Geek
Member
- Joined
- Aug 15, 2017
- Messages
- 920
It comes to my attention that there are a lot of members here who are trying to tackle the 3s/4s 12v conundrum.
So I thought perhaps it would be good to spark a conversation regarding this situation. To outline my thoughts:
1 -Buck or boost? Should you go for a higher voltage and use a buck converter, or a lower voltage and boost. Considerations are availability and efficacy.
2 - Low voltage protection - in using buck or boost converters you loose any low voltage protection (that the inverter may offer), this means using a BMS to protect your cells. There are several other options out there.
3 - Power draw and loss - obviously it is just not feasible to use high current boost converters. High current buck converters also have drawbacks.
So why this discussion when the conclusion should clearly be 12v Li-Ion cannot work?
1 - Many 12v inverters will operate at 16v - on paper - will these inverters in fact operate at 16.4 - 16.8. This would open a huge - number of possibilities. The cutoff is typically 10v = 3.3v per cell. 3.3 - 4.1 is an agreed good operating range for salvaged laptop cells.
2 - Aside from high draw applications 12v/3s is very cost effective - inverters are cheap, and can be quite reliable. Plenty of Chinese manufactures seem to cater to the camping/ 12v automotive standard.
3 - Plenty of accessories exist for 12v applications - ie cigarette lighter socket in the car.
4 - Most important - 12v UPS - There are untold numbers of these discarded every year, a useful source for an inverter. Not to mention the principal of this forum is salvage and re-use (as opposed to melt down and recycle)
So to begin, my thoughts - using a 4s system. You loose under voltage protection. Unless you introduce a diode to drop the voltage. This is where my testing shall begin. Can I get a 12v UPS to operate correctly of a 4s battery (without a BMS).
So I thought perhaps it would be good to spark a conversation regarding this situation. To outline my thoughts:
1 -Buck or boost? Should you go for a higher voltage and use a buck converter, or a lower voltage and boost. Considerations are availability and efficacy.
2 - Low voltage protection - in using buck or boost converters you loose any low voltage protection (that the inverter may offer), this means using a BMS to protect your cells. There are several other options out there.
3 - Power draw and loss - obviously it is just not feasible to use high current boost converters. High current buck converters also have drawbacks.
So why this discussion when the conclusion should clearly be 12v Li-Ion cannot work?
1 - Many 12v inverters will operate at 16v - on paper - will these inverters in fact operate at 16.4 - 16.8. This would open a huge - number of possibilities. The cutoff is typically 10v = 3.3v per cell. 3.3 - 4.1 is an agreed good operating range for salvaged laptop cells.
2 - Aside from high draw applications 12v/3s is very cost effective - inverters are cheap, and can be quite reliable. Plenty of Chinese manufactures seem to cater to the camping/ 12v automotive standard.
3 - Plenty of accessories exist for 12v applications - ie cigarette lighter socket in the car.
4 - Most important - 12v UPS - There are untold numbers of these discarded every year, a useful source for an inverter. Not to mention the principal of this forum is salvage and re-use (as opposed to melt down and recycle)
So to begin, my thoughts - using a 4s system. You loose under voltage protection. Unless you introduce a diode to drop the voltage. This is where my testing shall begin. Can I get a 12v UPS to operate correctly of a 4s battery (without a BMS).