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 > Automatic, smart battery charger?

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full_mosey

Oklahoma

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Posted: 01/11/18 01:40pm Link  |  Quote  |  Print  |  Notify Moderator

I would like to hear some comments and suggestions.

In July 2017, I made some progress on understanding the settings in the MS SS MPPT 15L solar controller. I then modified several settings which move towards a more automatic charging approach. I use two overnight low Voltages(OLV), 12.6 and 12.4, as triggers . These two OLVs drive three charging profiles for the day.

Each AM, the controller executes a start up process(charge_state=4) when the charge_state switches from Disconnected(3) to Bulk(5). This seems to be driven by the appearance of Array Volts. At this time, the day's profile is established.

I set up three profiles.

1. Storage - there is a one hour timed ABS stage before float because the OLV was 12.6 or above.

2. Extended Abs - there is a two hour timed ABS stage before float because the OLV was between 12.6 and 12.4.

3. Cancelled Float - there is unlimited ABS because the OVL was below 12.4.

Now we can see this working in a graph.

[image]

This covers 7 days; Jan 5 - 10 in full and Jan 11 up to 9:40AM.

Jan 5,6 - this is a perfect definition of Storage in good solar; One hour of timed ABS. [emoticon]

Jan 7 - Bad solar day! The controller was stuck in Bulk and never made it to ABS.

Jan 8 - Good solar. The controller AUTOMATICALLY adjusted ABS to 2 hours because OLV dropped below 12.6(not shown).

Jan 9,10 - AUTOMATICALLY Adjusted back to Storage with good solar.

Jan 11 9:40 - I am looking out at the bad weather and predicting a repeat of Jan 7. Tomorrow's forcast is Sunny and the controller will AUTO-correct the same as it did on Jan 8.

Here is a summary of possible profiles since I started logging in May 2017.

Count Profile Avg Min Volts
---------- ------------ -------------
14 Cancel Float 12.26
105 Extend Abs 12.53
99 Storage 12.68

I switched to the SSMPPT15L because the programming features greatly exceed the TRISTAR 45 PWM.

I must shout out to MS for patiently answering many questions, thanks guys!

HTH;
John

* This post was edited 01/11/18 01:46pm by full_mosey *

pianotuna

Regina, SK, Canada

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Posted: 01/11/18 02:05pm Link  |  Quote  |  Print  |  Notify Moderator

Hi John,

Who makes the SSMPPT15L?


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

full_mosey

Oklahoma

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Posted: 01/11/18 02:14pm Link  |  Quote  |  Print  |  Notify Moderator

Morningstar SunSaver MPPT 15L

pianotuna

Regina, SK, Canada

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Posted: 01/11/18 02:18pm Link  |  Quote  |  Print  |  Notify Moderator

ty

Lwiddis

Rincon Parkway, Ventura, CA

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Posted: 01/11/18 03:10pm Link  |  Quote  |  Print  |  Notify Moderator

Only 15 amps max?


2015 Winnebago 2101DS TT & Tahoe LTZ, 300 watts WindyNation solar-parallel & MPPT, Trojan T-125s. TALL flagpole for US flag. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - old MOS 1542 & 1560.


full_mosey

Oklahoma

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Posted: 01/28/18 01:48pm Link  |  Quote  |  Print  |  Notify Moderator

Lwiddis wrote:

Only 15 amps max?


Yes.

If you are thinking I could benefit from a higher Amp controller, consider this.

Only 1% of daylight minutes have even reached the 15A max. Most of that has been in Summer when my two 12V fridges are working hard.

With 280 Watts flat, I expected only 75% power, 0r 210W. That is the spec'd rating of the controller and, in practice, it has turned out to be a good match.

HTH;
John

full_mosey

Oklahoma

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Posted: 01/28/18 02:20pm Link  |  Quote  |  Print  |  Notify Moderator

I ran a little test today to see what would be the maximum solar Amps as the sun is low. I am prepping for an Alaska drive-about.

[image]
Here you see the daytime process as read from the controller each minute. During bulk the battery Volts slowly rise to the Abs setpoint, then Volts hold for one hour, then switch to the float setpoint. Just before Noon I switch on a 500W inverter load. The battery Volts drop immediately and the controller switches back to bulk.

[image]
Here you see the same time frame with attention given to Amps. The controller transitions from bulk to abs at 5.5A to float at 3A. As soon as the 500W load is invoked, the controller collects the maximum Amps commensurate with the insolation. It is a clear day. At 12:30 solar Noon, the Amps top out at 10.5 and begin to decline.

HTH;
John

full_mosey

Oklahoma

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Posted: 02/04/18 01:51pm Link  |  Quote  |  Print  |  Notify Moderator

With the suggestion from MEXICOWANDERER, I analyzed my collected data and decided that the Abs times have been too short and need to be lengthened because the switch to float was too far above 0.5% = 1.35A on average. The bank is 270Ah and 0.5% is 1.35V. Having too short Abs times can result in slowly sulphating the battery over time. I do load capacity tests that seem to show the bank is in good health.

On 2 Feb 18, I began charging without float which leaves only Bulk and Abs. I have been observing how long in Abs it takes for the Amps to stay low. Next, I can make timer settings to the MPPT.

A Raspberry Pi 3 B(RPi) computer collects data from the Morningstar Sunsaver MPPT 15L(MPPT) 24/7/365 at one minute intervals. The Rpi is used to analyze the data and it could be used to make immediate adjustments to the MMPT. I am hoping I can find MPPT settings that can be more permanent without relying on the RPi to make ad-hoc changes. The RPi runs a web server and I can examine the data and change MPPT settings remotely as well.

With this analysis I hope to know what MPPT settings are needed to regularly top-up the bank and when the genny is needed to catch up. The main charging goal of the genny is to speed up the Bulk charge in the morning and let the MPPT finish the Abs and Float charging.

Below are two graphs which show the MPPT charging on 2 Feb:

Volts:
[image]

This shows the MPPT has no problem holding the battery at the Target Volts for 6 hours. Surely that is enough time to call the battery charged, or is it?

Amps:
[image]
Now we see the Amps in play. What I want to see is a flattening of the Amps which should indicate the appropriate time to switch to Float. This graph suggests that 2A and 4 hours Abs would be reasonable. You can see that morning is the best economic and strategic time to run a genny or use shore power to shorten the Bulk time.

HTH;
John

pianotuna

Regina, SK, Canada

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Posted: 02/04/18 01:59pm Link  |  Quote  |  Print  |  Notify Moderator

Hi John,

Thanks for taking the time to present the data.

I'd add another 200 watts of solar myself. Or is there no room?

full_mosey

Oklahoma

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Posted: 02/04/18 02:50pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Hi John,

Thanks for taking the time to present the data.

I'd add another 200 watts of solar myself. Or is there no room?


Thanks.

This is on my Savana van where I have a 10' x 5' area on the roof rack. I could fit two more 12V 58"x26" panels. I am already maxed out on the 15A MPPT controller which is rated for 200W but tolerates the present 280W.

Right now I want to make sure I am fully using the existing system. I am running driveway tests.

When camping/traveling, I do have the 6Ga charge line from the OEM 105A alternator to assist. I wont be driving any until March. I guess I could use a 10A portable charger to simulate morning Bulk charging, or any driving for that matter.

HTH;
John

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