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News and information about the Neato XV-11 Robotic Vacuum. All discussion and troubleshooting questions go here.
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Neato lithium ion battery revisited

April 14th, 2013, 10:12 pm

So, I have a Neato xv-21 and wish it had a lithium battery. In another thread it was mentioned neato will only use 54 watts out of a battery regardless of size. Some were thinking the bigger batteries would last longer because of this feature and not deep discharge everytime. So then if the neato only uses and charges to a preprogrammed maximum everytime why not put in overcapacity lithium ion cells such as used in the hobby industry and let it be? More specifically, 2s lipo in each side for a total of 4s lipo, this would equal the same working voltage as the 12s nimh combination.

Some smart person could do it first and monitor voltage discharge and charge cycles to be sure they weren't over discharged or overcharged by the neato charger. But wouldn't you think this would work?

Re: Neato lithium ion battery revisited

April 14th, 2013, 10:25 pm

I installed a set of LI-ion packs into a Neato. The charging system refused to charge them.

Re: Neato lithium ion battery revisited

April 14th, 2013, 10:26 pm

Even though it has the same voltage, LiPo will not work with the Neato charger.

Re: Neato lithium ion battery revisited

April 14th, 2013, 11:36 pm

Did you only connect the positive and negative (red/black) or did you also transfer the thermistor and its wires (yellow I think) to the li-on packs you made? (computer onboard may be rejecting your packs if no thermistor present) And to be sure of the result you did only put two li-on cells in each hole didn't you? (4 cells total)

Voltage is voltage doesn't matter where it comes from. It should have at least attempted a charge on them or did it start then quit after a while?

Re: Neato lithium ion battery revisited

April 14th, 2013, 11:43 pm

So I'm cycling (on a hobby battery analyzer) the dreadful Mcnair nimh original that came with the neato and finding out they can't tolerate a 1C discharge (3.2a) without getting almost too hot to hold in hand. At 3.2 amps they should last an hour at that rate. I never saw anywhere in this forum or in any post about anyone reporting the temperature issue. Maybe the reason the Mcnair packs are failing is because the battery temperature gets too hot and sets off an alarm in the neato to quit, that and combined with diminishing capacity.

Now can the 3800 and 4500 cells you guys are promoting tolerate a 3.2 amp discharge without getting this hot? I think this would simulate an hour of runtime in the neato.

Re: Neato lithium ion battery revisited

April 15th, 2013, 10:29 am

cwharper- Of course I did. I've been building LI-ion packs for the Roomba and Scooba for over 6 years so there is a little experience involved. The Neato will begin to charge the LI-ion packs and then stop. The packs were built using 1150 mAH 3.7vdc and wired 2S 2P for a total of 2300 mAH @ 7.4 vdc per side and included the thermistors.

The 4500 mAH packs I build for the Neato are tested using a 3 amp load and never exceeded 60C.

Re: Neato lithium ion battery revisited

April 15th, 2013, 11:31 am

In using NIMHs for RC car racing the secret was never charge them unless they were cooled to below 30C. When discharging during a race or post race on a balancer to drop them to 0V per cell(you heard that right) the packs were too hot to hold in your hand. Never hurt them.

I am not sure what temperatire the Neato thinks is too hot. I seem to recall the roomba failing the battery built-in test if the battery temp was > 60C.

Re: Neato lithium ion battery revisited

April 23rd, 2013, 7:11 am

Vic, what you are doing is very dangerous. Thermal runaway of lit ion is a concern when using a charger that will trickle

Re: Neato lithium ion battery revisited

April 23rd, 2013, 10:29 am

kamiraa wrote:Vic, what you are doing is very dangerous. Thermal runaway of lit ion is a concern when using a charger that will trickle


Not true. I use LI-ion cell phone batteries. Each and every one has a built in Power Control Board to manage the charging and discharging. I have been building and using LI-ion packs for the Roomba and Scooba for over 6 years with no issues. Those robots are always on a trickle charge.

Re: Neato lithium ion battery revisited

May 19th, 2013, 12:20 am

There was a report on another forum some one got Li ion working flawlessly in his neato.

Re: Neato lithium ion battery revisited

May 19th, 2013, 2:20 am

jin7 wrote:There was a report on another forum some one got Li ion working flawlessly in his neato.


Seems unlikely given the significant differences in managing LiOn batteries vs NiMh

Re: Neato lithium ion battery revisited

May 19th, 2013, 7:18 am

djos wrote:
jin7 wrote:There was a report on another forum some one got Li ion working flawlessly in his neato.


Seems unlikely given the significant differences in managing LiOn batteries vs NiMh


The guy added other circuits with his li-ions apparently.
Hes yet to share the tech details.

Re: Neato lithium ion battery revisited

May 19th, 2013, 11:01 am

they really should have put these in the units to begin with... nimh are pretty much horrible for anything with a motor..

Re: Neato lithium ion battery revisited

May 19th, 2013, 12:05 pm

dustbunnies wrote:... nimh are pretty much horrible for anything with a motor..

It might seem that way, but in reality I think it has more to do with poor battery management: I have about a dozen NiMh tool and robotic cleaner packs which are all now well over 6 years old, and even with heavy/daily use they all still work virtually as good as new. And of course there's the Toyota Prius which uses NiMh cells, which because they're also properly managed, are guaranteed for 10 years.

Lithiums might be a nice idea, but Neato + Lithiums = Vorwerk VR100 at double the price!

Re: Neato lithium ion battery revisited

May 19th, 2013, 5:10 pm

LiOn cells seem to come in 3.7v or 3.2v. So how do you get a pack to match the voltage of six NiMh cells in series used in Neato's? A pair seems a bit on the low side. Don't see any 4500mah cells either.
Not to mention incompatibility of the charging algorithm programmed.

Re: Neato lithium ion battery revisited

May 20th, 2013, 6:41 am

Most people use 4 cells in series to get a 14.8V battery. Multiple groups of cells wired in parallel are used to increase the capacity. Pre-made packs for RC are typically labeled with the configuration. For example 4S2P means 4 groups of 2 parallel batteries wired in series.

A fully charged 12 cell NIMH pack will very often exceed 14.8V when fully charged but will quickly drop. So a robot designed for NIMHs "should" work with LiIONs.

Re: Neato lithium ion battery revisited

May 20th, 2013, 1:56 pm

robocleaner wrote:
dustbunnies wrote:... nimh are pretty much horrible for anything with a motor..

It might seem that way, but in reality I think it has more to do with poor battery management: I have about a dozen NiMh tool and robotic cleaner packs which are all now well over 6 years old, and even with heavy/daily use they all still work virtually as good as new. And of course there's the Toyota Prius which uses NiMh cells, which because they're also properly managed, are guaranteed for 10 years.

Lithiums might be a nice idea, but Neato + Lithiums = Vorwerk VR100 at double the price!



I can see that.... they are cheap and do work... if the cells are all good and the packs are treated right they should perform well enough. The way the robot comes right back and charges right after depleting the batteries isn't great for battery life but oh well... as long as the battery temps when discharged aren't getting too high they should be ok.

Re: Neato lithium ion battery revisited

May 20th, 2013, 6:12 pm

In Germany someone did the job. No idea how :)



http://www.roboter-forum.com/showthread ... en-Upgrade

Re: Neato lithium ion battery revisited

May 20th, 2013, 6:47 pm

I would suspect that since the mod was performed in Germany it was performed on the VR version and not on a US Neato model that does not have the charging system firmware to support LI-ion packs.

Re: Neato lithium ion battery revisited

May 28th, 2013, 1:45 am

it doesnt seem like it, he replied:

Google translated -
" The term has now been about 2 weeks approx 1h. The batteries are from Samsung regarding what are considered very safe ignition. You are qualifziert to 150 ° C and 12v (3-fold over charging voltage!) The batteries cost about 30 € and the BMS (4x) from 40 € so accounts for 70 € for the hobbyist. If it continues to run one months stable, I release unto you the schematic ... Otherwise, if I have to change what again, I'm constantly having to edit went to ... " - Hausmann
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