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Converting to Lifepo4 in Sprinter Class C coach. Need Suggestions!

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srssrs

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Nov 16, 2021
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I am converting from LA to Lifepo4. Have determined I can fit 8 - EVE230 cells with BMS in my battery cavity beneath my steps. I was originally going to build two 12v. batteries and wire them in parallel like my original LA configuration. But, I am reconsidering using all 8 cells together and making a 4S2P battery which produces 12v. (I hope I said that correctly.) I am considering using a 4S 12v. Overkill BMS to monitor all 8 cells.

I will have 3 - 215 watt Hightec solar panels mounted on my roof wired in parallel (I think) due to some possible shading. I will stay with my 1000 watt stock inverter for now but may upgrade later to a 2 or 3K unit. I need to add an MPPT controller and upgrade my stock charge converter.

This is all new to me but I am constantly reading the posts on this forum and have tried to learn and research as much as possible.

I hope some of you may be able to make suggestions as to specific items I might want to look at. At this point I have only purchased my panels but have been communicating with Amy at Docan regarding the purchase of my cells. I still need to purchase a solar controller, the BMS, charge converter, etc. Thank you for any and all suggestions......Steve
 
Your plan limits your amp output to the BMS limit… if you keep it two banks in parallel, you get twice the amperage… and 12V inverters pull a lot of amps.
 
4S2P is two batteries in parallel. I think you are asking about building 2PS, where 2 cells are in parallel, with four of those in series.

I purchased my cells from the other Amy at Shnzhen. Whoever you get them from ask about the busbars That come with the cells. 1/8” aluminum can be good for 200 amps, but I have no idea the conductivity of aluminum busbars. I don’t plan to ever discharge each bank more than 50 amps, but if I go down to one battery, it could be 100 amps. I see postings that people recommend double stacking the aluminum busbars,

I purchased my BMS off Overkill from Will recommendation. Overkill at 120 amps on a 1 kw inverter with the 12 volt 120 amp version should be OK. When the batteries are full charged, this is enough, but if you plan to push these batteries to a low state of charge where the voltage is really low close to the 2.5 volts per cell and run the inverter at full output plus the 15% inverter losses, you could be pushing the 120 amp limit of that BMS.

I did not see anything about fusing. Lithium should be a Class T fuse, and those are pricey. Also, they take up a bit of space: with the holder, 7” X 2” is what each Class T fuse took.

I think by charge converter you mean a AC to DC converter. I have not found a good one I’d leave plugged in for lithium batteries all day long, but I did got this one based off Will’s recommendation and its the only one I found that could charge 12 volts 70 amps and plug into a 15 amp 120 VAC outlet. The others that charged that much would be 240 VAC:

www.aimscorp.net

AC Converter / Battery Charger 12/24 VDC Smart Charger 75 Amps - Listed to UL 458/CSA

Get versatility, fast charging and a warranty with the AIMS 12V and 24V AC 75-Amp Converter/Battery Charger from AIMS Power.
www.aimscorp.net www.aimscorp.net
 
OK - I understand what you both are saying. So maybe I should go back to my original plan. Build two 230ah batteries, each with their own BMS and connect the two in parallel. This would give me 460ah x 80% or approximately 368ah of battery (far greater than the 160ah of LA I am replacing). And if I decide to upgrade to a 2K inverter, they could then handle a higher discharge rate. I only plan to run small electronics, a toaster or a small coffee maker (not all at the same time) off the inverter.

Can you point me in the direction of the Class T fuse? I need to educate myself on that. I will inquire regarding the busbars - thank you.

I boondock for the most part and would rely on my solar charging and alternator charging primarily. Do I really need a AC to DC converter that produces 70 amps? I will occasionally plug into shore power. I also will run a diesel generator occasionally.
 
srssrs said:
OK - I understand what you both are saying. So maybe I should go back to my original plan. Build two 230ah batteries, each with their own BMS and connect the two in parallel. This would give me 460ah x 80% or approximately 368ah of battery (far greater than the 160ah of LA I am replacing). And if I decide to upgrade to a 2K inverter, they could then handle a higher discharge rate. I only plan to run small electronics, a toaster or a small coffee maker (not all at the same time) off the inverter.

Can you point me in the direction of the Class T fuse? I need to educate myself on that. I will inquire regarding the busbars - thank you.

I boondock for the most part and would rely on my solar charging and alternator charging primarily. Do I really need a AC to DC converter that produces 70 amps? I will occasionally plug into shore power. I also will run a diesel generator occasionally.
Click to expand...
diysolarforum.com

Class T fuse and holder... bigger than i thought.

I just ordered a new class t fuse and holder. It arrived today, and I am impressed at the size of this kit. I took a picture with it on a DVD case for reference. Bonus points if ya guess the movie title.
diysolarforum.com diysolarforum.com
Here is a thread I started on one I bought.
 
srssrs said:
I boondock for the most part and would rely on my solar charging and alternator charging primarily. Do I really need a AC to DC converter that produces 70 amps? I will occasionally plug into shore power. I also will run a diesel generator occasionally.
Click to expand...
No you don’t need the 70 amps. Depending on volatages, you may be able to keep what you have. It’s more of a how long do you have access to shore power or how long do you want to run your generator if have a few cloudy days. Those batteries have so much useable capacity its tempting to use a lot more wh, which could take time to recharge.

For me, with my LA batteries, I could only charge them at 10.5 amps with the WFCO charger I had in my RV. I could use 80 - 167 ah out of 225 ah useable a night when Boondocking. I did not need to top up with the batteries every night with the charger, but I wanted about 40 ah, about 500 wh, added on a cloudy day when there was little solar power added. To get that power, I needed to run the generator 4 hours.

When I upgraded to 24 volt and lithium, I find I’m using twice the power. I bought the dual voltage 70 amp 12 volt 35 amp 24 volt charger I linked. If I have a could day, I can turn it on for two hours and get 1700 wh back in a couple of hours. I don’t want to run that generator more than I have to.

As it is though, that charger hasn’t been delivered yet, so I just hope for no cloudy days when I take the RV out, and so far that has worked. Hope does not make the best contingencies though.
 
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Here is a thread of others (including me) doing the same thing. i have pix in post 3. feel free to ask for more.

diysolarforum.com

New LifePo4 Battery Build Questions?

Adding Solar and LifePo4 to Winnie View 2014J model. I am going to replace 2 - Group 27 LA batteries but want to keep them in the same location (under the steps). My area to work with is 7-3/4" wide by 22" long. I believe I can fit 2 - Lifepo4 batteries in place of those if I build with 4 -...
diysolarforum.com diysolarforum.com
 
chrisski said:
No you don’t need the 70 amps. Depending on volatages, you may be able to keep what you have. It’s more of a how long do you have access to shore power or how long do you want to run your generator if have a few cloudy days. Those batteries have so much useable capacity its tempting to use a lot more wh, which could take time to recharge.

For me, with my LA batteries, I could only charge them at 10.5 amps with the WFCO charger I had in my RV. I could use 80 - 167 ah out of 225 ah useable a night when Boondocking. I did not need to top up with the batteries every night with the charger, but I wanted about 40 ah, about 500 wh, added on a cloudy day when there was little solar power added. To get that power, I needed to run the generator 4 hours.

When I upgraded to 24 volt and lithium, I find I’m using twice the power. I bought the dual voltage 70 amp 12 volt 35 amp 24 volt charger I linked. If I have a could day, I can turn it on for two hours and get 1700 wh back in a couple of hours. I don’t want to run that generator more than I have to.

As it is though, that charger hasn’t been delivered yet, so I just hope for no cloudy days when I take the RV out, and so far that has worked. Hope does not make the best contingencies though.
Click to expand...
Thank you. I looked at your build and it looks great. Like how you labeled everything and the organization of your wiring, fuses, and breakers. I totally understand what you are saying. Thank you for your input.
 
Based on a 2000w. inverter, and assuming I may at some point try to pull 1800w., what size class T fuse would I need? Also, what is the normal location of this fuse? Would the battery cutoff switch be placed just before this fuse?
 
I used a 200 amp fuse for my 12 volt 2000 watt in inverter and it never blew. I only used the 15 amp AC output, so it could not pull more than 1800 watts From the inverter. With the inverters and fusing, its not just the AC watts, but the DC losses for the inverter. Those 1800 watts from the inverter pull close to 2100 watts from the battery.

For a better explanation, try here:


The fuse is the first thing you put on after the positive battery cable before the switch.
 
Thank you all! I will read that info.

Any other recommendations on MPPT charge controller or BMS?
 
@chrisski I've ordered that Aims charger; I have a friend in Corpus Christy, Tx. living in a 30-foot towable who swears by it. I found one for $265 on Amazon. I have a 400ah bank at 24-volts and only need something around 30 amps while on shore power or generator. My little Class C is only a 28-foot setup up for 30 amp service.

I was going to add the 2s2p thing in there, but that's been covered. My energy demands are higher, but 3000 watts, a little less than 30 amps, would be fair on the high side. Trying to pull more than 2000 watts out of a 12-volt system is fraught with issues, so I went to 24-volts using a 2s2p with four 12-volt 200ah batteries. 4kw at 24-volts is the same as 8kw at 12-volts, if I'm not mistaken, with much more potential, and potential is what makes the whole circle go round and round. :cool:
 
How are you going to fit them under the steps? My Sprinter step opening is 8" wide, battery is 7, not much room for a "Battery fixture". Also you`ll need to insulate that battery area. Be sure to locate the inverter as close as possible to the battery.
 
To me, a sprinter class RV is typically referred to as a Class B. It's an RV within the confines of the van. Class C is on a van chassis, but it's a cut-a-way with a box added, the RV part. Not nick picking, just trying to keep scale in mind; it's essential for visualizing.
 
swill4wd said:
How are you going to fit them under the steps? My Sprinter step opening is 8" wide, battery is 7, not much room for a "Battery fixture". Also you`ll need to insulate that battery area. Be sure to locate the inverter as close as possible to the battery.
Click to expand...
When time allows I'll take a photo of my battery compartment under my steps. The top opening measures 7.5" x 24" but the compartment itself measures about 9.25" x 28" x 12.5" high. Typically Winnie provides 2 - LA Group 24 batteries that are generally about 80ah. each. There is room to place two Chins (or other) 100ah. Lifepo4 batteries in parallel but I wanted as much capacity as possible. Since I was unable to find commercially made Lifepo4's that would fit in that space that were greater than 200ah, I have decided to build my own. I plan to insulate the sides, ends and bottom with foam insulation (per Mister Sandals suggestion). My calculations show that a 4S EVE230 battery will measure 6.84" x 8.4" x 8.05" without a BMS. I can fit 2 of these in parallel in this compartment. It will be tight but doable if I place the BMS at the end of each battery.
 
Cajunwolf said:
To me, a sprinter class RV is typically referred to as a Class B. It's an RV within the confines of the van. Class C is on a van chassis, but it's a cut-a-way with a box added, the RV part. Not nick picking, just trying to keep scale in mind; it's essential for visualizing.
Click to expand...
Yes that is a misconception regarding Sprinters that some people have. It is true that they build class B's on the van chassis, but I have a Winnie View (2014) built on the 1 ton (3500) Sprinter chassis. It is a full class C with dual rear wheels, etc. The class B's do not have dual rear wheels.
 
Cajunwolf said:
To me, a sprinter class RV is typically referred to as a Class B. It's an RV within the confines of the van. Class C is on a van chassis, but it's a cut-a-way with a box added, the RV part. Not nick picking, just trying to keep scale in mind; it's essential for visualizing.
Click to expand...
I have seen PLENTY of cutaway sprinter RV’S and several cab only sprinters designed for add on chassis.
 
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