Inverter recommendations

Dzl said:
Above my pay grade.

If you want to be cautious, probably not, but I really can't say.

Here is the resource I meant to link to in my last post from Samlex (see the last page). For a circular saw, they recommend an inverter with a continuous rating of 3x the rated power of the saw. Which, like you said earlier, would be 5400W. I suspect you might be able to get by using the 30 second rating or 5 minute rating rather than the continuous rating so long as you keep your cuts short and your duty cycle low. I believe the main factor at play here is temperature, so giving the inverter time to cool between cuts would probably help. The Victron Webinar video answers some of these questions as it pertains to Victron at least.
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I watched the webinar and other video and learned a lot, thanks. I think my saw needs a much bigger inverter. I also read a blog about saws, lol, 4500 watts on startup...
 
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smoothJoey said:
The problems come with having shore power that can be disconnected.
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All I was trying to do was plug the camper into the rv with the converter, a/c breakers pulled. THe GFCI said no dice, and found out then about having UL listed (or ETL, apparently same standards) inverters. Cheap ones are not going to work, they HAVE to have neutral/ ground bonded, and cheap inverters can not handle that.
 
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Dzl said:
Some good discussion in these two posts as well
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Following your suggestions for reading including
Nordkyn Design: Introduction to Lithium Battery Systems // MarineHowto: Lifepo4 on boats. I find this series particularly interesting because I was a cruising sailor for 20 years before starting on this van project, now being not in a position to venture offshore for any reasonable amount of time. The eye opening info in Eric's articles seems to be the lack of realistic "what if" senarios being part of the design criteria suggested by some of the YouTube resources many of us have used to get started going down the lithium road. My question is do you think I can use the Van starter battery as a dump in the event of a high or low voltage disconnect leaving the solar charge controller with no where to go, particularly if I was not "home" when it happened. I have 50 amps coming from the starter batteries to the Kisae DMT 1250 as well as 400 ah of solar. I am using a 50 amp breaker on the drivers seat to turn that charge source on when I drive and I know I would need to leave that on for the van batteries to be the the dump, also necessitating adding an ignition sense wire and some kind of relay/switch for the current to go the other way....can that be automatic? Also the Ford had a "live" all the time, without ignition power stud on the side of the drivers seat with the batteries, twin AGM'S under the drivers seat. Eric has the SLA in parallel with the LifePo4, in my case is that necessary? If you think I should repost this else where you won't hurt my feelings. Put it here because obviously you have read the articles. Thanks



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Mex Rider said:
Following your suggestions for reading including
Nordkyn Design: Introduction to Lithium Battery Systems // MarineHowto: Lifepo4 on boats. I find this series particularly interesting because I was a cruising sailor for 20 years before starting on this van project, now being not in a position to venture offshore for any reasonable amount of time. The eye opening info in Eric's articles seems to be the lack of realistic "what if" scenarios being part of the design criteria suggested by some of the YouTube resources many of us have used to get started going down the lithium road.
Click to expand...

I fully agree, one frustration I have with many of the solar hobbyist / DIY, vanlife, rv electrical youtube channels (including some of my favorite channels) is they really gloss over, ignore, and/or sidestep any discussion or demonstration of safety and best practices without any disclaimer or acknowledgement that they are doing so. This is why I really like the marine resources, there is much more of a culture and respect for safety and properly thought through system design, and as you said thinking through the 'what-if scenarios' and risk assessment. The stakes are higher so I suppose that makes sense.

My question is do you think I can use the Van starter battery as a dump in the event of a high or low voltage disconnect leaving the solar charge controller with no where to go, particularly if I was not "home" when it happened.
Click to expand...

It is my understanding that this isn't really a problem that needs solving. If I understand correctly what you are worried about (1) the BMS (or some other protection device) disconnecting the house batteries, while (2) the solar charge controller is still connected to the PV array. It is my understanding that this (while once thought to be a potential problem) is not an issue. At least with Victron and I believe Epever charge controllers. They do not need 'dump load' in the same way that a wind turbine would. See here. This has been confirmed by Victron. What charge controller are you using? Am I correctly understanding your question?

edit: I believe this is the particular Nordkyn article you are referencing right? I forgot how much was covered by this series, I think its time for a reread, There is soooo much info packed in this series and the marinehowto article, I'm lucky to retain 10% per read through.
 
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The problem comes down to voltage spikes and is not particular to SCCs. If you take a simple buck converter there is a series inductor that is used to limit the current so that voltage can be regulated. If the load suddenly goes away, or drops, it's up to the control circuit/program to react quickly and cut back the on time of the transistor. The cheapies tend to have poor control, or deliberately loose control to make up for other design deficiencies, so they will spike up when the load goes away. That may well not be a problem for the SCC but any voltage sensitive loads still connected may not agree with getting 2 times their normal supply voltage for a moment. Victron, and probably other higher end SCCs, get it right and keep things under control. I've not tested an epever yet, but I suspect they may have voltage rise problems given their position in the market.

There are also SCCs that autosense battery voltage continually because of poor firmware etc and they will, from direct observation, go completely loopy if the battery goes away.

So while SCCs do not need a dump load you still need somewhere to throw the energy if the battery goes away. A hefty capacitor could do it if you play in the cheaper end of the pool.
 
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gnubie said:
The problem comes down to voltage spikes and is not particular to SCCs. If you take a simple buck converter there is a series inductor that is used to limit the current so that voltage can be regulated. If the load suddenly goes away, or drops, it's up to the control circuit/program to react quickly and cut back the on time of the transistor. The cheapies tend to have poor control, or deliberately loose control to make up for other design deficiencies, so they will spike up when the load goes away. That may well not be a problem for the SCC but any voltage sensitive loads still connected may not agree with getting 2 times their normal supply voltage for a moment. Victron, and probably other higher end SCCs, get it right and keep things under control. I've not tested an epever yet, but I suspect they may have voltage rise problems given their position in the market.

There are also SCCs that autosense battery voltage continually because of poor firmware etc and they will, from direct observation, go completely loopy if the battery goes away.

So while SCCs do not need a dump load you still need somewhere to throw the energy if the battery goes away. A hefty capacitor could do it if you play in the cheaper end of the pool.
Click to expand...

Would the sort of surge protector often used for lightning protection potentially fit the bill? (of course this would might end up being as expensive as just buying a better controller)

Edit: actually don't answer here, we are going waaay off topic in an inverter reccomendation thread, lets continue over here where we will be on topic, and others might find the convo useful.
 
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Dzl said:
I fully agree, one frustration I have with many of the solar hobbyist / DIY, vanlife, rv electrical youtube channels (including some of my favorite channels) is they really gloss over, ignore, and/or sidestep any discussion or demonstration of safety and best practices without any disclaimer or acknowledgement that they are doing so. This is why I really like the marine resources, there is much more of a culture and respect for safety and properly thought through system design, and as you said thinking through the 'what-if scenarios' and risk assessment. The stakes are higher so I suppose that makes sense.



It is my understanding that this isn't really a problem that needs solving. If I understand correctly what you are worried about (1) the BMS (or some other protection device) disconnecting the house batteries, while (2) the solar charge controller is still connected to the PV array. It is my understanding that this (while once thought to be a potential problem) is not an issue. At least with Victron and I believe Epever charge controllers. They do not need 'dump load' in the same way that a wind turbine would. See here. This has been confirmed by Victron. What charge controller are you using? Am I correctly understanding your question?

edit: I believe this is the particular Nordkyn article you are referencing right? I forgot how much was covered by this series, I think its time for a reread, There is soooo much info packed in this series and the marinehowto article, I'm lucky to retain 10% per read through.
Click to expand...
Yes, that was the article and so now I understand no dump needed for SCC but something to protect loads against potential spike and I did move over and read the whole thread, thank you. Going to finish the Nord. series, contemplate my design and ask more dumb questions ... but over on the appropriate thread. Thanks, as always for your help.
 
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Mex Rider said:
Yes, that was the article and so now I understand no dump needed for SCC but something to protect loads against potential spike and I did move over and read the whole thread, thank you. Going to finish the Nord. series, contemplate my design and ask more dumb questions ... but over on the appropriate thread. Thanks, as always for your help.
Click to expand...

Sounds good (y) have you selected a charge controller yet?
 
I have the Kisae DMT 1250, seemed like a way to save a lot of money on a B2B charger in addition to the Mppt....I pick up my panels across the border on Thursday, 2-200 watt Rich Solar and also a power supply so I can balance and install the fortune cells.
 
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