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Old 01-18-2022, 10:04 AM   #1
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Running portable power bank through solar controller?

This morning I woke up with what I thought was a brilliant idea, but so far it didn't work. I have an SAE port to my chassis batteries, and thought what if during the night when I'm running the heater, if I had a portable power bank plugged into that SAE Port, wouldn't that keep the house batteries charged up overnight?

Electricity is electricity, so what does it matter if it's coming from a solar panel or a power bank? I have a Hulkman Aloha 100, which is a pretty powerful jump starter, and another power bank as well. So I decided to plug the Hulkman in from its DC out port to the SAE connector to the solar controller. Initially I got a green blinking light on the controller like it was charging, then it went red very quickly Just checking to see if maybe the polarity was reversed, I put a polarity reversal fitting on the cable, and it still went red. I plugged it back in without the reverser, and it went green then red again.

Maybe I need a bigger controller? I posted the specs on it (in white), and the specs on the Hulkman. The controller says it puts out 10 amps max, but as far as the voltage in, it doesn't list a limit on the amps. However I kind of suspect that's what it is. My other power bank puts out 10 amps as well, so I don't see any use in trying that.

I just thought that would be a great idea, since I only have two Trojan T-105s, and no room to add batteries. This would be a great way to keep the batteries up overnight, when boondocking in cold areas with the propane heater.

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Old 01-18-2022, 10:21 AM   #2
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My guess is that many solar charge controllers require the charge voltage to be 5v higher than battery voltage before they will turn on. So, unless your power source can be set to 18v output, it’s not likely to work through your solar cc.
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Old 01-18-2022, 10:41 AM   #3
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Originally Posted by Marine359 View Post
My guess is that many solar charge controllers require the charge voltage to be 5v higher than battery voltage before they will turn on. So, unless your power source can be set to 18v output, itís not likely to work through your solar cc.
That very well could be, however when I have my solar panels plugged in and it's cloudy, it doesn't turn red, it just doesn't blink green. It seems like the red light would indicate either reverse polarity, or too much amperage coming in? I appreciate the response.
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Old 01-18-2022, 11:34 AM   #4
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For that, you’ll need to read the manual for the CC. You didn’t say what make/model it is. Is it pwm or mppt, or max in/out.
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Old 01-18-2022, 12:13 PM   #5
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For that, youíll need to read the manual for the CC. You didnít say what make/model it is. Is it pwm or mppt, or max in/out.
It's a Battery Tender and I posted the specs above in the white picture. It's pwm.

https://www.batterytender.com/batter...nel-controller

I just read on a solar panel forum about a guy trying to do a similar thing, and someone responded that he actually needed to cut the voltage down to 13.6 with a diode or something.

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Old 01-18-2022, 02:06 PM   #6
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Looking at the manual this device is not designed for what you are trying to do. Since it does not current list it is faulting as your house battery are drawing more than the 10 amps the device can handle. It is designed for a small PV array.

When the red fault led is on it is connecting your source battery to house battery with no regulation. Essentially paralleling the two battery banks.

Snip from manual:
1. This device does NOT current limit the output, therefore you must ensure that you DO NOT EXCEED the 10Amp output rating. If the 10Amp output is exceeded the RED error LED (#9) will flash on the front panel. The output regulator will then stop, however current will still pass through the regulator. Once the current has dropped below 10Amps the regulator will reboot.
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Old 01-18-2022, 02:20 PM   #7
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Originally Posted by Steve-W View Post
Looking at the manual this device is not designed for what you are trying to do. Since it does not current list it is faulting as your house battery are drawing more than the 10 amps the device can handle. It is designed for a small PV array.

When the red fault led is on it is connecting your source battery to house battery with no regulation. Essentially paralleling the two battery banks.

Snip from manual:
1. This device does NOT current limit the output, therefore you must ensure that you DO NOT EXCEED the 10Amp output rating. If the 10Amp output is exceeded the RED error LED (#9) will flash on the front panel. The output regulator will then stop, however current will still pass through the regulator. Once the current has dropped below 10Amps the regulator will reboot.
Thank you so much for taking the time to look at the manual, and pointing that out. You're exactly right. Oh well, it was a thought.

By the way the controller did reset, and I now have a solar array hooked up to it. It's nice that they have all kinds of idiot-proof safeguards built in, for people like me
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Old 01-20-2022, 03:03 PM   #8
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Another question, I've been Googling trying to find answers, with not too much success.

Say I have a lithium potassium 100 amp hour battery, and hooked it through that SAE connector, and even though it's going to cause the regulator in the solar controller to shut off, would that battery then be able to trickle charge the two Trojan t105s overnight safely?

Or is there another interface I could use? Also this raises the issue if I had that LiFePO battery hooked up through the smaller wires of the SAE cables, that could create a problem if I use the boost function to try to start the engine, right?

All I want to do is have some way that overnight I can have a trickle charge going into the chassis batteries, if I'm using the heater while boondocking. The way it is now, if I wake up in the middle of the night, the voltage meter in my bedroom is reading around 12.1 volts and I don't like that. I'll usually get up and run the engine for a little while to charge it back up.

I actually have space in the compartment next to the chassis battery compartment that I could keep a lithium battery, so maybe there's a way I could wire it where it would safely be charged through the alternator? I've read a little bit about DC DC Chargers, but I'm just dipping my toe into this. Otherwise, I could just charge it during the day via solar.
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Old 01-20-2022, 06:07 PM   #9
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I finally came up with a simple plug-and-play solution. A trickle charger on the house batteries, plugged into a power bank inverter. Within 20 minutes it already had the voltage from 12.6 up to 13, and I'm waiting to see if it kicks the BIRD in and charges the chassis battery as well. The charger only draws about 9 watts, so it could easily last all night long. With the same power bank I was running my little TV and satellite box for 5 hours, and it was drawing an average of 45 watts. I'll put a SAE pigtail on the batteries, so all I have to do is open it up and hook it up. Of course I can charge up the power bank during the day with my solar, and frankly it might even last a couple nights. We shall see...
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Old 01-21-2022, 08:00 AM   #10
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Just to update this, I let the trickle charger run 4 hours last night, and the BIRD did kick in and it started charging the chassis battery as well. After 4 hours the power station was down to 62%, so it should at least last overnight with a little reserve left. It lost about 9 to 10% charge per hour.

Of course I didn't have the heater on, so when the heater's on it's going to be different, but I have a pretty good feeling this might keep the battery at least at around 12.6 v overnight.

I'm going to make a fused pigtail, and leave the SAE connector hanging out under the step with some protection. Then I can just plug in the trickle charger without even opening up the lid.





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Old 01-25-2022, 11:59 AM   #11
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This set-up has been working beautifully. I now have a fused pigtail connected to the battery bank, and hanging out from under the step lid. I'm using a different one amp charger now, and if it's on 8 hours the powerstation gets down to about 25%. Then I put it on charge with 120 watt suitcase solar array, and it charges back up to 100% in about five and a half hours. This particular Power Station isn't really pure sine wave, so I'm mainly going to use it for this purpose. I have another one that's pure sine wave, that works much better for the TV and satellite box.

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Old 01-25-2022, 12:55 PM   #12
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Quote:
A trickle charger on the house batteries, plugged into a power bank inverter. Within 20 minutes it already had the voltage from 12.6 up to 13, ... The charger only draws about 9 watts,
...
I'm using a different one amp charger now
You do get that this is a pitiful amount of power and isn't really going to add much to the running capacity of your T105's? 12.6v is nearly 100% charged to begin with and the boost you're seeing to 13V is just surface charge. Depending on the load your low of 12.1V is somewhere between 50% and 75% SOC which would be pretty light duty service for deep cycle. Charging one battery to fill another is only compounding inefficiencies, adds cost and complexity.

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Old 01-25-2022, 02:03 PM   #13
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You do get that this is a pitiful amount of power and isn't really going to add much to the running capacity of your T105's? 12.6v is nearly 100% charged to begin with and the boost you're seeing to 13V is just surface charge. Depending on the load your low of 12.1V is somewhere between 50% and 75% SOC which would be pretty light duty service for deep cycle. Charging one battery to fill another is only compounding inefficiencies, adds cost and complexity.



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My ONLY goal with this setup is to keep the house batteries from deeply discharging overnight, if I'm using the heater. During the day I'll plug them back into a 120 watt solar panel. If I use a higher power charger, it's going to deplete the power station too fast, and it wouldn't last overnight.

In fact this is a fairly inexpensive and very simple solution. I don't want to replace the house batteries with lithium or AGM, or go to a permanent solar setup in the motorhome.
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Old 01-26-2022, 06:37 AM   #14
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I get that's the goal, just saying that you can't meet that goal with what you're doing.

The most a 1A charger will provide overnight, say 8 hours, would be 8Ah. A ~7A running blower motor cycling 35% over 8 hours would require about 20Ah. 20Ah represents about 10% of the capacity of your batteries so augmenting with the lithium pack reduces that to about 6%. "Less" discharge to be sure but it's not really contributing to any "deep" T105 discharge. Doesn't account for any other loads you may have but the most you'll ever get doing this is 8Ah, which is a 4% difference in the capacity of your bank at whatever SOC you're operating at. So while it doesn't "hurt" to do this, it's not helping much either and is only serving to turn some of your solar-sourced power to heat through the inverter and churn through lithium pack life, with little practical net difference to the T105's.

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