Solar Kit

waynefi wrote:

jrnymn7 wrote:
wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.

About 0.1v seems to be a mismatch between the meters. This seems to be about 16 gauge wire, which would be .004 ohms/foot. 3 amps over 30 feet at .004 ohms/foot should be 0.36 volts

There could be additional losses at the connections, and for sure if there's a circuit breaker or fuse in the circuit. Is that 30' one way, or round trip?

jrnymn7 wrote:
wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.

About 0.1v seems to be a mismatch between the meters. This seems to be about 16 gauge wire, which would be .004 ohms/foot. 3 amps over 30 feet at .004 ohms/foot should be 0.36 volts

Regarding DAS's early float, is it not possible, just as BFL pointed out earlier, that voltage drop could be causing the controller to be "seeing" a higher Vbatt, and going into float prematurely?

Or it could simply be how the controller is programmed. Many chargers are factory preset to go into float too early, it seems.

Page 46 of 56 of the manual says float is at 13.8v default, and has an upper and lower limit. Does this mean the controller is adjustable? If so, DAS could set float at the upper limit of 14.2v to extend abs charging ( a little low, but way better than 13.2v).

Manual

wayne said,

"I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected."

That is excessive voltage drop for only 3.5a. For example, I see .09v (point zero nine) drop at 45a. It may be simply a disagreement in meter readings, between the controller's display and whatever you used to read voltage at the batteries? Confirm all readings with a single handheld meter, to be sure.

DAS26miles wrote:
What ever happened to the OP 64Thunderbolt. Sorry I ran off with his topic.

That is okay. He started a good topic and it grew and I'm sure he has learned like we all have. :)

DAS26miles wrote:
SkiSmuggs, what do you think about it not topping off and leaving 5 amps? Do you have the ViewStar 1024n controller? If so, can you adjust the charging limits?

Yes, and there are lots of parameters that can be changed, but haven't looked at it lately so I can't answer that. It will be May before I get back to it as it is buried for the winter. At that time, I hope to move the controller to the RV and re-wire. I am also now thinking about a couple of 100w panels on the roof. I think I have found a good path from the roof to the basement via the control panel wall as a lot of wires run up from the basement into that wall.

He could solve that by having more wattage. Double the wattage has the same effect as having a longer charging day. Of course, striking the panels and moving them is twice as much effort, too.

BFL13 wrote:
Seems like there is nothing wrong with the solar equipment. Just not enough time in daylight at this time of year. Add to that the long time it takes to recharge a battery from 90% to Full anyway.

What ever happened to the OP 64Thunderbolt. Sorry I ran off with his topic.

I just bought a Renogy 100W suitcase solar kit. I'm trying to figure out what the effect of the 15ft thin wires between the controller and the battery will be.

I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected.

The controller manual describes three modes, "bulk" where all the panel current is passed through to the battery, "boost" where the PWM controller limits current to hold the boost voltage, and float where it holds a lower voltage. Boost mode has a time limit on it, which can be set up to 180 minutes.

I have set the "boost" voltage on the controller to 15. While the battery is low, the controller will just pass through all the panel current. The voltage at the panel will be nearly 1 volt higher than the battery, but the current vs voltage curves for solar panels seem to show that the current doesn't drop much until panel voltage gets over 16, so the voltage drop across the wires won't matter much.

Once the battery gets better charged, the controller will see 15 volts, and start decreasing the current. That will decrease the voltage drop across the wires, so the controller won't need to drop the current much. But the boost phase won't charge as fast as it could, and the 180 minute timer will start prematurely, so it could drop into float mode early.

I don't think I need to worry about over-charging, since this is only a 100W panel, and the kit will only be connected when I am dry camping, so it will always start the day with the batteries a bit down.

DAS26miles wrote:
Forgot to mention the panels were up 6 hours and I moved them for maximum affect.

Another question: The controller has a readout that gives temperature and SOC. Where is the state of charge from, panels, contoller or batteries?

I'm guessing that the SOC readout only works if all loads are connected through the controller, so it can count amps in and amps out. This controller has lots of parameters that only make sense if the load is connected that way. Otherwise, they are useless and confusing. It's not like the manual explains what the parameters are!