Lithium vs SLA

[Jwh92020]

How many of you have batteries mounted on the tongue? Lithium or SLA/AGM? I'm thinking of mounting mine of the tongue to offset galley weight. Winters in OK get pretty cold with lots of below freezing temps and we all know how lithium and cold don't play nice. I'm thinking that for the amp hrs I need to run lights, vent fan and device charging - less than 35, I could run a single 100 amp hr SLA and not have to worry about cold weather. If I need to expand the system, I can switch to lithium and deal with cold temps at that point. Thoughts?

 

[gearsoup]

Do you plan on winter camping, or is this a 3-season affair? I'm not planning on anything more than 3 season, so am opting for a lithium

 

[Pmullen503]

Lithium batteries can tolerate freezing if you are not asking them to discharge or charge at high levels.

Electric cars have heaters to warm the battery to precondition the battery for rapid charging in cold weather.

 

[Jwh92020]

Do you plan on winter camping, or is this a 3-season affair? I'm not planning on anything more than 3 season, so am opting for a lithium

It's not so much winter camping as it is outdoor storage. We have lots of beautiful sunny, sub freezing days during the winter. That is an issue for lithium.

 

[Jwh92020]

Lithium batteries can tolerate freezing if you are not asking them to discharge or charge at high levels.

Electric cars have heaters to warm the battery to precondition the battery for rapid charging in cold weather.

THe trailer will be parked outdoors, which means shutting off the panels during sub freezing weather. Unfortunately, my budget doesn't allow for self heating batteries.

 

[reaver]

Most batteries come with low temp protection these days. You could get a 50Ah LiTime battery for about $150, which would give you twice the capacity in almost the same space.

To get around the temperature issue, get some USB powered heating pads, and tape it to the battery. This will allow you to heat the battery to the point where it can charge. Or, you can use a low amp rv water tank heating pad, with a built in temperature sensor. This will heat the battery when it's close to freezing, and shut off when it gets to a certain temperature. This is what I do on my batteries, and it works very well.

 

[Pmullen503]

THe trailer will be parked outdoors, which means shutting off the panels during sub freezing weather. Unfortunately, my budget doesn't allow for self heating batteries.

Cold isn't the problem, it's expecting them to run at or near capacity when they are cold. Like trying to run a electric cabin heater or water heater. Unless you plan to use the camper in sub freezing temperatures you have nothing to worry about.

 

[mikevet]

is it worth the expense of the mount and price of extra cables for the little extra weight up front? Most lithiums are pretty light. can you locate heavier items closer to front? water tank, spare tire, bike rack etc?

 

[featherliteCT1]

I presume you mean a Lifepo4 battery. IMHO, the advantages of a Lifepo4 battery over a Sealed Lead Acid battery or an AGM battery are great. You might consider removing the battery during winter storage of your trailer and keeping the battery in your heated house.

 

[Jwh92020]

is it worth the expense of the mount and price of extra cables for the little extra weight up front? Most lithiums are pretty light. can you locate heavier items closer to front? water tank, spare tire, bike rack etc?

The spare can go up front, not much else. I already have battery boxes, and the only "long" cable run would be 4 gauge from tbe battery box to the fuse block in the valley area. I have about 50 ft of red & black 4 gauge wire (I scored a manor deal on 4 ga, 10 gauge, 1/0 & 2/0 wire), so the cost is not a signifiant factor.

 

[Jwh92020]

I presume you mean a Lifepo4 battery. IMHO, the advantages of a Lifepo4 battery over a Sealed Lead Acid battery or an AGM battery are great. You might consider removing the battery during winter storage of your trailer and keeping the battery in your heated house.

I could do that, but if I forget once, I'd lose a battery. On mild to warm winter days, I'd take the trailer out.

 

[Tony Latham]

When I built my current teardrop six years ago, I gave considerable thought to LiPo batteries. They didn't pencil out, and I bought a quality Group 24 AGM. 37 usable amps for $220. That's $5.90 for each amp.

That battery still has life in it, but I just ordered a 100 amp Watt Cycle battery for $180 (after watching Will Prowse test and tear one down). That's $1.80 per usable amp.

Why replace a battery that still has life? It's because I don't know how much, and each spring we do a month-long southwest trip, and I don't want to be fighting low voltage issues–and the China tariffs are scheduled to kick in in November, as near as I can tell.

We live in the middle of Idaho, and it gets cold. There will be some mornings when the solar charge controller won't be able to recharge, as the low-temperature sensor in the battery will prevent it, but we'll have a ton of available amps. Since we don't camp with daytime temps below freezing, it won't be a problem; our solar system will catch up.

When the snow flies, I'll pull the battery and stick it in my shop. A five-minute task.

Tony

 

[featherliteCT1]

I could do that, but if I forget once, I'd lose a battery.

I hear ya!

Just to quantify things, the spec sheet for my EVE LF280K cells (280Ah) says not to store the cells below minus 4 deg F for one month (0 deg F for one year), even though the cells can be discharged (i.e., used to power loads) down to minus 22 deg F.

 

[vomre939]

I stuck my lithiums on the tongue last winter thinking I’d ruined them the first night it hit like 12°F. They just got sluggish when I tried charging in the morning. Running stuff off them was totally normal. The only time I had issues was when I woke up before the sun and tried to top them off with solar and they basically refused until they warmed up. So if you’re mostly using them overnight and charging midday, you’re probably overthinking it.

 

[Tony Latham]

and they basically refused until they warmed up.

As you may know, a quality lipo will have a low-temp cutoff for charging. Cheap ones don't, and charging below 32º, from what I have heard, will kill them.

Tony

 

[Pmullen503]

As you may know, a quality lipo will have a low-temp cutoff for charging. Cheap ones don't, and charging below 32º, from what I have heard, will kill them.

Tony

The cut off isn't that sharp but you are essentially correct.

Safe charging and discharging rates drop as temperature drops. Depending on the chemistry, that curve will look different. Trying to charge or discharge a frozen battery anywhere near its capacity will damage the battery.

Storage alone does not. So it's OK to disconnect your (storage charged) trailer battery and leave it in the trailer over winter.

 

[outintheforest]

At this point, the only downside to LiFePO4 batteries are that you shouldn't charge them directly from your alternator. You need a DC-DC charger - the voltage of the two systems are slightly different, and you don't want your alternator trying to shove 14v into a fully charged lithium battery.

If you haven't stayed up to date with batteries, you'd be shocked at how much the industry has changed in just a few years. And prices have fallen like a stone. If you learned about "lithium" batteries 3 years ago, it's time to re-educate yourself.

For example you can get a 50ah LiFePO4 for about $150, which is less less than the price of a 100ah sealed lead acid deep cycle battery. They have the same usable capacity, but the lithium is less than half the size and weight. The lithium battery will last longer.

I'm getting ready to buy a 8kwh (650 amp hour @ 12v) battery for $900. It's a single box that weighs 150 pounds, and would replace a 10-12 lead acid batteries.

Pros for LiFePO4

• Light weight (a truck battery size weighs about 25 pounds)
• More capacity for the size
• Use of all the capacity, unlike lead (you actually get 100ah from a 100ah battery)
• Longer lifespan than lead-acid
• You can get fancy battery management systems that give you all the data
• You can get more capacity in a single battery, saving $$ on cables

Negatives

• Alternator charging should be done with a DC-DC converter
• Charging below freezing will reduce the lifespan - but
  • some are so small it would be easy to keep them inside the trailer
  • some have low temperature charging protection and won't take a charge when it's too cold
  • some have built in heaters

 

[Pmullen503]

At this point, the only downside to LiFePO4 batteries are that you shouldn't charge them directly from your alternator. You need a DC-DC charger - the voltage of the two systems are slightly different, and you don't want your alternator trying to shove 14v into a fully charged lithium battery.

A battery of the size you are considering probably has a built in BMS that will protect the battery from moderate over voltage.

For anyone considering switching to lithium batteries, the presence (and quality) or absence of the BMS (battery management system) is an important consideration.

 

[featherliteCT1]

the presence (and quality) or absence of the BMS (battery management system) is an important consideration.

I agree. For me, personally, I would not buy a Lifepo4 battery without the Bluetooth feature so that the protection parameters can be adjusted and, most importantly, to the read the individual voltages of each cell so that I can monitor whether the battery is balanced.

 

[outintheforest]

A battery of the size you are considering probably has a built in BMS that will protect the battery from moderate over voltage.

For anyone considering switching to lithium batteries, the presence (and quality) or absence of the BMS (battery management system) is an important consideration.

They all have a BMS. The larger units have a BMS you can interact with, through an app, Bluetooth or something similar. But even the "small" 25ah batteries have a BMS to manage charging, max current discharge, etc.

I guess it's possible they exist, but I've never seen a LiFePO4 battery without a BMS. You can buy individual cells, but those aren't batteries.