Hi, I'm a Ham Radio operator, Computer tech, and I'm here to learn.

[SOLAR_FL]

Joe as all things you get what you pay for.

Trojan T-105. 6 volt 225 AH Golf Cart Batteries. They can deliver 100 amps no problem.
US Battery US2200 6 volt 220 AH Golf Cart Batteries that can deliver 75 amps no problem

The batteries I can get the easiest are made by Exide, and the model is GC2 GC-135 with these specs:

6V 135 min @75 amps

20hour rate 226 < this is the one you told me to pay attention to, right?

So with two of these is series, what kind of load could I put on them for 6 hours? I tend to think it wil be really low, like 10 - 12 amps. Am I close?
Tnx Joe

[thastinger]

for 6 hours to not exceed a 20% DoD or totally drained?

[Sunking]

Drained to what point?

20% or 50%?

[SOLAR_FL]

Drained to what point?

20% or 50%?

20% or 50% of which value?

My question was simpler than the answer. What is the maximum I can draw on a full charge for a duration of 6 hours? I think the answer I was looking for is measured in amps, or watts, so I was not expecting percentages.

Tnx, Joe

[Naptown]

226 ah x .2 for a 20% DOD = 45.2 ah
45.2/6= just over 7 amps
The formula is the same for all discharge % just change the .2 to the DOD you want to use.

[SOLAR_FL]

226 ah x .2 for a 20% DOD = 45.2 ah
45.2/6= just over 7 amps
The formula is the same for all discharge % just change the .2 to the DOD you want to use.

Thanks Rich

[Sunking]

20% or 50% of which value?

My question was simpler than the answer.

Sorry Joe but the question is not cut and dry simple. At 6 hour discharge rate to 50% DOD with the Peukert factor calculated is 30 amps.

[SOLAR_FL]

Sorry Joe but the question is not cut and dry simple. At 6 hour discharge rate to 50% DOD with the Peukert factor calculated is 30 amps.

So under optimal conditions, with batteries charged to 100%, The batteries could deliver 30 amps for 6 hours? I would think that they use more than two of these in most gold carts.

[thastinger]

So under optimal conditions, with batteries charged to 100%, The batteries could deliver 30 amps for 6 hours? I would think that they use more than two of these in most gold carts.

golf carts use 8 of them...and most suck them dry...which is why they don't last more than 3 years in golf cart application.

[SOLAR_FL]

My second panel arrived today, so did the 100 feet of 10 gauge with connectors on both ends, and two H connectors to put my panels in parallel. I need to get some U channel to make a place to hold the panel so they face the sun for most of the day, and my two gold cart batteries. I think I have everything else I will need in the garage.
Today I learned that compact fluorescent light bulbs do not like crappy modified wave inverters. It would not even flicker with 111 volts coming out of it.

I'm sure that the controller I am testing did not like the output of a 24 vdc switching supply in place of a solar panel, that was where the clicking noise was coming from. The supply could not run with the controller loading it, it was fine once I removed it. The next test I will do will be with the two panels connected to it. I hope to do that Saturday if it doesn't rain.

[inetdog]

I'm sure that the controller I am testing did not like the output of a 24 vdc switching supply in place of a solar panel, that was where the clicking noise was coming from. The supply could not run with the controller loading it, it was fine once I removed it. The next test I will do will be with the two panels connected to it. I hope to do that Saturday if it doesn't rain.

An MPPT CC will try to draw as much current as it can from the source, as long as it is within the needs of the battery. With panels, the current is limited and the CC will find that it gets the most power at Imp of the panels, but the panels will not be damaged when the CC tries to draw more current during the MPPT checking process. If the source is a fixed voltage power supply, the CC will try to draw more and more current until the supply shuts down to protect itself.
With input from batteries, it could be even worse.

[SOLAR_FL]

An MPPT CC will try to draw as much current as it can from the source, as long as it is within the needs of the battery. With panels, the current is limited and the CC will find that it gets the most power at Imp of the panels, but the panels will not be damaged when the CC tries to draw more current during the MPPT checking process. If the source is a fixed voltage power supply, the CC will try to draw more and more current until the supply shuts down to protect itself.
With input from batteries, it could be even worse.

You are right on the money, the batteries needed over 4 amps to charge, the switching supply fell short by near one full amp. and I found this by putting one of my linear 13.5 volt supplies that can deliver 30 amps into it. To my surprise, my Fluke said I was drawing 4.5 amps into the batteries, and the supply was outputting 4.6, or there about. Does that say that MPPT is working? The MPPT as I understand it is a bit more complicated than adjusting the output to something near the input. A smart engineer could design a controller to mimic that type of behavior. I would think it takes someone with a profound understanding of MPPT, and true solar panels to drive it to judge if it's working.

The controller is charging my UPS batteries, and this will be the last test I do using them in that way.

When I put the inverter/75 watt light bulb load on the controller, the current being drawn from the 30a supply jumps to 7.5 amps from about 5.3 amps. This controller does have a temperature probe that is supposed to be in close proximity to the batteries. So it uses battery temperature to decide what to do. I wonder if I warm the temp sensor, if it would eventually cut the charge to the batteries to protect them. I guess I could test that at some point over the weekend.
The broken English instructions do say to put the sensor close to the batteries, so if they are not right close to the charger, use and extension cable to move it closer.

[Sunking]

So under optimal conditions, with batteries charged to 100%, The batteries could deliver 30 amps for 6 hours?

To 50% DOD. Golf carts are 48 volt.

[Sunking]

Joe quit using power supplies to test the CC. It is not going to tell you anything. For now float your batteries directly connecting your DC supply to the batteries.