lithium-ion battery pack but still not necessarily a good one. Most vendors who sell these lithium-ion packs are relying on an internal cell protection circuit and the Roomba’s over discharge circuit to shut the pack down. Neither of these circuits are actually designed for that purpose. The Roomba’s circuitry is adjusted to optimally discharge NiMH packs and the internal cell protection is worst yet. That is ONLY a last resort and should never be relied on to repetitively be used for that purpose. If the cells somehow become out of balance, this can start happening a lot. The symptom is that the Roomba won’t park or go to a red light, it will simply die in the middle of the floor and become entirely lifeless. The power button won’t do anything until you charge it enough to be recognized. Another problem with the 400 series is that the Li-Ion pack makes the Roomba much lighter and it seems to have a harder time making contact on the dock without the added weight holding it down.
Scooba – This one is one of the worse of all. Personally I have a BAD habit of not taking the battery out right away when the Scooba dies. While I was fixing a Scooba for a friend one time, I was probing around trying to diagnose a problem and found that even when the Scooba is TOTALLY off, it’s still drawing quite a bit of power. I tested the output leg on the 78XX series regulator and found voltage there and a few other places. The logic was all still hot and drawing power as well. The power switch on the Scooba is essentially soft power. This is probably the case with the Roomba too although I haven’t tested it. The difference being the Scooba isn’t designed to dock. Not only that, I’ve always charged the battery out of the unit in the Scooba Charging Base
The bottom line is that you are far better off sticking with NiMH battery packs for the Roomba, Scooba and Dirt Dog. I have used the Tenergy Scooba Battery
If you like the content on this site, please support it by using this link to order from Amazon. You know you were going to go there and buy stuff anyhow so why not help me pay the hosting bill.
Thanks for your info on Lithium batteries used in a roomba, I have been contemplating it for a while. But I guess I will just by another NiMH.
You MIGHT get lucky but at the prices they try to charge for the lithium scooba packs, it’s not really worth the risk.
You may want to update your information because I have a lithium battery in my roomba right now, and it indeed has cell balancing technology built right into the pack. I bought it from http://www.lithiumpowerinc.com for $80. They told me in an email that they are working on one for the Scooba line as well.
How long have you been using the pack now? Longevity was my main issue. The battery life was fabulous while they lasted but that was never long enough for the price.
Though it’s not a good idea in your opinion, thousands of people are using Lithium batteries in everything ROBOTIC lawn mowers to ROBOTIC gutter cleaners
The lithium battery in my Roomba is going strong like new.
It’s just not fair that a google search for “scooba lithium” brings up your page first.
Just because it was your opinion in 2010 that Lithium batteries are “not a good idea” doesn’t mean things don’t change.
You should test a pack out for yourself, or take this page down. It’s not fair to those who sell an excellent product (with 2 year warranty).
.
I have a roomba, if I charge it then unplug it and leave it for a week, the battery has been drained. The roomba does seem to use power while off. I looked into Lithium but a complete discharge of a lithium batter will be very hard on its longevity. Until iRobot makes a roomba that specifically designed with lithium in mind, I’ll be sticking to NiMH despite it reaching it’s half life in 2.5 years.
I have many many roomba. Most are dead. I have stop using scooba the 500s 600s. I now have 3 770s and 780. All were NimH. I have made many many battery packs trying to improve on OEM packs. Tenergy I had high hopes for. I have stop making packs due to poor cell rating and short life span.
Using LiIon on 770 and 780 for about 6 months. Cleaning schedule are each day so my roomba see a lot of charge dis-charge cycles. So far LiIon and the charging circuits have held up.
The problem is that the roomba has no internal cell balancing circuitry to deal with lithium cells. Many of the packs designed have no balancing circuitry either and simply rely on the over and under voltage protection circuitry to keep the battery in good health. That’s like driving your car around and using the redline cutoff as your shift indicator and then still exepecting to get 100,000 trouble free miles. The Tenergy cells have been a real mixed bag for me. Some good and some bad. Glad to hear you are having good luck with your lithiums right now. Did you build them or buy them? Did you add in a cell balancer?
I have a scooba 5900 which I’ve had for almost a decade. It went through NiMh battery packs about every six months. The first few were replaced under warranty. The rest bought on my dime.
I finally bought an LiIon aftermarket battery. It has a built in charge balancer/regulator board and last about 50% longer than the regular battery.
The amazing thing is that 5 year later and hundreds of uses, it still holds the same charge and works as good as the day I bought it. One of the best purchases I’ve made.
Which one did you buy and from where? I’m sure people that stumble onto my blog would be interested as would I. I bought several Lipos and they were all terrible but I believe they did not have balancer boards built in. I think the theory was to use built in cell protection circuitry to do the job which is just totally unacceptable.
I purchased it from Roomba Exchange. I don’t think they’ve been made for years. I can no longer find them. At least I still have one that works great and hopefully will for at least a few more years. Unfortunately Li-Ion batteries don’t last much beyond 400 or 500 cycles before they go down hill fast.
BTW, you couldn’t just use Li-Ion batteries in place of NiMh batteries without some sort of circuit that converts the constant charge current to the pulse type needed by Li-Ion. It wouldn’t work and would be very dangerous. So yea, don’t just swap one type of battery for another. Li-Ion requires very specific charging algorithms that constantly monitor the charge rate, temperature and backoff on the pulse charging as the batteries charge rises.
What a load of doublespeak. It’s sad because this is one of the first results that Google shows.
The iRobot NiMH battery packs do not have individual cell taps either. So there is no “protection circuitry” for the NiMH packs that’s worth a damn, and I can attest to that after having one nearly catch fire in an iRobot fast charger. Given that finding end-of-charge is already screwed up for the NiMH chemistry for just 1 cell, putting, what, 12 cells in series without any taps works about as well as you would expect — i.e. it doesn’t. That’s why the NiMH packs die so quickly.
Furthermore, there are multiple lithium battery types. You don’t seem to be aware of this. The LiFePO4 cells are much more robust, easier to charge, and have better energy/power density. Usually the packs don’t go out of balance until end-of-life anyways, and they’re way more difficult to blow up so the taps are a little overkill anyways. The RC guys have been beating the crap out of these cells for, wow nearly 8-9 years now. Even at the time of writing, this article was still 4-5 years behind the times.
The charging circuitry needs to be change, but the charging lithium batteries is way easier than looking for some screwy delta-peak-whatever on NiMH cells. Some people have been zip-charging LiFePO4’s for hundreds if not more than 1000 cycles. It’s an easy change.
It’s ridiculous for iRobot to continue selling NiMH packs. To the point where the Roomba is more like an overcomplicated scheme for spurring the sales of NiMH batteries.
I wrote this blog post to prevent people from buying the lousy lithium batteries that I saw offered for about $150 for the Roomba 400 series at the time. I went through about 3 of them before giving up on them. Not to say that there are not better packs available now. Looking around now I see many choices for less than half of what I spent but I’m still a bit wary of them.
I agree with you entirely, it is pitiful that iRobot does not use lithium batteries in their vacuums. I have a set of Makita cordless tools with lithium packs and they are phenomenal. The difference though is that they are bundled with a charger that can properly deal with the cell chemistry and structure.
In my opinion, Roombas’ built in charger is very primitive and not suitable for charging a pack of lithium cells that are strewn together in series. You make a great point that it’s hardly even suitable for charging the NiMH packs. The Makita packs have a breakout header that goes to a balancing battery charger which I still feel is the best way to do it. I have a couple of RC plane and car packs. They also use balancing chargers. Not to mention the Shorai lithium-iron battery in my motorcycle which also uses a balancing charger.
I disagree that multiple charging taps are overkill. I’m all for anything that can make my battery last longer and adds a margin of safety. It’s not like balancing controller chips are all that expensive. Trusting individual cell protection to protect against an out of balance situation still seems like a bad idea.
You mention the RC guys beating the crap out of LiFePO4 packs… Yes, those are great packs and would serve nicely in a Roomba but I am not aware of any of those without balanced charger breakouts. If guys are charging those with NiMH chargers and getting away with it, more power to them. But why?
The battery is not the only place iRobot cheaps out on though. These vacuums are built like toys. While they are putting lithium batteries in our Roombas, I’d urge them to consider brushless motors and metal gears. A few minor changes would easily make these Roombas worth the $300-$600 they are charging for them.
Any thoughts on the claims of the Roomba X-Life batteries? They claim to last twice as long as the normal stock battery. From your experience, is there any validity to this claim?
Thanks!
I have not used them or seen them so I can’t comment but perhaps I’ll buy one for my next replacement pack.
Sometimes articles like this are just wrong. There is no reason a Li-ion battery system can’t work – all Li-ion batteries have built in circuitry (for safety and other reasons). One would want to optimize the circuitry to work with Roomba systems.
It looks like that is just what they did over at lithiumpowerinc – comes with a years warranty.
Thanks for reading. You are correct, there is no reason Li-ion systems can’t work in a Roomba. You are incorrect about your next point however. You say “all Li-ion batteries have built in circuitry (for safety and other reasons)”. They do not. “Protected” li-ion cells have built in circuitry for over charge and under charge protection. There are many more non-protected cells out there. You are correct when you say the protection circuits are built in for safety. They are NOT tuned for cell longevity however. If you discharge a li-ion cell enough that it triggers the built in over-discharge protection, you have gone too far and are shortening the life of your cell. Using built-in cell protection as your only means of controlling charging/discharging is a lot like driving around town and only using your e-brake to stop your car. Sure, you might be able to get the job done but that e-brake is only there in case your hydraulic braking system fails (aside from parking).
I maintain my original point which was to say that if you want to use li-ion cells in a roomba, you need a pack that has a cell balancing circuit. This circuit pretty much has to be external to the cells. I took another look at Lithiumpowerinc’s offerings. My guess is that if you take one of these packs apart, inside you will likely find a small circuit board that performs that balancing functions as well as puts in a hard discharge cutoff at 80% as stated on their website. If this is the case, this product would be well worth the money. Next time I need a pack, I will likely buy one from these guys since it sounds very promising.
Let me point out that my blog post here is 5 years old. At the time I wrote it, there were a couple of hucksters offering lithium packs that were simply built up by stringing a bunch of protected cells in series. Some of my friends, family and I purchased these packs with high hopes and we found them to be extremely expensive and short lived. The first times we used the packs we were amazed by the incredible run times but they died in the matter of a couple of months. Our research into why this was happening led to this blog post.
If the guys at Lithiumpowerinc would like to send me a couple of packs, I’d be glad to give them an honest review here on my site and I’d even put a link to the new review in straight from this page. Otherwise, I’ll simply purchase a pack next time I need one and write it up sometime in the future.
i personally use the lithium mod for both of my scooba 5800 and 5900 but the battery packs have balancing connectors and i charge them using a IMAX B6AC+ and it has been working very well, the battery pack has no protection, but no problems so far, for the cells i just teared appart some laptop batteries i had lying around, the best part is capacity wich is rated about 8400 mah, i would recommend doing this only if you have soldering and electronic skills… but has many benefits i didn’t included pretection circuitry on te battery pack so i could fit the 12 cells 18650 lithium ion batteries, that way i can have the same weight of original battery pack…
I’m wary of the Lilthium Power Inc battery linked in an earlier comment. They sell directly on Amazon, and there’s a single account that posts glowing “surprised” reviews of the product… and then the same account claims to be the manufacturer when replying to other reviews and product questions. That kind of astroturfing makes me suspicious of any mention of the company whatsoever.
I agree. Very suspicious.
That said, Tenergy recently sent me a lithium pack to review. I’m not sure if it’s the same pack that Lithium Power sells. I’m going to give it a fair shakedown here and eventually post my results. Here are my initial thoughts. http://www.notanon.com/gadgets/tenergy-li-ion-4400mah-roomba-400-battery-review/2015/10/03/
I had a pack for my 560 from http://www.lithiumpowerinc.com (which mentioned in the earlier comment). It died after a week without charging. It also failed when I tried to recharge it manually. Any laptop pack would have over discharge protection that lowers the output voltage when the internal voltage is down which stops the current drawing. I don’t see any reason a roomba pack this expensive without one.
I too ventured into the lithium world with a roomba but instead of buying a pack for it, I removed the old cells and installed new cells in my old pack. So I built a charge balance circuit and a voltage regulation circuit into my pack. With a soldering iron and about $3. Worth of parts you can easily overcome these issues. In total I spent about $40 building my pack. There’s no shortage of diagrams and parts list on the net to build these circuits. I don’t see why a 0.5vdc voltage difference would cause circuit problems but I heeded your warning none the less and put in a voltage regulator. Problem with the packs online is they’re all made in China and they could give a rats ass about your device or battery longevity. Matter of fact they probably want to shorten it’s life since lithium doesn’t suffer from cell crystals or memory issues. I replace all of my standard cells with lithium. I’ve done so with great success in drills, inficon refrigerant leak detectors, rechargeable refrigerant scales and numerous other tools and items that use nicad and nimh. Thanks for the info.
Then what is best for the ROOMBA, then? I have found after many ruined sets that NIMH don’t like to have all their battery cells charged in series as a single group, even. Every time I have used a pack charger, one or more cells in the set have always gotten out of balance, and stayed there, sometimes even leading to leaking and venting. It looks like one or more cells with less capacity always get overcharged, maybe that is why the ROOMBA goes through so many NIMH battery packs. I have found that NIMH like to have their cells individually charged, even charging them in pairs in the cheaper chargers have led to me literally frying some cells with a crinkled wrapper to show for it. Maybe the ROOMBA needed to use a different charging cutoff. It looks like there are no protected NIMH cells, but it probably wouldn’t be a bad idea for this application.
The Roomba has a poorly designed charging circuit based on my observations. Things would be drastically improved by a balancing charger. You are correct, inevitably one or more of the cells in a series pack always get out of balance. This is especially bad in the case of the Roomba because it has a 10 cell pack. When the cells start to drift out of balance, some will end up getting over-charged and others will end up over-discharged. Take a look at a quality piece of equipment such as Makita lithium ion cordless tools. Right away, you’ll notice a bunch of extra tabs on the battery for individual cell balancing.
irobot doesn’t do this because it costs a little extra(maybe a lot extra to balance 10 cells) and they can make more money by having a “good enough” charger that ultimately fries packs every few months. We all keep buying them. Is there really a better robotic vacuum? I haven’t found it…. All this being said, I would far rather overcharge or overdischarge a NiMH pack than a Lithium pack. In most cases they will overheat and vent instead of explode and catch fire.
I guess you could always try replacing the NIMH with NiCad cells, though I have also fried the more robust NICAD batteries in the pack charger, even, though set at the slower charging speed of .9 AMPS. However, this would likely lead to the imbalance problems over time as I mentioned earlier, though the NICAD might last a few months longer. Of course, the run time would be shorter. All I can seem to find for NICAD C cells is the Tenergy NiCad C cell at 3500MAH. They took only about an hour to charge in my MAHA at 2 AMPS, so they may be more like 2000-2500MAH. I would suggest staying away from any ROOMBA devices until they add better circuitry. And you are right, the protection on the lithium cells are not designed for longevity. They are probably cutting the power at 2.5 volts, which is way too low, when it should be cut off at 3.0-3.1 volt per cell. Oh, and this is exactly why the ROOMBA circuit is bad for NIMH, just like you said. Even with a well matched pack, you would get overcharge with a Delta drop. (the same one or more cells overcharged problem, and having them lose capacity, going out of balance) You would need to cut the charge sooner, when the voltage stopped rising. However, virtually none of the current chargers use the zero slope detection method. The Panasonic 7 hour charger that comes with Eneloops probably does, though you would not be able to pick up a negative delta V voltage drop at that slow rate anyway.
The reason why quality NIMH last a long time in the MAHA chargers is that the chargers charge each cell individually, so that none get overcharged, which is why the voltage drop detection method works for that system. Try it in a pack charger setup though, and you will have problems. Of course, lower quality cells have always gone out of balance on me, no matter how smart the charger. It’s too bad you couldn’t just use Eneloops with the ROOMBA, and just charge the Eneloop up in a smart charger. Since the ROOMBA uses 10-12, you would have to try to find one that does so many at a time. I guess having so many cells in the ROOMBA gives much more opportunity for a pack to go bad, which is probably why so many people went through so many NICAD packs on the power drills. It just took a little longer due to the more robust chemistry. Then you have the iffy quality cells used to make the packs that may not be matched to begin with. This happened to me when I had a bait and switch done on me, and I got the D size NICAD instead of NIMH. Poorly matched, and they were garbage. I got my money back and recycled them. (no name brand on a yellow green wrapper) I reckon that those cells in the ROOMBA pack might come out of the factory with up to 10% mismatch.
Ya the real answer is that you should not be charging any battery in the roomba at all. You should custom build any pack you use with a 24 pin balanced charger connector. When the cleaning cycle is done, pull the pack out and charge it on a balanced charger.
Almost practical on the 400 series. Totally ridiculous on the 500 and up.
I was just wondering how a 24 pin balanced connector might be constructed or hooked up to the charging system. I reckon that it will require you to be handy with a pliers and soldering iron. . I was in a shock to see how much they charged for the IROBOT. I am wondering if a Battery Management System does exactly that, handle the balancing.
Hi Geordy,
I’m looking for replacement battery for my 500 series roomba and stumbled upon your website. Do you have any comments on the Li-ion batteries from CyberTech on amazon (Link: https://www.amazon.com/gp/product/B00SWHC39E/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2N2XU9MDOANQ2) that claims the following on their battery pack?
– Patent battery balancing technology for expanded battery life; remains fully functional after 800 charge cycles
– Built-in over-charge, over-discharge, over-voltage, over-current, and over-temperature protection
Are those the protection you have been wanting in the battery packs when you originally wrote the article?
Their description certainly talks a good talk. The 800 cycles is most likely a rating of the individual cells, not the pack as a whole even though it would lead you to believe that it is. To me, this line is a giveaway “Built-in over protection circuits provide safety and reliability”. The key word is “circuits”. That means they are built into the cell which once again gets back to my point. They are improperly relying on safety features instead of using a properly designed conditioning circuit. I’ll throw out my analogy here again. It’s like driving your sports car around town with your pedal to the floor everywhere and using the rev limiter as your only governing device. Your car will not last long this way and neither will your lithium batteries.
The part that confuses me a bit is the “Patent battery balancing technology”. In my idealistic world, that would mean a proper dedicated balancing circuit board that was hooked to all cells and controlled the charge current for the cells individually. I’m 99% sure this is not the case.
If you read the reviews, it looks solid until you see this one “Absolute junk! The other reviews are suspicious.” That guy might be on to something.
On the other hand, it’s $56 instead of the $140+ I have spent on lithiums for various things. Not much more than a cheapo Tenergy pack. Of course on the other hand, the Tenergy pack might not burn your house down while you’re out. 🙂
The typewriter is better than printers because it needs no electricity and fewer parts and doesn’t go bad. I’m gonna spread it to the world that the typewriter is better. Nimh and nicd are the typewriters of batteries. Before printers there were electric typewriters ,a few may still use typewriters like myself. It’s a free country as long as you don’t become stubborn and violate the establishment clause of technology.thnk you
Nimh kills roomba 500 and up because the excess voltage of nimh fries the infra red emitters causing it to go in circles. Li ion doesn’t go over 4.2v per cell at full charge from working volts at 3.7 per cell. Repairing nimh damaged 500 and up far exceeds the cost of li ion batteries that are now way cheaper than in 2010. You can even build them with pcbs that can take wide input voltage per specs. Time spent on labor costs more than buying a new one. But alright for hobbyists best wishes!
I never said lithium isn’t better. Clearly it is way better. The roomba is the problem. Irobot is the one that is refusing to get with the times. They insist on using cheap charging circuitry that fries ALL battery chemistries prematurely. I suspect someday they will start shipping Roombas with lithium batteries from the factory. Or maybe they just let the competition overtake them finally and we’ll all be talking about a different brand here.
So you are saying that the infrared emitters on the 500+ are driven from an unregulated supply rail?!? If this is really the case then the design of these things is way worse than I thought. Do you have any evidence of this that you can share here?
I’m selling my roomba and getting a shop vac
Geordy – Appreciate the information , I just bought a li-on battery from the link below. I have a 552 model roomba and paid about $121 with a 30 return and 1 year warranty. Too bad I ordered before I saw this, I do have experiences with lead acid batteries and li-po batters – used in RC planes and Quad , HEX copters. Do you have any knowledge on how I could charge this battery outside the roomba as I have a external charger that could potentially charge/balance the battery better then with the roomba charger? Thanks!
http://www.irobotbatterycanada.com/product-page/4487142431
$121 is pretty pricey for 2017. Lead acid are basically like car batteries. They are fine but really heavy and they don’t like to be over-discharged. RC car/plane Lipos have the same problems as other lithium batteries with regard to charging/balancing/etc.
The only way you could charge the battery outside of the roomba with any better success would be if it included a balancing port. A balancing port basically just gives you a direct set of wires to each individual cell in the battery pack. If you want to see some guys who do it right, check out these guys. They make lithium batteries for motorcycles. If you see that little grey cover between the battery terminals, that is the balancing port. The charger they sell plugs into there. http://shoraipower.com/products
original article is definitely out of date, but comments are germane. I have used an R4 Li-Ion 4400 mAh replacement batt from Lithium Power in my Roomba 400 for ~ 18 mo. now. At $60 I think it was a good purchase. It does have a full balancing and protection circuit (more on this later). Time will tell if it lasts; usually li-ion is good for several years, but as with NiMh or NiCd, care is crucial.
I also use and have used standard NiMh packs, and because charging these heats up the machine and themselves so badly, and this is very hard on both, I charge all packs in the machine on regular charger, but it’s wired to a timer so they only charge for ~16 min, then rest and cool for 5 hrs. This way everything stays room temp. After lite shows green OR they’ve gotten 4-5 cycles, I remove them from the machine until next use. And before the next use, I again charge them for 2-3 16″ cycles.
Lithium R4 pack charges MUCH more quickly than the NiMh packs and NEVER has heated up the machine or itself, even if left on the charger a long time. BUT it doesn’t have any more endurance than good NiMh packs — with both types, I get 42″-48″ of cleaning on carpet until light goes yellow or sometimes red. I NEVER let the light go red for long.
With both types, and my intermittent charging method, I cannot trust the charging light to go green when full charge is reached. Sometimes it will, but normally I just use ~6 x 16″ cycles which brings packs to full voltage (unloaded).
At about 10 months of use, the lithium R4 pack went dead, tho it appeared to charge. All cells inside were equal and measured 3.7 v. So an expert online guessed that the balance/protection board had gone bad, and he was right. For <$13 I found a 4S 10A protection board on eBay, wired it in, and the pack is back to full operation. Details of rebuild are here:
http://www.robotreviews.com/chat/viewtopic.php?f=4&t=231&start=600
Alas the Lithium Power R4, for 400 series, does not appear to be still for sale.
They are still making packs for later models.
Bottom line: when my current NiMh or lithium packs go bad, I will rebuild with li-ion cells +/- new protection/balance board if needed. Cost should be $25-35 depending how much needs replacing. This is very feasible for anyone with a little electronics skill.
Thank you for taking the time make this comment. This is valuable information for anyone considering using a lithium pack in a Roomba. Your timer setup sounds very clever. 4 or 5 cycles is really enough to charge them?
I don’t know anything about the R4 pack but I have a Lithium Power S3 pack sitting on my desk here. I put it into service November of 2016 and when I went to use it a couple of days ago, it’s pretty much shot. I get about 5 minutes of runtime with it. During that amount of time, I would say I only cycled it 10 times or so. IMHO, whatever balancing/conditioning board in the pack needs to handle the harshness of the stock chargers OR they need to offer a proper external charger suitable for this sort of battery pack. Otherwise, my original opinion stands that lithium packs are still a bad idea for these older models of robots.
I’m glad to hear when you opened your R4 pack up that you did in fact find a balancing/protection board. That means they are in fact doing what they are promising. It’s disappointing that this board failed in 10 months however. I would argue that 99% of the target consumers for this sort of pack would not be capable of the replacement procedure you outlined in your link. Also, I am mildly concerned about your comment in the other thread mentioning that the new balancing board offers slightly better runtime. That can only mean that the new board has slightly less conservative parameters for protecting the circuit. Let me ask you this… Does your Roomba die at the end of the cycle or does the voltage drop enough for it to go into a normal docking procedure?
I’ve noticed that some of the newer robots are offering lithium packs from the factory. This is good news. They will be forced to make the proper changes for this chemistry.
What about the 800 and 900 series? My 805 came with Lithium from factory.
Kinda strange that iRobot didn’t move into Lithium sooner, not exactly a new technology, and able to clean a larger room in one activation logical? and not until you get a very expensive 900 series do you get the recharge&resume feature.
I’m going to assume that the newer units such as the 800 and 900 series having been designed properly from the ground with lithium batteries in mind. I don’t have any of them to test out so far but I’ve generally heard they are better the the old models.
I have got Roomba 600 Series. (Roomba 620 exactly)
I have bought Li-Ion battery 14,4V 4400mAh (non original)
Now (after one month) Roomba shows Charging Error.
I have checked the voltage (load by 10ohm resistor) and it has 16.89V !!!!!!!
Be carefully what are you buying.
There was something else some of you mentioned. There was mention of cheap charging circuitry frying batteries. You guys are right. If the circuit is charging lithium ion to 4.3 volts, that is too high, the pack will not last. Depending on the protection on the cells will not lead to long life.
I purchased three lithium ion batteries for my roombas (3) and they all failed with charging errors (5) and led me to believe all my roombas were broken. All three ended up getting scrapped and I have three expensive Lith-ion batteries just sitting.
which series of Roombas?
IMO for the amount of money Roombas cost, they should come standard with 1) brushless motors 2) metal brush deck gears 3) lithium batteries