Ordered a 100 Ah Lithium Battery

[WaltP]

I made the first real test of my solar system in Utah last month, admittedly a state with usually a lot of sun exposure.
I have 160W solar on the roof and another portable 100W panel, and a 1500W pure sine wave inverter.
In the mornings I was able to run a standard 12 cup coffee maker, followed by a standard 2 slice toaster, and then heat a microwave breakfast package in a 700W microwave oven . As long as I did them sequentially I had no problems.
Come mid afternoon I was back up to a full charge.

Because the nights were generally cool I never had need for an AC.
I hope this is a useful data point.

Walt

[Franswa]

my situation/attitude is much the same...and it defines my camping "schedule"...


running AC with solar in our relatively poorly insulated trailers certainly sounds like a challenge...

[jwcolby123]

Originally Posted by John in Santa Cruz

...

I wouldn't try to mix lithium and lead-acid batteries, pick one and stick with it. lead-acid better figure on no more than 50% of the AH capacity is actually usable in a day. With LiPo, you should in theory be able to use about 80% of the capacity.

IF your solar panels 'follow the sun', figure on about 4-6 hours of rated wattage per day usable output, if they lie flat, figure less. Keeping this system happy will likely require 500W or more of solar capacity... and on cloudy muggy days, good luck.

Lead acid isn't actually all that usable compared to Lipo. Get rid of them, replace with an equal weight of Lipo and cruise into the sunset!

[jwcolby123]

Originally Posted by Donna D.

No, solar doesn't run anything. It's function is to charge the batteries. IF you don't have enough amp hours in your batteries, it won't matter how much solar you have.

I don't think that is quite true. The following discussion is for Lipo of course.

600 watts of solar will provide ~50 amps at 12v (in good sun). Of course you can't reliably use them without feeding them into a battery to buffer the current... but the panels ADD to the available current from the battery.

For example, a 100ah battery with 3 200 watt solar panels supplying current means that total current available to the load is 100a (battery) plus ~50 amps from the panels or 150 amps (max) while the panels are contributing. So you could actually draw 50 amps more than the batteries can supply by themselves.

Then consider that if the total load is less than 50 amps (what is available from the panels) the batteries will end up charging from the panels as long as they are able.

If the batteries are at 50% charge and the load is 100 amps, then the battery will provide 50 amps and the panels will provide 50 amps, i.e. 50 amps flow out of the battery. However if the load drops to 20 amps, the panels will dump 30 amps into the battery. i.e. current will flow into the battery.

I imagine that a 20 amp load could actually run off a panel without any battery attached as long as the panel reliably provides more than 20 amps. The problem of course is when a cloud covers the sun... Or the sun goes down.

[jwcolby123]

Originally Posted by Huck

Check out Jim's video. He now runs 2 5000 btu air conditioners with 1185w of solar and only 3 225 Ah AGM batteries. ...

All the calculations change when you switch from AGM to Lithium.

A lithium battery can charge at full current from empty to full. Lead acid of any kind only charge at full current for a small percentage of the time. after which most of the current from the panels doesn't go anywhere, i.e. is wasted. It is NOT "consumed", it just isn't put into the battery.

With Lithium it all goes into the battery right up to the point where the battery is fully charged.

Furthermore a lead acid of any kind can only provide full current for a small time. The voltage drops quickly and thus the watts likewise (V*A), whereas a lithium can provide full current the whole time until it abruptly shuts down (discharged). The lead acid will be struggling to provide 11.1 volts or even less at high current whereas the lithium will provide 13.1 the whole time.

In essence a lead acid battery is a variable (and fairly high) resistance current source whereas a lithium battery is a constant (low) resistance current source.

[John in Santa Cruz]

I replaced my 2 GC2 batteries for under $200, and it would cost about $1600 to use equivalent 2 battleborns.

so I can replace my batteries 8 times over. yes, the 2 battleborns have maybe 30-40% more usable power (220AH * 50% for the lead acid, vs 200AH * 80% for the battleborns), but to date I've never had my lead acids down much below 75%, or 50% of their useful capacity, sooooooo.....

[WaltP]

I basically agree. But there is a style of use where the Battleborns, or equivalent, can be a huge advantage. If you want the ability to use AC while boondocking, by far the best way to accomplish that is with two battleborns, a big inverter, and the more solar the better, and pray for clear skies. Of course that assumes deep pockets.

Walt

[zack sc]

This is an excellent thread. Really helpful and interesting. Much appreciated.

[jwcolby123]

Originally Posted by John in Santa Cruz

I replaced my 2 GC2 batteries for under $200, and it would cost about $1600 to use equivalent 2 battleborns.

so I can replace my batteries 8 times over. yes, the 2 battleborns have maybe 30-40% more usable power (220AH * 50% for the lead acid, vs 200AH * 80% for the battleborns), but to date I've never had my lead acids down much below 75%, or 50% of their useful capacity, sooooooo.....

Before we move on, according to battleborn themselves, their batteries can provide their entire current every time, i.e. 100 amp hours times 100%, They do this by actually overrating their batteries and reserving the excess to protect the battery from too low or too high charge.

Additionally the lead acid battery cannot actually provide 50% of their current in any real world fashion. According to what I have read. yes they can IF you only pull 5 amps per hour for 20 hour. As soon as you pull a large current draw for any reason at any point, that "discharge cycle" is toast and you will not achieve that 50% draw during that cycle. And the difference is startling as in as little as 20% total current available.

So the numbers you quote are lead acid manufacturer's specs under VERY specific conditions, mostly not very useful.

No one is attempting to persuade you of anything, just educate folks. The fact is that you don't need to replace two lead acid batteries with two lithium batteries. One Lithium will provide MORE performance that approximately four lead acid batteries, in every meaningful way, and do so for 10 years and thousands of charge cycles.

But if you don't need that performance then so what? If all you do is run a few LED lights and a water pump for a few seconds to wash your hands then it is pointless to discuss Lithium.

Come time to run a heater fan all night, or an air conditioner for many hours, and still have the current to cook your microwave breakfast and blow dry your wife's hair, all before the sun comes up to recharge... then suddenly the Lithium becomes a real winner. It can provide 100 amps of real 13.1 volt current.

And yes, they cost much more. However I was seeing a person discussing a total cost of $3000 to completely redo their electric, and was discussing using several AGM batteries. That probably makes no real sense.

[Franswa]

Originally Posted by John in Santa Cruz

I replaced my 2 GC2 batteries for under $200, and it would cost about $1600 to use equivalent 2 battleborns.

so I can replace my batteries 8 times over. yes, the 2 battleborns have maybe 30-40% more usable power (220AH * 50% for the lead acid, vs 200AH * 80% for the battleborns), but to date I've never had my lead acids down much below 75%, or 50% of their useful capacity, sooooooo.....

THAT is my experience as well....Run a heater fan all night, AND run AC for HOURS(?), blow dry the wife's hair and cook breakfast in a microwave is NOT.
The cost of solar panels has dropped so much lately that to solve the old "use/production/storage" equation adding more panels is the most cost effective change one can make these days.

[John in Michigan]

Lead acid may be sufficient where there is unlimited amounts of sunshine (AZ, CA, TX, NM, etc), but in the Northern US and Canada, not so much. Many places where we camp, we have to deal with lots of tree coverage, a week or more of dense cloud coverage, and far less sunshine in general in the Fall.

In these situations, my lead acid battery is very slow to top off or doesn't top off at all. Lead acid batteries require many hours to get you that last 20%. (Again that may be fine where there is loads of sunshine. We've been to those places too, and lead acid worked there.)

We switched to LiFePo4 to tide us over when there just isn't enough sunshine to carry us through a week when we want to run the furnace, charge the accessories, etc.

[CarlD]

Here are a couple other considerations.

LFP is expensive but prices are coming down.

If you have a compressor refrigerator you will consume about 35 amp-hours per day. Solar can easily provide enough power to run it during the day AND re-charge the battery. When it is really hot out consumption will naturally go up. If you have a couple overcast days you're going to get charge anxiety. A 100 Ah LFP battery will run you for about 2.5-3 days with little charge, depending on ambient temperature. This estimate does not include other loads.

Also you have to consider that amp-hours are only an indication of battery capacity. To compare lead acid and LFP batteries you have to use watt-hours because of the different voltage. LFP batteries are about 8% higher voltage and therefore will supply 8% more energy than an equivalent amp-hour rated lead acid battery.

Another consideration that was touched on earlier is the use of a MPPT solar charger. A lead acid battery will not accept high current for 80% of its charge time so your solar charger will not operate in MPPT mode. A LFP battery will accept whatever you give it right up till full charge

Lastly, consider the weight. One 100 Ah LFP battery provides about the same performance as two 100 Ah lead acid batteries. The LFP is half the weight of a lead acid battery. You get 1/4 the weight and half the volume with a LFP battery.

[jwcolby123]

Originally Posted by Franswa

THAT is my experience as well....Run a heater fan all night, AND run AC for HOURS(?), blow dry the wife's hair and cook breakfast in a microwave is NOT.
The cost of solar panels has dropped so much lately that to solve the old "use/production/storage" equation adding more panels is the most cost effective change one can make these days.

Precisely. Usage is very much an individual experience. Where and when you camp likewise.

Solar doesn't do you a bit of good when the sun isn't shining. You can add 100 more panels and not get a drop of charge in some circumstances. If all you do is visit quartzite, then more panels are good, Deep in a forest under a tall tree canopy and see how much good it does you.

So to simply say "buy more panels" is misleading at best.

I ran lead acid for years. But... I never used much current. A few LED lights and a water pump described me well.

I am about to rebuild my electrical. I expect to use a real refri running on DC, an instapot for cooking. A microwave for cooking. Probably an induction stovetop sometimes. A bunch of LED lights. I have a built-in propane heater which requires a fan to even turn on. My 19' Scamp has a small AC powered air conditioner. I will use my laptop for remote work.

There is no "normal" usage, only normal for me, or normal for you. So if a lead acid works for you, run with it, cheap and reliable for you. Not so much for me.

[jwcolby123]

Originally Posted by CarlD

Here are a couple other considerations.

...

Also you have to consider that amp-hours are only an indication of battery capacity. To compare lead acid and LFP batteries you have to use watt-hours because of the different voltage. LFP batteries are about 8% higher voltage and therefore will supply 8% more energy than an equivalent amp-hour rated lead acid battery.

Even this isn't even remotely true. A 100ah Lithium battery will provide 100 amps at 13.2 volts for an entire hour. Without complaint, without damage.

Try to draw 100 amps from a 100ah lead acid battery and see what happens! You will get 100 amps for a few moments and then the voltage will drop to 11v or even 10, or nine. And then the current starts to radically drop as well.

And how do you figure out whether and when you have hit "50%" of the power available? Quite simply you can't. Most likely you don't even know that you are killing your battery. All you know is that your lights are very dim... Hmmm...

Originally Posted by CarlD

... Lastly, consider the weight. One 100 Ah LFP battery provides about the same performance as two 100 Ah lead acid batteries. The LFP is half the weight of a lead acid battery. You get 1/4 the weight and half the volume with a LFP battery.

I drive truck. They all carry house batteries which are lead acid 6v kinds of things. But... the truck is designed to haul 80,000 lbs. My tractor weighs 24000 lbs. The weight of several lead acid batteries is not even a consideration. But they STILL suck!

In the truck 'house' I have a resistive heater and an AC that will run, very poorly and not very long, off the house batteries. When I run the heat, it lasts about an hour and the controller beeps at me and turns the entire house system off. The AC works better... it will run for a couple of hours, then beeps and turns the entire house system off. And the battery voltage is left about 11.9 volts! These batteries are much bigger and store way more current than those used in an RV. And they still suck (for that purpose).

Lead acid was never designed to provide lots of current for long periods, and to this day still cannot provide that. If they could then Lithium would not exist.

[CarlD]

[QUOTE=jwcolby123;815082]Even this isn't even remotely true. A 100ah Lithium battery will provide 100 amps at 13.2 volts for an entire hour. Without complaint, without damage.

Try to draw 100 amps from a 100ah lead acid battery and see what happens! You will get 100 amps for a few moments and then the voltage will drop to 11v or even 10, or nine. And then the current starts to radically drop as well.

The characteristic you are describing is modelled using the Puekert formula. The Puekert constant for LFP batteries is very low due to the very low internal impedance, unlike lead acid batteries. In my comments I am referring to the standard rating of the batteries, typically 20 hours not a high discharge rating.
In reality it is meaningless to specify the watt-hour capacity of a lead acid battery without specifying the discharge rate and temperature, because it varies so much, which is why standard values were created. Here is a link to a wikipedia description of the Puekert formula. Happy reading.

[CarlD]

whoops. forgot to past the link. Here it is.

https://en.wikipedia.org/wiki/Peukert%27s_law

[jwcolby123]

Originally Posted by CarlD

The characteristic you are describing is modelled using the Puekert formula. The Puekert constant for LFP batteries is very low due to the very low internal impedance, unlike lead acid batteries. In my comments I am referring to the standard rating of the batteries, typically 20 hours not a high discharge rating.
In reality it is meaningless to specify the watt-hour capacity of a lead acid battery without specifying the discharge rate and temperature, because it varies so much, which is why standard values were created. Here is a link to a wikipedia description of the Puekert formula. Happy reading.

I understand full well. But unless you specify that, folks spew the "50%" total nonsense that the LAB folks say their batteries will provide. In today's world, few folks are happy with 5 amps for 20 hours.

How many times, just in this thread, has %50 been mentioned for LAB as if the next guy down the line should expect to get that?

The truth is MOST LIPO will give 100% of their rated capacity (not 80%) with little if any risk of damage to the battery (with a proper battery minder).

And MOST LAB will give between 10 and 50% of their rated capacity with huge risk of damage over a short period of time (and a battery minder won't help in the slightest).

M R LABs.
No M R not!
See M lights a dimin?
Hmmm M R LABs.


No problem, buy 10 more LABs, they're cheap.

[WaltP]

One of the things that appealed to me when I bought the Escape 17B was the LABs being mounted on the back bumper, freeing up a lot of interior storage space.
If I switched to Lithium I'd need to move them inside. A big disincentive.

Walt

[AlanKilian]

I just use a cheap 35AH 12 Volt SLA battery to power my fan and water pump.

It's super cheap and won't burst into flames and burn down the trailer like a LiPo can if improperly charged, or made from cheap Chinese cells and Battery Management System.

(Watch YouTube LiPo explode for some scary fun!)

If you need 100 Amp discharge and run all your appliances all day and night, my solution will not work for you and you may need to figure out how to use LiPo without making a dangerous situation for you and your family. You can do it so that if things go bad you won't wake up dead, but it's not as easy to make safe as Lead Acid batteries.

Each of us has different needs and no one battery/solar/generator solution is better than any other for everyone.

[Borden]

Originally Posted by amy in maine

WHOAAAA!!! IMPRESSIVE!!

It'll be fine, once he gets a hold of that lithium battery he'll soon ditch all the lead acid batteries

He doesn't have to do it NOW but I am VERY confidant he will EVENTUALLY be able to!! YAY!!!

Agree and the lithium gel pack we got was half the weight and lasted a lot longer on a charge then the lead acid.