Electrified lawn care lithium battery upgrades

Discussion in 'Off-Topic' started by TheForce, Mar 20, 2015.

  1. TheForce

    TheForce He who posts articles

    This year I am upgrading my battery powered lawn equipment to lithium batteries. I will try to document the upgrades as much as I can. This first post will have all the information.

    I'm starting with my Ariens AMP riding mower.

    Ariens has discontinued this and no longer makes an electric riding mower. Read my review of it here. http://www.cleanmpg.com/forums/showthread.php?t=31097


    To start off I'm replacing the 20 SLA batteries in a 4S5P configuration for a total of 48v 75Ah

    with 16 CALB CAM80FI LiFePO4 80Ah cells.

    The batteries were ordered from http://evtv.me for a total of $2,215.12. The reason I picked these cells was because of their height and capacity. A bit pricy but they should outlast the mower and will pay for themselves in about 10-12 years given that lead batteries will last about 4 years and their cost.

    With these lithium batteries I expect to be able to cut my whole yard every year on one charge. With the lead batteries every year seen about a 25% reduction of run time. Since I have a robot lawnmower that cuts 90% of my yard I dont have to worry about loss of run time but if something happens to my Lawnbott I can still use my riding mower to cut my whole yard if needed. I also plan on using a 5000W pure sine wave inverter with these batteries as a temporary backup source for power when the electric goes out.

    To go along with this battery upgrade I will be installing a proper volt meter and amp hour counter so I can tell how much juice I have in the batteries and how much the mower is using. The included fuel gauge and amp meter on the mower is just crap and you cant even see the fuel gauge in direct sunlight. Plus the fuel gauge does not really tell you anything and has never been helpful.

    I'm currently in the process of bottom balancing the lithium cells. I will update with more information and pictures as I go. I hope to have the mower ready before the grass gets too high.

    Black & Decker 36v Cordless Push Mower


    The original SLA batteries were 10Ah. I ordered 10Ah LiFePO4 batteries from http://www.batteryspace.com
    Price was $291.00 not including battery holders and connection plates which were $12.76 and $14.52. The total was less with a 5% discount.

    I could have ordered the 15Ah batteries but after measuring it would have been a tight fit. Plus 10Ah was getting me plenty of cut time anyway and they was cheaper. I could have even gone with 20Ah cells but that would have required a battery box modification. These will be a drop in replacement of the SLA batteries.


    Black & Decker 36v Cordless Trimmer


    The original Ni-Cad batteries were 2400mAh. I ordered 3300mAh LiFePO4 batteries from http://www.batteryspace.com Price was $90.24 with solder tabs. I ordered these with the push mower batteries and received a 5% discount on the total.

    I could have gone with 5000mAh cells but after measuring I don't think I could fit them into the Ni-Cad battery box without heavy modification. I estimate I should at least have 25-30 minutes of cut time with these batteries which should be plenty for me. On a good day the original batteries would let me get about 90% done so I think these lithium batteries should be OK. Worse case I can always buy larger batteries next year and make a fanny pack out of them for longer run time.

    Last edited: Apr 5, 2015
  2. bestmapman

    bestmapman Fighting untruth and misinformation

    Nice Jay. Good to hear from you again.
  3. TheForce

    TheForce He who posts articles

    I've been busy the past few weeks trying to bottom balance all these cells. Bottom balancing is very time consuming. I did manage to order cells for my push mower and trimmer. I've updated my first post with some info and pictures.

    I should have my riding mower batteries bottom balance by April 11th. I'm at the stage of just taking out a few milliamps now to get them all the same voltage. My target is 2.500v which is at the very far end of the LiFePO4 discharge voltage. My wire crimper and some heat shrink should arrive before Saturday and if the weather is nice I should have a test ride either that Saturday or Sunday.

    The following week I should have the push mower ready for a test cut.

    The trimmer I'm not too worried about as I have to make some kind of battery mount and so some testing with the stock NiMh charger to make sure it does not over charge the lithium cells. Worse case I'll just spend about $30 on a lithium charger for it.
  4. TheForce

    TheForce He who posts articles

    Well I got the batteries for the riding mower bottom balanced, installed, and charged. The bad news is that half way cutting my yard the front right wheel fell off my mower. I have replacement parts on order and should have a working mower again Saturday. If the weather is good I'll try to do another test.

    Here are some notes on the charging and cutting process.

    While charging the weakest cell was at about 3.9v at the end of the charging cycle. The total pack voltage was 57.7v at end of charge. 57.7v divided between 16 cells is about 3.61v per cell. This is under charging the cells by a little. Undercharging the cells will let them last much longer so this is a good thing and I can keep using the stock charger that came with the mower. After settling down the voltage was about 53v. During cutting I was using about 40-50 Amps and the voltage dropped to about 50.5v for the entire half yard cut. Lithium cells have a very flat discharge curve. With SLA batteries I would have been around 46v. Since I did not get to finish my yard I dont know if I can rely on the voltage as a fuel gauge or if I will have to use the amp hour counter as a fuel gauge yet.

    According to the meter I put in about 40Ah when charging and that seems about right if the meter is correct.

    Right now my Lawnbott is trying to get the rest of the yard cut but its having a hard time since the grass is pretty thick in some spots. Hopefully I can do a proper test this weekend and maybe get some video and more pictures of the upgrades.

    Here is a picture comparing the SLA to the LiFePO4 batteries. SLA 48v 75Ah ~200lbs, LiFePO4 48v 80Ah ~80lbs

    Last edited: Apr 14, 2015
  5. TheForce

    TheForce He who posts articles

    I just made a quick overview video of my Ariens AMP lithium battery upgrade.

    EdwinTheMagnificent and ALS like this.
  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    This is nice !
  7. Die2self

    Die2self Saving more by using less!

    nice upgrade.
    I too after struggling with stupid 2 cycle and 4 stroke trimmers, am going to drop some money and get a good 0.5-1.0 acre battery power trimmer. I am looking at the Kobalt 80V, DeWalt 40V or Troy Built 40V.

    I played with two gassers yesterday and neither would start up and keep running. My back muscles are all sore today because of all the pulling on the strings.
  8. 08EscapeHybrid

    08EscapeHybrid Moderator

    I was tired of gas trimmers that wouldn't start, and since my yard is small I bought an electric string trimmer at Harbor Freight for $20.
    NeilBlanchard and BillLin like this.
  9. NeilBlanchard

    NeilBlanchard Well-Known Member

  10. Die2self

    Die2self Saving more by using less!

    They didn't have the greenworks trimmer at Lowes. I hoed and hummed about the decision at Lowes last night and bought the Kobalt 80V one which was $50 less than the Dewalt. Also, the kobalt is capable of using the Trimmer+ attachements making it able to be more then just a Trimmer if I want to go that directions.

    Comes with a MASSIVE battery. The typical run Voltage is 72V for it. I just they just wanted to Peak it so that it would be the highest Volts in the industry right now. The Charger is also massive and comes with it's own fan that sits right under the battery and forces air through it to cool it while charging.

    When I use it next I will report back on it.
    BillLin likes this.
  11. How do you like your lawnbott?

    I need to do something different, either hire it out or buy something that mows by itself. Trying to mow this weekend was miserable due to my allergies
  12. S Keith

    S Keith Well-Known Member

    I don't see it here, and I watched the video. If you mentioned it, I missed it.

    Model of battery meter?


  13. Die2self

    Die2self Saving more by using less!

    Tested out the Kolbalt V80 battery powered trimmer last night.

    It is not light, and after trimming for the property, my arms were almost like jelly (maybe this is my new upper body workout:p). I was holding it weird to do edge trimming and I put on a strap I had laying around. But I must not have it setup right as it felt I was holding it up most of the time. The Huge battery out back and the heavy gears in the front does wear on you. However, i had it on the low setting and it ran about the same RPMs as i usually use on the gassers I have had. There was very little vibration and just the noise of a drone is all you heard. I didn't even put on ear plugs. I really like that. I handled the whole yard trimming with ease and still had 1 out of 3 lights left on the battery when I plugged in for charging.
    The bump button was good, with just a little bump on the ground it spooled out and you just keep running. The string also didn't feel like it was grabbing at the chain link as the gassers did.

    All in all once I get the setup right, it should be very good indeed.
    BillLin likes this.

Share This Page