RV batteries that do not lose voltage

[RV Vagabond]

Are there RV batteries that maintain full or close to full voltage as the state of charge percent drops to around 50% ?

[Cminnie]

Originally Posted by RV Vagabond

Are there RV batteries that maintain full or close to full voltage as the state of charge percent drops to around 50% ?

Lithium Ion batteries fit your criteria. They have cycling and longevity advantages as well but are expensive.

[SV K]

Yes, lifepo4 (lithium iron, not lithium ion) do just that. Yes, they cost more, but for our way of traveling they are invaluable.

[Tony Lee]

Depends how much you are prepared to pay for a relatively small advantage. AGM batteries deliver higher current with less droop because their internal resistance is lower.

Are you looking for less voltage droop at high currents or less voltage drop between 100% and say 40% charge at normal discharge currents

[redcolorado]

I do not have lithium ion batteries in the MH but have thought about it. But I have several tools that use them. They are great but they will stop without any warning when they reach their discharge point. I do not know if that is true of lithium ion batteries in RVs, anyone know?

[twinboat]

Most " Drop In " lithium batteries come with BMS ( battery management system ) in them.

They monitor the cell voltage to keep them balanced and shut them down if the voltage gets to low or high.

[Old Scout]

Yup--love the Li-ion bats in my Dewalt tools--they provide full power right up to the point where they shut-down. The old Ni-Cad would slowly drain/grind to a stop.....guess you need to decide how much you want to spend to get this capability in an RV application. Frankly, we don't do much dry camping so good, old lead/acid bats are ok for me...

[vsheetz]

Originally Posted by RV Vagabond

Are there RV batteries that maintain full or close to full voltage as the state of charge percent drops to around 50% ?

May I ask why?

[Sudsy]

I fly electric model airplanes. some big ones that will fly for hours. I fly with an autopilot and cameras and video transmitters that allow me to "be in the airplane".

On Lithium/Polymer batteries.

THEY Are very EXPLOSIVE!!!! If not charged properly with a computer controlled charger they will explode. Ask me how I know. I charge the batteries for my planes (some batteries weigh over 3 lbs.) in the grill out in the yard. I had a small 2200 mhr three cell LiPO explode while charging (the charger was set for NiCad) and the resulting fireball was more than impressive. I just can't imagine what one the size of a battery that would serve in a MH exploding would look like or the damage it would do. THEY ALSO CAN EXPLODE IF DAMAGED IN A CRASH. I have seen this also. Plane crashed and then explodes before the owner can get to it to try to remove that battery.

I for one would never consider a set of LiPo's for my motor home. Honestly I have never heard of a LiPo for a truck. But I can guarantee there would be a lot more to it than just changing out battery.

As far as the OP, it's just the way batteries work. As the charge decreases so do3s the voltage. When voltage decreases amperage increases over the same load. So the lower the batteries get the faster they drop off.

Sudsy

[Triangle Drifter]

Hate to think what a lithium battery would be for RV use.

There is another option that is commonly used in the marine world & top end class As where nothing but the best will do. AGM (Absorbed Glass Mat) batterys. They are not cheap either but do have redeeming qualities about them, one of them being that they can endure long periods of storage with no maintenance & lose very little charge. They have a service lifespan much longer than the cheap wetcell battery. In use they are not as good as the lithium in usable cycle time but they are far better than the wet cell at holding the voltage. The AGM is also zero maintenance & does not need to be mounted in a vented area like a wet cell. It does not even need to be mounted upright.

In 2010 I swapped out my wet cells for a single 4D Lifeline. 7 seasons later it is still going strong. It sits November to April disconnected with no maintenance charging & has power to operate trailer legs when reconnected.

[keymastr]

Never say never Sudsy. Tesla made it work. The drop-in replacements by companies like Battleborn have their own BMS, (battery management system), which is supposed to control charge profiles and keep the batts healthy. My problem with them is they must be in a heated/cooled space to be reliable since they can be damaged if you try to charge them when it is below freezing. I don't want any battery inside with me no matter what kind it is. I have seen explosions and fires from all of them and in my case they would have to go under my bed or in the pass through, which is under my bed also.

They are getting better though. Eventually they will figure out the temperature thing and the explosion risk. Then they will need to figure out the life expectancy since they often do not live up to the claims of double.

Currently you can get one that looks just like a regular battery but is about twice the available power and charges much faster. They charge to 100% at the bulk charge rate needing no period of several hours at a slower charge the way standard batts do. They also currently cost $1000 each.

Those are the reasons I will not be adding them. But they will fix those problems. Whether they can ever fix them for a price that is competitive is the question. I can buy a lot of batteries for $1000.

[twinboat]

Originally Posted by Sudsy

I fly electric model airplanes. some big ones that will fly for hours. I fly with an autopilot and cameras and video transmitters that allow me to "be in the airplane".

On Lithium/Polymer batteries.

THEY Are very EXPLOSIVE!!!! If not charged properly with a computer controlled charger they will explode. Ask me how I know. I charge the batteries for my planes (some batteries weigh over 3 lbs.) in the grill out in the yard. I had a small 2200 mhr three cell LiPO explode while charging (the charger was set for NiCad) and the resulting fireball was more than impressive. I just can't imagine what one the size of a battery that would serve in a MH exploding would look like or the damage it would do. THEY ALSO CAN EXPLODE IF DAMAGED IN A CRASH. I have seen this also. Plane crashed and then explodes before the owner can get to it to try to remove that battery.

I for one would never consider a set of LiPo's for my motor home. Honestly I have never heard of a LiPo for a truck. But I can guarantee there would be a lot more to it than just changing out battery.

As far as the OP, it's just the way batteries work. As the charge decreases so do3s the voltage. When voltage decreases amperage increases over the same load. So the lower the batteries get the faster they drop off.

Sudsy

Lead acid batteries are explosive if charged improperly too. There are plenty of other dangers with them, if treated badly. We all just take their danger for granted.

The danger isn't in the chemistry as much as in the energy large batteries contain.

[MWKingSD]

Originally Posted by twinboat

Lead acid batteries are explosive if charged improperly too. There are plenty of other dangers with them, if treated badly. We all just take their danger for granted.

The danger isn't in the chemistry as much as in the energy large batteries contain.

I had a lead acid battery in an F150 pickup explode on me once. Came home from work, changed clothes, got back in the truck to go somewhere, turned the key, and BBBBBBBAAANNNGGG went the battery. Seemed like .357 kind of loud and it really got my attention. After my pulse came down from the moon, looked under the hood and the top of the battery was peeled open and acid sprayed all over.

Presumably there was some free hydrogen outgassing & trapped under the hood, and a spark somewhere set it off. No fire but if a human had been near it - ouchie. So yeah, lead acid batteries aren't entirely safe either. I remember this every time I have to jump start something.

[Gary RVRoamer]

Lithium ion battery chemistry (LiFePo4, LiMn, etc) maintains a fairly constant voltage over 70%-80% of its energy capacity (amp-hours), so the simple answer is yes. There is a modest initial voltage drop and then the voltage stays pretty much constant as the amps are consumed. Then it drops steeply at the very end, and typically a Battery Management circuit built into the battery simply shuts it off, leading to the perception that it works at full voltage right to the end.