Which BMS do you have?I have a 12v200ah lifepo4 with 200a bms/400a max...is there a downside or danger with using a 3000w/6000wp pure sine wave inverter?
No problems. It would would eliminate one weak link during momentary power surges and allow for future upgrades.I have a 12v200ah lifepo4 with 200a bms/400a max...is there a downside or danger with using a 3000w/6000wp pure sine wave inverter?
I think 4000 watts is a bit much. More of a wire size thing than the batteries.My system is 24 volts with two banks L-16 552 amp hour (real solar batteries) 4000 watts
A lot of the generic brands specs do not differentiate idle consumption between sizes and may not be a problem with the newer high freq types.Just to power that 2000 watt invert I mentioned with your 200 ah of batteries, depletes your batteries by 12%. This and other idle draws adds up quickly.
3000w is just the label on the side. You determine the power through a inverter up to its rating and for many brands buying 3000w when you worked out you need only 2000w means you understand the actual quality.so not enough power for a 3000 watt inverter
The ampere time plus has a 200a bms with 400 max.Which BMS do you have?
Its unusual for a BMS rated for 200 amps continuous to have any significant surge duration at 400 amps.
3000 ac watts / .85 conversion factor / 10 volts low cutoff = 352.941176471 service amps.
I expect most 200 amp BMSs would die in minutes if exposed to 350ish amps of current.
Yes, I was looking for future upgrades, as well as higher spike protection. I was going to limit the loads too as protection.No problems. It would would eliminate one weak link during momentary power surges and allow for future upgrades.
What if you use one battery/ inverter lead as recommended from a smaller inverter (say the 2000w model or calibrate your own to match) that will activate the low voltage inverter disconnect at loads below that of the BMS?
I would just limit the loads rather than do this but it is a possible solution to those concerned about the BMS being called upon as a circuit breaker
If I limit discharge manually, would there be any potential for reducing battery life? I was going to use under the battery rating anyway, the 3k/6k inverter was more of a future upgrade and spike protection idea.You have the potential to exceed the discharge rating of the battery and reducing the battery life. I recommend 400 ah for 2000 watts and 600 ah for 3000 watts as a minimum. I also recommend 24 volts or higher to drive a 3000 watt inverter.
excellent points you make, didn't thing of idle draw problems associated with excess inverter power.Your BMS likely limits you to 100 amps or 1200 watts or 200 amps and 2400 watts, so not enough power for a 3000 watt inverter, especially if you will use it for any length of time.
Idle draw is also a problem. I have a 24 volt 300 watt inverter that has a normal idle draw of .3 amps, or 7.2 watts. In eco mode, that inverter will automatically uses next to nothing. I also have a 12 volt 2000 watt inverter that has an idle draw of 1 amp or 12 watts. No ecomode for that. So a larger than needed inverter will lead to more than needed draw. Just to power that 2000 watt invert I mentioned with your 200 ah of batteries, depletes your batteries by 12%. This and other idle draws adds up quickly.
I need a system that will run a couple of fridges and a freezer, modem/router, device battery chargers, couple led lamps, maybe a small floor fan.I think 4000 watts is a bit much. More of a wire size thing than the batteries.
When you say 4000 watts, how exactly do you define that?
For me, I say 12 volts is good for 1000 watts, but you can have a 2000 watt inverter to make brief excursions above 1000 watts, like to warm, not cook food for a couple minutes at a time, four to six times a day. Wiring would be 2/0 or 4.0. Not to run 2000 watt appliances like an air conditioner.
I say 24 volts is good for 2000 watts. With that I will run my microwave as much as I want to cook food. Even the frozen chicken pot pie that takes 20 minutes. I may run an air conditioner with a 24 volt system if it a 3000 watt inverter will start it, but constant draw will be about 1000 watts (80 amps).
I like the idea of sticking to a 100 amp limit to avoid wire from getting too thick.
These are some of the links from my signature block that have me stick to some rather low limits: 12 Volt Safety Design [] Basics of OffGrid Design [] Batteries and Inverters
Battery life is the same whatever inverter size you use if you have the same load on each one.If I limit discharge manually, would there be any potential for reducing battery life?
My thoughts too, and also having more power to expand rather than limit power, is there a downside to this thinking? I can't think of one.A lot of the generic brands specs do not differentiate idle consumption between sizes and may not be a problem with the newer high freq types.
3000w is just the label on the side. You determine the power through a inverter up to its rating and for many brands buying 3000w when you worked out you need only 2000w means you understand the actual quality.
The only downside is that in buying an oversized inverter to compensate for any label disinformation, to run much smaller loads is the realisation that those smaller loads are actually the optimum for that inverter. There isn't much extra capacity in modern high frequency generic inverters specially when it comes to start up loads. Thus the reason why it is best to go big at first.My thoughts too, and also having more power to expand rather than limit power, is there a downside to this thinking? I can't think of one.
Yes if you only load up the inverter to 1000 watts max you will have no issues.If I limit discharge manually, would there be any potential for reducing battery life? I was going to use under the battery rating anyway, the 3k/6k inverter was more of a future upgrade and spike protection idea.
One thing to add on to this on output going down as heat goes up, and maybe needing to get a bigger than expected inverter.The only downside is that in buying an oversized inverter to compensate for any label disinformation, to run much smaller loads is the realisation that those smaller loads are actually the optimum for that inverter. There isn't much extra capacity in modern high frequency generic inverters specially when it comes to start up loads. Thus the reason why it is best to go big at first.
Each fridge-freezer compressor will draw around 100W while running, but lots of amps to start. Good call on oversizing the inverter.I need a system that will run a couple of fridges and a freezer, modem/router, device battery chargers, couple led lamps, maybe a small floor fan.
Yes this fits in with the idea of going for the much larger size than required and with the prices usually not much greater for the bigger one.If I do use solar AC, if this inverter’s output is reduced by 50% because of heat, then I may need to go larger than what I had thought at first.