I am thinking about upgrading my solar some and this is my plan. I will locate my 2 agm deep cycles, 30 amp mppt solar controller and 2000 watt inverter all in the old generator location that I removed several years ago. Presently there is just one agm in there now.The generator comppartmment is well vented as the orignal door is on the compartment. There is plenty of room for this equipment and air movement. My concerns are All though agm's should not out gas except if extreme overcharging occurs. It still makes me a little nervous. The second concern is The propane compartment is above the genrator compartment. That kind of makes me nervous. Like what if the propane leaks and falls and kinda get side tracked into the generator compartment below. Of course the original design had the generator running below the propane:).So what do you all think?This is on my 98 Lance Truck CamperThanksDave

Makes sense to me. I have the 2000w inverter under the kitchen counter with the AGMs (no venting normally,so ok inside IMO--technically maybe not, but I am ignoring that--I will not overcharge them to cause venting)Only thing not mentioned in OP is battery charger/converter. I have mine handy to the inverter so they share the fat, short wires to battery bank along with the solar wires.Do have a Trimetric or other means to measure amps for the AGMs. To know if they are full, you must see that they get down to accepting 0.5a/100AH. Not possible without an ammeter. Death to AGMs if you don't.

Upgrading your solar system is a great idea. What did your energy say you use or what do you want to be able to use...amp hours?

Ah, the old "What if an asteroid comes through the living room drapes?It is difficult to achieve 17+ volts needed to vent an AGM battery. You'll be too busy putting out fires at the refrigerator and converter to notice. The smoke detector will scream, blackout city with lighting and the fuses would have to first, go on vacation.Runaway converters are as rare as a teenager missing burger night.I hope the intended humor helps you chuckle away an active imagination :)

I would move the inverter up into a protected portion of the living quarters or into the compartment NEXT to the battery compartment. Two reasons for this. one is thermal control the living space is likely cooler than the storage spaces in the summer.And add more battery.. I'm not sold on the alleged advantages of AGM by the way. I think the major advantage is to the sellers (More profit).

wa8yxm wrote:I would move the inverter up into a protected portion of the living quarters or into the compartment NEXT to the battery compartment. Two reasons for this. one is thermal control the living space is likely cooler than the storage spaces in the summer.And add more battery.. I'm not sold on the alleged advantages of AGM by the way. I think the major advantage is to the sellers (More profit).When I traveled by horse line-shack to line-shack my uncle thought I was nuts to change the lighting from standard kerosene to hurricane lamp. Shoot the pot-bellied stove was good enough to warm things up, firewood was lodgepole pine. Yeah, I did have to wait a bit for water to boil to make cowboy coffee but my day got off to a great start.Battery? I didn't need no stinking battery!

Inverter in repurposed generator locatoin with agm batteries

marcsbigfoot20b
Explorer
Jun 29, 2019
The best part of MPPT and series panels is that 3 100 watt panels in series will be around ~57volts.
In parallel around ~18 volts.

Now throw in major overcast skies.

MPPT maybe half panel output......let’s say 27 volts.
PWM parallel half output .... maybe 9 volts.

MPPT will at least charge some amps.
PWM at 9 volts = nothing.

Even 3 amps is better than nothing for X hours.
dave17352
Explorer
Jun 29, 2019
Ambient cooler and or cloudy days will still make for a cooler panel. Which will make for higher voltage. But of course if it is cloudy we won't be getting much current :(
BFL13
Explorer II
Jun 29, 2019
With 6.2 Isc, you would get 12.4 aimed at high sun. Flat on roof is less due not being aimed. How much less depends on how high the sun is anyway, where you are at that time of year.

In May at 49N with a single 130w panel (8.2 Isc) and PWM I got 8.1 aimed and 5.1 flat at 10 am, and 8.3 aimed and 7.2 flat at high noon.

If you were there then, your 12.4 would be 7.2/8.3 x 12.4 = 10.75 at high noon.

Flat vs aimed less diff going South so at 23N on 21 June sun is overhead no diff.

Don't confuse ambient cool temps with panel heating temps. The panel gets hot in the sun even when it is not that hot out ambient. Just put your hand on the panel! I took some temps with my IR gun on the back of my tilted up panel aimed at the sun at different ambients, so I have seen how that works.

Yes, solar is interesting, plus it is even useful! :)
dave17352
Explorer
Jun 29, 2019
BFL13 wrote:
With PWM you get Isc value for amps to the battery. Flat on roof will not get as many as aimed.

With MPPT it is all about watts. Let's say you have 300w aimed (series or parallel makes no diff) You lose 10% of your watts due to panel heating. So now you are at your 270 watts. Lose say 2% wiring loss from array to controller (which is pretty good) Now at 264.6 watts. Controller efficiency say 97% (it could be more like 95%) so now at 256.7 watts output.

Amps to battery is output watts/ battery voltage (assuming no wiring loss on that leg)

258/13 = 19.8
258/13.5 =19.1
258/14 = 18.4

With panels flat on roof you start with less than 300 then lose the 10% for heat and go from there.

The PWM does not lose amps from heat, in fact amps go up slightly, so you don't lose. Still get same as whatever Isc is at the time.

Only good reason to get MPPT instead of PWM for that sort of work is if you get one 300w panel instead of three 100s. Now you must have MPPT to get the buck converter in it so you can go from 24v panel to 12v battery.

And, in the above calculation where controller efficiency is mentioned, don't forget the efficiency is lower when dropping voltage, so 24-12 loses more than 12-12. That might be a good reason to stay in parallel with the three 100s and MPPT.

However, it can be wiring gauge that makes a practical difference to your installation plan. Just don't expect a bunch of amps that won't ever happen in real life.

Well we will see. The higher voltage will have less resistance. I payed 89 bucks for the mppt and I can go from series to parallel if I want to get to the nitty gritty. But knowing that I was seeing 10 amps before if I see 18 to 20 now I will call it a win! :) It is not always extremly hot when I am camping. Many times it is nice and cool which would negate the panel heating loss. All in all in will be a interesting experiment. Solar is fun that I know for sure.
BFL13
Explorer II
Jun 29, 2019
With PWM you get Isc value for amps to the battery. Flat on roof will not get as many as aimed.

With MPPT it is all about watts. Let's say you have 300w aimed (series or parallel makes no diff) You lose 10% of your watts due to panel heating. So now you are at your 270 watts. Lose say 2% wiring loss from array to controller (which is pretty good) Now at 264.6 watts. Controller efficiency say 97% (it could be more like 95%) so now at 256.7 watts output.

Amps to battery is output watts/ battery voltage (assuming no wiring loss on that leg)

258/13 = 19.8
258/13.5 =19.1
258/14 = 18.4

With panels flat on roof you start with less than 300 then lose the 10% for heat and go from there.

The PWM does not lose amps from heat, in fact amps go up slightly, so you don't lose. Still get same as whatever Isc is at the time.

Only good reason to get MPPT instead of PWM for that sort of work is if you get one 300w panel instead of three 100s. Now you must have MPPT to get the buck converter in it so you can go from 24v panel to 12v battery.

And, in the above calculation where controller efficiency is mentioned, don't forget the efficiency is lower when dropping voltage, so 24-12 loses more than 12-12. That might be a good reason to stay in parallel with the three 100s and MPPT.

However, it can be wiring gauge that makes a practical difference to your installation plan. Just don't expect a bunch of amps that won't ever happen in real life.
2oldman
Explorer II
Jun 29, 2019
dave17352 wrote:

You seem to be saying the extra voltage over the charging voltage is of no value. Interesting.
I'm not sure what he's saying, but the general idea is that mppt does a better job of conservation of watts. I personally like to feed them as much voltage as they can take.
dave17352
Explorer
Jun 29, 2019
dave17352 wrote:
BFL13 wrote:
dave17352 wrote:
2oldman wrote:
dave17352 wrote:
Going in series and mppt should double my panel output.
not sure what you mean by this..

Adding another panel will double your output.

Right now I have 2 100 watt panels with a pwm charger so max I can get is about 10 amps. With 3 100 panels and ( I am adding one) and a MTTP charger I can utilize all the volts. So lets say I am drawing 270 watts /14 volts roughly 20 amps. The mttp charger makes all the difference. I guess I should have said by going with the mttp and adding one panel I can harvest twice the energy. :)

Actual results--three 100w panels in parallel with PWM aimed at high sun, you get 6.2 amps (same as Isc) each for 18.6 amps. Swap to an MPPT controller with them in parallel--still 18-19 amps, change to series with the MPPT, still 18-19 amps.

You lose panel watts from panel heating, so your MPPT "advantage" disappears. You can get a little more amps with MPPT when the battery is low, but not enough to change your day's haul of AH that you would notice between battery 13 and 14.5 volts like you see RVing.

I am going to be going in series with these panels now. My Panels are rated and 5.29 amps at 18.9 volts. I have used these panels for two years and the most I ever get is 10 amps. With these panels in series at peak light I hope to get close to 270/14= 19.28 amps. I think I will gain about 5 amps overall. But we will see and I will update how many amps I see. I have done a lot reading on the net and it seems to be the concensus that series and mppt will net me a worthwhile gain.

You seem to be saying the extra voltage over the charging voltage is of no value. Interesting.
dave17352
Explorer
Jun 29, 2019
BFL13 wrote:
dave17352 wrote:
2oldman wrote:
dave17352 wrote:
Going in series and mppt should double my panel output.
not sure what you mean by this..

Adding another panel will double your output.

Right now I have 2 100 watt panels with a pwm charger so max I can get is about 10 amps. With 3 100 panels and ( I am adding one) and a MTTP charger I can utilize all the volts. So lets say I am drawing 270 watts /13 volts roughly 20 amps. The mttp charger makes all the difference. I guess I should have said by going with the mttp and adding one panel I can harvest twice the energy. :)

Actual results--three 100w panels in parallel with PWM aimed at high sun, you get 6.2 amps (same as Isc) each for 18.6 amps. Swap to an MPPT controller with them in parallel--still 18-19 amps, change to series with the MPPT, still 18-19 amps.

You lose panel watts from panel heating, so your MPPT "advantage" disappears. You can get a little more amps with MPPT when the battery is low, but not enough to change your day's haul of AH that you would notice between battery 13 and 14.5 volts like you see RVing.
BFL13
Explorer II
Jun 28, 2019
dave17352 wrote:
2oldman wrote:
dave17352 wrote:
Going in series and mppt should double my panel output.
not sure what you mean by this..

Adding another panel will double your output.

Right now I have 2 100 watt panels with a pwm charger so max I can get is about 10 amps. With 3 100 panels and ( I am adding one) and a MTTP charger I can utilize all the volts. So lets say I am drawing 270 watts /13 volts roughly 20 amps. The mttp charger makes all the difference. I guess I should have said by going with the mttp and adding one panel I can harvest twice the energy. :)

Actual results--three 100w panels in parallel with PWM aimed at high sun, you get 6.2 amps (same as Isc) each for 18.6 amps. Swap to an MPPT controller with them in parallel--still 18-19 amps, change to series with the MPPT, still 18-19 amps.

You lose panel watts from panel heating, so your MPPT "advantage" disappears. You can get a little more amps with MPPT when the battery is low, but not enough to change your day's haul of AH that you would notice between battery 13 and 14.5 volts like you see RVing.
MEXICOWANDERER
Explorer
Jun 28, 2019
AGM batteries WILL VENT (out gas) under "extreme overcharging". If they did not, they would explode.

Recombinant caps that change vapor back into liquid really subdues pressure build up. You've got to, with your own hands, work with these batteries to get a better understanding of the subject. And the likelihood or not of malfunction.

I have rehabilitated many different group sizes to above 17 volts and only two, vented. Both were not Lifelines. Do not rehab an AGM while still in the rig.

The last battery explosion I saw was on an older Tioga. Owners started the generator, connected a transformer battery charger, then ventured to a beach bar. Gor plastered. People started yelling. They heard a pop and then a sulfur reek covered the beach like Yellowstone Park. it was unbreathable near or inside the rig. The batteries were outside.

What a mess.

They were in no mood to discuss anything the next day. They fiddled with the batteries, got a jumo start then headed north.

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