What are the advantages of RV batteries compared to AGM batteries

Until about a year ago, I was rather skeptical about the convenience of Lithium Iron Phosphate (LiFePO4) batteries compared to good traditional lead-acid batteries (whether liquid electrolyte, AGM, or Gel).

But then my usual curiosity prompted me to investigate some aspects, and today I must confess that if I had to change the batteries, I would switch to Lithium. For heaven’s sake, I installed two good quality AGM RV batteries of 220 Ah each about two years ago. Therefore, a total of 440 Ah for my needs are more than adequate, and I sincerely hope they will last at least another 4-5 years, seeing and considering that I treat them very well.

The solar panels give me a great energy contribution, such that the battery voltage rarely drops below 12.4 Volts and this, for those who don’t already know, is the best way to make lead batteries last a long time. The problem with batteries, especially the lead-acid ones commonly used on board our vehicles, is that their life decreases the more thoroughly they are discharged. However, Lithium batteries are light years ahead, so much so that I have estimated that when the time comes, my current ones will be replaced by 200 Ah Lithium, which will still be more than enough to replace the current capacity of 440 Ah.

I will begin by listing the advantages of lithium RV batteries (we are talking about Lithium Iron Phosphate or LiFePO4) compared to lead batteries.

  • Much greater resistance to charge and discharge cycles: about 10 times more
  • The higher energy density (savings in weight and space)
  • Greater voltage stability
  • Peukert coefficient is very close to 1, which means the possibility of delivering very high currents for long periods without capacity reduction (explained later)
  • They can be charged with very high currents, which means they recharge in a very short time (from 0 to 100% theoretically in one hour)
  • Greater energy efficiency for each discharge/charge cycle
  • No sulphation issues or loss of capacity if not 100% charged
  • Less self-discharge
See also  How to Trade with Keltner Channels?

If, on the other hand, I have piqued your curiosity and you want to go deeper, I will now explain each of the previous points in detail (but then watch the video anyway, please)

Resistance to charge and discharge cycles

I will never stop repeating it: battery life is not measured in years but in the number of discharge/charge cycles, and it will be shorter the more deeply they are discharged at each cycle.

Lithium Iron Phosphate batteries support about 2000 cycles even if discharged almost completely (DOD of 90-100%). This number rises in a non-linear way so that already with a DOD of 80%, we can reach 4000-5000 cycles, and with a DOD of 30%, we exceed 10,000 cycles.

You immediately understand that a Lithium Iron Phosphate battery, under the same conditions of use, is destined to last even 10 times longer than an excellent lead-acid battery. Alternatively, you may “only” last three or four times as long but install half the capacity by cycling more deeply.

Higher energy density

What is the so-called energy density? It is the amount of energy that can be stored in a certain volume of battery. Put. It means that LiFePO4 lithium batteries, with the same capacity, are smaller and weigh less than lead batteries.

For example, data in hand: a 100 Ah lead battery weighs 30 kg and occupies a volume of about 13 liters. The 100 Ah LiFePO4 battery weighs 13 kg for a volume of only 8 liters.

Therefore, another benefit of lithium batteries is saving weight and space. My current 2 batteries have a total capacity of 240 Ah and weigh 120 kg. I could put 2 200 Ah Lithium batteries in their place, saving 60 kg of weight and a lot of space.

See also  Setting Sail Locally: How Henrietta and Bowie, TX, Enhance the Boating Experience

But for the reasons listed in the previous point, I could also put only 200 Ah of Lithium by discharging them more deeply without fear of damaging them, and in this case, I would save at least 90 kg, going from 120 to only 25-30 kg and freeing up a lot of space.

Lithium batteries are also indicated in cases where the installed batteries are insufficient, but there is no space to install more. Replacing the current lead-acid batteries with lithium-ion ones would be more usable energy despite having the same nominal capacity, or a higher capacity could also be installed since Lithium takes up less space.

Greater voltage stability

This is also an important feature of lithium batteries. Any battery decreases its voltage (Volts) as it discharges, but lithium batteries do this to a much lesser extent.

When a lead battery is 100% charged, it has a voltage of 12.8 Volts which drops to 10.8 Volts when completely discharged.

A 12v lithium battery has a full charge voltage of about 13.5 Volts, which soon drops to 13 Volts, then stabilizes around this value until the charge drops to 20%, at which point the voltage will reach 12. .8 Volts. Therefore less than 1 Volt of excursion, against almost 3 Volts of a Lead-acid battery.

But that’s not all: the voltage of a lead-acid battery undergoes a drop when it is forced to supply a high current, equal to or greater than 20% of its capacity (for example, 20 Ampere for a 100 Ah battery) and this drop is even more marked if the battery is partially discharged or old. With Lithium, this does not happen or happens to a much lesser extent.

The electrical and electronic devices we have on board do not like voltage drops, so switching to Lithium will surely improve their functioning.

Peukert’s coefficient almost equal to 1

It suffices to know that the effective capacity of a battery decreases as the intensity of the current it supplies increases.

See also  For Those Who May Be Unfamiliar, A Redirect Url Is One That

The nominal capacity of a lead-acid battery, precisely, for this reason, is generally calculated assuming that it is subjected to a discharge with the constant current for 20 hours (on the technical sheets, we speak of a C20 discharge). In other words, the discharge current will be 5% of the battery capacity: 5 Ampere for a 100 Ah battery. 5 Ampere x 20 hours is exactly 100 Ah.

If the discharge current is higher than this value, the capacity decreases. And for lead-acid batteries, the decrease is anything but negligible. For example, if we require a current of 50 Amperes from a 100 Ah battery, we could expect the battery to discharge completely in 2 hours (50 Ampere x 2 hours makes 100 Ah). Instead, we will discover that it will already be completely discharged after just one hour.

This is a known and very unpleasant problem of lead-acid batteries, which lithium batteries do not have; under the conditions of the previous example, a 100 Ah lithium battery could deliver 50 amps for 2 straight hours.

This is the reason why the latter is particularly suitable for being used to operate equipment that requires a lot of power. For example, electric winches and espresso machines.

Also, because lithium batteries do not suffer particularly even when they are subjected to discharges with high and continuous currents even higher than 100%-200% of their capacity (therefore 100 or 200 Ampere for a 100 Ah battery), think about electric cars, which have been talked about a lot (even too much) in recent months: these must deliver very high power during acceleration and all this power could not be obtained from lead-acid batteries.

The case of sailboats is known in which the installation of lithium batteries has made it possible to replace the traditional gas cooker with an induction one!

Leave a Reply

Your email address will not be published. Required fields are marked *