tag:blogger.com,1999:blog-8411847840819033424.post2459719586366168713..comments2024-01-09T04:19:47.554-08:00Comments on Brent's Travels: Charging FWC Camper’s LiFePo4 Battery From Tacoma Brent’s Travelshttp://www.blogger.com/profile/15567067726984425896noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-8411847840819033424.post-83560952384626848482018-10-19T07:27:52.569-07:002018-10-19T07:27:52.569-07:00Happy Runner,
Re: why charge 12v to 120v to 12v
...Happy Runner,<br /><br />Re: why charge 12v to 120v to 12v<br /><br />When I started designing my Prius 30 Ah LiFePo4 house battery setup 4 years ago, I had been told by Bioenno to use 4 amp 120v charger. I then told them that 4 amp charge rate was too low for my desire. I requested 10 amp charge rate and they approved 30 Ah battery could accept 10 amp charger. That meant I could charge my house battery over two times faster from the Prius. I wanted an hours drive to nearly replenish the 12 Ah I used over the previous night. I have moved from this logic and would put solar on my Prius as I did for my friend in her RAV4.<br /><br />I then asked Bioenno about 12v to 12v charging and was directed to a cigarette plug charger that charged at 1.5 amps. This was a good backup but - backup only.<br /><br />It wasn’t until Bioenno had some vague words in their FAQ about charging off vehicle direct as long as vehicle charge circuit puts out at least 13.7v that I contacted them about this idea. I created this new setup in my FWC camper using the step up transformer to the adjustable voltage and current power supply that I can set to 14.2 -14.5 (bioenno’s Numbers) and dial in 10 amps that I no longer needed to convert dc to ac to dc<br /><br />BUT!!!!<br /><br />I keep the 120 v charger for when I connect to shore power😊. Also I keep it to charge LiFePo4 to the point of tripping the internal circuit to balance the cells. I believe that balancing of the LiFePo4 cells should occur every once in awhile. Solar charging will do this too when using the Bioenno LiFePo4 charge controller.<br /><br />In the prius situation the prius didn’t care about the minimal power loss from converting voltages as the load didn’t really use extra gas while driving.<br /><br />The other thing was that LiFePo4 was an investment for me at the time and I was careful to follow the rules. Over the last 3 years we have all learned more about LiFePo4 technology. There is a belief that charging to 80-90% vs 100% and tripping cell balancing every time that it is possible LiFePo4 will have more than the 2k charge cycles. It is also true that heat can degrade LiFePo4 and that allowing the LiFePo4 circuitry to auto shut off in low battery will have an affect. No unified opinion exists yet that I know of. <br /><br />This means charging just below 14.6 as my charging off the engine does gives more cycles. Although this may be true l, I don’t care since my solar charge controller charges to the 14.6. <br /><br />I am thrilled with the responsiveness of Bioenno and the product as it is so much better than lead acid worries about killing batteries under low voltage situations.<br /><br />Please advise what smart Charger you are using. <br /><br />As for auto load switching in the prius house battery conversation. That’s a great idea. I share my designs with the hope that others can expand on them. If you need thoughts on this let me know.<br /><br />Brent<br />Brent’s Travelshttps://www.blogger.com/profile/15567067726984425896noreply@blogger.comtag:blogger.com,1999:blog-8411847840819033424.post-2237523550018824022018-10-18T18:15:42.098-07:002018-10-18T18:15:42.098-07:00[quote]400 watt pure sine wave inverter tied to 12...[quote]400 watt pure sine wave inverter tied to 12 volt vehicle battery powering the Bioenno 10 amp charger. This is a straight forward design that I used in my Prius while driving or in Ready mode. [/quote]<br /><br />I have been following and learning from your blog as I have done Prius camping about three months a year for the last couple of years. Planning, designing, and engineering is half the fun.<br /><br />Is there a reason you went DC to AC to DC (inverter) to charge the LiFePo4 battery? Frankly that never occurred to me. I looked for a DC to DC solution and Kevin at Bioenno recommended a 12v DC to 14.6v DC Smart Charger that I am using. I assume there is some conversion loss from going DC to AC to DC, but I really don't know.<br /><br />I would be interested in your thoughts.<br /><br />Oh, your battery isolator idea got me thinking. This year I'm going to try having a circuit that automatically switches the load to house battery when there is 0 volts (i.e. Prius off) but when there is voltage (i.e. Prius on) runs the load from the Prius (and charges the house battery).<br />Happy Runnernoreply@blogger.comtag:blogger.com,1999:blog-8411847840819033424.post-28580212155595834612018-10-13T16:58:09.376-07:002018-10-13T16:58:09.376-07:00This comment has been removed by the author.Brent’s Travelshttps://www.blogger.com/profile/15567067726984425896noreply@blogger.comtag:blogger.com,1999:blog-8411847840819033424.post-288394423146723372018-10-10T06:27:32.558-07:002018-10-10T06:27:32.558-07:00Excellent Brent. A little confusing, maybe it’s me...Excellent Brent. A little confusing, maybe it’s me.. do you have a schematic you can post or send?<br /> At what point did you tap into for the Engle freezer? I’ve found 24V. to my Engle to be generally 50-75 WH a day less draw then 12V. Not a big difference as I am not solar yet in the Prius.Anonymoushttps://www.blogger.com/profile/13056824402542968519noreply@blogger.com