Genuine Black and Decker 36v Battery Model RB3610! OEM battery housing does not come with batteries. Works with:

CM1936 Cordless Lawn Mower
SPCM1936 Cordless Lawn Mower
CTL36 Tiller 
Note that this battery housing can also replace the Black & Decker RB3612 as the housing exterior measurements are the same size.  

I have sold twenty-seven other identical battery housings lightning-fast (Craigslist, OfferUp, Mercari, and eBay)!  This listing is for the battery housing which is impossible to find anywhere and is no longer sold by Black & Decker or in any third-party store or on any website!  Comes with battery connectors/cables.  You will source and insert either two or three* fresh 12V, 10 amp-hour generic batteries that slip inside of the plastic housing.  See, e.g., my photo showing a shopping cart at mightymaxbattery.com for a set of three for $62.99 with no tax and free shipping using code "buddy10" for 10% off your purchase: 
https://www.mightymaxbattery.com/shop/12v-sla-batteries/12-volt-10ah-battery-tall-with-faston-battery/.
Replacement 36v battery housing for SPCM1936, CM1936, and CTL36.
Original equipment made by Black & Decker for trustworthy, maximum performance.
*you will need two additional connector cables if you desire to add a third battery inside of this housing.  These cables are simple electrical components you can find anywhere -- hardware stores, online, etc., for less than a dollar each.  You will then discard the OEM Black & Decker white plastic battery organizer that holds the two 12-volt, 10-amp batteries where Black & Decker normally inserted three 12-volt, 12-amp batteries.  This will increase your output and runtime by 33%!  You do not have to increase your runtime if you like a shorter battery life.  There is no need to buy anything but two batteries in that circumstance and this is how Black & Decker configured the battery housing for some of its mowers.  For others, it inserted three batteries.  It's your decision -- longer runtime or shorter runtime.  I like a longer runtime and more powerful battery, but everyone has different tastes.  Some would prefer to come indoors and watch tv and sip a cold drink for a few hours while the battery is charging instead of finishing their mow in one fell swoop.  Not I!
Photo 1 is a stock photo.  Additional photos show a representative housing you will get, with typical light markings and/or light scratches from use.  And, I have sold many of these housings on eBay.  The last eight I sold on eBay were as follows:
July 31, 2023, after just listing it for FOUR MINUTES IT SOLD! -- $229.55 included shipping and sales tax.  See eBay item 195878326978; 
July 7, 2023, for $207.57 including shipping and sales tax.  See eBay item 195857430715.  It sold in less than three hours;
September 28, 2023, for $229.55 including shipping and sales tax.  See eBay item 195913493152.  It sold in less than two hours; 
April 5, 2024, for $231.71 including shipping and sales tax.  See eBay item 196054597570.  It sold in less than four hours; 
April 8, 2024, for $232.84 including shipping and sales tax.  See eBay item 196054597570.  It sold in less than five hours;
April 16, 2024, for $228.47 including shipping and sales tax.  See eBay item 196054597570.  It sold in less than seven hours; and
May 15, 2024 -- two discounted as a bundle for $426.80 including shipping and sales tax.  See eBay item 196054597570.  They sold in less than three hours! Hurry!
Why not keep an extra, spare Black & Decker RB3610 (or two) around for those lawn-mowing sessions where the juice runs out of your battery?
Click Buy-it-Now before someone else buys them with no sales tax from my Craigslist Chicago, OfferUp, or Mercari listings!  Don't let this get away!  You'll never see another one!  
Ships lightning fast!  Item ships tomorrow as long as tomorrow is not a Sunday.