Deep Cycle Marine Battery

Best RV Starting, Dual Purpose and Deep Cycle Batteries

Electric systems commonly found in fishing and recreational boats are very similar to the electric systems found in recreational vehicles (RVs). Boat and RV batteries must power various devices ranging from tablets and smartphones to refrigerators, TVs, microwave ovens, AC units, etc. when main engine(s) are powered down and not producing electric energy.

Published: December 28, 2018.

Such batteries also must supply enough energy to avoid issues with power spikes when the RVs are powered via solar panels and/or wind turbines and some larger unit is turned on.

Note that in a single battery RV electric systems, one battery is used for both powering various electric and electronic devices and for starting the main engine.

Mechanically these batteries must be robust and resistant to vibrations and must be able to operate in any position, without spilling out the electrolyte.

All those requirements put a large stress on RV batteries and choosing a proper one can be a challenge.

Single Battery RV Electric Systems

exide edge fp agm24dp 1mRV electric systems rarely rely on just one battery, but smaller RVs can save some weight using just one battery. Also, using a single battery makes an electric system simpler and easier to maintain.

Batteries for such systems are commonly Sealed Lead Acid (SLA) batteries (AGM or gel cell) designed as true Dual Purpose Batteries, and functioning as both RV house battery and as RV starting battery.

As RV house battery, such batteries must be able to power number of devices for certain amount of time without external power source.

As RV starting battery, such dual purpose batteries must be able to safely start a motor even when they are partially discharged.

When choosing a dual purpose battery be sure to check required cranking Amps and power and energy consumption of devices found in your RV. Just to be sure, always add certain reserve (20-50%) to your battery and if possible, keep a good and charged Jump Starter in your RV, even if you have solar panel(s) and wind turbine chargers.

Dual Batteries RV Electric Systems

RV electric systems based on dual batteries or even dual battery packs are more resilient and more often found on larger RVs and larger leisure and fishing boats. Such systems are also more complicated, harder to maintain and they cost more, but their pros and cons are generally in their favor. IMHO of course.

Since batteries or battery packs are separated according to their purpose, batteries can be optimized for their intended use, and issues with one battery doesn't reflect at the other battery.

optima 34m bluetop mCranking battery is used just for starting main RV motor, allowing that battery to be smaller and optimized for short but powerful bursts of electricity. And when the main motor is turned on, its alternator supplies energy to power all the lights and appliances found on RV, and to charge both batteries.

When replacing RV cranking battery note maximum cranking Amps of the old battery, but also of the RV's motor (if possible to find) and measure available space. New cranking battery obviously must be at least as strong as the old battery and it must fit old battery compartment.

Note: SLA AGM maintenance free cranking batteries are highly recommended.

Best RV house battery or battery pack supplies energy for longer period of time. Deep cycle sealed lead acid batteries are preferred choice for this purpose, for several reasons:

- they tolerate cyclic use very well,

- although their price vary depending on desired voltage, capacity and required power output, SLA batteries are the best buy batteries at the moment in terms of price and performances,

- mechanically they are very robust batteries and very resilient to vibrations and even mechanical impacts,

- SLA AGM and gel cell batteries can operate in any position.

On the other hand, SLA batteries tend to be heavy - that is why they are positioned low in the RV and boat, where they can significantly lower the center of gravity (not so important in RVs, but essential in boats and yachts).

When replacing RV house battery, note voltage, capacity, maximum current and the number of old batteries and replace them with the new batteries:

vmaxtanks mr197- new batteries must be of the same size to fit the battery compartment,

- have same voltage to achieve the same output voltage,

- have at least the same maximum output current to be able to supply available devices,

- have at least the same capacity.

Fortunately, although lead-acid batteries are 'old' type of batteries and their advances are relatively slow, in most situations it is possible to buy batteries of the same size that are improved in terms of capacity, output power and durability, when compared with the batteries that are 5+ years old - just be sure to replace ALL old batteries (not just one, for example) with new batteries of the same brand, type and size, preferably from the same batch!

Note: RV house battery packs use 6V, 8V or 12V batteries to achieve 12V, 24V, 36V or even 48V. Be absolutely sure that new batteries have the same voltage as the old ones, or in the best case you will also need new fuses, not just batteries :)

Lithium RV Battery

battle born battery lifepo4 100ah 12v mLithium batteries for recreational vehicles offer many benefits, one of the most important ones is weight savings. Also, lithium batteries tolerate much larger number of full charge/discharge cycles, have very low self-discharge rate, they are recharged faster etc.

On the other hand, lithium ion batteries initially cost more and must be charged with special chargers - unless one uses lithium ion 'plug and play' drop-in replacement batteries for lead-acid batteries.

Such lithium ion batteries come with electronic protection system that monitors parameters of the battery and if required, protect it. Electronic protection systems commonly monitor charging and discharging current, voltage, temperature, condition of cells and other parameters important for safe operation.

Plug and play drop-in lithium ion replacement batteries can be charged with SLA chargers, including on-board alternator, solar panels, wind turbines, power generators etc. and can be connected in parallel and series like normal SLA AGM batteries.

Note: since such protective electronic systems vary, before buying lithium ion batteries, check with the manufacturer if their model is safe for exact application that you have.

Just like AGM batteries, when buying lithium batteries one must choose according to their maximum discharge rate, voltage, capacity, dimensions, terminals etc.

Some rather light lithium ion batteries can achieve high discharge rate although their capacity is rather limited - such batteries are excellent choice as RV starting battery replacement.

On the other hand, some lithium ion batteries have rather limited maximum discharge rate, but their capacity and durability is better in terms of weight and price when compared with high-discharge models - they are excellent choice as RV house battery replacements.

RV Battery Life Expectancy

lithium btl09a120c tBattery life in RV and marine applications depends on many things, including:

- number and depth of charging and discharging cycles. Although deep cycle batteries tolerate very well cyclic use with deep discharges, if they are rarely discharged below 50% (yes, 50%), they will last much longer when compared with the batteries that are commonly discharge up to or even below 80%.

- battery type: SLA batteries commonly achieve 300-500 charge/discharge cycles, while lithium ion batteries can achieve 10x that much. Also, lithium ion batteries can be left for months without adverse effects on their capacity, especially if they are left semi-charged (this also depends on the type of lithium battery!). On the other hand, SLA batteries should be charged every month or so, to prevent buildup of sulfates on the battery's plates.

- battery temperature: too low and too high temperatures can shorten battery life. If you are not using your RV during the winter for months, remove the batteries and place them in the area that never falls below freezing temperatures. Also, during summer, be sure that RV is in shade as much as possible and that battery compartment is well ventilated.

For short: good SLA AGM battery should be able to achieve 300-500 deep discharge/charge cycles when being charged with intelligent SLA AGM battery chargers, while avoiding very low and rather high temperatures and long periods of being not used. Good lithium ion battery should be able to achieve 3000-4000 (yes, thousands!) of deep discharge/charge cycles, while avoiding very low and rather high temperatures, especially when being charged with lithium ion battery chargers. Drop-in lithium ion replacements for SLA batteries when being charged with SLA chargers should behave (at least in theory) just as 'normal' lithium ion batteries charged with lithium ion chargers.

Again, lithium ion batteries are great stuff, just be sure to check with the manufacturers that they fit your exact application!

The following table lists best and most popular starting, dual purpose and deep cycle batteries commonly used in marine and RV applications:

Best RV Solar Kit

windynation 100w solar kitRV solar kit requirements vary significantly, but one of the most popular is WindyNation's '100 Watt Solar Panel Complete Off-Grid RV and Boat Kit'.

Such solar kit has everything one needs for being off-the-grid energy independent:

- 100 Watts Solar Panel,

- 30-Amp P30L LCD Display Solar Charge Controller with Battery Temperature Sensor,

- 40 feet 12 AWG Solar Cable,

- all necessary connectors, and mounting hardware,

- 100 Ah, Group 27, deep cycle 12V BattaMax AGM battery.

Such RV solar kit can provide on average 350 Wh (~30 Ah at 12V) of charge per day - this also depends on the available sunlight. But, good thing is that included charge controller can handle up to four 100W solar panels for 12 volt systems and eight 100W solar panels for 24 volt systems.

This solar kit is designed for RVs, homes, boats, back-up, remote power use and other (almost) maintenance-free off-the-grid applications - it does require 'some' maintenance from time to time, like checking the cables, terminals and other connectors and similar.

For more reviews and recommendations check WindyNation 100 Watt Solar Panel Off-Grid RV Boat Kit Amazon link (link opens in the new window).

Long Story Short: whether you require good starting battery for your RV, or deep cycle RV house battery or your RV runs using dual purpose batteries, it is very important to replace old batteries with new ones that are as good or even better than old ones. Be careful about batteries' type, capacity, voltage, terminals, size and other technical details, especially if you want to save weight (and money in the long run) and opt for lithium ion drop-in replacements.

And whatever you do, stay safe!

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