Fire danger from using existing 14 -16 gauge wiring with 300 watts solar???

[OregonPerson]

Hello,

Is it a fire danger to charge my 2017 Promaster 3500 12V AGM chassis/starter battery utilizing a 3x100 watt solar array through a 30A PWM using the previously installed 14-16 gauge 20 foot run from wiring cabinet in the rear to the separator under the hood in front?? (Originally had 100 watt panel and a 8A Samlex PWM charge controller)

I realize there will be a large amount of loss utilizing the existing wire run but it is basically being used as a trickle charger for the starting battery for winter storage outside in Oregon.

My used 2018 Pleasureway Lexor TS primarily utilizes the 3x100 watts of roof mounted solar (increased from original 100 watt panel) to charge 2x100 Ah of Lithium coach batteries using a separate GoPower 30A PWM charge controller. The controller was flush mounted about 10 ft from the batteries.

[booster]

Originally Posted by OregonPerson

Hello,

Is it a fire danger to charge my 2017 Promaster 3500 12V AGM chassis/starter battery utilizing a 3x100 watt solar array through a 30A PWM using the previously installed 14-16 gauge 20 foot run from wiring cabinet in the rear to the separator under the hood in front?? (Originally had 100 watt panel and a 8A Samlex PWM charge controller)

I realize there will be a large amount of loss utilizing the existing wire run but it is basically being used as a trickle charger for the starting battery for winter storage outside in Oregon.

My used 2018 Pleasureway Lexor TS primarily utilizes the 3x100 watts of roof mounted solar (increased from original 100 watt panel) to charge 2x100 Ah of Lithium coach batteries using a separate GoPower 30A PWM charge controller. The controller was flush mounted about 10 ft from the batteries.

That wiring is way small for any connection from the engine to the coach batteries, not only form the solar to engine, but from the engine to the coach batteries for alternator charging.


Are you sure this isn't just a voltage sensing wire and not the primary current carrying wire? It just doesn't make sense if you have even a single battery in the coach to be that small.

[OregonPerson]

Sorry for the confusion. The 2x100AH "coach" Lithium batteries are located at the rear of the campervan and is wire sized appropriately and was fed by a single 100 watt panel which I have since added 2 x 100 watt panels wired in parallel for a total solar array of 300 watts.

My question is referring to a separate 20 ft 14-16 gauge run to the 12V AGM "chassis/starter" battery that was originally installed using a separate 8A Samlex charge controller. This has not been utilized since I adding the additional panels. Now that my campervan is being winterized and being stored outside I wanted to swap out the 8A charge controller with a 30A but utilize the existing wiring but wondering whether it would be a fire danger??

[booster]

300 watts is going to be able to do 15+ amps.


You might want to plug in the numbers into the Blue Sea Circuit wizard to know for sure. It is very conservative and you will need to know the right wire size and temperature rating of that wire.


Circuit Wizard - Blue Sea Systems

[booster]

The other question would be about what the separator is going to do. If you put charge voltage on the starting side of the separator from the solar it probably is going to close and connect the coach batteries to the starting batteries.


How big is the wiring for the separator to coach batteries?


It seems like if you used a low current drain separator you could just run the solar to coach batteries like you have now and let it go to starting battery through the separator (two way version) and let the solar maintain both as it should be plenty big enough for that. Much simpler, I think, and the way a lot of systems are used.

[markopolo]

Is it:

30A PWM correctly installed to charge the lithium batteries.

Currently unused 14 or 16 AWG wire to the chassis battery.

You want to maintain the chassis battery.

If so:

Don't parallel the lithiums and chassis battery via that unused wire.

PW has used SurePower separators. Those SurePower separators use approximately 36Ah per day to stay closed so the single solar panel likely couldn't keep up with the never ending power draw.

Possible solution:
Turn off the SurePower separator when storing the coach (possible as easy as adding a switch on the ground wire - someone here could confirm that). That will save approximately 36Ah per day. Use an Amp-L-start under the hood to maintain the chassis battery. AMP-L-START Starting Battery Charger/Maintainer - Overview Page

Things to consider:
* You should not charge lithium batteries if they are at or below 32F.
* Many advise to not store lithium batteries at a high state of charge. Storing at 50% SOC is commonly mentioned.

[mikeehlert]

IMG_7034.jpg
Checking the attached chart, for thirty amps out of the charge controller, you should have 10 gage. Using 16 or even 14 is unsafe and yes there is a fire hazard. If your unable or unwilling to replace the undersized wire, why not just stick with the 8 amp charge controller? That is more than enough to trickle charge your chassis battery.

[booster]

Originally Posted by markopolo

Is it:

30A PWM correctly installed to charge the lithium batteries.

Currently unused 14 or 16 AWG wire to the chassis battery.

You want to maintain the chassis battery.

If so:

Don't parallel the lithiums and chassis battery via that unused wire.

PW has used SurePower separators. Those SurePower separators use approximately 36Ah per day to stay closed so the single solar panel likely couldn't keep up with the never ending power draw.

Possible solution:
Turn off the SurePower separator when storing the coach (possible as easy as adding a switch on the ground wire - someone here could confirm that). That will save approximately 36Ah per day. Use an Amp-L-start under the hood to maintain the chassis battery. AMP-L-START Starting Battery Charger/Maintainer - Overview Page

Things to consider:
* You should not charge lithium batteries if they are at or below 32F.
* Many advise to not store lithium batteries at a high state of charge. Storing at 50% SOC is commonly mentioned.

Yep, that is what I thought also, no reason for the second wire. I think I would change the separator to a low power use on just for durability and not using that much of the solar, especially if the van is stored in Oregon in the winter with poor sun conditions. Depending on freezing conditions, the lithium batteries could be shut off to prevent constant float as long as the solar controller maintained a 12v reference off the starting battery.


If this is a lithium setup with a Surepower separator, I think those are the ones where the separator would close off lithium batteriey voltage, draining them if in storage, so that would likely also be going on. Maybe this is why the original 100 watts was only to the starting battery, but not done very well as they would get tied together other times.

[OregonPerson]

Booster, Thanks, unfortunately I don't know the size of the wire from the coach batteries to the separator. The SurePower separator used in my campervan is not two way. The original wiring was from a single 100 watt panel with the feed split to two different controllers, a 30A PWM which fed the Coach Lithium batteries and then a separate 8A PWM controller with a run to the separator/starting battery.

Marcopolo, Thanks......the 14-16 gauge is run through a different PWM solar charge controller than the one used for the coach batteries. I'll look into your suggested solution but there is a disconnect key/switch for the coach batteries to prevent charging by either solar or alternator/separator which I have pulled out during storage due to temps below freezing early in the morning.

Mikeehlert, Thanks.......With 300 watts solar array, I have the potential of around 20A feeding into the 8A Samlex PWM controller. Isn't that going to burn out the 8A controller or any fuse between the array and the controller??

[markopolo]

If getting rid of the Surepower unit then replacing it with a DC/DC charger would be a good way to go. Then both voltage and current getting to the lithium batteries is controlled when the engine is running. Voltage is somewhat controlled in the existing setup but current is not controlled. The alternator must get maxed out periodically with the existing setup. An Amp-L-start would be needed to maintain the chassis battery.

[markopolo]

Originally Posted by OregonPerson

.................... The SurePower separator used in my campervan is not two way. .......................

Yes, that expectation is likely why/how that model ended up in the coach. It doesn't always work as expected though.

The 1314-200 needs to see 13.2V at the chassis battery to latch. Once latched it stays latched until voltage drops to 12.8V. Because it is latched, the lithium batteries higher voltage keeps it latched until they (and the chassis battery) drop below 12.8V. It unlatches when your lithium are nearly depleted.

Driving the van causes it to latch and it stays latched after turning the engine off because of the lithium batteries higher voltage. That's the unexpected part. It acts somewhat like a 1315-200.

You're disconnecting the lithiums for winter storage so it will unlatch.

Applying a charging voltage (such as solar) to the chassis battery will cause it to latch again.

The relay drive current for the 1314-200 & 1315-200 is 1.5 amps. http://www.texasindustrialelectric.c...4_1315_200.pdf

That's why it's not a good choice to use with solar.

As you are using the disconnect switch for the lithiums then two solar arrays / two solar controllers might work. 200W+30APWM to the lithiums and 100W+8APWM to the chassis battery. The Surepower unit would still cycle on and off so having a switch to disable it while in storage is still beneficial. It's better to have the 1.5A go to the chassis battery rather than wasted holding the separator latched.

[Rlum]

Originally Posted by markopolo

Yes, that expectation is likely why/how that model ended up in the coach. It doesn't always work as expected though.

The 1314-200 needs to see 13.2V at the chassis battery to latch. Once latched it stays latched until voltage drops to 12.8V. Because it is latched, the lithium batteries higher voltage keeps it latched until they (and the chassis battery) drop below 12.8V. It unlatches when your lithium are nearly depleted.

Driving the van causes it to latch and it stays latched after turning the engine off because of the lithium batteries higher voltage. That's the unexpected part. It acts somewhat like a 1315-200.

You're disconnecting the lithiums for winter storage so it will unlatch.


.
Applying a charging voltage (such as solar) to the chassis battery will cause it to latch again.

The relay drive current for the 1314-200 & 1315-200 is 1.5 amps. http://www.texasindustrialelectric.c...4_1315_200.pdf

That's why it's not a good choice to use with solar.

As you are using the disconnect switch for the lithiums then two solar arrays / two solar controllers might work. 200W+30APWM to the lithiums and 100W+8APWM to the chassis battery. The Surepower unit would still cycle on and off so having a switch to disable it while in storage is still beneficial. It's better to have the 1.5A go to the chassis battery rather than wasted holding the separator latched.

I have a PW Lexor TS (2016). I use a small solar panel via an inexpensive controller(10amp PWM). Make sure for the separator, you disconnect the ground. I placed a on/off switch. If your chassis battery voltage gets up to 13.4 volts, switch will close. Your house batteries are now connected in parallel. If this stays this way. You will completely discharge your house batteries. You can get a small inexpensive solar panel with cheap controller for under $80.00 total. I just place mine on windshield during winter months. If I use the van in 3-4 weeks, I do not even place the solar trickle charge system.

[OregonPerson]

Thanks Rlum,

Maybe because I haven't been pulling the separator ground when the Lexor is just sitting for a few days Is the reason the chassis AGM battery goes down to 12.2 from a full charge. It is a new OEM AGM battery about 30 days old.

Your suggestion sounds like the least expensive and complex solution. Using the current 8A Samlex PWM controller, just take it from existing mounting location and wire run, connect it to a small solar panel placed in windshield, and use a couple alligator clips connected to a couple lines directly to the chassis battery.

[Rlum]

Originally Posted by OregonPerson

Thanks Rlum,

Maybe because I haven't been pulling the separator ground when the Lexor is just sitting for a few days Is the reason the chassis AGM battery goes down to 12.2 from a full charge. It is a new OEM AGM battery about 30 days old.

Your suggestion sounds like the least expensive and complex solution. Using the current 8A Samlex PWM controller, just take it from existing mounting location and wire run, connect it to a small solar panel placed in windshield, and use a couple alligator clips connected to a couple lines directly to the chassis battery.

What I did. I bolted onto the battery and slid a solar disconnect thru the access panel. This solar disconnect stays under the drivers seat. When/if I want to connect solar controller to it, it is easily available. No need to remove cover and connect alligator clips. A few bucks more but worth it for the convenience.

[mikeehlert]

Mikeehlert, Thanks.......With 300 watts solar array, I have the potential of around 20A feeding into the 8A Samlex PWM controller. Isn't that going to burn out the 8A controller or any fuse between the array and the controller??

No, the controller will only let through 8 amps. It will block everything above that to its isolation limit..... on the back rating label. That’s why it’s safe to use with the small wire. Especially in Oregon where the sun angle is always low.

[booster]

Originally Posted by mikeehlert

Mikeehlert, Thanks.......With 300 watts solar array, I have the potential of around 20A feeding into the 8A Samlex PWM controller. Isn't that going to burn out the 8A controller or any fuse between the array and the controller??

No, the controller will only let through 8 amps. It will block everything above that to its isolation limit..... on the back rating label. That’s why it’s safe to use with the small wire. Especially in Oregon where the sun angle is always low.

This is from the Samlex manual for the 8 amp unit.

NOTES:As the Bulk Charge Stage is a constant current stage, the controller does not control thevoltage and the voltage seen at the output terminals of the controller will be the actual battery voltage (this will rise slowly towards the Absorption / Gassing Voltage under the influence of the constant charging current). Also, the controller does not control the current and the Bulk Charging Current will be equal to the Short Circuit Current Isc of the Solar Panel. Constant current is ensured by the constant current characteristic of the Solar Panel in the region of up to 15V

They also require a 10 amp fuse in the circuit on the battery side.


This would all indicate that the controller does NOT limit the current, and I don't think any controllers do as they all have max panel input ratings.

[mikeehlert]

Originally Posted by booster

This is from the Samlex manual for the 8 amp unit.





They also require a 10 amp fuse in the circuit on the battery side.


This would all indicate that the controller does NOT limit the current, and I don't think any controllers do as they all have max panel input ratings.

I have never seen this behavior before..... basically requires by passing all the regulation circuitry.

Anybody else seen this behavior from your charge controller? I know mine limits current. Why else are they rated by current?

[booster]

Originally Posted by mikeehlert

I have never seen this behavior before..... basically requires by passing all the regulation circuitry.

Anybody else seen this behavior from your charge controller? I know mine limits current. Why else are they rated by current?

They are rated by current so you know what controller to get for any given solar panel array. You have stay within the total max current and max open circuit voltage for your panel array. Typically you would see a max of about 6 amps and max voltage of about 21.5v in a modern 100 watt panel. After that you have to calculate differently for series or parallel to get the proper totals for the array.


Basically, the controller doesn't do any current regulation at all, it just sets the voltage to charge profile and the batteries set the current, up to the max available. That is why they spec battery bank sizes also, so you don't send too many amps to a small battery.

[mikeehlert]

BTW, I just reviewed the Amazon listings for 30 Amp charge controllers from $13 to $130. Most explicitly say they limit current in their descriptions. I did not review install manuals.

[booster]

Originally Posted by mikeehlert

BTW, I just reviewed the Amazon listings for 30 Amp charge controllers from $13 to $130. Most explicitly say they limit current in their descriptions. I did not review install manuals.

Could you post a link to ones that say that?