The battery in my robomower died over the winter, so I need to find a replacement. So, I could get a robomower battery from ebay, but they want $175+!!! Froogle prices are about the same. Hard to spend that kind of money when the mower only cost me $185!

So I took the battery pack apart, and found that it contains two standard lead-acid batteries. Here's the information I found on these batteries:

So then I try looking for someone who sells this battery. Turns out it's only sold in Europe. I can't find anyone selling it in the states. So now, I'm trying to a domestic equivalent for this battery. And then find a good price on it. Can somebody knowledgeable about lead-acids help me find equivalent batteries?



Added info: just wanted to point this out for people in the future who might stumble across this thread while looking for their own replacement batteries - the terminal type isn't important. These batteries have the bolt-hole, but there are "adapters" in the battery case that convert this to the tab style. So either kind will work just fine with no modifications necessary.

This looks promising: Powerstream: B&B Battery

The following three models appear to be the correct size and voltage, and differ only in the terminals:
EVP20-12-B1 (in stock), $45.66 ea
EVP20-12-T2 (special order)
EVP20-12-I1 (special order)
Here's the terminal diagram for that first one:

That looks like it should work. Can anyone see a reason why it would not?

Total with shipping would be $112.45
Still seems like a lot to spend on batteries.

Found another: Solar4Power: Deep Cycle Batteries

The ES1712 VRLA-AGM Battery appears to be the correct size, voltage, capacity & terminal.
Total for 2 batteries + S&H = $96.20
Getting better.

According to this page, the B&B EVP20-12-B1 is equivalent to an Interstate SLA1118

how bout this?

or this?

I think I need a battery designed for cyclic applications, which is why they cost more.

A UPS is almost always fully charged. The robomower is almost always running its battery pretty far down every time. Most lead-acids will not last long if they are constantly run down that far.

Let me try again...

how bout this one?

__________________________________________________________________

It may also be worth calling batteries.com to double check and see if they have anything comparable.
batteries.com has this promo running right now:
25% off orders $9.99+, Free 8 Pack of AA Alkaline Batteries, and Free Shipping Code: RAIN

Wow, that looks like a match. And only $27????
I'll investigate more, to see what I'm missing, but everything looks good so far.

Ok, they make up some of it on shipping. $80.94 shipped for two batteries. Still the best price so far.

Also found this: Jameco Electronics: Tysonic TY-12-18, $32.85 ea.
$93.52 shipped for two.

I need to find a local store so I can save on shipping.
I guess a place that sells golf carts or motorized wheelchairs.

Another one: Powerizer LA-12V18-NB, $35.99 ea.
$95.11 shipped for two.

Look up in the Yellow Pages local medical supply businesses. Some probably do in-house service on the motorize wheel chairs they rent to customers and might have the batteries. Otherwise, someone there might tell you where to get them.

http://www.batteries.com/productprofile.asp?appid=265095

Our Price: $27.99

that's definitely the best deal because of the current batteries.com coupon, but apparently garsh mentioned that it's not a deep cycle battery.

you could get two for $42 shipped plus some free AA's.

I might just get 2 of these and just plan on replacing them sooner. That's a pretty good price. Any idea how long the current promotion lasts?

Batteries.com coupon exclusions


Still, it comes to $53.23 shipped for 2 batteries & the free AA's.

Ok, I ended up going with this. We'll see how it works. Local prices were pretty high.

Thanks for your help guys!

Well, after running with these for several weeks, I found that they do not last as long as the original batteries. They don't even last for a full 2 hours of cutting. I'll probably live with them for the rest of this summer, but I'm going to have to find something better.

Still, can't beat the price!

These batteries are dying a quick death. They don't seem to last much more than an hour now. At this rate, I'll have to start cutting my own lawn.
I decided to order two of these. They should arrive on Monday.

How are the Tysonic batteries working for you? I bought some batteries off Ebay and they aren't doing so well after 1 year. Thanks.

Well, they're doing much better than the batteries.com ones. But just this week it's been hitting the "low battery" indication just before finishing the entire 2-hour run. I've been running the mower almost every single day this summer (except for rainy days).

If I were to do it again, I would try the B&B batteries. They seem to behave better under high discharge (300 cycles for 100% discharge, versus 200 cycles for the Tysonic).

so this is for a robotic lawn mower? how cool. does it really work?
what do you have? several acres? how does the thing not get "stuck" all the time?
(you know, like a RC car would)

Yep.Nope. I have about half an acre. It'll take that thing about 5 days, running 2 hours each day, to adequately cut the whole thing. That's a lot longer than it takes me, but then I don't have to push it & sneeze my head off the whole time. This thing is a LOT larger than a Roomba, if that's what you're thinking of. It's a bit larger than a normal-size push-mower deck. But it doesn't work very well on hills, and if you have any ruts in your yard, it can get stuck in them.

Thanks for the info.

20AH B&B batteries (EVP20-12) are much cheaper from Digikey.com - $85 shipped for 2. Check out this yahoo group post.

http://groups.yahoo.com/group/RoboMower/message/10921

http://www.bb-battery.com/productpages/EVP/Evp20-12.pdf

The Tysonic batteries aren't lasting much longer than an hour now. So I'm going to try something else.

I found MK Battery model ES17-12. And I found several places selling it:

• Solar4Power, $44.10 ea + $15 S&H = $103.20
• Infinigi, $43.34 ea. + $25.94 S&H = $112.62
• The Best Guard, $34.50 ea. + $29.75 S&H = $98.75
• Med-Worldwide, $37.10 ea. + $18.74 S&H = $92.94

The Depth of Discharge curve seems slightly better than the Tysonic batteries at 100% discharge, but otherwise it doesn't seem much better.

Thanks, mtran1977. I think I'm going to try these. I found this article about converting a Prius to be pluggable, and it confirms that these BB batteries have some of the best characteristics of lead-acid batteries.

In addition to Digikey, Battery Universe also seems to be selling these for $39.95 ea., plus $15.59 S&H, for a total of $95.49. Digikey is quoting a 14-week lead-time on this item right now, so I'm going to try ordering from BU.

edit: I ordered them and they have them in stock, so they're shipping out today!
I hope these batteries will last for more than one year.

Found another inexpensive vendor for the BB EVP20-12:

Powell Electronics, $39.13 ea., $8.95 S&H, total: $91.91

They have a 9 week lead time advertised, though.

Well I received them today. Instead of the BB EVP20-12 batteries, they sent Universal Battery UB12180 batteries.

They are the same size & voltage, but are not deep cycle batteries and will not work in this application.

Between this and the Penguins being down 3-0 going into the 3rd period, I'm quite angry. I managed to fire off a decently-worded email asking them to send the correct batteries & provide instructions for returning these incorrect batteries.

I just placed an order with this company. The 9 week lead time is gonna suck, but I don't appear to have much of a choice if I want this battery.

Ok, I'm going to try to find the best price on the Yuasa battery. The specs on this battery appear to be even better than for the BB battery (600 cycles at 75% DOD, ~370 cycles at 100% DOD).

• Rapid Electronics, $79.90 ea, free shipping, total = $159.80

And that's all I could find who would ship to the US.

update: I found out that the Yuasa now seems to be called Enersys. That's part of the problem with trying to find this battery. I guess it's not being manufactured anymore, because I can't find the NPC17-12 on Enersys's website.

Another possible replacement: the Panasonic LC-X1220P
Specifications
Doesn't provide DOD characteristics though.

The valve portion is a dead give away indicating they are gel cells. Only gel cells have valves for the sole purpose of venting off excess gases ONLY during an over charge or over voltage situation. (Don't go over 3 volts of battery voltage during charging - gel cells can't take this for long or they will vent and deteriorate) Otherwise they are completely sealed off from the real world not requiring any pressure differentiai because they don't vent like the old lead acid batteries do. I wonder if you can go to a Sears store and get an acceptable replacement? They have Optima batteries that are sealed gel cell batteries.Hawker batteries are on Ebay as well, and they have a great reputation. Be careful around all these batteries. Although they are small. They pack twice the punch as a full car battery.

garsh...in your searches did you find an overall good place for these special type batteries?

I need a Yuasa NP7-12

the local batteriesplus has it for $29.99. I'm guessing it's a generic replacement which is fine.
Batteries.com has one for $21.22 with $7 shipping. (I missed a 35% off coupon by a few days)

Not really.

Battery Universe appears to sell that particular brand/model: link
They also include a list of equivalent make/models at the bottom of the page.
I'm not sure how the price compares. Yuasa (now called EnerSys IIRC) seems to be considered one of the best makes available.

thanks...found it for $24.90 shipped http://www.pacificbattery.com/slaspecial.html

After skimming the following article, I thought of Garsh's search for a decent battery for the mower. But, if this new technology pans out, folks won't have to worry about Robomower quiting on the back 40.

Reclusive green-tech startup whispers a eulogy for the battery

To keep your Robomower and the kids company.



Zeno Could Be Next Robot Boy Wonder

Garsh;

I've read this thread and am in the same predicament this season - need a new battery but don't much want to pay $200. It seemed like you tried a lot of different batteries - what was your conclusion as far as best battery for the value?

Thanks so much,

James

Unfortunately, I found myself in the same predicament again this season. I run the mower once a day for 2 hours, every day that it's not raining. And the bad news is, I've yet to find a set of batteries that lasts more than one season.

I first tried these non-deep-discharge batteries because of the great sale that was going on at the time. Big mistake. They were never able to last for an entire 2-hour cut, and after two months they were barely lasting for an hour.

Next, I got the Tysonic deep-discharge batteries. These did pretty well, and they were the least expensive deep-discharge batteries I could find. But since they still didn't last an entire 2 hours at the end of the season, I tried another brand the next year.

Next, I tried the BB deep-discharge battery. More expensive, but it appeared to have better discharge characteristics. In the end, they didn't last any longer than the Tysonic batteries, so I wouldn't recommend paying a premium for them.

This year, I just ordered the Tysonic batteries again. In fact, they were just delivered today. I'll charge them up tonight and run the mower with them tomorrow. We'll see if they can make it through a whole cutting season.

I think I'm going to reprogram the mower to cut for less than 2 hours. The batteries should last longer if you don't run them down as far in between chargings. Maybe I'll try 1.5 hours and see how that goes.

Good luck!

Thanks, Garsh. Are these the Tysonics you ordered, and was this the cheapest you could find?
http://www.discountpv.com/batteries/TY-12-18

Currently my batteries are lasting about 1.5 hours but because of a problem with my battery pack a couple of years ago I have an extra case, so I might get the Tysonics and a Fast Charger, but $175 for the Fast Charger is again way too steep. Anyone know of an appropriate charger for the Robo battery with perhaps clips that could be clipped to the terminals of the case?

Ideally (for me at least), I'd be able to get 2 full mows each time it goes out but that $175 is a bitter pill...

This is my 4th year on a Robomower and battery life has been an issue - after both my first and second seasons I sent the battery back to Friendly Robotics for Warranty Replacement because they had both failed despite careful winter maintainance and moderate use. I suspect this may be an inherent problem with the battery or the mower.

I like the Robo in all other regards (and love standing on my deck drinking beer and watching it work), but the batteries are a pain and each year I time how long they last at the beginning of the season and they've never broken 2 hours.

Yes, and yes.
A good, 24 volt fast-charger is hard to find, at least at a good price. You could consider opening up the battery case, disconnecting the two batteries from each other, reconnect them in parellel, and then use a good automotive 12v charger to charge them. I've done that. It's more work, but much easier to find a cheap 12v fast charger.
I'm coming to that conclusion too.

Once this thing finally dies, I think I'm going to break down and shell out the money to get a Lawnbott. They use Lithium batteries which should last a lot longer. Plus they weigh a lot less. But I'm going to try to keep my Robomower running for at least one more season.

Okay, I'm a little clueless here but I'd like to look around for just such a charger (and will happily post results here). What would I be looking for as far as a charger - 24-volts and "x" number of amps? Would something like this do the trick?:

http://www.hardwareandtools.com/invt/1151976

Thanks again for all of your help. At this rate we should have a replacement set for all the overpriced Robo consumables!

I can't give an opinion on the quality; but what I read sound good. Recharging at a slow pace and over charge cut off would be something I would look for. At least a 2 year warranty, since that charger ain't cheap. Since many small vehicles in service by the miltary use a 24 VDC electric system, one might look into what charger(s) are used by the Defense Department.

Also pick up a good "gravity" battery tester. Repeat recharging will kill any battery over time. The tester will let you know when a cell goes bad. When it's necessary to add water to a battery, always use distill water. Finally, if you value your vision, wear those safety glasses.

Yes, that looks good. An equivalent 12v charger can be had for less than half of that amount.
A tester is unnecessary for this application.
The mower will let us know when the cell goes bad - it will stop running.
And these are sealed batteries, so adding water is not an option.

Hello guys,

For this info it would be best to join Robomower@yahoogroups.com
Let me cover some things though.
The "capacity" listed on the case is for a slow, 20hr discharge. For a 20AH batt that's a 1 amp rate for 20 hours.
Robomower draws current at around 3-5 amps, and 7-9 when stuck on something and the wheels spin. I'm uncertain of the best rate for approximation, but for an ideal yard where it NEVER gets stuck, if you have a 20AH batt and want to find the 5 amp capacity you look for the (5/20=0.25) 0.25CA rate. For lower capacities you'd have to look at a higher CA number. If your mower keeps hitting "low batt" when its gets stuck on stuff, that's 7 amps and look at the 0.35CA rate.

But not all batts are created equal, even though they come in the same case. The spec sheet of one designed for deep cycling like this should have cycle life depicted, and you want one rated for 300 cycles at 100% Depth of Discharge. I've seen ones only rated for 175x. If it's not listed, assume it's like 175. I've been through a number of "bargain" packs that lost capacity in a VERY short period of time.

At this time the batt which seems to be a safe bet is the B&B EVP20-12. This should yield about 3-4 hrs of runtime and is rated for 300x 100% DoD's. But here's the thing- as one person here experienced, the vendor may advertise an EVP20-12, but in fact he's saying it's an EVP20-12 replacement- and it'll be a crap battery, the only similarity is the physical size! I just got off the phone with refurbusa.com who clarified that indeed the one they list under EVP20-12 under a suspiciously cheap price is another type entirely, one blatantly NOT equivalent and unsuitable for Robomowing. Only 17.2AH, 175x 100% DoD rating, and a pretty low 7 amp rate capacity. It's from a name-brand mfg, but it is a cheaper product designed for standby float use, unlike the EVP20-12 is for frequent deep cycling.

Digikey.com is the vendor I'd recommend for the B&B EVP20-12. Only this model, "B&B" is not a magic name. B&B makes other batts including standby/floats in this case and they will likely crap out just like anybody else's. Digikey will never play substitution games! Right now that's $123.90 + shipping for 2x batts to make up one Robomower pack. This is much cheaper than anywhere else online I've found for B&B EVP20-12, actually. Unfortunately, the price of lead has absolutely skyrocketed in the last 2 years and lead-acid batts cost like twice as much across the board (if it makes you feel better, remember gas is 3x more!).

No brick-and-mortar in-town business will be able to give a comparable price, even when factoring in shipping. Literally, it would not be unusual to see a shelf price nearly 2x this and it's extremely unlikely you're going to find anything but the standby/float types which will crap out real fast in Robomower duty. You will probably see much more than the Digikey price for a B&B EVP20-12 stuck on this cheap, unsuitable type on an in-town business, so basically I think it's a waste of time to even look.

I actually tried this battery (bought from digikey, in fact), and found that it didn't last any longer than the Tysonic batteries. I was quite disappointed, since it does seem to be the best battery based on the spec sheet.

Perhaps I'm just too hard on the batteries, but I was hoping they would last more than one season.

Interesting. They SHOULD last much longer. Even if we're talking about running them all the way down, they'll last longer. Are you SURE you got the EVP20-12, not another type of B&B battery?

The post you quoted was made two years ago.
The price of lead has skyrocketed since then.

Hi Guys... I just googled and ended up here. Great stuff. I am in the same boat as others... probably cheaper though and not technical with batteries... I just chatted with Digi-key...14 week lead time? Also they did not recomend the BP20-12 as a replacement. They did not have an alrernative either.

Yep, I just now double-checked.That's a general purpose battery. In general, lead-acid batteries are not meant to be discharged very far. They don't last very long when used that way. Deep-cycle lead-acid batteries are better for these applications, but their lifetimes are also pretty limited when you're always running them down to empty.

The Tysonic batteries mentioned earlier aren't bad. You might want to get a pair of those for now, AND order the EVP20-12's in time for next season. That's assuming that my personal experience with the EVP20-12 was not typical, and that they really are a much better battery.