Battery Dilemma

[SolarPoweredRV]

Cross country camping this July in my fancy new 21BHE. Reservations at mostly full service campgrounds but some nights without water/power. Came with a single 12v battery. Will that be enough juice? Or will we need to be super careful?

That is hard to say, if you are going to hit cold weather I would say no, because, the RV Furnace is a real Power Hog. I would suggest the next time you go camping to simply not hook up the camper to the campground utilities and try camping without power and see how far you and your family get without hookups. Worst case, you wake up in the middle of the night and you have to run out and plug in.

If you do find that your battery is not sufficient, I would strongly encourage you to go the Lithium route (LiFePo4) for your replacement battery(ies).

[ultramafic]

Mike: Congrats on taking the DIY plunge into LiFePo4 batteries. Your problems with not being able to keep the batteries topped off while dry camping will disappear with the switch to Lithium.

You are correct in that the RV Furnace is a Power Hog, manufacturers should really use a more efficient DC motor in the RV furnaces.

Please document your build process and your sources for the batteries so others will be encouraged to build their own batteries. Building your own LiFePo4 battery is the cheapest option to upgrade your RV battery to Lithium currently available.

So far i have ordered, cells off alibaba 4 x 280 amp to total 12 volt, they have shipped, and i think really on a ship, so might not get here till summer.. haha

I also ordered a new converter for a direct swap from amazon, progressive dynamics which of course arrived already and i have also ordered a daly bms for the cells if i recall correctly i got one good for 120amps.. I know the daly does not have low temp shutoff so I will have to be careful with that for sure.

My intention/hope is to remove my dual 6 volts in the front compartment and put the new lithiums back in their place same with the new converter behind the false wall in the pass through. I hope I am not missing anything and maybe anything that I have missed will become apparent when I start my re an re.

I intend to top balance the cells when they arrive, then build them in series secure them together, add the BMS and wires then hook them up to the trailer.

If it all works out I may get a second set of the cells and wire in an Inverter in a separate system (to the trailer electrical system) to a household plug from the pass through for dry camping. That is down the road, firstly I want to get this set up going.

mike

[SolarPoweredRV]

So far i have ordered, cells off alibaba 4 x 280 amp to total 12 volt, they have shipped, and i think really on a ship, so might not get here till summer.. haha

I also ordered a new converter for a direct swap from amazon, progressive dynamics which of course arrived already and i have also ordered a daly bms for the cells if i recall correctly i got one good for 120amps.. I know the daly does not have low temp shutoff so I will have to be careful with that for sure.

My intention/hope is to remove my dual 6 volts in the front compartment and put the new lithiums back in their place same with the new converter behind the false wall in the pass through. I hope I am not missing anything and maybe anything that I have missed will become apparent when I start my re an re.

I intend to top balance the cells when they arrive, then build them in series secure them together, add the BMS and wires then hook them up to the trailer.

If it all works out I may get a second set of the cells and wire in an Inverter in a separate system (to the trailer electrical system) to a household plug from the pass through for dry camping. That is down the road, firstly I want to get this set up going.

mike

Sounds like you are quite far along with your project.

You mentioned that the BMS does not have thermal protection from charging the batteries below 32 degrees. I also had to protect my batteries from being charged when cold, I used this thermostatically controlled relay to open the "On/Off" switch on my Victron Solar Charge Controller to prevent the batteries from being charged if the battery temperature is below 35 degrees (you can set your own temp parameters).

If you decide you need to thermally protect your batteries, here is the device I used:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Good luck on your build and hope you get your cells very soon.

[ultramafic]

Sounds like you are quite far along with your project.

You mentioned that the BMS does not have thermal protection from charging the batteries below 32 degrees. I also had to protect my batteries from being charged when cold, I used this thermostatically controlled relay to open the "On/Off" switch on my Victron Solar Charge Controller to prevent the batteries from being charged if the battery temperature is below 35 degrees (you can set your own temp parameters).

If you decide you need to thermally protect your batteries, here is the device I used:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Good luck on your build and hope you get your cells very soon.

That is of interest for sure. I am thinking that if everything works, and I do get a second set of cells i might look more into a better BMS that has low temp cut off for the set in the factory location.. I would place the second set hopefully in the pass through which has heat and I would be able to use the current BMS there with far less risk.

We dont camp when its super cold so I am not overly worried about frozen charging and if it was that bad i could throw a space heater in the compartment to keep it warm before starting up the charger. At least that is the plan.

Thanks for link though. I will have to do some more research into that too.

Mike

[SolarPoweredRV]

That is of interest for sure. I am thinking that if everything works, and I do get a second set of cells i might look more into a better BMS that has low temp cut off for the set in the factory location.. I would place the second set hopefully in the pass through which has heat and I would be able to use the current BMS there with far less risk.

We dont camp when its super cold so I am not overly worried about frozen charging and if it was that bad i could throw a space heater in the compartment to keep it warm before starting up the charger. At least that is the plan.

Thanks for link though. I will have to do some more research into that too.

Mike

In reality, if you are fully charged before the cold weather hits, with 280ah of battery, you will probably not need to charge up until mid-day and by that time your batteries should be above freezing.

In reality, it would probably take several hours well below freezing before your batteries would begin to get down to 32 degrees, especially if your battery is inside a hold (even a non temp controlled hold) so you can easily control charging of the battery in that case.

For example: last Christmas we were facing overnight temperatures in the mid 20's (yes, even in Florida), we began preparing the day before by filling our on-board water tank and removing our water hose. It would have been no extra trouble to disconnect our Solar system from the batteries and to switch our Inverter/Charger to Inverter only mode to protect our batteries. Then, on the next day when the temps rose above 40 we could have turned on the Solar Controller and enable the Charge mode on the Inverter/Charger.

The key is knowing about the "No-Charge" limitations and being conscious about protecting your battery in those rare cold weather circumstances.

[ultramafic]

Ok... I have a hefty update. My cells arrived a week or so ago. They took about 40 day to arrive at my house and the courier simply dropped them on my doorstep which was good since that meant no import fees or taxes owing.

The cells were undamaged and appeared in good shape. I got around to top balancing them over the last week or so.. That took forever fyi for 280ah cells and a small charger.

I wired them and the daly bms that i bought off amazon up today and got it sorted for a few tests. Few quick things on the daly, It came with a bluetooth module and what looked like a temp sensor... I was hopeful.

I had some difficulties in starting the bms up... it would t read more than 10 volts with a multi meter, shorting it out to reset didn't work but hooking up my 45 amp charger did activating it fully. I was worried I wired incorrectly but it was totally fine no issues in the wiring.

The bluetooth module and Daly app were not super easy to figure out at first but I found out that location services have to be on or it wouldnt work for me. Not a fan of that but... I tried the temp sensor or what looked like one and sadly it didnt seem to stop charging when i placed the probe into ice water... oh well didnt expect that anyway.

I finally got the app working and this was the cats meow, the connection was pretty easy once everything was working and WOW inside the app there were parameters for just about everything... INCLUDING LOW TEMPERATURE SHUTOFF which for some silly reason was set at negative 20 Centrigrade... after i reset that to 2 degrees C and tested again IT WORKED.... I WAS STOKED.

I currently have it running a pure sine wave inverter 2000w for testing purposes and its pulling 53 amps heating my laundry room to tropical temeratures on a space heater.

I have used double sided tape to keep the cells together and have put a strap around them for lifting purposes for going in and out of the trailer... I am so stoked to put these things up against my fridge fans... sadly the virus is making this ever so complicated with restrictions in my area..

There will be some tweeking left to do such as getting them set up in the trailer, installing the new p dynamics converter but that is for another day as i have to go to work now ...

I can try to answer some questions but may not be able to respond quickly and I am not an expert by any means so answers could be limited.

I dont think i can post pics either but i could possibly text or email some. All in I think I spent 650 on the cells and about 80 on the bms, the charger was 250, i think, and then there were some misc connectors and items for minimal costs. All costs in canadian dollars fyi.

Mike

[Ynot4me2]

Ok... I have a hefty update. My cells arrived a week or so ago. They took about 40 day to arrive at my house and the courier simply dropped them on my doorstep which was good since that meant no import fees or taxes owing.

The cells were undamaged and appeared in good shape. I got around to top balancing them over the last week or so.. That took forever fyi for 280ah cells and a small charger.

I wired them and the daly bms that i bought off amazon up today and got it sorted for a few tests. Few quick things on the daly, It came with a bluetooth module and what looked like a temp sensor... I was hopeful.

I had some difficulties in starting the bms up... it would t read more than 10 volts with a multi meter, shorting it out to reset didn't work but hooking up my 45 amp charger did activating it fully. I was worried I wired incorrectly but it was totally fine no issues in the wiring.

The bluetooth module and Daly app were not super easy to figure out at first but I found out that location services have to be on or it wouldnt work for me. Not a fan of that but... I tried the temp sensor or what looked like one and sadly it didnt seem to stop charging when i placed the probe into ice water... oh well didnt expect that anyway.

I finally got the app working and this was the cats meow, the connection was pretty easy once everything was working and WOW inside the app there were parameters for just about everything... INCLUDING LOW TEMPERATURE SHUTOFF which for some silly reason was set at negative 20 Centrigrade... after i reset that to 2 degrees C and tested again IT WORKED.... I WAS STOKED.

I currently have it running a pure sine wave inverter 2000w for testing purposes and its pulling 53 amps heating my laundry room to tropical temeratures on a space heater.

I have used double sided tape to keep the cells together and have put a strap around them for lifting purposes for going in and out of the trailer... I am so stoked to put these things up against my fridge fans... sadly the virus is making this ever so complicated with restrictions in my area..

There will be some tweeking left to do such as getting them set up in the trailer, installing the new p dynamics converter but that is for another day as i have to go to work now ...

I can try to answer some questions but may not be able to respond quickly and I am not an expert by any means so answers could be limited.

I dont think i can post pics either but i could possibly text or email some. All in I think I spent 650 on the cells and about 80 on the bms, the charger was 250, i think, and then there were some misc connectors and items for minimal costs. All costs in canadian dollars fyi.

Mike

Hi Mike, thanks for taking the time to document and post all of this. A lot of us are really paying attention, I know I am. You should be able to post pics and I really really think you should create your own thread on this. This is so exiting and it's not even my mod. Lol

[SolarPoweredRV]

Ok... I have a hefty update. My cells arrived a week or so ago. They took about 40 day to arrive at my house and the courier simply dropped them on my doorstep which was good since that meant no import fees or taxes owing.

The cells were undamaged and appeared in good shape. I got around to top balancing them over the last week or so.. That took forever fyi for 280ah cells and a small charger.

I wired them and the daly bms that i bought off amazon up today and got it sorted for a few tests. Few quick things on the daly, It came with a bluetooth module and what looked like a temp sensor... I was hopeful.

I had some difficulties in starting the bms up... it would t read more than 10 volts with a multi meter, shorting it out to reset didn't work but hooking up my 45 amp charger did activating it fully. I was worried I wired incorrectly but it was totally fine no issues in the wiring.

The bluetooth module and Daly app were not super easy to figure out at first but I found out that location services have to be on or it wouldnt work for me. Not a fan of that but... I tried the temp sensor or what looked like one and sadly it didnt seem to stop charging when i placed the probe into ice water... oh well didnt expect that anyway.

I finally got the app working and this was the cats meow, the connection was pretty easy once everything was working and WOW inside the app there were parameters for just about everything... INCLUDING LOW TEMPERATURE SHUTOFF which for some silly reason was set at negative 20 Centrigrade... after i reset that to 2 degrees C and tested again IT WORKED.... I WAS STOKED.

I currently have it running a pure sine wave inverter 2000w for testing purposes and its pulling 53 amps heating my laundry room to tropical temeratures on a space heater.

I have used double sided tape to keep the cells together and have put a strap around them for lifting purposes for going in and out of the trailer... I am so stoked to put these things up against my fridge fans... sadly the virus is making this ever so complicated with restrictions in my area..

There will be some tweeking left to do such as getting them set up in the trailer, installing the new p dynamics converter but that is for another day as i have to go to work now ...

I can try to answer some questions but may not be able to respond quickly and I am not an expert by any means so answers could be limited.

I dont think i can post pics either but i could possibly text or email some. All in I think I spent 650 on the cells and about 80 on the bms, the charger was 250, i think, and then there were some misc connectors and items for minimal costs. All costs in canadian dollars fyi.

Mike

Wow Mike, Congratulations !!!!

Just to put some perspective on costs:

For the battery and BMS, you spent 780 (canadian) for a 280 Ah battery, that works out to about $280 per 100 Ah. When you compare that to ~ $1300 (Canadian) for a Battle Born battery that is a very, very, good cost savings !!!!

Based on the above figures and a 30% Canadian exchange rate, the US equivalent would be around $240 compared with a $900 cost for a 100 Ah Battle Born battery.

Glad the project came together.

[ultramafic]

To touch on a couple more things.. Alibaba was a very confusing web site. Once my order was made I paid up and they held off shipping for i think it was 10 days for the payments to clear. Then Alibaba apparently holds the funds ti you confirm receipt of the product. It was an interesting business model. Another thing was that they billed in my home currency with payment being processed out of Vancouver which probably save a few percentages in foreign currency transaction fees.

Trying to post photos from my phone, dont know how it will turn out..

Those are a couple images of the parameter settings, there were more options on top of those..

this one is the temp probe..

The bluetooth module

This was all it would let me add.. will try again for a few more in the morning.

Mike

[Ynot4me2]

Thanks again Mike. The pics are great. This was suppose to be my project for next winter but now I'm tempted to swap DW craftroom project that was planned for this summer with this. Just scared of the repercussions of this decision might have. Lol