House Battery

[Dooley]

Grand Design Imagine 22 MLE. Presently have deep cycle battery. Put on charger. Charges to 100% but depletes charge quickly. Not under load. I always use shore power, so is a battery absolutely necessary? Additionally, is it imperative to buy a deep cycle? I do plan on buying a new battery. Thanks for any advice.

 

[Bungy]

Grand Design Imagine 22 MLE. Presently have deep cycle battery. Put on charger. Charges to 100% but depletes charge quickly. Not under load. I always use shore power, so is a battery absolutely necessary? Additionally, is it imperative to buy a deep cycle? I do plan on buying a new battery. Thanks for any advice.

No a battery is not necessary but you will have to be plugged into shore power to operate slides, levelling system etc. A deep cycle would be preferably as it will suffer less damage when continually depleted.

 

[Dooley]

No a battery is not necessary but you will have to be plugged into shore power to operate slides, levelling system etc. A deep cycle would be preferably as it will suffer less damage when continually depleted.

thank you, sir, I appreciate the response.

 

[Riverbug]

If the battery came with the camper, it likely wasn't a great one to start with. If it is always on shore power, it should last several years. I get 6+ years out of my trolling motor batteries. The key is to keep them charged and not deplete below 50% as that causes additional degradation. A battery left to deplete to 0% will quickly lose its ability to hold a good charge.

 

[kb0zke]

Remember that the battery provides the power for the trailer brakes when the safety pin is pulled. No battery = no trailer brakes if the trailer breaks away.

 

[SailingOn]

I always use shore power, so is a battery absolutely necessary?

There is a sudden, brief, surge in power demand when the slide motor starts. That surge puts a strain on the converter (supplying 12V from shore power) and voltage can drop briefly. The voltage drop can strain the slide motor. The battery supplies this surge.
Manufacturers therefore tend to require an installed battery whenever the slide is activated.

 

[Second Chance]

No a battery is not necessary but you will have to be plugged into shore power to operate slides, levelling system etc. A deep cycle would be preferably as it will suffer less damage when continually depleted.

This is not necessarily true. In many cases, the converter/charger can't provide enough amperage to operate slide or leveling systems. The battery/batteries provide the extra "oomph" for these momentary, high-draw situations.

Rob

 

[sande005]

Likely the battery was drained too low in the past. Even just once (if really low) can result in big loss of capacity. The red battery switch does not actually disconnect everything - there are a few things like smoke/propane detectors, maybe the audio gear, etc. that still pull power when the switch is off. So the battery drains. Many rewire to make it a true off switch, or add one near the batteries. Those of us that are lazy just disconnect one terminal when the rig is parked. Then nothing will pull current. Over very long times (many months) the battery will loose charge by itself, but if starting from full can take a really long time. Longer the colder the weather.
Typical Auto store battery tests focus on how well the battery can supply a surge of current, like for starting a car. So they may pass that test, but still not be able to sustain lower levels of use for any length of time.
Deep cycle batteries are better a resisting damage from going below 50% capacity, but are not immune to it.
2 6v golf cart batteries give much greater capacity, and are much more forgiving from going too low. But there is the issues of cost, weight, space and possibly a little redoing of the connections.
Best are, of course, lithium - but they have their own costs, issues with cold weather and possibly needing a converter upgrade to be able to be fully charged.

 

[Chiefday]

Grand Design Imagine 22 MLE. Presently have deep cycle battery. Put on charger. Charges to 100% but depletes charge quickly. Not under load. I always use shore power, so is a battery absolutely necessary? Additionally, is it imperative to buy a deep cycle? I do plan on buying a new battery. Thanks for any advice.

Use Battle Born lithium batteries. They are a 100% better than lead based batteries

 

[Hoopy Frood]

And ungodly expensive!!

 

[Biery-Bullock]

Like others who have posted, you should have a battery for the break-away brakes, tongue jack, smoke/CO detectors and maybe other critical items when not on shore power. LiFePO4 batteries are smart and, therefore, cannot be damaged from depleting them (like FLA batteries will). I got a LiTime battery and love it because it has more energy than 2 FLAs (needed for the 50% depth of discharge limit) for LESS $$$! And way less than a Battle Scar Born battery. Depending on the year of your rig your converter may only charge the lithium battery to 85%, but that's still better than you have with a single FLA battery and WFCO (if that's what you have) will help you upgrade it.

 

[TimtheToolMan]

The lithium BMS does provide some protections and will help many batteries last longer. Lithium can be damaged if stored too long at a low charge because they also have the self-discharge issue. If this happens once it may be dead.

50% DOD for deep cycle battery is a myth and 80% is fine for a good LA. When LA is deeply discharged it needs to be recharged soon to not lose capacity. Lithium does not need to be recharged soon.

I have upgraded to Lithium because the cost was not a lot more than LA. My charger and converter were fine but moving the batteries and adding heaters was time consuming and even doing myself, there are additional costs. The Zamp ZS-30A solar controller will not wake up batteries with built in heaters so I did not get self-heating.

Lithium have a number of benefits over LA, but they are not bullet proof. If there is no plan to keep camper for quite a number of years or if LA works fine for your use and if you are pretty good at taking care of LA, staying with LA would be more cost effective.

 

[Riverbug]

50% DOD for deep cycle battery is a myth and 80% is fine for a good LA. When LA is deeply discharged it needs to be recharged soon to not lose capacity. Lithium does not need to be recharged soon.

Depends on what your goals are for the lead acid battery. I don't think anybody is saying discharging below 50% kills the battery; it causes additional degradation. If you consistently recharge before it drops below roughly 50%, you will get significantly more life out of the battery than if you consistently discharge to 20%. Pretty much a no-brainer there. Similar to completely depleting a lead acid battery is going to do irreparable harm to the battery. That still doesn't mean its DOA, but the life cycle is shortened each time you do that.

In the old days, RV converter chargers were terrible at maintaining the batteries (often overcooked them), and people didn't understand that "deep cycle" didn't mean you could consistently deep discharge batteries and expect them to have long life. Anyone that has had to replace their batteries after two or three years will understand this. But if you treat them with respect, such as having a multi-stage charger, not letting them go dead, keeping them above about 50% fairly consistently, you can routinely get 6, 8, or more years out of lead acid batteries. Deplete them to 20% consistently, and that is highly unlikely in my experience.

 

[redfernclan]

One thing I have not seen in the answers, check the water in the battery. Maintainers and on board chargers are notorious for overcharging batteries. They have gotten better, but I still keep an eye on them.
If your battery is low on water, it will not have the stated capacity.

 

[TimtheToolMan]

Depends on what your goals are for the lead acid battery. I don't think anybody is saying discharging below 50% kills the battery; it causes additional degradation. If you consistently recharge before it drops below roughly 50%, you will get significantly more life out of the battery than if you consistently discharge to 20%. Pretty much a no-brainer there. Similar to completely depleting a lead acid battery is going to do irreparable harm to the battery. That still doesn't mean its DOA, but the life cycle is shortened each time you do that.

In the old days, RV converter chargers were terrible at maintaining the batteries (often overcooked them), and people didn't understand that "deep cycle" didn't mean you could consistently deep discharge batteries and expect them to have long life. Anyone that has had to replace their batteries after two or three years will understand this. But if you treat them with respect, such as having a multi-stage charger, not letting them go dead, keeping them above about 50% fairly consistently, you can routinely get 6, 8, or more years out of lead acid batteries. Deplete them to 20% consistently, and that is highly unlikely in my experience.

There is a small gain in total energy produced over life of battery when discharging to 50% vs. 80% DOD. 50% DOD produces more cycles but 62% of energy per cycle than 80%. Graph is Interstate GC2 AGM.

If anyone is interested in this topic, look this information up in the manuals from the top name manufactures that have extensive documentation and they all likely have similar graphs to Interstate.

 

[DarrellGKing]

And ungodly expensive!!

I am using 600Ah of LiTime. Been using them for 4 years. A bit better price on Amazon.

 

[Dooley]

thanks for all the responses. I replaced battery.

 

[redfernclan]

Thanks for the update.

 

[Riverbug]

There is a small gain in total energy produced over life of battery when discharging to 50% vs. 80% DOD. 50% DOD produces more cycles but 62% of energy per cycle than 80%. Graph is Interstate GC2 AGM.

If anyone is interested in this topic, look this information up in the manuals from the top name manufactures that have extensive documentation and they all likely have similar graphs to Interstate. View attachment 111213

Good graphic. It appears we're saying the same thing, but perhaps have a different perspective on what constitutes a "small gain". To me, a difference of 35% in battery life cycle is pretty significant. If one can expect 1,100 cycles at 50% discharge and 700 cycles at 80%, then it's worth treating the batteries accordingly to get the extra life out of them. I'm talking in terms of consistency. Not saying one never goes below 50%; just that the more you can keep from doing it, the longer life you can get out of the battery. Just my opinion. Nobody has to agree with me.

 

[TimtheToolMan]

Good graphic. It appears we're saying the same thing, but perhaps have a different perspective on what constitutes a "small gain". To me, a difference of 35% in battery life cycle is pretty significant. If one can expect 1,100 cycles at 50% discharge and 700 cycles at 80%, then it's worth treating the batteries accordingly to get the extra life out of them. I'm talking in terms of consistency. Not saying one never goes below 50%; just that the more you can keep from doing it, the longer life you can get out of the battery. Just my opinion. Nobody has to agree with me.

I very much like your positive attitude!

Discharging two times (2 cycles) to 60% state of charge (2 x 40%=80% used) produces the same energy as once to 20% SOC (80% used). When cycled like this until not useable, both will have very close to the same battery life but first takes twice as many cycles to produce the same energy as the second. Just counting cycles at different discharges produces a false impression of longer life.

Another way of wording it, if 40% of battery is used every day and in case 1 recharged daily (60% SOC) and in case 2 battery is recharged every other day (60%SOC day one and 20% SOC day two), the energy output is the same for either case and battery longevity, when used either way, is very close either way.

Using more of a battery's capacity versus using more batteries is right sizing the battery set, be it lithium or lead acid batteries, and reduces initial cost, replacement cost, weight, complexity, space, ... Most RV batteries age out or are abused and do not die from being cycled.