# McTrumpy: T-105 and help with small off-grid system

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Registered Users Posts: 14
I am very new to all of this as well and I am learning alot just reading in this forum. Are the Trojan T-105's the 6 volt 225 AH batteries you are talking about or does Trojan make a T-105 12 volt?
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Re: am I even close

T 105''s are 6 volt batteries.

Tony
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Re: am I even close
Mctrumpy wrote: »
I am very new to all of this as well and I am learning alot just reading in this forum. Are the Trojan T-105's the 6 volt 225 AH batteries you are talking about or does Trojan make a T-105 12 volt?

They're the 6V. But when you put two in series you get 225 Amp/hrs @ 12 Volts.
Great value in a battery, those.
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Re: am I even close

I believe the T-105 is only 6 volt size... However, there are several versions (with different ratings).

Full Trojan Product Line PDF (?)

The L16 battery is available in both 2 volt and 6 volt battery configurations.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 14
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Re: am I even close

Ok, I understand now. The T-105's are wired in series. So, when you are calculating the amount of amps you need to fully charge the batteries, do you take the total amp per hour of the entire battery bank, or just the amp hour rating of the batteries you will be using?
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Re: am I even close

When you place cells in series, the voltage adds.

When you place cells in parallel, the current adds.

When you place cells in series/parallel, then both current and voltage will add (based on actual configuration).

Note, there is no advantage to power with two batteries in series vs in parallel... Power = Voltage * Current.... So when you put two batteries in series, the voltage doubles and the Power doubles.

When you put the same two batteries in parallel, the current doubles and the power still doubles.

For many reasons, larger systems are generally easier and cheaper to build if the battery bank voltage is higher (48 volts vs 12 volts as an example).

Also, it is usually difficult and more expensive to parallel more than 2-3 strings of batteries in parallel. Lots of parallel strings means difficult to balance current among the various strings, lots of battery caps to check water on, and (for me) more difficult to find a bad cell (shorted or open cell) when there are lots of strings tied together in parallel (plus each string should have its own fuse/breaker which adds costs too).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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Re: am I even close
Mctrumpy wrote: »
Ok, I understand now. The T-105's are wired in series. So, when you are calculating the amount of amps you need to fully charge the batteries, do you take the total amp per hour of the entire battery bank, or just the amp hour rating of the batteries you will be using?

Total capacity of the bank. When you put two (or more) batteries in series it essentially becomes one battery at a higher Voltage but same capacity. Total power, as measured in Watts, goes up.

Example:

2 100 Amp/hr 12 Volt batteries in parallel = 200 Amp/hrs @ 12Volts = 2400 Watts
2 100 Amp/hr 12 Volt batteries in series = 100 Amp/hrs @ 24Volts = 2400 Watts

When you're talking about recharging you have the two factors: one of "replacing" the used Amp/hrs (which is just a way of saying Watt hours without the inherent Voltage factor) and another of getting sufficient charge current to remix the electrolyte.

So with the above example, the 12 Volt set would need 10 Amps minimum (5%) @ 14.2 Volts = 142 Watts and the 24 Volt set would need 5 Amps @ 28.4 Volts = 142 Watts.
• Registered Users Posts: 14
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Re: am I even close

I am currently putting a solar system together myself and the total daily watt hour that im going to use is about 1300. I ordered 3 Kyocera 135 watt panels from NAWS and I was looking at the Trojan T-105's as well but I think I will be falling short of the needed amps. If I were to get one more 135 watt panel, would this be enough for the Trojans or should I just go with 12 volt batteries with the lower amp/hour rating?
• Solar Expert Posts: 5,436 ✭✭✭✭
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Re: am I even close

How many t-105s?

2= 225 ah if memory serves
4= 450

So your 1300 wh would be ~100 ah

3 135 panels might put out net/net

135*3=405/2=202.5*4= 810 ah. This assumes a total net system efficiency of ~50% and 4 hours of good sun. So it looks like you are going to be a bit light on the total charging ah/day.

405 watts of panel, might put out ~22 amps under ideal circumstances (depending on controller). 22 amps is ~10% of a 225 ah battery bank, or ~5% of a 450 ah bank, all within the realm of reason.

Your ~810 ah daily draw would be ~30% of a 225 ah battery, or ~15% of a 450.

If it were me, and I had the money, I would add a panel, and go with 4 batteries, keeping the depth of discharge small, and the recharge rate high. Also gives you some room to grow, and some reserve

Tony
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Re: am I even close

Yes, that would make more sence. Four batteries rather than many 12 volt batteries.
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Re: am I even close
Mctrumpy wrote: »
I am currently putting a solar system together myself and the total daily watt hour that im going to use is about 1300. I ordered 3 Kyocera 135 watt panels from NAWS and I was looking at the Trojan T-105's as well but I think I will be falling short of the needed amps. If I were to get one more 135 watt panel, would this be enough for the Trojans or should I just go with 12 volt batteries with the lower amp/hour rating?

McTrumpy, I'd suggest starting a new thread!

IMHO - You are way short and need to have other ways of charging/more panels or both. but perhaps summer is your high use and you live in New Mexico...

Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
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Re: McTrumpy: T-105 and help with small off-grid system

McTrumpy,

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 14
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New to solar- need some help with solar system..

Ok, I am starting a new thread from some advice from another thread. My budget is not great, but I will have to buy the components slowly. Im not in a hurry here to get a solar system up and running right away. I want to do it right though. I am reading as much as I can and this forum is really a great place to start.

I am new to this forum and Id like to say hello to everyone here!

This solar system im starting is more of a "Cool" factor than anything else! Do I need solar? No. But I am interested in it very much and want to get my feet wet. It will power my garage for a small candle business I have and I want to use solar. The main loads are some lights and a wax melter that draws 600 watts on high.The wax melter is on for about 2 hours. I added up the watts per hour and it comes to 1300 watts. The lights are the fluorescent bulbs two @ 22 watts. Thats it. I have purchased 3 Kyocera 135 watt panels and just purchased another 135 watt panel tonight for a total of 4 panels. Thats about all im going to be able to afford at this time. I have been looking at the Morningstar tristar 45 amp MPPT charge controller to be my next purchase when the funds become available. Is this a good controller? Any help would be appreciated!
• Registered Users Posts: 14
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Re: McTrumpy: T-105 and help with small off-grid system

Opps! I started a new thread as well, didn't see this one, sorry about that!
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Re: New to solar- need some help with solar system..

Maybe Bill will merge this into the other thread.

I'd just like to hand out the usual start-up information:
In other words, the question to ask is: "I need this much power, how do I get it?"

But from an experimenter's POV, this rule doesn't really apply. But you still need to have some sort of goal, be it "what can I do with these panels I've already got?" or "What panels do I need to charge these batteries?"

You've got a goal of supplying 1.3 kW/hrs (per day we assume) and have four 135 Watt Kyocera's. That's 540 Watts which will probably supply 1.5 kW/hrs per day under good conditions. This is within the realm of a 12V system, so it would be about 38 Amps at charging Voltage of 14.2. The Morningstar MPPT 45 is a good controller, but do you really need it? Nope. You could still use a PWM controller on this system. Less money, but a need for heavier wires to connect the panels and the need for a fuse on each panel. With the MPPT you could put the panels in series, increasing the Voltage but lessening the current. Smaller wire, one fuse.

There's options, you see. I suggest you plan it out a few different ways on paper, including the relative costs and complexities, and see what works best for your circumstances.
• Registered Users Posts: 14
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Re: New to solar- need some help with solar system..

Well, I would like to have some possible future growth of this system as well. Would the morningstar be a good investment for a possible larger system than what im starting with now? And would it be a better way to go to wire the panels in series? Would the lesser current still be enough to charge a 12 volt battery bank? Thanks for the help!
• Solar Expert Posts: 5,436 ✭✭✭✭
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Re: New to solar- need some help with solar system..

Find a propane or gas fired wax melter. 600 watts is a huge draw for 2 hours on a smallish system. As a rule, resistance electric heating is very inefficient use of electricity.
Understanding that there are fire issues with wax, but there may be a gas fired one out there.

Aside from the big draw,1.3 kwh/day is do able. Just for the record, we burn ~600 wh/day. We do this with ~400 watts of panels, into ~450 ah of battery. This draws the battery down ~ 10-20% on an average day.

So in the real world you are going to need a system ~ twice as big to cover your 1.3 kwh/day. That said, your battery is going to have a hard time taking a 600 watt, 2 hour draw without the voltage dropping through the floor.

Like I said, the 1.3 kwh load is doable,, the 600 watt heater is going to be tough.

Tony
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Re: McTrumpy: T-105 and help with small off-grid system

You guys are keeping me on my thread trimming toes!

Have fun,
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 14
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Re: New to solar- need some help with solar system..

The wax melter is thermostat controlled as to not let the wax reach flash point. So, the melter turns on and off during the melting process to keep the wax at a 175 degree temp. It may not be using the full 600 watts but i figured to go with the rated watts to be safe. I guess that I may have to ditch the wax melter on the solar and just use my laptop and small tv I have in the room.
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Re: McTrumpy: T-105 and help with small off-grid system

Many times the heaters will draw full wattage--but end up cycling (10% on, 90% off) once things are heated up.

A kill-a-watt meter is a great tool for you to measure you loads and determine what will be needed from your power system.

You can power the wax pot from solar--but at a cost (more panels, more batteries)--but it may be worth it too you. Measure your load (peak watts, and Watt*Hours/kWH) and then size the system from there. Also, it matters if this is a once per day or once a week type operation too.

May be it is worth \$1-\$2,000 dollars to you (for the larger array+battery bank)--or building a propane / alternate fuel setup is better in the long run.... Really is your choice.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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Re: McTrumpy: T-105 and help with small off-grid system

I did a quick search, and noticed that there are wax melters that use water as a transfer medium. Perhaps a simple double boiler system with the water being heated with propane. It seems like you could rig up something to make it safe to keep the flame away from the wax, like a thermo-siphon system. (Just thinking out loud here) I don't know how dangerous melting wax is with a gas flame.

Tony
• Registered Users Posts: 14
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Re: McTrumpy: T-105 and help with small off-grid system

Yes, I think I will get the kill-a-watt meter, as for more panels, I would have room on the roof for two more panels but thats about it. If that would be enough to power the system I will do it, but I have a feeling it won't be. Probably draining the batteries more than 50% which isn't good.
• Registered Users Posts: 14
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Re: McTrumpy: T-105 and help with small off-grid system

Yes, I will get the kill-a-watt meter, as for more panels, I have only enough room on the roof for two more. If this is enough to power the system ill do it, but if not I can use my honda generator for the melter. I usually make candles 3 days a week so its not everyday. And the days are random for its only when I get orders. On holidays such as Halloween, Christmass and Thanksgiving, im busy most of the week for that is when I have the most orders.
• Registered Users Posts: 14
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Re: McTrumpy: T-105 and help with small off-grid system
icarus wrote: »
I did a quick search, and noticed that there are wax melters that use water as a transfer medium. Perhaps a simple double boiler system with the water being heated with propane. It seems like you could rig up something to make it safe to keep the flame away from the wax, like a thermo-siphon system. (Just thinking out loud here) I don't know how dangerous melting wax is with a gas flame.

Tony

Yeah, the flame would make it much to dangerous to melt the wax. They do have wax melters that have water surronding the inner wax chamber but this is good for keeping wax melted at all times so that it is ready to use as needed. But I have a very small business and it just wouldn't be cost effective for the volume I do.
• Registered Users Posts: 14
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Re: McTrumpy: T-105 and help with small off-grid system

Well, im going to sleep on all of this info I have received tonite. Thank you everyone for your help and maybe ill see ya on here tomorrow! Goodnight...
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Re: McTrumpy: T-105 and help with small off-grid system

How often do you make candles?

Everyday?

If you have the choice of when you your melting wax often you could plan it out to melt during solar noon, in thios manner you would only be drawing perhaps 300 watts off the batteries with the panels providing the rest, after a couple hours you would also have some solar remaining to top off the batteries.

This might be work, I wouldn't want to run off batteries alone. I cook rice in the Micro wave in the afternoon, I have a PWM charge controller and @1300 watts array with good exposure. During the 30 minutes or so that the microwave(900 watt) is running, the voltage runs at about a draw reducing only slightly over the 30 minutes.

Also I think the resistance type current draw would be suitable for a Modified Sine wave inverter, though others here would know better. That would save you a few bucks, and could be used later as a back up as you grow your system.

If your in a sunny area, you might be able to make candles 4-5 days a until the days start shortening up significantly in late August, early Sept.

Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
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Re: McTrumpy: T-105 and help with small off-grid system

İf you don't have to melt everyday possibly a solar concentrator (like the solar oven) heating water would be cheaper by far.
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Re: New to solar- need some help with solar system..
Mctrumpy wrote: »
Well, I would like to have some possible future growth of this system as well. Would the morningstar be a good investment for a possible larger system than what im starting with now? And would it be a better way to go to wire the panels in series? Would the lesser current still be enough to charge a 12 volt battery bank? Thanks for the help!

When you wire panels in series to feed an MPPT controller you don't lose any potential charge current; the controller down converts the higher Voltage into current, limited by its maximum output (45 Amps). You still get "12V @ 45A" to the batteries (actually about 14.2V). But the higher Voltage array lessens current flow and line loss in the wiring to the controller, and eliminates the need for many separate fuses as would be found on a parallel-wired array.
• Solar Expert Posts: 5,436 ✭✭✭✭
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Re: McTrumpy: T-105 and help with small off-grid system

From what I have been told, MSW is fine for resistance heaters. That said, be careful as any electronic controls may not like MSW. Also, many MSW inverters don't run very efficiently.

Personally, I would try to put everything else on the solar, and leave the melter to the grid.

Tony
• Registered Users Posts: 14
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Re: New to solar- need some help with solar system..

So, it makes more sence to wire the 4 panels in series to also reduce the size of wire needed to wire the panels. Im going to get the Morningstar MPPT 45 amp controller. What should I do about my battery bank? What can I use for this system? Im not going to use the wax melter for its just to much for such a small pv system.
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Re: McTrumpy: T-105 and help with small off-grid system

Roughly, Vmp ~ 2xVbatt is usually around the optimum conversion voltage for the MPPT controller... You can go higher if that will cut down on your copper costs (or reduce your wiring losses) in the panel to controller connection (normally, 3% maximum for the run--most people aim at 2-1% wiring run loss).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset