Lithium Battery

[CPT Davenport]

Is 100AH lithium enough storage to keep 85L 2 way fridge and camper running? I will be running 200w panels.

 

[Charlie]

I have the 85L 2-way fridge, a 100Ah lithium battery, and 350W of solar. It works fine for me; I estimate that I can run for 2-3 days without any solar. In really hot weather when the fridge runs a lot more, it may be less. On average I tend use about ~20% of the battery capacity overnight.

The solar panels don't directly impact how long the battery can keep the camper powered up; that's strictly a function of the battery capacity. But if you can count on getting good solar output from the panels everyday, 100Ah seems fine. You said "panels", so perhaps you will have 400W of solar. My panels do a great job of topping off the batteries, even on overcast days.

The addition of an Orion 30A DC/DC charger was a really game changer for me. It will top up my battery after a long cold night, within about 90 minutes of driving.

 

[CPT Davenport]

Thanks for the break down of your system. I will have 200w total from my panels. DC/DC charger is on my list as well. I may add an addition panel of the back port if My 200w don't keep up.

 

[dscobell]

Ditto what Charlie said regarding percent used each day. In my case, I added 6awg wire from truck to camper and a Zamp 90w solar panel for a total of 250w . With my DC to DC charge I can top off the camper battery in about 30 minutes. I also use an 80w portable panel if there is shade on the roof, when it is warm and/or the 85L fridge is parked facing the sun. That keeps the battery topped off until dark...

 

[BBZ]

I have a 160 panel and used about 10-15% of my battery (200ah lithium) overnight if running fridge and furnace.. If sunny, it is usually fully charged by noon even in the winter months..

 

[BrianG]

Last month I spent nine days on the east coast of Baja. I had no trouble getting my BB100 back to 100% SOC everyday. I was running my 85L 2 way 24/7 and our roof fan at about 30% all night every night. I only had my 160 Zamp panel on the roof, but I had full sun everyday. Didn’t use my dcdc charger on the one side trip we did. Daytime temps were in the 70’s, night in the low 60’s. All Victron equipment and ‘yes’ I was surprised at the 100% SOC at the end of each day with only my roof panel. Don’t count on this in higher temps and without full sun.

 

[CPT Davenport]

These are all good numbers and stats, thanks you guys. I originally was going to mount 2 of my rigid 100w panels. I think now that I will buy the Renogy 175 semiflex panel and start with that and a folding panel as a back up. I purchased a 100ah Relion lithium battery, but need to build the rest of my system. Here is what I think I need so far. Please let me know if I'm missing something or should look at other options or variations.

1. Relion 100ah lithium
2. Renogy 175w panel
3. Victron 12/12 30 DC-DC (ISOLATED OR NON ISOLATED?)
4. Victron MPPT charge controller (ANY SUGGESTIONS ON WHICH MODEL?)

I need help with fuse types, sizing and locations.

Do I just get an adapter to go from the SAE to MC4?

 

[Charlie]

These are all good numbers and stats, thanks you guys. I originally was going to mount 2 of my rigid 100w panels. I think now that I will buy the Renogy 175 semiflex panel and start with that and a folding panel as a back up. I purchased a 100ah Relion lithium battery, but need to build the rest of my system. Here is what I think I need so far. Please let me know if I'm missing something or should look at other options or variations.

1. Relion 100ah lithium
2. Renogy 175w panel
3. Victron 12/12 30 DC-DC (ISOLATED OR NON ISOLATED?)
4. Victron MPPT charge controller (ANY SUGGESTIONS ON WHICH MODEL?)

I need help with fuse types, sizing and locations.

Do I just get an adapter to go from the SAE to MC4?

3: Orion 12/12-30: either isolated or non-isolated will work, but if you get the isolated you will need to tie the two negative terminals together in order for your marker lights to work (they are grounded through the FWC ground wiring). The isolated unit is made for keeping electrical noise from interfering with your sophisticated electronics in the camper, such as your ham radio or fancy audio gear . But since you are not using that while driving, it isn't an issue. I got the non-isolaed version.

4: I have the Victron MPPT 100/20: Rated for 290W of solar input. Although I have 350W of panels, due to sun angle they are never putting out that much.

I got an SAE to MC4 adapter which made for a clean install. Note: in my system, the FWC wires coming from the SAE plug on the roof to the battery compartment had the wrong polarity (red/black reversed). I think others have seen this as well. So BE SURE TO CHECK THE POLARITY with sun on the panels before connecting to the MPPT.

Also, be a little careful about running panels on both the roof and from the rear connector. They will be in parallel, and I seem to recall that you really want to have identical panels, configured in the same way, in this situation. Certainly you don't want different voltages coming from the top and rear connectors. Unless you put in a separate MPPT for each set of panels.

 

[CPT Davenport]

Thanks for the reply Charlie. I just ordered the 100/20 charge controller and the non-isolated 12/12-30 DC/DC unit. I think this set up will meet my needs and power demands.


Anyone with advice on fuse type, location and sizes for these units?

 

[Charlie]

Thanks for the reply Charlie. I just ordered the 100/20 charge controller and the non-isolated 12/12-30 DC/DC unit. I think this set up will meet my needs and power demands.


Anyone with advice on fuse type, location and sizes for these units?

I go mostly with circuit breakers, as discussed below. Powerwerx sells Eaton-Busssman switchable circuit breakers which are half the price of Blue Sea, and appear to be identical. They were sold out of the one I needed a month ago, but the salesman revealed that they have an in-house brand which appears identical, and was even a bit cheaper. Talking in person to their sales staff was really great; they are eager to please.

I put a 25A Bussman CB285 breaker near the MPPT, in the positive solar panel input to that module. It provides protection on that circuit and lets me disconnect it so that it is not feeding power to the system.

Some people would say that you need a fuse right near the solar panel to protect the wiring from the source to the MPPT, but I don't have one. But if I did, I would size it to be something like 2x the max Amp output from the panels. You can get inline MC4 fuses that integrate nicely right on the roof.

I have a 50A CB285 circuit breaker between the positive terminal of the house battery and the rest of the camper. Protects the downstream circuits, and also lets me disconnect the house battery as a power source.

I have a 50A CB285 circuit breaker in the engine compartment, on the positive leg of the supply to the Orion Tr-Smart DC/DC charger. Protects the downstream wiring, and allows me to disconnect the vehicle battery as a power source.

Often you get the recommendation to use the CB187 circuit breaker. It's hard to figure out what's different from the 285 series, but it is twice the price. Turns out that it is certified for spaces with explosive vapors (think bilges). It's much larger and not needed for our campers.

In general, the guidance is to put the circuit breaker as close to the power source as possible, since its function is to protect downstream wiring. Circuit breakers are thermal devices, and their time to trip is actually quite long. They are intended for catastrophic events like short circuits, and actually will stay connected for (perhaps) minutes at their rated capacity. My personal sizing criteria is ~2X the expected load (I'm sure to get some opinions on this idea).

 

[CPT Davenport]

So would this sequence be ok for the charge controller?

Solar panels
275w total--->20amp fuse--->Victron 100/20 controller--->30amp fuse--->positive on 100AH battery---->50amp fuse---->BlueSea box

 

[ckent323]

Between your solar panel(s) and the Victron Solar Controller, determine the short circuit current for your solar panel(s).

The Solar Controller can handle the current from the panels (unless an undersize controller was selected). Make sure the peak current from the panels does not exceed the input current of the Solar Charge Controller (at least not by very much). The fuse consideration is mainly to protect the wire.

Solar wiring is often 10 gauge. 10 Gauge wire will carry 30 A safely, so if the panel(s) short circuit current is less than 30A you don't need a fuse.

If the short circuit current is greater that, then use a 20 A or 30 A fuse.

However, as others have said, even if you don't need a fuse, it may make sense to put a breaker switch inline between the panel(s) and the Solar controller so you can disconnect the panels if necessary.

You do need a fuse between the Solar Charge Controller and the battery to protect the Solar Controller against reverse polarity which will damage it. The fuse should be a size that matches the Solar Controller output current (or perhaps slightly larger). My guess is that 30 A is probably OK.

You do need a fuse between the battery and the house loads. Depends on wire size but I will assume 10 ga house wiring so a 30 A fuse should be OK.

You may want to consider putting a fuse on the house battery side of the BlueSea ML ACR in the truck and another at the house battery in the camper. That protects the wires from a short on either side. These fuses again depend on wire size. You are trying to protect the wire so size the fuse at the current carrying capacity of the wire.

if 8 ga 55 A
if 6 ga 75 A
if 4 ga 95 A
if 2 ga 130 A

https://www.altestore.com/diy-solar-resources/wire-sizing-tool-for-12-24-and-48-volt-dc-systems/


I hope this is helpful.

Regards,
Craig

 

[CPT Davenport]

Super helpful guys! It is all slowly making sense. It is hard not having the camper here so I can visualize the system and locations of everything. I take delivery on July 20. Just trying to get most of my goodies ahead of time because when I hand over that cashiers check for the full amount, I'm gonna be busted.

 

[Outnabout]

This post is very helpful as I am looking at replacing AGM with 100ah Lithium. Price points and storage are competitive with AGM now. I need advice as I do the switch. I already have a Victron Smartshunt. My plan is:

1. Replace old PWM controller with Victron 100/30.
2. Leave BlueSea ACR in place but disconnect ground so Lithium and truck alternator/battery do not see each other but running lights still work.
3. Follow advice given on this thread as to fuse placements.
4. Determine brand of battery and necessary additions such as heater, etc.
5. Use new system only charging from existing 160w roof mounted panel supplemented with 100w portable panel as needed. If needs are not met then DCDC down the road with wire upgrade.

Any advice is gratefully appreciated. Thanks.

 

[Jon R]

Two comments:
1) If I understand you correctly, what you described will not allow the running lights to work. The running lights will be powered by the truck light circuit, and you need a return to the truck negative battery pole for them. You want to leave the camper and truck negatives connected and instead disconnect the positives to isolate the two battery systems, if you want them isolated.
2) Make sure you really need a battery heater for your planned usage. I think most of us have gone without them.

 

[Outnabout]

Thanks. What you say about the running lights makes perfect sense but when I disconnected the ground on the ACR the running lights work and the truck battery is isolated from the camper.

Also, I appreciate your take on the heater for the battery. It does seem to me that it is one more element that could be problematic and the batteries so have a low temp cut off so they wouldn’t charge in too a temp which I believe is ~32F

 

[Jon R]

I misunderstood what you were describing. Disconnecting the ground from the ACR prevents the ACR from closing to connect the truck battery positive to the camper battery positive. I thought you meant you had disconnected the main negative connection between the truck and the camper.

With your clarification, I think what are doing is an acceptable, safe way to accomplish what you are trying to do.

 

[rubberlegs]

Our lithium battery (SOK) has a heater which we've only needed once. It was below freezing for about a week, and down to 17F at night. But it didn't seem to work. It's energized by the charger, not the battery itself, so our 100W solar panel wasn't enough to heat it. But it also didn't heat while driving, which was disappointing. Good thing it only cost $10 more than the non-heating version. We still haven't sorted out what's wrong -- where we live it rarely gets below freezing.

 

[Outnabout]

I misunderstood what you were describing. Disconnecting the ground from the ACR prevents the ACR from closing to connect the truck battery positive to the camper battery positive. I thought you meant you had disconnected the main negative connection between the truck and the camper.

With your clarification, I think what are doing is an acceptable, safe way to accomplish what you are trying to do.

That’s what I thought. I have a fair knowledge of electrical but not enough to just dive in without some guidance. Thanks for getting back to me and confirming what I was thinking!

 

[Outnabout]

Our lithium battery (SOK) has a heater which we've only needed once. It was below freezing for about a week, and down to 17F at night. But it didn't seem to work. It's energized by the charger, not the battery itself, so our 100W solar panel wasn't enough to heat it. But it also didn't heat while driving, which was disappointing. Good thing it only cost $10 more than the non-heating version. We still haven't sorted out what's wrong -- where we live it rarely gets below freezing.

Thanks for sharing your experience with heated battery. I think I would probably get by without the heated. I will most likely only camp in the snow a few times and then I have the heater to keep the battery above cut off.

On the plus side, it sounds like the low temp cut off worked as it should. Overall, are you happy with the SOK?