Starry-Nights
New Member
- Joined
- Nov 4, 2019
- Messages
- 23
Had a couple of older threads on my layout including one that got Will to post a solution with a relay to get around problem of small BMS cables needing to handle large inverter draws. An update is needed; a lot has changed.
This is my 1st system, and owe a huge thanks to Will for the videos that kept me up many nights and helped me make choices. I bought many major components including the 8 Fortune cells, Daly BMS, inverter and Sterling B to B from Electric Car Parts Co. They have been great, offering excellent near instant knowledgeable support. The Fortune cells with the many bus bars made the battery super easy to build and it has performed flawlessly. The inverter is similar to the AMS ones, but ECPC gets them directly from the source company, Sigineer, with a better configuration and price. The owner actually visits China often to work with suppliers. You even stand a good chance of him answering a support or sales inquiry call!
BMS WITH RELAY CONTROL? First, I did install a 500amp relay per Will's diagram and recent video, but it (relay) failed instantly. Returned. When I mentioned concern about amp load through Daly BMS to Electric Car Parts, they said cables and insulation were really good and since short should be able to handle large load. OK, I tested, running both induction cooktop and heat gun at same time. Cables remained cool, but there was a problem - the 250 amp breaker to the inverter trips after about 2 minutes! I think this is a defective cheap breaker because the 3000W inverter display was showing it was at just 80% load. Since I rarely would ever be using over 2000 watts and disliked the complexity of the constantly-powered relay in the system, decided to not use a relay. I will keep an eye on temps and change if there is an issue. https://www.wirebarn.com/Wire-Calculator-_ep_41.html would seem to confirm the short BMS cable length is able to handle the load, even with a 1% drop.
LOW TEMP CONTROL: I live in NH and have been building a Sprinter van so I could spend winter months in Arizona, but unfortunately a surprise health issue will have me grounded until May, about the time it is wonderful here. So, Van is in driveway getting froze and snowed on. Since the Daly BMS has no low temp control, I added an inexpensive thermostat that cuts charging at 35 degrees and resumes at 37. Works flawlessly. To improve things, enclosed battery in foam insulation board and added a small 12 volt RV elbow pipe heater (https://www.amazon.com/gp/product/B01N6N721Y/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1) Have it under a 3/16" aluminum sheet that acts as heat spreader. The tiny heater cannot keep up with really low temps, but if you give it a head start and it gets up to say 40F, it will usually not fall to the cut-off temp unless it drops into single digits. The fact that it needs a head start makes it difficult to control thermostatically, but current draw is so low, I've just been leaving it on. Options would larger heater or add 2nd one. Of course, this would not be an issue if I was in Arizona now!
System seems to be working really well and love flexibility of charging options beyond solar, despite the fact these are hardly needed. Hope to see Will review the Sterling B to B unit sometime; there is certainly a huge difference in review scores on Amazon. At the time Renogy didn't offer a 12v to 24v B to B solution, and I don't think they have one now. Sterling is widely used in Marine which I am coming to realize is a much tougher environment!
This is my 1st system, and owe a huge thanks to Will for the videos that kept me up many nights and helped me make choices. I bought many major components including the 8 Fortune cells, Daly BMS, inverter and Sterling B to B from Electric Car Parts Co. They have been great, offering excellent near instant knowledgeable support. The Fortune cells with the many bus bars made the battery super easy to build and it has performed flawlessly. The inverter is similar to the AMS ones, but ECPC gets them directly from the source company, Sigineer, with a better configuration and price. The owner actually visits China often to work with suppliers. You even stand a good chance of him answering a support or sales inquiry call!
BMS WITH RELAY CONTROL? First, I did install a 500amp relay per Will's diagram and recent video, but it (relay) failed instantly. Returned. When I mentioned concern about amp load through Daly BMS to Electric Car Parts, they said cables and insulation were really good and since short should be able to handle large load. OK, I tested, running both induction cooktop and heat gun at same time. Cables remained cool, but there was a problem - the 250 amp breaker to the inverter trips after about 2 minutes! I think this is a defective cheap breaker because the 3000W inverter display was showing it was at just 80% load. Since I rarely would ever be using over 2000 watts and disliked the complexity of the constantly-powered relay in the system, decided to not use a relay. I will keep an eye on temps and change if there is an issue. https://www.wirebarn.com/Wire-Calculator-_ep_41.html would seem to confirm the short BMS cable length is able to handle the load, even with a 1% drop.
LOW TEMP CONTROL: I live in NH and have been building a Sprinter van so I could spend winter months in Arizona, but unfortunately a surprise health issue will have me grounded until May, about the time it is wonderful here. So, Van is in driveway getting froze and snowed on. Since the Daly BMS has no low temp control, I added an inexpensive thermostat that cuts charging at 35 degrees and resumes at 37. Works flawlessly. To improve things, enclosed battery in foam insulation board and added a small 12 volt RV elbow pipe heater (https://www.amazon.com/gp/product/B01N6N721Y/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1) Have it under a 3/16" aluminum sheet that acts as heat spreader. The tiny heater cannot keep up with really low temps, but if you give it a head start and it gets up to say 40F, it will usually not fall to the cut-off temp unless it drops into single digits. The fact that it needs a head start makes it difficult to control thermostatically, but current draw is so low, I've just been leaving it on. Options would larger heater or add 2nd one. Of course, this would not be an issue if I was in Arizona now!
System seems to be working really well and love flexibility of charging options beyond solar, despite the fact these are hardly needed. Hope to see Will review the Sterling B to B unit sometime; there is certainly a huge difference in review scores on Amazon. At the time Renogy didn't offer a 12v to 24v B to B solution, and I don't think they have one now. Sterling is widely used in Marine which I am coming to realize is a much tougher environment!