Moving topsoil with electric BCS and Ravenna utility trailer

[@Electric-Motor]

Super good and simple solution 👌

[@audriusradziunas5451]

About to build a battery for my electric walk behind tractor, but have a few questions, maybe you'll know the answer: 1. Did you use a pre charge resistor/relay? If yes, how did you approached the timing of it, cus it only needs to be active for a second before turning on main contractor and that 1 second of manual switching will get annoying really fast. Is there an automatic version cus I can't find anything for 72v system. 2. Did you use contactors on both positive and negative or just one? 3. Do you use some sort of timer for contractors so that they don't discharge the battery if you forget? 4. Does the motor need a filter, so that dust doesn't destroy the brushes or the bearings? 5. Oh, do the batteries heat up, do they need extra cooling while working in the greenhouse or in direct sunlight? Planning to use lithium batteries from Kia EV6 20s1p for now , but dang 2,4kW 6s2p pack costs only 170€ ,how times have changed, few years back such capacity pack would have been ~800€.

[@reidallaway]

Hi Andrius. 1. For smaller machines like this in the 5-10kW power range I think it is perhaps not always necessary to complicate life with precharge resistors, relays and timers. You can surely find a small solid state DC timer module that would manage the precharge sequence for you but you can also just put a precharge resistor across the contactor so that it trickles some current into the controller and keeps the capacitors full. For short term storage of a few days to weeks I think there is no major concern of draining the battery through an "always on" precharge resistor like this. A battery disconnect switch or simply a plug you can pull might be good for long term storage if your battery is not removable. Many BMSes can also be wired with a switch to shut them down, isolating the battery quickly and easily for storage. 2. Most of my electric machines Do have contactors for main power, always only one is needed, either positive or negative, and usually I've used precharge resistors. I think some of the smaller 24V systems don't have contactors and I can't remember if the most recent 48V tractor had a precharge resistor. I've never set up a sequencing timer or separate relay for precharge. 3. Many controllers will take care of managing the contactor coil based on inputs and various kinds of logic and if you use a controller that has been designed to manage the contactor it will usually have an inactivity timeout to release the contactor. 4. I have sometimes tried to put dust filtration on the intake side of an air-cooled DC motor but I'm not terribly worried about it wearing out the brushes prematurely. One of our early conversions, the BCS 2-wheel tractor, finished 4 years of service and brushes might have worn a bit, had I measured them 4 years ago, but they certainly didn't look like I needed to think about ordering new ones for at least another decade. 5. I have not had any problems with batteries getting hot while working but I rarely have the opportunity to run them really hard. If I use a pair of 1kWh 24V batteries in parallel on the BCS and drain them at close to full power (≈150A combined) for 30-40 minutes the packs will be noticeably warm when I finish but I don't have a big charger for them and I just put them to charge indoors, out of the sun and they're cool at the end of recharge. If you can tolerate Facebook as a platform there's a pretty good group I help to moderate called The DIY Electric farmer where you could get ideas, answers and encouragement. facebook.com/groups/diyelectricfarm There's also tons of useful info on www.endless-sphere.com, though more geared to e-bike tech, or diyelectriccar.net. Both of those sites have huge searchable forums databases with decades of accumulated knowledge.

[@JohnMarsing]

That's pretty cool

[@firenbubble]

Ah c'est génial comme machines ! Autant la petite pelle Kubota que la remorque électrique =p