Community Forums

twinboat · 03-04-2017, 11:28 AM

You need to find the max bulk voltage of YOUR batteries and set it to that.

They do vary between brands and types.

billdreamlv · 03-04-2017, 12:02 PM

Quote:

Originally Posted by lnanne

But we assumed volts over the safe bulk setting of 14.4 would hurt the batteries. Are you saying we could set it higher (it goes to 15)? We don't need an MPPT if the safe bulk range is 14.4, is that right? Feel like I'm missing something here.

We have a MPPT controller by Midnite Solar.

MidNite Solar Products

It has 150 amp capability. It shows the incoming voltage and the charging voltage. In the morning and evening time, the incoming voltage from the panels drops and, of course, when the sun is behind the clouds and at night the voltage goes to zero. My concern is that the 17v panels don't always have 17v on them. Once you put a load on the panels, the voltage will drop as well. So, check your incoming voltage to the charge controller and I think you will find your answer. A hybrid of parallel and serial connections to 4 panels is what we have and we generate about 37v on each leg when it is fully producing. The MPPT charge controller then adjust the incoming voltage to 13.6v. As the sun goes down the voltage drops because our panels are flat on the roof. The charge controller will stop or slow charge once your incoming system voltage minus the load goes below 13.6v the batteries. You can see that there isn't very much room between 17v and 13.6v. You would need a very expensive controller to do the latter. I don't think your Xantrex controller can boost voltage below 13.6v incoming voltage to 13.6v outgoing voltage. Just my opinion.

lnanne · 03-05-2017, 02:36 PM

Yes, we're quite frustrated we don't have a solar monitor and knew going in that could be an issue. If you don't have any problems then you don't need to know that separately from the battery (although we like to know things like that). We can spend another $100 or so on a display but we want to make sure this controller will meet our needs with additional panels and possibly lithium. We stated that with the installers so we sure hope this controller is good for that!

So, do we assume it's the batteries and buy the Costco 6 volt GC batteries while we make sure it all works or buy a solar display to see what the solar is doing? Or both?! Chasing issues never seems to stop! But we're sure learning a lot!

billdreamlv · 03-05-2017, 03:44 PM

You can make a simple solar panel monitor by getting a cheap volt meter and a couple of clip leads. Hook the positive lead to the incoming positive voltage from the panels and the negative lead to the negative side while they are still connected to the charge controller. Make sure it is on DC volts. This will tell you what is going on with your panels. Leave it connected and look at it several times a day to get an idea of your charging capacity. If it is low then change your panel configuration. If it looks OK then change your batteries.

lnanne · 03-05-2017, 04:58 PM

Quote:

Originally Posted by billdreamlv

You can make a simple solar panel monitor by getting a cheap volt meter and a couple of clip leads. Hook the positive lead to the incoming positive voltage from the panels and the negative lead to the negative side while they are still connected to the charge controller. Make sure it is on DC volts. This will tell you what is going on with your panels. Leave it connected and look at it several times a day to get an idea of your charging capacity. If it is low then change your panel configuration. If it looks OK then change your batteries.

We're plugged in again for a few weeks but we'll take a day and experiment with that. Thanks!

ByeTheWay · 04-28-2017, 08:53 PM

Although often used, voltage is a poor way to determine the state of charge of a battery Amps in/out is much better

lnanne · 04-29-2017, 08:14 AM

Quote:

Originally Posted by ByeTheWay

Although often used, voltage is a poor way to determine the state of charge of a battery Amps in/out is much better

We've actually been relying more on the hydrometer and the Trimetric monitoring amps in/out BUT because our results have not been making any sense, we weren't sure which part of our setup was not right. We finally reached the point where we felt we'd learned as much as we could with these hybrid batteries and replaced them a couple of days ago with Costco Interstate golf cart batteries.

What a huge difference. With the old batteries we could not get the solar to replace the amps used and kept losing ground each day. So far with these, we recharged within 3 amps (but we've only had one day!). Again we were told the hybrids were good (by Interstate) although we never were able to get them to read in the good range on the hydrometer. So whether the batteries were bad OR that's how hybrids work when using them for boondocking, we are pleased so far that these new batteries are working as we expected by everything we'd read and were told. We mainly waited to make sure we made mistakes on the old ones before burying new. We've ruined so many batteries by our lack of knowledge. Hoping we've got it now!

PJStough · 04-29-2017, 08:43 AM

It is important to look at the recommended charging profile for your batteries. It seems that a lot of people set the charging voltages too low which means the batteries never get fully charged.

Here is a chart for Interstate golf cart batteries:

lnanne · 04-30-2017, 06:16 AM

Quote:

Originally Posted by PJStough

It is important to look at the recommended charging profile for your batteries. It seems that a lot of people set the charging voltages too low which means the batteries never get fully charged.

Here is a chart for Interstate golf cart batteries:

Thank you for passing that along - that's the exact chart we found BUT how do we knew what model our battery is? I don't see a model on the label. We can call Interstate on Monday.

We set our Xantrex C60 solar controller at 14.8 for bulk instead of 14.4 and we set float at 13.4 which matches the chart you sent. Our controller doesn't have an absorption setting to set at 15.4 (the manual says it will keep absorption at 1 hour at the same volts as bulk). If anyone has any experience or thoughts on that we'd love to hear it! Interstate wants the 15.4 for two hours and we're compromising on bulk and making it higher but not sure that's ok.