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Rv DIY battery

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brad2388

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Im currently looking into replace our lead acids with a built pack with eve 280 ah cells. My converter is not lithium rated but its a WFCO WF-9865. They also make that converter in a AD version that is lithium. Im planning on changing this inverter to a lithium version either the WFCO or the Progressive Dynamic. But my question is heating pads. We have low temps below 32 degrees but we are only using this pack for moving between campgrounds and will mostly be stored. Will the cells stay warm enough when moving to another campground to be able to be charged back up when we get there? I have a 1500 watt inverter built into the camper that runs the refrig. Also the truck has a charge line from the engine but im sure its not enough to "charge" as long as the refrig is running.

Also what is the best voltage to store this pack at? Since most of the time we will have shore power.

Thanks
 
Are you building your own battery? Otherwise consider a battery with an included internal heater.

Careful with 'lithium' converters. Some are not good for lithium batteries. I would stay with the 9865 until there is an issue to address. The voltage and charging profile will not harm the battery. Worst case it may take a bit longer to charge. This really only matters when speed charging with a generator with limited run time or just wanting to stop the noise sooner than later. Some of the lithium converters hold the voltage at 14.6 indefinitely. 14.6 volts is the very max for health of a lithium battery where 14.2 - 14.4 is better. Even 13.8-14.0 works fine. Full charge can still be reached with the 9865 in normal mode of 13.6 volts.

The charge line from the vehicle should be sufficient to power an internal heater. Propane fridge takes almost no DC power. Compressor fridge will have a moderate draw. And yes not much actual charging will get done except for a super long drive or if the system is upgraded.

Store disconnected at 13.0 to 13.2 volts is fine.
 
time2roll said:
Are you building your own battery? Otherwise consider a battery with an included internal heater.

Careful with 'lithium' converters. Some are not good for lithium batteries. I would stay with the 9865 until there is an issue to address. The voltage and charging profile will not harm the battery. Worst case it may take a bit longer to charge. This really only matters when speed charging with a generator with limited run time or just wanting to stop the noise sooner than later. Some of the lithium converters hold the voltage at 14.6 indefinitely. 14.6 volts is the very max for health of a lithium battery where 14.2 - 14.4 is better. Even 13.8-14.0 works fine. Full charge can still be reached with the 9865 in normal mode of 13.6 volts.

The charge line from the vehicle should be sufficient to power an internal heater. Propane fridge takes almost no DC power. Compressor fridge will have a moderate draw. And yes not much actual charging will get done except for a super long drive or if the system is upgraded.

Store disconnected at 13.0 to 13.2 volts is fine.
Click to expand...
Perfect! Yes im planning on building it. I have built 3 golf cart packs. Two with lifepo4 and one with nissan leaf modules. This will be my first for a always on shore power storage battery. The camper currently has two group 27 batteries that are 4 years old and they are getting tired.
There isnt anything wrong with the converter other than no lithium profile but if it will be ok ill keep it until it dies. There is also a 190 watt panel on the roof that has a lithium setting on the controller.

Thanks for the input! Ill proceed building.
 
There are some BMS with a heater control circuit to maybe flip on a relay or control direct. I used the silicone bee hive heaters stuck to the side of the cells with silicone adhesive. One pad per cell. Two 12v heaters in series to reduce the actual heat output. I used a temperature controlled relay board to control the heaters. On at 38 off at 43 seems to work very well in temps down to about 20.
 
Here is how I made my battery heating.

I used amazon rv tank heater pad under the batteries (eight 272ah Lishen cells)

Facon 12" x 18" RV Holding Tank... https://www.amazon.com/dp/B077VLB1KK?ref=ppx_pop_mob_ap_share

Then a Mica sheet (heat transparent- electric insulation) between the battery cells and the heat pad.
Made a wood box around and under it.

Used a relay to operate the heat pad- (didn’t like the heat pads start and stop temps. It wanted to heat when the battery didn’t need heat. My bms controls the relay - has worked very well so far - in mid-20’s the battery stays above 38F.

Insulation- very important- the 1/2” plywood floor and 3/4” plywood sidewalls keep some heat, but a plexiglass top doesn’t help much. I also made a “battery box cover” taped up the “bubble wrap insulation”into a box shape to cover the top and sides to help keep heat in for the winter.

1708963818523.jpeg

Not much to see when it was all done.

Good Luck with your project.
 
Last edited:
Rocketman said:
Here is how I made my battery heating.

I used amazon rv tank heater pad under the batteries (eight 272ah Lishen cells)

Facon 12" x 18" RV Holding Tank... https://www.amazon.com/dp/B077VLB1KK?ref=ppx_pop_mob_ap_share

Then a Mica sheet (heat transparent- electric insulation) between the battery cells and the heat pad.
Made a wood box around and under it.

Used a relay to operate the heat pad- (didn’t like the heat pads start and stop temps. It wanted to heat when the battery didn’t need heat. My bms controls the relay - has worked very well so far - in mid-20’s the battery stays above 38F.

Insulation- very important- the 1/2” plywood floor and 3/4” plywood sidewalls keep some heat, but a plexiglass top doesn’t help much. I also made a “battery box cover” taped up the “bubble wrap insulation”into a box shape to cover the top and sides to help keep heat in for the winter.

View attachment 198557

Not much to see when it was all done.

Good Luck with your project.
Click to expand...
Do you have any trouble putting the mat under the batteries? Does the weight or bouncing around going down the road mess up the pad?
 
brad2388 said:
Im currently looking into replace our lead acids with a built pack with eve 280 ah cells. My converter is not lithium rated but its a WFCO WF-9865. They also make that converter in a AD version that is lithium. Im planning on changing this inverter to a lithium version either the WFCO or the Progressive Dynamic. But my question is heating pads. We have low temps below 32 degrees but we are only using this pack for moving between campgrounds and will mostly be stored. Will the cells stay warm enough when moving to another campground to be able to be charged back up when we get there? I have a 1500 watt inverter built into the camper that runs the refrig. Also the truck has a charge line from the engine but im sure its not enough to "charge" as long as the refrig is running.

Also what is the best voltage to store this pack at? Since most of the time we will have shore power.

Thanks
Click to expand...

I hear 1 option is to set it AGM and then get a solar charger that is lithium compatible. The AGM will charge up to 80% and then using solar you can get the rest of it charged.

This hinges on if you have solar panels on your rv...
 
AGM charging often goes 14.4 and hold for an hour. Easy 100%. No equalization is good too.
 
SalmanFarooz said:
I hear 1 option is to set it AGM and then get a solar charger that is lithium compatible. The AGM will charge up to 80% and then using solar you can get the rest of it charged.

This hinges on if you have solar panels on your rv...
Click to expand...
I have a 190 watt onboard panel and a controller. I do plan on putting the controller in lithium mode. That should get the rest of it charged up.

How should i set the charger cut off voltage to on a battery thats going to be connected to a charger all of its life?
 
So i have built the pack and installed it in our RV. The converter on the coach floats at around 13.1-13.2 volts. Which is lower than i have my bms to disconnect for a full charge. So the solar is charging the batteries up and when the sun goes down the voltage drops to the 13.1-13.2 of the converter. If i cycle power the converter goes back to 13.6.

My question is can i swap this converter out to something better and something that will stay at 13.6? This converter is a 65 amp converter. I also just ordered a victron 75/15 MPPT controller inplace of the gopower PWM. Im getting pulses from the pwm controller and its flickering my lights.
 
brad2388 said:
Do you have any trouble putting the mat under the batteries? Does the weight or bouncing around going down the road mess up the pad?
Click to expand...
I'd put some non conductive insulation under the batteries and put the heat mat on the sides of the batteries. There is a lot of motion as the RV goes down the road that would end up grinding the mat if below and possibly creating a path to ground with the batteries themselves.
 
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