Keep those batteries warm - Renogy 100aH

I’ve just spent the last three days getting the internal temperature on my Renogy 100aH Smart battery with heater (req 3A of charge to operate) from -11 to 6 degree’s C.

I forgot that last year I was running a heater in the box when the truck is parked. So this is just a reminder post to get your winter battery maintenance plans in place :smiley:

This is the spec section in case you’re scouring the internet trying to figure out what the error is. It’s in the manual; but that’s in the truck…:stuck_out_tongue:


Ok, So here’s the next question. Anyone else running a Renogy Lithium Smart battery with heat?

I am trying to get my NOCO Genius 10 charger to trigger the heater. But…these chargers are too smart and won’t put out 4A of charger because the battery is on float. So the battery has gone into low temperature charge protection.

As it stands Renogy’s solution is to buy their AC/DC charger; but I can’t see the difference when I look at the manual. It’s still only going to provide 2A< once the battery is charged.

I have my system hooked up so my Solar charger (Renogy Wonderer), DC to DC charger, an now AC DC charger all connected directly to the battery. I’m trying to have ‘shore’ power but I can’t get it to function as desired.

My next thought is to connect the NOCO charger to the Truck Battery, move the DCDC charger switch to a N/O relay for the 12V then just turn the switch on and allow the charger to charge both the Truck AGM and power the DCDC charger in hopes that it will provide the correct current to trigger the heater.

The thought is, that the heater function works when I run the DCDC charger when the truck is running. Being fairly familiar with electricity and electronics I’m finding it tricky to fool all this ‘smart’ technology.

I don’t have your exact setup but I needed to charge my house battery and didn’t have a lithium charger.

My solution was to charge my starter battery (Oddessy AGM), and have my DCDC controller (Renogy DCC50S) charge my house battery (SOK LiFePO4). Has been a working interm shore power solutions for me.


Hey Ron, that is my thought too. Is it enough to trigger the battery heater?

It worked on my setup; got 12A when it was charging. I’m not familiar enough about your NOCO charger and what triggers your Renogy battery’s heater.

Backstory: My battery charger was only designed for AGM/Flood, and needed to charge my LiFePO4 house battery with the right charging parameters; which the DCDC had. Did a little research to backup my theory of connecting it to the starter battery and having the DCDC charger the LiFePO4 and it all checked out. Have used it 5 times already to charge without issue.


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Ok, I think it will work then. The NOCO does have a Lithium setting; but the issue is that it won’t trigger a charge until the battery requires it. The heater requires a constant stable 4A of charge present to activate the self heater. I’m hoping the DCDC charger will control that portion.

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Ok, so I’m bench testing running the NOCO to the Truck, have the DCDC on a switch. As it stands, it appears to be prioritizing the House battery and has pulled the Truck battery below acceptable voltage levels (8 volts) which is not ideal.

So; seems like the mismatch between the two charging rate capacities may be a factor. @Ronmastas What is the max current your charger puts out vs you DCDC charger?

Secondly, did you use a relay to trigger your DCDC charger when your truck battery is say at 13V with a cutout Voltage of 10V?

There is no doubt that running the setup I have on the test bench will destroy my truck battery; leaving me stranded with no Cold Cranking Amps left.

I don’t have a recorded number but what I recall was my ACDC charger was putting out 12A when I was initially charging the house battery. IIRC my shunt on the house battery was seeing ~10A.

FYI: The AC/DC battery charger I’m using.

I don’t use a relay to trigger my DCDC. It’s voltage sensing built into the Renogy DCC50S works for me. It has an optional wire to connect if the vehicle is equipt with a smart alternator.

Also, what is the voltage of your LiFeP04 right now?

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What a day. I was able to get it working; I think. I let the truck battery charge until it was over 13V, then I engaged the DCDC charger. The self heater turned on and it topped up the battery while maintaining the truck battery. I will have to go out again and double check in a bit to be sure it hasn’t killed my truck battery again.

The voltage on the LifePo4 has ranged throughout the day about 13 -14 V. But I was fiddling around with different configurations. I’m hopeful.

Mock up in the truck in ‘test’ mode with NOCO Gen10 in ‘Supply’ mode

Test fit

Finished product, salvaged copper buss bar, 2x 150A ANL fuses, salvaged clear plexiglass, random bolts. Total cost = time :joy:

Start battery floating/trickle charge, DCDC on, Current Limit engaged, Self heating on

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Well back to the drawing board, it warmed it up that once. Then once it was fully charged I guess it makes no more call for current. SO….the heater doesn’t turn on. This was the battery in the morning.

That’s with the configuration above and the NOCO charger on AGM charge mode connected to the truck battery. DCDC charger activated via switch, current limit installed.

So tried it with the NOCO in Supply mode and was able to get it to work.

Then a few hours later, I’m back to where I started. It won’t engage the heater. I tried resetting everything. The battery is at 100% charge, but the temp is 2C and dropping.

Are you sure the heater should maintain 5c when not charging? Or should engage at a lower temp? Usually it’s ok to discharge down to -10c or so but needs to be at least 5c to charge. That’s how my pack is set up.

I’m not familiar with this exact control narrative but you would think it would charge to 100%, turn off the heater if above -10c. When capacity drops below say 80% it will engage the heater and top the battery off when the internal temperature is above 5c? Or else it will just waste power keeping the pack warm while it trickle charges or is on float.


Some random salad thoughts I have:

Maybe the temp isn’t low enough to activate.
If your BMS shows status of the charging MOSFET, look there.
Is the state of charge on the battery a variable if it will activate the heater? I.e., if it’s near a full charge


This is what I would expect too. Discharge at low temps is fine but charge is the issue.

The charge and discharge levels I’m aware of. What you’re describing is that same detail I’m trying to get from Renogy. Will it heat up if the internal temp is -10 with a full charge?

The manual just says it turns on automatically at 5C and off at 10C; but maybe the key is what you describe and what I think as well. It will not heat up if it’s not requiring a charge and is in float. Maybe I should connect the load. Idle it pulls like 0.6A with all the Bluetooth and LED’s, USB sockets. See if that triggers a charge cycle and warms my batteries up.

Discharging the battery some significant amount to see if that changes things would be my move to going forward.


So, I got a response from Renogy. It was as I suspected, there are thresholds that for reasons beyond me they do not include in their specs. Here is the response to how Renogy’s Self-Heating functions in cold weather charging:

Good day!

I have got a response from our related department.

  1. The PWM controller output voltage is square wave, which cannot start the RBT100LFP12SH-CA heating film.


  1. RNG-DCC1212-40 must receive IGN voltage signal before it will run (if the engine is not started and 12V signal is introduced from other position to make RNG-DCC1212-40 run, it may lead to over discharge of main battery).
  2. When the battery temperature is lower than 5℃, the battery will detect the internal voltage and external voltage, when the voltage difference ≥ 0.5V, the heating function will be triggered, when the battery temperature is ≥ 10℃, or the voltage difference < 0.5V, the heating function will be turned off. The charging voltage of Li-ion battery charger is usually 14.4V, so when the battery is charged to about 14V, the heating function will not turn on even if the battery temperature is lower than 5°C. This logic allows the battery to be charged more safely in a low temperature environment. After the battery stops charging, the voltage will fall back until the difference with the external voltage is greater than 0.5V, and the heating function will be triggered again, therefore, at the end of charging, the heating function may be observed to be triggered intermittently.


  1. The battery low temperature charge/discharge alarm and protection threshold are shown below.


I hope this helps and gives you enough information to work with. Please let me know if there is anything else I can do to help. You may also give us a call or talk to us online.

Have a nice day!

Best regards,


So I’m still running into a problem with my configuration. It’s currently -19C here in Williams Lake. The NOCO 10A charger connected as described above seemed to do the trick to keep the house battery warm. The issue is; it has killed my truck battery.

So obviously not ideal. I’m wondering if it’s the lack of current limit on my DCDC charger right now. I’m going to test it with the jumper installed and see if that solves the problem.

I’m also thinking that the DCDC charger is 40 Amps, the Battery charger is 10Amps…so without the current limit the charger will pull 30Amps off the battery. That’s my theory. I’m thinking if I put the current limit in the DCDC should only pull 20A, so then only 10A off the battery if needed. Ideally I would swap this DCDC charger out for the 20A version.

That theory seems to make sense to me. Is there anyway to limit current on the DCDC?

Suffering similiars woes myself. I wanted to verify my setup today now that the weather has dipped to 0C. Like you, my battery heater isn’t turning on because my Renogy DCDC is trying to protect my battery and not sending a charge due to the temp. Also, my internal battery BMS disconnected the charge MOSFET till it reaches 5C (confirmed this by heating the camper till the BMS saw 5*C).

I going to try to get the Bluetooth module for the Renogy DCDC and set a custom parameter for the battery, hopefully I can disable the charge disconnect, or at least shifting the charge disconnect to a lower temp.

The Bluetooth modules from what I experienced do not allow any mods. They are solely for monitoring. On the Renogy DCDC there is a LC terminal. If you give that terminal 12 volts it will 1/2 the current of the charger. If you look at the response from Renogy; you can see that you require the voltage of the battery to hit a threshold before it turns on the heater to allow the charge.

Are you running your DC to DC charger with keyed or non keyed power? It really should be keyed power only so you can’t drain down your starting battery… might want to toss in a solenoid in there to stop discharge of your starting battery.

Also this whole thread (and others like it) is the reason I haven’t gotten a heated battery. Seems they are more finicky to set up than they need to be.

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