Switch to Lithium?

[BobG-ESC]

Thank you!

I'll look for an existing cutoff and if not, I appreciate the guidance on a switch.

I've never thought about disconnecting the solar panels but see how it could make sense when the converter is available.... I have more to learn!

I have a Victron system. I set the charging parameters the same for the charger as for the solar charge controller. I think they work together if I plug into shore power.

You are right that with your system you need to disconnect the solar panels in order for the converter (charger) to charge the batteries when your solar charge controller is at a higher voltage. You have a tricky situation, but it may work just fine with both solar and shore power turned on except if the batteries get really low. In your system, the converter will work at night and solar will take over during a sunny day. Hopefully the sunny day will happen often enough (once a week is enough) to top off the lithium battery and cause their BMS to balance the cells.

I only disconnect the solar panels when I am working on the electric system or remove the batteries for storage. However, the disconnect needs to be between the panels and the solar charge controller. Solar electric code requires the disconnect to disconnect both hot and negative. I don't do that with my plastic trailer. I don't see how the hot wire can short out and electrify the trailer because my hot wires don't get near any metal that could electrify the trailer. I don't have a ground wire on the solar panels either so it can't get shorted and then electrify the trailer. I guess solar could get shorted to another electrical wire in the electric locker but not likely.

 

[BobG-ESC]

Shiny,
This is what I used for solar disconnect. I may have used different breaker. I have 2 MPPT solar controllers.

Midnite Solar Baby Box Enclosure for 1-4 Din Rail Breakers

MNEPV Midnite Solar MNEPV 1 to 63 Amp 150 VDC Breakers for Solar Panel Arrays

150VDC din rail mount breakers (13mm wide). We do not stock the 3, 4, 5, 6, or 9 Amp models of MNEPV circuit breakers. These are drop-shipped from the manufacturer, but it requires a minimum order quantity of 12. Please email us or give us a call if you have any questions.

www.solar-electric.com

 

[John in Santa Cruz]

I used a marine style battery switch, 12-48VDC and 275A for my solar panel cutoff. My panel is 36V at 10A at full power.

https://www.amazon.com/dp/B07413JWLD

 

[BobG-ESC]

I used a marine style battery switch, 12-48VDC and 275A for my solar panel cutoff. My panel is 36V at 10A at full power.

https://www.amazon.com/dp/B07413JWLD

That is a cost-effective solution if the solar panels are under 48 VDC. I have 2 series arrays: one is 2 panels and the other is 4 panels. The array voltages are about 80 volts each.

 

[Shiny]

FWIW, there was no solar panel cutoff on my 2014, with the stock Escape 160W panel of that era. The panel was hard wired to a GoPower GP-PWM-30 "30 AMP PWM DIGITAL SOLAR CONTROLLER", and that in turn was hard wired to the battery such that it would charge the battery even if the battery disconnect switch was flipped.

This is what I remember on ours, but I'll check it out.

 

[BobG-ESC]

This is what I remember on ours, but I'll check it out.

If you have a shunt, you probably reconnected the solar charge controller on the load side of the shunt too?

 

[Shiny]

......
You are right that with your system you need to disconnect the solar panels in order for the converter (charger) to charge the batteries when your solar charge controller is at a higher voltage. You have a tricky situation, but it may work just fine with both solar and shore power turned on except if the batteries get really low. In your system, the converter will work at night and solar will take over during a sunny day. Hopefully the sunny day will happen often enough (once a week is enough) to top off the lithium battery and cause their BMS to balance the cells.

I only disconnect the solar panels when I am working on the electric system or remove the batteries for storage. However, the disconnect needs to be between the panels and the solar charge controller. Solar electric code requires the disconnect to disconnect both hot and negative. I don't do that with my plastic trailer. I don't see how the hot wire can short out and electrify the trailer because my hot wires don't get near any metal that could electrify the trailer. I don't have a ground wire on the solar panels either so it can't get shorted and then electrify the trailer. I guess solar could get shorted to another electrical wire in the electric locker but not likely.

Thanks again Bob

I was hoping for exactly what you described - converter would win at night and run at a high enough current to get the batteries as far as they can get, then the solar will kick in during the day.

I looked at my log from our last trip in September and it appears we were using no more than 50 AH per day, so I'm not too worried about it.

I really don't recall ours having a disconnect but checking that is on my list.

Mike

 

[Shiny]

Shiny,
This is what I used for solar disconnect. I may have used different breaker. I have 2 MPPT solar controllers.

Midnite Solar Baby Box Enclosure for 1-4 Din Rail Breakers

MNEPV Midnite Solar MNEPV 1 to 63 Amp 150 VDC Breakers for Solar Panel Arrays

150VDC din rail mount breakers (13mm wide). We do not stock the 3, 4, 5, 6, or 9 Amp models of MNEPV circuit breakers. These are drop-shipped from the manufacturer, but it requires a minimum order quantity of 12. Please email us or give us a call if you have any questions.

www.solar-electric.com

View attachment 1111268

Thank you!

 

[Shiny]

I used a marine style battery switch, 12-48VDC and 275A for my solar panel cutoff. My panel is 36V at 10A at full power.

https://www.amazon.com/dp/B07413JWLD

Thank you.

We have two panels installed by Escape. I think they are GoPower as I mentioned earlier.

I have no idea if they are wired in parallel or series.

If I guessed right, they are 24.1V and 9.5A so I can cover it for now with a breaker rated for at least 50V and 20A

Mike

 

[Shiny]

If you have a shunt, you probably reconnected the solar charge controller on the load side of the shunt too?

Please clarify, I'm not following well. I remember putting the shunt in the ground leg of the batteries so I'd capture current flowing from any source. ??

 

[BobG-ESC]

Please clarify, I'm not following well. I remember putting the shunt in the ground leg of the batteries so I'd capture current flowing from any source. ??

Two things.

If your 2 solar panels are connected in series, then the voltage to the solar charge controller would be the sum of the 2 voltages. If the panels are connected in parallel, then the voltage would be the highest of the two panels and the current would be the sum of the two panels as long as they are both the same voltage.

The other thing is the solar charge controller negative should be connected on the load side (not the battery side) of the shunt. This is so the shunt will count the amps going into the battery from the solar charge controller. John said his original solar charge controller came connected directly to the battery so when he added a shunt, he would have moved the solar charge controller connection to the load side of the shunt.

 

[Shiny]

If I guessed right, they are 24.1V and 9.5A so I can cover it for now with a breaker rated for at least 50V and 20A

Our GoPower GP-PWM-30-UL Solar Controller is rated for max input of 35V.

Since the panels are spec'd at 24.1V open circuit, I'm assuming the two panels are wired in parallel.

Does a miniature breaker rated for 20 A sound right? Voltage rating won't be an issue and I've never seen 20A charge current when I've been paying attention, but guess the lithium might pull more than our FLAs?

 

[BobG-ESC]

I don't know what a miniature breaker is rated for. If you are thinking of an AC 1/2 slot breaker for solar disconnect, I don't think those are rated for DC voltage. Look at the switch that John suggested if you are looking for a solar disconnect switch.

 

[John in Santa Cruz]

Two things.

If your 2 solar panels are connected in series, then the voltage to the solar charge controller would be the sum of the 2 voltages. If the panels are connected in parallel, then the voltage would be the highest of the two panels and the current would be the sum of the two panels as long as they are both the same voltage.

The other thing is the solar charge controller negative should be connected on the load side (not the battery side) of the shunt. This is so the shunt will count the amps going into the battery from the solar charge controller. John said his original solar charge controller came connected directly to the battery so when he added a shunt, he would have moved the solar charge controller connection to the load side of the shunt.

yes, indeed I did.

 

[Shiny]

I don't know what a miniature breaker is rated for. If you are thinking of an AC 1/2 slot breaker for solar disconnect, I don't think those are rated for DC voltage......

I'm kicking around a few options for a disconnect. I have not been back at the camper but I suspect there is no fuse between panels and solar controller.

Is there a reason to put a fuse or DC breaker between the panels and my solar controller? What scenario would put too much current into these wires?

I don't see how the current could ever go higher than the max panel output.... 20A is the max expected from my 2 panels so if a fuse or breaker is recommended, then I'll go with a fuse or trip rating of 30A, since that is the max panel current supported by the GoPower controller.

I do want to disconnect both legs, so I'm looking at double pole switches or ganged miniature DC breakers.

The main reason I'm adding a disconnect is if the solar panels prevent me from charging with my non-lithium-capable converter when the solar is too slow. This makes me want easy access to the disconnect (not inside the bench). It seems easiest to locate in the wall of the bench where the batteries are... maybe next to where Escape mounted the GoPower controller.

If I use a breaker, I think this will work (20A DC):

I could probably cut a hole in the wall and mount it using a strap, similar to this commercial panel-mount kit:

I found this switch that might also work with just a hole in the wall and a strap across the back. I would probably put a fuse or re-settable breaker in line, just because. I like this idea the best, as IMO it's the least intrusive, easiest to install, and most intuitive to use:

I find options for 20A flush-mount breakers like these that I could put in one leg of the panel wires if there's a reason to protect them from overcurrent:

Let me know what you think and thank you all.

Mike

 

[Shiny]

....
The other thing is the solar charge controller negative should be connected on the load side (not the battery side) of the shunt. This is so the shunt will count the amps going into the battery from the solar charge controller. John said his original solar charge controller came connected directly to the battery so when he added a shunt, he would have moved the solar charge controller connection to the load side of the shunt.

yes, indeed I did.

I'll refresh one of my two remaining brain cells when I next visit the camper.

My shunt and monitor have been working great for a couple years so however I installed it, I must have followed directions that worked... at least for the solar power.

Mike

 

[Shiny]

How important is the type of fuse used on each battery? Online suggests Class T are preferred for ability to block very high currents.... but I'm not sure how this happens if the BMS is doing its job ??? Maybe the BMS is slow to protect against a short?

The MRBF style seems convenient with fewer connections. Are they adequate? What's the downside? Stick with a name brand like Bussman?

Or is something like an AMG style OK?

Do I size the fuses to match the BMS max continuous discharge current (100A for the batteries I ordered), peak discharge current (170A), cables, or ??

We have a 1500W inverter, so the max "operating" current will be well below the max battery output of 200A....

Thanks,

Mike

 

[Centex]

How important is the type of fuse used on each battery?

IMO proper selection and sizing of the main battery fuse(s) requires an understanding of the purpose of the fuse and the battery's built-in protections:

• Protect main battery cables from over-current; and,
• Avoid damaging the BMS / blowing the battery's internal BMS-protection fuse

The more restrictive of the above rules the selection, all in consideration of a worst-case 'dead-short' (e.g. a short-circuit across the main battery circuit).

Protect main battery wires from over-current

• Select fuse Amps of whatever type lower than the ampacity of the main battery cables

Avoid damaging the BMS / blowing the battery's internal BMS-protection fuse

• Select fuse Amps and type such that the fuse will blow before internal battery protections are 'tripped'

Example (my case, YMMV)

• My main battery cables, considering length of run, have an ampacity of over 600A
• My battery's BMS is rated for a maximum discharge current of 200A (continuous), 400A (15 seconds), 650A (0.5 seconds)
• My battery's internal BMS protection fuse is rated at 250A slow-blow
• I selected an "extremely fast short-circuit response" 250A Class T fuse

• Protective of battery cables
• Selected to blow before the battery's internal protection devices are tripped to be protective of the BMS circuitry itself

Note that the short-circuit response time of a Blue Sea Class T fuse is an order of magnitude faster than an MRBF fuse (time - current graphs attached) which may be critical for BMS protection in worst-case short-circuits. And yes, I'd avoid no-name branded / sourced fuses for this critical application (beware of Amazon knockoffs / forgeries).

But wait, what about protection of my inverter and other equipment?

Protection of that equipment and its wiring is not the purpose of the main battery fuse; that equipment and its wiring should be protected by fuses / breakers 'downstream' of the main battery fuse (located between the main battery bus and each piece of equipment). In my case that's a 200A breaker for the inverter input circuit (other equipment has much lower current breakers or fuses).

One person's opinions, just for your consideration, Have Fun!

 

[BobG-ESC]

Mike, you do not need a breaker or fuse between the solar panels and the solar charge controller. The conductors (wires) should be sized to handle the maximum amps of the solar panels. They are probably 10 AWG to minimize voltage drop. The panels are not capable of burning those size wires.

You do need a disconnect switch (a breaker switch can be used) between the solar panels and the solar charge controller. Whatever you use should be rated for the short circuit DC voltage produced by the panels. Most people with an Escape trailer, including me, only switch the positive conductor. Use the switch that John uses. I have read that some of the ones you listed are not a good product.

You do need a fuse or breaker on the positive (+) output conductor from the solar charge controller. Size the output wire at least the maximum charge controller output current with less than 3% voltage drop on the circuit. Size the fuse on the charge controller output wire to protect the output wire at the maximum current output rating of the wire.

Match the battery fuse to the size of the battery cable. "T" fuses are fast acting and are generally recommended by inverter manufacturers. It could be that your inverter manufacturer recommends a wire size and a fuse type and rating. Size the battery cables to carry at least the amps required by the inverter at maximum peak load with less than a 3% voltage drop. Size the battery fuse for the wire capacity. I am getting a little over my head here so maybe someone with more knowledge will help you on this. Since my inverter was the biggest load, I sized the cables and fuse between battery to inverter per the inverter manufacturer's recommendations.

Edit: I just noticed Alen E responded to your questions. He has it figured out so do what he says. My batteries have a serviceable fuse inside them that protects the battery BMS.

 

[Shiny]

IMO proper selection and sizing of the main battery fuse(s) requires an understanding of the purpose of the fuse and the battery's built-in protections:

• Protect main battery cables from over-current; and,
• Avoid damaging the BMS / blowing the battery's internal BMS-protection fuse

The more restrictive of the above rules the selection, all in consideration of a worst-case 'dead-short' (e.g. a short-circuit across the main battery circuit).

Protect main battery wires from over-current

• Select fuse Amps of whatever type lower than the ampacity of the main battery cables

Avoid damaging the BMS / blowing the battery's internal BMS-protection fuse

• Select fuse Amps and type such that the fuse will blow before internal battery protections are 'tripped'

Example (my case, YMMV)

• My main battery cables, considering length of run, have an ampacity of over 600A
• My battery's BMS is rated for a maximum discharge current of 200A (continuous), 400A (15 seconds), 650A (0.5 seconds)
• My battery's internal BMS protection fuse is rated at 250A slow-blow
• I selected an "extremely fast short-circuit response" 250A Class T fuse

• Protective of battery cables
• Selected to blow before the battery's internal protection devices are tripped to be protective of the BMS circuitry itself

Note that the short-circuit response time of a Blue Sea Class T fuse is an order of magnitude faster than an MRBF fuse (time - current graphs attached) which may be critical for BMS protection in worst-case short-circuits. And yes, I'd avoid no-name branded / sourced fuses for this critical application (beware of Amazon knockoffs / forgeries).

But wait, what about protection of my inverter and other equipment?

Protection of that equipment and its wiring is not the purpose of the main battery fuse; that equipment and its wiring should be protected by fuses / breakers 'downstream' of the main battery fuse (located between the main battery bus and each piece of equipment). In my case that's a 200A breaker for the inverter input circuit (other equipment has much lower current breakers or fuses).

One person's opinions, just for your consideration, Have Fun!

Thank you. I understand and appreciate the advice and underlying rationale.

I just checked and GoPower also recommends T Type for our inverter.

I also sent email to the sales contact at SOK to see what they recommend. I do not know how their BMS is protected, but I'll just plan to use the Type T and move on...

As to ampacity of the cables, I was surprised to see GoPower recommending 2 gauge cables for our 1500W inverter. After reading, I think we need larger to be safe. More like 1/0...

What size cables did Escape use? My guess is 2...

And finally, I understand I need a fuse for each battery. Is it best to run each battery to a bus bar with a 100 or 125A fuse, then a 3rd 200A fuse between bus bar and inverter? This kind of makes more sense to me and depending on what SOK says, might allow lower cost fuses between batteries and bus bar, along with smaller cables.

Mike