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 > Trojan T-1275 Trouble

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BFL13

Victoria, BC

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Posted: 01/09/19 06:46pm Link  |  Quote  |  Print  |  Notify Moderator

There is such a thing as supplying an MPPT controller with a DC power supply and use the MPPT controller's charging profile. That is because the controller is a "buck converter". You need to organize that power supply to have an appropriate input to get the MPPT controller output you want.

I am not clear that you can do that at all with a PWM controller, so you will have to look that up if your controller is PWM.

You can confirm the output voltage of your controller with a multimeter. It should be 14.8 at 25C, or as adjusted for temperature from that. It should stay at 14.8 long enough to get the job done, and not drop to 13.6 too soon. Some have a built-in two- hour time limit at the 14.x and then drop to their 13.x. "Too soon" is before the SG is back up to 1.275


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2112

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Posted: 01/10/19 02:03am Link  |  Quote  |  Print  |  Notify Moderator

MakerMK wrote:

So I've decided to try the Schneider again, but instead of powering it with the solar panels I'll feed it with an adjustable power supply set at the same voltage that the solar panels provided.
If your power supply will reach 16.2V, why not just equalize using the power supply? Charge it @14.8V until the current is down and then adjust it up to 16.2V for an hour.

THIS is what I use to equalize and float while in storage


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MakerMK

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Posted: 01/10/19 01:07pm Link  |  Quote  |  Print  |  Notify Moderator

Success! By using the Schneider controller powered by a lab power supply I got hydrometer readings in the green for all six cells. This was after charging and equalizing.

The controller is a Xantrex C35 PWM type. It can be set up for different charging profiles so it is pretty ideal for atypical batteries. But of course it doesn't work if the power supply has a bad connection.

So I'm good to go as long as I am using the solar panels. Not so sure about the charge system in the camper though. Apparently the voltage isn't high enough for the T-1275.

Thanks so much for the advice!

BFL13

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Posted: 01/10/19 01:22pm Link  |  Quote  |  Print  |  Notify Moderator

Good info. What voltage did you set the power supply at to run the solar controller?

MakerMK

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Posted: 01/10/19 07:02pm Link  |  Quote  |  Print  |  Notify Moderator

I set the voltage at 38 volts, but because the max current was set at 3 amps the voltage seldom got that high. The meters were swinging all over the place as the controller did it's thing. Kind of hard to say an exact voltage that it was operating at. The solar panels deliver about 44 volts in good sunlight.

BFL13

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Posted: 01/10/19 07:19pm Link  |  Quote  |  Print  |  Notify Moderator

MakerMK wrote:

I set the voltage at 38 volts, but because the max current was set at 3 amps the voltage seldom got that high. The meters were swinging all over the place as the controller did it's thing. Kind of hard to say an exact voltage that it was operating at. The solar panels deliver about 44 volts in good sunlight.


I must have missed something. 38 and 44 volts is like "24v" panels so to charge a 12v system you need an MPPT buck converter type controller. You can only use a PWM 12/24 controller (like you said you have) if your battery system is also 24v with those sorts of input voltages.

what is really going on there?

EDIT--are you using 24v panels and only getting half the amps as your usual set-up, until you get an MPPT controller? You can do that if the total Voc does not go over about 50v and fry the controller.

* This post was edited 01/10/19 07:26pm by BFL13 *

MakerMK

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Posted: 01/10/19 07:33pm Link  |  Quote  |  Print  |  Notify Moderator

I got out the manual for the charger that the camper has. As was suspected by BFL13, the camper's charger falls short of what the Trojan T-1275 needs. It hasn't been a problem yet because all of our trips have been short. But long trips are in our future and I'm a bit worried about the situation. I guess as long as I can use the solar panels with the Schneider controller things will be fine, but I'd rather not be 100% dependent on them. Time for some research!

MakerMK

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Posted: 01/10/19 07:55pm Link  |  Quote  |  Print  |  Notify Moderator

BFL-13- My system is not MPPT. I hooked it up according to the instructions (I thought, anyway) and it was my understanding that the controller takes care of the voltage difference between the power source and the battery. Am I wrong to make that assumption? Feel free to let me know if I'm doing something stupid, I have a pretty thick skin! The solar system always worked well, at least until the connector failed. My main concern now is with the WFCO controller that came with our camper. It seems that the voltages that it produces are not suitable for the T-1275 battery. And the manual has no mention of a way to adjust the voltages. So, what's next?

BFL13

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Posted: 01/10/19 08:01pm Link  |  Quote  |  Print  |  Notify Moderator

First please identify your panels as to their specs ie, Isc, Voc, wattage Vmp, Imp if you have that but don't need it.

Second, how are they (how many) connected for series or parallel or both?

This will clear up whether you have the right controller.
----------
EDIT--OP says two 100w panels. to get 44 volts output that means they are in series. Wrong! they should be in parallel. Now voltage will be 22v and your amps will be 12 instead of just 6. That will help [emoticon]
-----------

To get better charging for your T-1275, I recommend the adjustable voltage PowerMax and use it as a portable charger, leaving the WFCO in place for when on shore power. That saves you from a bunch of wiring work.

https://www.boatandrvaccessories.com/pro........er-converter-battery-charger-w-led-light

This is not the same charger, but use it like this when off grid:

[image]

* This post was edited 01/10/19 08:16pm by BFL13 *

MakerMK

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Posted: 01/11/19 10:08am Link  |  Quote  |  Print  |  Notify Moderator

BFL13- My original plan was to travel with the solar panels and use them when power is unavailable. Maybe I should rethink that and use them to charge the battery even when there is power available? Another thought is to use a simple power supply to drive the Schneider charge controller and don't even use the camper's built in charger. I'm sure that your suggestion to get another charger would work, but wouldn't it be more cost effective to make use of what I already have?

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