Stepping down 50 or 30 amp service to 15 amp service

[TimeOutside]

My knowledge of power is basic, but the answer I've received goes against my understanding. I have a Jackery solar 'generator'. On the side of the device it says, "AC 100V-120V 15 A MAX". One use I have for the device is to use it in my little camper. On occasion I may be in an actual campground. All campgrounds I've ever been in have either 50 amp or 30 amp service. So, I wrote Jackery and specifically asked, "Can I charge the Jackery Explorer 1000 v2 on 30 amp service?" They wrote back, "You won't be able to since the maximum input is 15 A." I am puzzled. I thought a device would only pull the amperage it could use. That it wouldn't matter if I plugged it into 100 amp service; it would only draw 15 amps if that is the maximum it could use. Is my understanding wrong? If not, why would an electronics company place such a warning on their device? I don't want to destroy an $800 device by plugging it into a 30 amp service. If 15 amps is indeed the maximum I can input to the device then how do I go about stepping down the service from 50 or 30 amps to 15 amps?

Thanks in advance,
Andrew

 

[Avo Mk8]

My knowledge of power is basic, but the answer I've received goes against my understanding. I have a Jackery solar 'generator'. On the side of the device it says, "AC 100V-120V 15 A MAX". One use I have for the device is to use it in my little camper. On occasion I may be in an actual campground. All campgrounds I've ever been in have either 50 amp or 30 amp service. So, I wrote Jackery and specifically asked, "Can I charge the Jackery Explorer 1000 v2 on 30 amp service?" They wrote back, "You won't be able to since the maximum input is 15 A." I am puzzled. I thought a device would only pull the amperage it could use. That it wouldn't matter if I plugged it into 100 amp service; it would only draw 15 amps if that is the maximum it could use. Is my understanding wrong?

Your understanding is not wrong, and I don't know why you got the response you have, unless ----
the manufacturers might be concerned about feeding the power unit from a supply capable of delivering a high/very high current, because in the event of a fault in the product, and they haven't included adequate protection themselves, there could be a big bang (and/or a fire!)
But products built to the proper standards, eg UL, ISO etc, and independently tested, would incorporate the necessary protection inside. As a matter of interest, does the unit have any product approval logo's on it, UK, CE, or test house (eg Intertek) marks?

If not, why would an electronics company place such a warning on their device? I don't want to destroy an $800 device by plugging it into a 30 amp service. If 15 amps is indeed the maximum I can input to the device then how do I go about stepping down the service from 50 or 30 amps to 15 amps?

Not 'stepping down' but limiting fault current could be achieved by putting a 15A fuse in the supply lead somehow!
It wouldn't blow until 20A or more, but it would give additional protection.
It shouldn't be necessary if the unit is designed properly. But if you've been told by customer services 'No', that puts forum members in a difficult position answering, because we don't know the engineering of the product, or why they've said that.
You might try asking them again, and asking for a proper technical explanation, if it's not due to a misunderstanding.

 

[TimeOutside]

...does the unit have any product approval logo's on it, UK, CE, or test house (eg Intertek) marks?

I am not familiar with all the different approval logos. I've attached the label from the back at the bottom of the post. Do any of these tell us anything?

You might try asking them again, and asking for a proper technical explanation, if it's not due to a misunderstanding.

I will, but meanwhile...

...but limiting fault current could be achieved by putting a 15A fuse in the supply lead somehow!

Pending a technical answer from Jackery, putting a 15A fuse or breaker in the circuit would be a good safety. Can you explain how I would best go about it? I've not dealt with AC fuses since I was a kid, but I can put a single breaker in a small one or two position box. Perhaps something like I've shown below. I'd just need to assure I'm selecting matching parts and know how to wire it correctly.

Thank you for getting back to me so quickly on this matter,
Andrew

 

[Avo Mk8]

I am not familiar with all the different approval logos. I've attached the label from the back at the bottom of the post. Do any of these tell us anything?

Yes, of the SGS logo's, the one on the right confirms it has been verified by this reputable test house. I just looked up the product on the SGS website, and it has been tested to ANSI/CAN/UL 2743:2020, which is the standard for Portable Power Packs. So all OK.

I've not dealt with AC fuses since I was a kid, but I can put a single breaker in a small one or two position box. Perhaps something like I've shown below. I'd just need to assure I'm selecting matching parts and know how to wire it correctly.

Can't really give detailed instructions. I was hoping to find an in-line cable mounting fuse or mcb, such as the sort of residual current devices they put on hot tubs etc, but an overload protection version (breaker/fuse) doesn't seem to exist.
You have a workable idea, but needs to be indoors and with robust cable clamps etc. Can you get a suitable extension lead incorporating a fuse?
Given the fact the product has safety certification, and you've had unsubstantiated advice (that seems odd) from the manufacturers, I would encourage you to ask the question again, if necessary asking for a rationale.
I suspect the unit in other peoples hands probably gets plugged into all sorts of sources of power without a second thought

 

[TimeOutside]

You have a workable idea, but needs to be indoors and with robust cable clamps etc. Can you get a suitable extension lead incorporating a fuse?

Yes, I have access to the inside wiring where I can splice in fuse or breaker with a suitable housing.

My thoughts were to do the following:
Note: The Jackery has a pass-through function with a 20 ms transfer/static switch. I'd pass all power through the Jackery, but it will only output 15 amps. If I want to run the air conditioner on the camper then I need 30 amps.
• Split the 50, 30, or 15 amp shore power, once inside the camper, into two leads. One main and one backup.
• The backup lead would go to the 15 amp mini-breaker and then to the Jackery. This would be to keep the Jackery charged.
• The main lead would to go an automatic/manual transfer switch. (My understanding is that, although an uncommon situation, the transfer switch can accommodate both main and backup loads being live at the same time. (This would be the case since if there is shore power the Jackery would be passing through live power from the backup line.) The main would supply power by default, but switch to the backup line from the Jackery if the main is interrupted. Then if there is no shore power then the switch would automatically serve power from the Jackery through the backup line. Here is the URL to the transfer switch I was considering: Amazon.com - https://www.amazon.com/dp/B08T94Q6NG.)
• The transfer switch then supplies power to the camper's distribution center.

Do you see any issues you see in the proposal above? If so, what would you recommend?

Thanks again,
Andrew

Whoops! I initially forgot to attach a diagram of my thoughts. Here it is:

 

[Avo Mk8]

I'm not up on the Jackery unit, but I don't think it gives 15A out sustained, more like 12A, but UK versions no doubt different.
Are you working with typically a 120V supply?
'Pass through' seems to refer to being able to use outlets/charge devices from the Jackery while the unit itself is charging.
I assume that when plugged in, eg to 'shore power', the electricity provided by the Jackery sockets is from its inverter, it's not directly shore power.
I think there are possibly safety issues here and I don't feel confident to comment on the automated approach.

 

[TimeOutside]

I'm not up on the Jackery unit, but I don't think it gives 15A out sustained, more like 12A, but UK versions no doubt different.

I agree that is more like 12A sustained. I ran quite close to 15A for about ten minutes and it tripped the overload.

'Pass through' seems to refer to being able to use outlets/charge devices from the Jackery while the unit itself is charging.

Yes, 'Pass through' means being able to use the outlets while the device is charging the internal battery.

I assume that when plugged in, eg to 'shore power', the electricity provided by the Jackery sockets is from its inverter, it's not directly shore power.

I will confirm with Jackery, but according to what I read the power supplied to any load comes directly from shore power. When the shore power is interrupted then the internal static/transfer switch starts supplying power to the load. That's why there is a 2 ms delay in switching from shorepower to inverter power.

I think there are possibly safety issues here and I don't feel confident to comment on the automated aapproach.

Would the use of a manual transfer switch alleviate your safety concerns? I you are concerned then, with my rudimentary knowledge, I am also concerned.

Thanks again,
Andrew

 

[Avo Mk8]

I will confirm with Jackery, but according to what I read the power supplied to any load comes directly from shore power. When the shore power is interrupted then the internal static/transfer switch starts supplying power to the load. That's why there is a 2 ms delay in switching from shorepower to inverter power.

OK that's useful to know. If that's the case I'm happier with the setup!

Would the use of a manual transfer switch alleviate your safety concerns? I you are concerned then, with my rudimentary knowledge, I am also concerned.

Yes it would. There are some hazards around these things and being directly in control seems somewhat safer to me, at least to get the system up and running to start with

Thank you for the clarifications.

 

[TimeOutside]

Thank you for the clarifications.

I'm glad to do so.

I'm awaiting confirmation from Jackery regarding whether or not shore power current goes through the battery and inverter to the load, or directly to the load. As soon as I receive a reply then I'll get back to you. But let me ask, is the diagram I posted above correct (assuming a manual transfer switch)?

Thanks again,
Andrew

 

[Avo Mk8]

I'm glad to do so.

I'm awaiting confirmation from Jackery regarding whether or not shore power current goes through the battery and inverter to the load, or directly to the load. As soon as I receive a reply then I'll get back to you. But let me ask, is the diagram I posted above correct (assuming a manual transfer switch)?

Thanks again,
Andrew

I think it looks fine. At least with a manual switch you have the opportunity to disconnect potentially excessive loads before you switch in the inverter!
Try and buy a reputable brand of switch rather than picking an unknown Chinese one from Amazon

 

[TimeOutside]

Try and buy a reputable brand of switch rather than picking an unknown Chinese one from Amazon.

What would be some of the brands to look for? Unless it is a common brand for other electronic items in the U.S., I wouldn't have a clue.

 

[Avo Mk8]

What would be some of the brands to look for? Unless it is a common brand for other electronic items in the U.S., I wouldn't have a clue.

Well me being in the UK probably makes me just as clueless.
There seem to be many forums and companies specializing in RV kit in the U.S. and maybe a search for transfer switches locally might reveal what people use, are happy with, and which ones catch fire! You might try asking on a forum (i appreciate you are, but this one has a bit of a bias to Europe and building installations rather than vehicles)

 

[TimeOutside]

Well me being in the UK probably makes me just as clueless.
There seem to be many forums and companies specializing in RV kit in the U.S. and maybe a search for transfer switches locally might reveal what people use, are happy with, and which ones catch fire! You might try asking on a forum (i appreciate you are, but this one has a bit of a bias to Europe and building installations rather than vehicles)

Understood. I'll check around.

By the way, just a few minutes ago I received a reply from Jackery regarding the power distribution. It does indeed use an internal transfer/static switch. If shore power is present then any loads attached are powered by directly from the shore power source. When the shore power stops, the source switches to the battery/inverter. That's good news.

Thanks again for all your help.

So, this weekend my wife, her best friend, and I are traveling 6.5 hours to Nashville, Tennessee (the source of 90% of American country music) to see a show and the sights. Then next week I'll try and get on this project. But one question before then...

When I go to split the shore power wire to the transfer switch and to the breaker, is what I have shown in the following diagram the correct way to do so?

Andrew

 

[Avo Mk8]

When I go to split the shore power wire to the transfer switch and to the breaker, is what I have shown in the following diagram the correct way to do so?

Yes your diagram is correct.

So a thought has occurred to me. With a manual transfer switch, if you inadvertently leave it in Jackery position, but shore power is available and connected, and you go about your business as normal, unaware, presumably the RV could be drawing anything up to average max current, say 20 or 25A or higher. Will the Jackery survive that current going through the IEC mains input connector? (that's presumably why it's marked current not to exceed 15A - makes sense now!)
Your 15A breaker won't save the day, because it won't trip thermally until 135% (20A) - and that would take quite a long time (many minutes) and magnetically it would trip at 30A
You would be better off fitting a 10A breaker to protect the Jackery.

So maybe there's an argument for actually using an automatic transfer switch, but that works the other way, where you are gaily using shore power, everything is on, the power on site goes off and your transfer switch operates and puts too big a load on the Jackery, which hopefully saves itself from overload, but leaves you in the dark!

If you go for the manual version, I would use a 10A breaker (trips at 13.5A after a while, or instant if big overload) instead of the 15A.

I guess the elegant solution, which may be impractical, is to put a transfer switch, or multiple switches, in the individual circuits of the things you need when no shore power, but not in the circuits for heavy loads, Aircon etc.

Anyway, forget all about it for the moment and have a great time in Nashville, I bet it will be fabulous!

 

[TimeOutside]

You would be better off fitting a 10A breaker to protect the Jackery.

I'll definitely use a 10A breaker. I didn't realize they didn't trip until so far above their labeled amperage. I'm not too worried about being left in the dark if the Jackery shuts off. The only thing that draws enough to shut it off is the air conditioner. The refrigerator would shut off too, but I imagine I'd notice the air conditioner being off before the refrigerator got too warm to ruin the food.