Roof and portable panel installation questions

[SCOTTinNJ]

Originally Posted by lewster

Scott, it depends on your cable size, which is directly related to the ampacity of that wire. I use 30 amp breakers for 6AWG and 50 amp breakers for 4AWG. It's a bit on the conservative side but I have never lost a breaker or had ant cabling burn up.

A disconnect switch on the array input cable and the breaker on the solar charge line will allow you to isolate your controller for re-sets or other reasons where electrical isolation is required. They are both part of every system that I install.

Thanks Lewster. Sounds perfectly reasonable.

[uncle_bob]

Hi

When you get the fuse / breaker to big for the wire, you get smoke and fire. I have empirical data ....

Bob

[TravlinMan]

Well, I'm hoping y'all can help me out. I just had my original Interstate Batteries replaced under warranty by Interstate Battery cause they were failin. Good news is they did it quickly and free of charge. But they told me my solar controller might be cooking my batteries. They said charge voltage should never go over 13.6 or 13.7. This seems strange to me, as I always thought the stock converter didn't give quite enough charge and it sit's at 13.6. But I called Airstream service and they also said not to let it go much over 13.6 or 13.7. But then I called renogy and they said to go with the manufacturer suggestion but that they would traditionally recommend numbers closer to what is originally programmed and that 13.6 sounded low to them....

Y'all think I should be setting my charge mode and boost mode to 13.7? And float at 13.6? What are y'all charging at? Thank you.

[TravlinMan]

As a follow up to my question above, I spoke with Jeff at the Interstate Battery headquarters in Texas, who was a very nice gentleman. He strongly agreed with Renogy's take on the matter and felt goin up to 14.6 during boost is preferred and encouraged. He thought 13.6 was fine for float but not for charge or boost and he also stated that in equalization mode, the batteries can take up to 16v with no harm.

I'm going with his take, as it is also Renogy's take. But there sure are a lot of varying opinions on this subject.

[lsbrodsky]

There really are not a lot of different "correct" takes on your question. Flooded Pb-Acid batteries have been around a long, long time and the right way to charge and maintain them is not open to interpretation. It does not matter whether you are charging from solar, battery charger, or alternator.
I am not going to be one of those guys who gives his expert opinion. The manufacturer of the battery has the data on how to charge their battery. If the website for Interstate does not, look at one of the other major manufacturers and set your Bulk, Absorption, and Float voltages accordingly.
Larry

[TravlinMan]

Well, see that was the problem. you'd think it was as black and white as you say... I thought it was. But I have gotten 4 different answers from the guy that worked at interstate (local), the guy that works at interstate hq, the airstream service dept. and various forums. I have looked for documentation and will continue to. But it does seem, right or wrong, that there are differences of opinion.

[lsbrodsky]

Of those, the only one I would believe is Interstate HQ, but only if he is in the technical/engineering group, not sales. I bet they print the specs, Lifeline does. The forum is full of "experts" and Airstream is a crapshoot for most technical advice. Cynical but that is what my experience tells me.

Larry

[TravlinMan]

Thank you, Larry. I did speak with a tech engineer at interstate HQ. His advice was most in line with the only documentation I have found, but even he admitted the documentation is a little confusing, especially since there is no 'U' in front of the SRM-24 on the battery. And the person who installed my new batteries at interstate in Grand junction had completely different info for me.

The documentation I found was here:
http://www.batteries-faq.com/activek...p?questionid=1

I did not receive any other documentation with the trailer.

Thank you.

[lsbrodsky]

No, it would not come with the trailer. That seems pretty technical and on point. I have not used plain lead acid batteries since 1981 so I really cannot comment on the numbers. I went to gel and then AGM, now Lithium. I learned in the Navy(submarines) that you do exactly what Exide(our batteries) recommends or you will have problems. If you are going to use Interstates, use their numbers.
Larry

[Kristof]

Hey,

Thought I would wade in here with an opinion. LoL.

I agree that there is some confusion out there. When you go deep in the technical details not many understand how things have changed over the past few years.

Yes Lead Acid is known. But what you do not know is that 13.6/7 charge voltages will only get your lead acid battery to 80 percent charge. Ever.

Solar is just taking off and with that the technology to eek every last amp out of your battery bank. So solar charge controllers were the ones that started to cheaply implement digital charging using PWM, PPT and MPPT techniques. These techniques created new discussions called bulk and maintenance charging. If you look at the selection of chargers out there now it is absolutely amazing how things have changed in 5 years.

What is a universal truth is that trailers are built with not the latest high end equipment, in fact it is usually legacy stuff that they got a bargain basement prices. My 2012 trailer has an inverter/charger system that uses 13.6/7 volt to measure and charge to. That is it.

My Sunforce 30 amp charge controller has 4 solid modes of charging and keeps and maintains the batteries in optimum condition at all times. Much more effective use of energy than the one that shipped with the trailer. The issue with most trailers, and you may have seen this in previous posts, is that a truly efficient solar system is "designed" from manufacture. The entire system does not look like what most RV's ship with today - although that is starting to change. My solar system runs directly to my battery bank and I have even bypassed the DC distribution panel in three DC outlets and fused them separately. Otherwise I could not run inverters to power everything I need to power at 115VAC directly from the battery bank with nothing in between and the right gauge of wire.

In synopsis the battery guy from the manufacturer is the one I would believe vice the trailer manufacturer.

Just Saying. LoL.

[Troutboy]

Scott, I used the same switch in your first post with my Victron system. I Alison used the same breakers. I bought most of my equipment from Amsolar and I have a wiring diagram with all the connections and fuses that amsolar approved. I have sent it to some folks, maybe even you, but if not I am happy to send it. Also, I documented my install on this forum, search my solar journey. The diagram is there as well. I have 500w on top, portable for future, 320 A-hr lithiums, Victron inverter and solar charger, BMS, battery monitor, etc. love the system, it works like a charm and hasn't hit below 80% yet, using furnace, microwave, and everything else.

[TravlinMan]

Thank you, Kristof. You are very correct about outdated items,

So, in terms of voltages... I cannot find any specific documentation for srm-24 interstate batteries, I'm assuming I can just go by the 12v specs on that faq page. Which means my bulk charge stage is perfect but my float voltage is a little high (should be 13.1 not 13.8) and my equalizer voltage is a little low (should be 15.3 not 14.8).

Y'all seem to agree I'm reading that correctly?

[SCOTTinNJ]

Originally Posted by Troutboy

Scott, I used the same switch in your first post with my Victron system. I Alison used the same breakers. I bought most of my equipment from Amsolar and I have a wiring diagram with all the connections and fuses that amsolar approved. I have sent it to some folks, maybe even you, but if not I am happy to send it. Also, I documented my install on this forum, search my solar journey. The diagram is there as well. I have 500w on top, portable for future, 320 A-hr lithiums, Victron inverter and solar charger, BMS, battery monitor, etc. love the system, it works like a charm and hasn't hit below 80% yet, using furnace, microwave, and everything else.

Yes. I followed your thread. Good work. If you don't mind sending the diagram I'd like it. Moved my batteries inside last week and my solar components are arriving tomorrow!

[Troutboy]

Scott, pm me your email and I'll send it....

[SCOTTinNJ]

Originally Posted by Troutboy

Scott, pm me your email and I'll send it....

Thanks. Email sent.

[uncle_bob]

Hi

The battery voltage that matters is the voltage at the terminals of the battery. As noted in dozens of threads here, the various voltage monitor gizmos can be off from each other by more than a half a volt. They also can be off from the battery terminal voltage by at least that much or more depending on what's going on.

The actual voltage that matters depends a lot on the actual temperature of the battery it's self. A normal AS battery monitor setup does not put a sensor on the battery to take this into account. Yes, you can get it done, but it's not standard. The difference over a normal outdoor camping temperature range is > 1V. It drops as temperature goes up. What's right on a cold battery at 60F in the morning isn't going to be right on a heavily charging battery at 95F in the sun later in the day (like by > 0.6V).

If you really want to check things in detail, get a good multimeter and a thermometer. Go out to the battery box and measure what's going on. Then grab the tables for the type of battery you have and see what's what.

Next up is the difference between float charge and topping off the battery. You *do* want to boost a bit to "fill up" the battery. If you have two different solar controllers, a shore power based charger / converter, and the charger on your Honda generator, you have a lot of gizmos that *could* (but generally don't) decide to top up the charge state. Topping up six or eight times an hour is not a good idea ...

Bob

[TravlinMan]

Interstate guy (in Texas) made it a point to mention that even though it's common, there shouldn't be more than 1 system handling the charge. So, if ya have a solar system and you're plugged into shore power, ya either wanna disconnect the shore power from the battery or shut down/disconnect the panels. He said even when I'm towin, it's either the 7-pin or the panels, not both.

[TravlinMan]

Originally Posted by uncle_bob

Hi

The battery voltage that matters is the voltage at the terminals of the battery. As noted in dozens of threads here, the various voltage monitor gizmos can be off from each other by more than a half a volt. They also can be off from the battery terminal voltage by at least that much or more depending on what's going on.

The actual voltage that matters depends a lot on the actual temperature of the battery it's self. A normal AS battery monitor setup does not put a sensor on the battery to take this into account. Yes, you can get it done, but it's not standard. The difference over a normal outdoor camping temperature range is > 1V. It drops as temperature goes up. What's right on a cold battery at 60F in the morning isn't going to be right on a heavily charging battery at 95F in the sun later in the day (like by > 0.6V).

If you really want to check things in detail, get a good multimeter and a thermometer. Go out to the battery box and measure what's going on. Then grab the tables for the type of battery you have and see what's what.

Next up is the difference between float charge and topping off the battery. You *do* want to boost a bit to "fill up" the battery. If you have two different solar controllers, a shore power based charger / converter, and the charger on your Honda generator, you have a lot of gizmos that *could* (but generally don't) decide to top up the charge state. Topping up six or eight times an hour is not a good idea ...

Bob

This information is so helpful, thank you, Bob. I have a temperature sensor for my solar controller that is not currently integrated into the setup but should be. It's easy to do, I just haven't done it. Maybe today. Thank you.

[NoResults]

After charging my stock interstate batteries to a storage of 13.2 I ran the fan for a few hours and let it sit with everything off. This morning it read on my Victron BMV 702 12.32 and a charged indication of 96% and a temp of 61F.

These readings off the Victron monitor don't seem to be correct. I have it set at 12.9 for a charged voltae 160 amp batteries total.

Any ideas?

Dave

[Kristof]

There is a range of reporting that is either preset or you can adjust to insicate charge level. Generally your voltage is in the less than half depleted category on presets.