Trojan T-1275 Trouble

[MakerMK]

Newbie here.

I have a travel trailer that has a Trojan T-1275 battery that is around three years old. The camper spends most of it's time in a pole barn hooked up to a couple of 100 watt solar panels and a Schneider charge/load controller. I check the water level when I think about it (I know, it should be on a schedule) and the last time I checked it was about 1/8" below the top of the plates and the charge level was low. I topped the cells off with distilled water and gave it a couple of days to recharge.

Well, it didn't recharge. I initially thought I must have ruined the battery by letting it get low, but after checking the wiring of my solar system I discovered a bad connection. A much better problem to have than a dead battery! I moved the camper to a source of AC power and let the camper's system (not the Schneider) charge the battery. The next day I took hydrometer readings and they were still deep in the red/recharge zone. I let it charge for another day and there was no change.

I decided to take a voltage reading, so I disconnected the battery and let it sit overnight. When I checked it, it read 13.1 volts! I grabbed the hydrometer again and the readings were all still in the red/recharge zone. I suspected the hydrometer so I checked it with plain water and it read 1.0, or more precisely the water level was at the point where 1.0 would be if the scale went that far.

What the heck? I'm no battery guru, but this seems crazy! Do any of you folks have an explanation for this? I'm at a loss.

[2112]

You can boost the Megawatt output to over 16V with THIS. There are lesser boost modules if the 30A model is overkill.

[theoldwizard1]

MakerMK wrote:
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?

I think that is what I would do !

You do not need a 30V power supply. If you are NOT going to equalize (i.e. leave the charge controller on manual equalize mode) than a power supply capable of providing at least 1V MORE than the Bulk Charging Voltage should be sufficient.

In other posts Megawatt Power Supplies have gotten good reviews. While their supplies only claim a maximum output of 15.5V if you called and asked I'll bet they can set you up with one that would do 16V.

[theoldwizard1]

MakerMK wrote:
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.

This is GREAT news ! Thank you for reporting back !

I skimmed that owners manual and the setup for that charge controller is not trivial, it is not that difficult either.

[theoldwizard1]

BFL13 wrote:
Yes it is sort of complicated till you do it in real life. Switch A makes it a typical three stage converter and if you monkey with the pot with the switch set to the left, it will change all three voltages at once. You can restore that to original though.

The real benefit is as a singe voltage manual charger with switch A to the right, set to any voltage you like with the pot B.

Maybe not a perfect solution, but much better than most other "smart" chargers which have no manual mode !

And the price is reasonable.

[MakerMK]

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?

[BFL13]

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.
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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 🙂
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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/products/powermax-pm3-60lk-12-volts-60-amp-power-converter-batt...

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

[MakerMK]

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?

[MakerMK]

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!

[BFL13]

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.

[MakerMK]

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]

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

[MakerMK]

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!

[2112]

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

[BFL13]

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