I need more power Scotty!

[Vic Harder]

Vic,Rando, ESUS, ntqsd,

At this juncture what would you do differently relative to Solar and truck to camper battery charging (for hose of us with house batteries).

Regards,

Craig

Pretty sure I would dispense with the portable panels, but we have yet to do a full year of camping, so I will hold off on that call.

I would install a bigger inverter from the get go. 350W doesn't cut it if you want to use bigger 110 appliances in the unit. Ask me again once I have it in and have (or have not) used it.

I could likely get away with much less AH capacity (especially if I choose not to use the bigger inverter).

Conversely, what I WOULD DO again is:

- Big AH capacity on roof
- Lots of gauges to keep track of what's going on
- ML-ACR with remote switch
- Big heavy wire from Alternator to Camper

 

[ntsqd]

Mine is probably the simplest build. Single 100W panel, Sunsaver Duo controller, BEP Marine Single Sense VSR, 2X 6GC AGM's, 6 ga. from starting batteries to camper batteries, TriMetric.

What I'd do different:
Dual sense VSR (Had the single left over from an aborted project)
Double the panels on the roof (with roof lifter shock thingies), wired in series
Appropriate Controller

I have thoughts of replacing the current VSR with a dual sense and putting the single in parallel with a marine battery bank selector switch on one of my project vehicles as it won't have solar so charging can only go in one direction.

I've been looking at panels, but the current rebuilding of the OE electrical system coupled with the interior remodel that we just finished has harshly impacted my timelines for other projects. So that will have to wait a while.

 

[Herve]

Hi Vic and all,

Great info here. I tried to read through some of this but got a bit overwhelmed with the amount of info.

I'm trying to figure out what charging voltage I should put on my MPPT charge controller.

I recently replaced my solar panel (previously 80w) and 2 camper batteries that were dead (I would drop below 11.5V in a single night running the fridge).

My setup:

In California, using camper mostly for weekend trips and but sometimes spending several days in the camper at one location.

Most of the draw comes from the CoolMatic CR-110 2 way Fridge (2.2 Ah/h at +25°C), have LED lights, fantastic fan etc... I also have a 800W inverter hooked to the battery with very thick wires and a 150A circuit breaker. But I only use it to charge cell phones etc...

Toyota Tundra with 55 AH truck battery and 150amp alternator.

Four Wheel Hawk Camper with factory installed solar wiring, IOTA DLS-30 and IQ-4.

Blue Star Solar Boost 2000e MPPT (http://www.blueskyenergyinc.com/uploads/pdf/Manual_BSE_SB2KE.pdf)

12v 180w solar panel (new, https://www.solarblvd.com/products/solar-cynergy-180-watt-12v-monocrystalline-solar-panel/)

Two 125 AH batteries = 250 AH (new, https://www.vmaxtanks.com/SLR125-12Volts-125AH-Deep-Cycle-Solar-AGM-Battery_p_38.html)

Yes, I have read this thread and I know i am supposed to have 1.5x the AH in solar W and I don't.
http://www.blueskyenergyinc.com/uploads/pdf/100214.pdf says
"A rule of thumb for proper battery charging is that there be at least 50 – 60W of PV power producing about 3.0 – 3.5A of charge current per 100 amp-hours of battery capacity. An absolute minimum with little or no loads is about 25W or 1.5 amps of charge current per 100 amp-hours."
So I am hoping I am still OK. My thinking was that the more AH I have, the less I will drain my batteries on weekend trips, as long as I stay within a range that will still make solar charging effective even though my solar panel will not be able to fully charge the batteries on its own. But feel free to criticize my decision here.

The MPPT manual says:

Charge voltage should be set to the battery manufacturers recommendations. The factory setting of 14.0 volts is suitable for most lead-acid chemistry batteries and does not typically require adjustment. For a predominately float application a somewhat lower voltage of 13.8 volts may be beneficial in decreasing water loss. For a heavily cycling application, a somewhat higher voltage of 14.5V may be beneficial in decreasing charge time and increasing amp-hours delivered.

The battery spec says:

Charging Voltage 14.4-14.9V
Charging Current 8A-35A (Do not use a charger with smaller amperage than the recommended Charging Current)
Float Voltage 13.5V-13.8V
Temperature Compensation:
Cycle use: -30mV/C
Standby use: -20mV/C

I have not yet taken the camper out since I replaced the solar panel and batteries so I do not know how it will behave "in the wild".

My immediate question is:

Should I leave the MPPT charge voltage at the factory default 14V, or increase it to 14.5V?

I'm not quite understanding if I'm operating in "charging" or "floating" mode. I'm guessing I should leave it at 14V because I'm not providing the minimum 8A of charging current just from the solar panel.


Other questions:

Should I set the temperature compensation to -30mV/C or -20mV/C? (currently set to -30mV/C, I do not have a battery temperature sensor)

What is the optimal way to keep the camper at home? (I turn off the DC system and keep the camper in the sun, but should I plug it in the house AC or not, given that I have the IQ-4)

Would I benefit by swapping the truck battery with a 120 AH battery?

Any other things I should to to optimize things?

Thanks!

Herve

 

[Vic Harder]

Hi Vic and all,


Blue Star Solar Boost 2000e MPPT (http://www.blueskyenergyinc.com/uploads/pdf/Manual_BSE_SB2KE.pdf)

12v 180w solar panel (new, https://www.solarblvd.com/products/solar-cynergy-180-watt-12v-monocrystalline-solar-panel/)

Two 125 AH batteries = 250 AH (new, https://www.vmaxtanks.com/SLR125-12Volts-125AH-Deep-Cycle-Solar-AGM-Battery_p_38.html)


The MPPT manual says:

Charge voltage should be set to the battery manufacturers recommendations. The factory setting of 14.0 volts is suitable for most lead-acid chemistry batteries and does not typically require adjustment. For a predominately float application a somewhat lower voltage of 13.8 volts may be beneficial in decreasing water loss. For a heavily cycling application, a somewhat higher voltage of 14.5V may be beneficial in decreasing charge time and increasing amp-hours delivered.

The battery spec says:

Charging Voltage 14.4-14.9V
Charging Current 8A-35A (Do not use a charger with smaller amperage than the recommended Charging Current)
Float Voltage 13.5V-13.8V
Temperature Compensation:
Cycle use: -30mV/C
Standby use: -20mV/C

My immediate question is:

Should I leave the MPPT charge voltage at the factory default 14V, or increase it to 14.5V?

I'm not quite understanding if I'm operating in "charging" or "floating" mode. I'm guessing I should leave it at 14V because I'm not providing the minimum 8A of charging current just from the solar panel.


Other questions:

Should I set the temperature compensation to -30mV/C or -20mV/C? (currently set to -30mV/C, I do not have a battery temperature sensor)

What is the optimal way to keep the camper at home? (I turn off the DC system and keep the camper in the sun, but should I plug it in the house AC or not, given that I have the IQ-4)

Would I benefit by swapping the truck battery with a 120 AH battery?

Any other things I should to to optimize things?

Thanks!

Herve

I was going to reply from the hip but decided to read the documentation you listed above first. I am glad I did. The language is very confusing.

1) Yes, do set Bulk charge at 14.5 (up to 14.9) The factory setting of 14.0 is for FLA batteries, not AGM.

2) You will be in bulk sometimes, float others. What they mean by floating mode is what I might consider "standby" as in, battery back up if the AC power fails, like for computer or phone systems. You are cycling your batteries.

3) You do have more than 8 amps. Optimally that 180 panel will put out 180/12 = 15A.

4) 30mv is OK, how much do you camp in temps above or below 25*C?

5) You can leave it in the sun, or in the shade with the IQ4 plugged in. Both are pretty good ways to keep your batteries topped up. IF you are storing for a long time, and the DC is fully disconnected, consider fully charging the batteries and then disconnecting them entirely. They should be good for a long time with no parasitic loads at all. I store my car all winter like this.

6) The truck battery is only used for starting the truck. The one you have is pretty darn small. Do you need to start it in the winter? Upgrade! I love the Optima Yellow tops...

 

[Herve]

I was going to reply from the hip but decided to read the documentation you listed above first. I am glad I did. The language is very confusing.

1) Yes, do set Bulk charge at 14.5 (up to 14.9) The factory setting of 14.0 is for FLA batteries, not AGM.

2) You will be in bulk sometimes, float others. What they mean by floating mode is what I might consider "standby" as in, battery back up if the AC power fails, like for computer or phone systems. You are cycling your batteries.

3) You do have more than 8 amps. Optimally that 180 panel will put out 180/12 = 15A.

4) 30mv is OK, how much do you camp in temps above or below 25*C?

5) You can leave it in the sun, or in the shade with the IQ4 plugged in. Both are pretty good ways to keep your batteries topped up. IF you are storing for a long time, and the DC is fully disconnected, consider fully charging the batteries and then disconnecting them entirely. They should be good for a long time with no parasitic loads at all. I store my car all winter like this.

6) The truck battery is only used for starting the truck. The one you have is pretty darn small. Do you need to start it in the winter? Upgrade! I love the Optima Yellow tops...

Thanks.

The panel says max 180 delivered as max 9.5 A at 19V. I'm guessing the MPPT would convert that to max 12.4 A at 14.5 V. Then I have two batteries in parallel so each gets max 6.2 A.

Couple things about that:

- Do you know why battery manufacturers request a minimum charging current / what could it be bad for ? (the battery manufacturer states "Do not use a charger with smaller amperage than the recommended Charging Current").

- Are people getting near max current out of their panel? I've never been near it with my new or old panel. I haven't taken my camper out with the new panel and only checked a handful of times in non optimal conditions and saw max 5 A. Also my panel is flat on the roof here in California so the rays are at an angle. With my older 85 W panel, I would routinely get less than 2 A and never above 3 A. I'm trying to understand if I should have low expectations or if there could be something wrong with my wiring or something like that.

I had heard that the camper would drain the truck and the camper batteries until 12.3 V and below only drain the camper batteries. Is that wrong?

Yeah I got a small group 24 battery instead of the Tundra OEM group 27 battery. Had to get a new battery in a rush in Bishop CA after the previous battery died on new years day at Eureka Dunes in Death Valley. They didn't even have any group 27 batteries... It's only a couple years old now so I was hopping to keep it longer and replace with something better later, unless it's true that the camper will use it too above 12.3V. The yellow tops are 75 AH and probably great replacement. I had thought of a 120A one to get more capacity for the camper (Shuriken SK-BT120).

 

[Vic Harder]

Thanks.

The panel says max 180 delivered as max 9.5 A at 19V. I'm guessing the MPPT would convert that to max 12.4 A at 14.5 V. Then I have two batteries in parallel so each gets max 6.2 A.

Couple things about that:

- Do you know why battery manufacturers request a minimum charging current / what could it be bad for ? (the battery manufacturer states "Do not use a charger with smaller amperage than the recommended Charging Current").

- Are people getting near max current out of their panel? I've never been near it with my new or old panel. I haven't taken my camper out with the new panel and only checked a handful of times in non optimal conditions and saw max 5 A. Also my panel is flat on the roof here in California so the rays are at an angle. With my older 85 W panel, I would routinely get less than 2 A and never above 3 A. I'm trying to understand if I should have low expectations or if there could be something wrong with my wiring or something like that.

I had heard that the camper would drain the truck and the camper batteries until 12.3 V and below only drain the camper batteries. Is that wrong?

Yeah I got a small group 24 battery instead of the Tundra OEM group 27 battery. Had to get a new battery in a rush in Bishop CA after the previous battery died on new years day at Eureka Dunes in Death Valley. They didn't even have any group 27 batteries... It's only a couple years old now so I was hopping to keep it longer and replace with something better later, unless it's true that the camper will use it too above 12.3V. The yellow tops are 75 AH and probably great replacement. I had thought of a 120A one to get more capacity for the camper (Shuriken SK-BT120).

Depending on which battery separator you have, yes - by default the camper and truck batteries are connected, unless either side drops below the set point on the separator. This is to preserve the other battery bank.

I'm not exactly sure why they recommend a minimum current for the charger. The recommend 10% of battery AH in most cases, I think to ensure you usually have enough time to recharge the batteries. There is also a battery "leakage" concern, as in, how much to they drain just sitting around, but that is way less than 8 Amps.

Most panels rarely put out more than 80% of rated power. Your MPPT will try and keep the output voltage about .5v higher than the current battery charge. So if you are at 50% SOC you will be at around 12.1v or so (depending on the load at the moment) ... 18-/12.6 = 14.3A * .8 = 11.4A to your batteries.

I never thought about the advantages of 6V batteries in light of how the current/voltage are split between a series connection vs how parallel 12V batteries would share the current. Fascinating.

 

[Herve]

Depending on which battery separator you have, yes - by default the camper and truck batteries are connected, unless either side drops below the set point on the separator. This is to preserve the other battery bank.

I'm not exactly sure why they recommend a minimum current for the charger. The recommend 10% of battery AH in most cases, I think to ensure you usually have enough time to recharge the batteries. There is also a battery "leakage" concern, as in, how much to they drain just sitting around, but that is way less than 8 Amps.

Most panels rarely put out more than 80% of rated power. Your MPPT will try and keep the output voltage about .5v higher than the current battery charge. So if you are at 50% SOC you will be at around 12.1v or so (depending on the load at the moment) ... 18-/12.6 = 14.3A * .8 = 11.4A to your batteries.

I never thought about the advantages of 6V batteries in light of how the current/voltage are split between a series connection vs how parallel 12V batteries would share the current. Fascinating.

I should probably check my battery separator but if Stan is right (http://www.wanderthewest.com/forum/topic/12674-battery-separator-question/?p=147437 step 2), then the truck battery should disconnect as soon as the truck engine is off. So more capacity in the truck battery won't help drain my camper battery more slowly when I'm stationary. Right?

 

[Vic Harder]

right

 

[VanGoOutdoors]

Ocala Meetup Oct 15 by Grant Wilson, on Flickr


solar?
Im a fan

 

[Vic Harder]

nice shot how many watts?

 

[VanGoOutdoors]

nice shot how many watts?

300 of renogy 100 watt panels
victron 100/15
victron battery monitor.

11 amps is around what i get in decent sun

 

[Vic Harder]

That's awesome. I just have a single 265W panel made by Canadian Solar. It maxes out my Victron 75/15 on any kind of decent sunshine. ;-)

 

[ckent323]

broverlanding,

I'm curious about roof weight. Are you using flex panels or solid panels?

Those panels in the picture look like monocrystalline panels which weigh about 17 pounds each without the connecting cables and mounts. I'm guessing around 60 - 70 pounds total with cables and mounts.

Can you lift the roof unaided or do you need to use a speaker stand or equivalent?

I have 2 monocrystalline panels on the roof of my Keystone and I think one more panel would make it too hard to lift without aid, particularly in the front (I do have the gas strut lifter helpers on the front -inside - but not on the back). My panels are mounted in the middle and in the back (similar in location to the two panels in the middle and back on your roof).

I am considering using a flex panel to add another 100 watts and placing it in the front location but that will still add close to 10 pounds with cables and mounting.

BTW: I am very happy with my Victron charge controller and battery monitor. They work great and the bluetoth app is very convenient to use.

Regards,

Craig

 

[VanGoOutdoors]

broverlanding,

I'm curious about roof weight. Are you using flex panels or solid panels?

Those panels in the picture look like monocrystalline panels which weigh about 17 pounds each without the connecting cables and mounts. I'm guessing around 60 - 70 pounds total with cables and mounts.

Can you lift the roof unaided or do you need to use a speaker stand or equivalent?

I have 2 monocrystalline panels on the roof of my Keystone and I think one more panel would make it too hard to lift without aid, particularly in the front (I do have the gas strut lifter helpers on the front -inside - but not on the back). My panels are mounted in the middle and in the back (similar in location to the two panels in the middle and back on your roof).

I am considering using a flex panel to add another 100 watts and placing it in the front location but that will still add close to 10 pounds with cables and mounting.

BTW: I am very happy with my Victron charge controller and battery monitor. They work great and the bluetoth app is very convenient to use.

Regards,

Craig

3 solid panels from renogy. The front is kinda harder, but its not all that bad. I dont struggle or anything.

 

[Happyjax]

Grant,

loved your Flickr stuff

 

[ckent323]

Broverlanding,

I just looked up the Renogy panels and optimum output is 18.9 V and 5.3 A. Voltage is under 60 V but current can be over 15 A. I note the short circuit current is 5.75A . I have seen my Grape Solar 100 W panels go slightly over the optimum current for short periods.

I am wondering what happens to your MPPT controller if the current is over 15 A.

I ask because I am considering adding another panel and I have been looking at the Victron 100/30 instead of the 75/15 or 100/15.

Regards,

Craig

 

[rando]

The Victron MPPT limits the battery current to 15A but you shouldn't use panels with an output over 20A according to the spec sheet.

 

[VanGoOutdoors]

The Victron MPPT limits the battery current to 15A but you shouldn't use panels with an output over 20A according to the spec sheet.

correct. I did contact them and they said this setup was fine. they said if i did another panel i should step up to be safe if its a full time use.

with the 100/30 i can also add a spare panel at the rear for a flexible panel or something.

 

[Vic Harder]

Yep, mine limits the current to 15A, but that isn't an issue often. If doing my system over again, i would also opt for the 100/30.

 

[Vic Harder]

I've got more build experience and solar thoughts over on my build thread:


And a recent trip up to a lake outside of Prince George, BC. gave us another data point: We were camped in partial shade. The 330W rooftop panel could NOT keep up with our demand (which includes a 1800W inverter cooktop) can can easily keep up when we are moving about and parked at sunny trailheads.