RV leisure battery acting up

[lucas]

Hi, I'm having some trouble with my leisure battery and want to consult with the experts here to make sure that a new battery is necessary, and also what I can do to avoid killing another one prematurely.

I have a 180ah regular car battery receiving charge from solar, and the alternator while driving. At one point I used this battery down to approximately 25%. This type of use is of course not recommended, but I was under the impression that it will not kill the battery unless it happens at least a handfull of times. Within a day or two the alternator for the car broke. It has since been repaired and I have managed to travel for a couple of months, but the performance of the leisure battery is exceedingly poor. It can have a charge of 13.9V from a good day of charging, and once I begin using it it will drop down to 12.7 within a minute.

Cheers,
Lucas

[SunEagle]

I am not exactly sure of the reason but IMO even going to 25% SOC once may have hurt that battery. On top of that issue you are finding that solar will not charge a battery anywhere as good as that alternator. Which means whatever the maximum that battery can handle it is no longer anywhere close to the original 180Ah rating.

You might want to look into replacing the battery to something that can handle deep cycles.

[jflorey2]

Within a day or two the alternator for the car broke. It has since been repaired and I have managed to travel for a couple of months, but the performance of the leisure battery is exceedingly poor. It can have a charge of 13.9V from a good day of charging, and once I begin using it it will drop down to 12.7 within a minute.

Dropping to 12.7V under load is not a problem. Dropping below about 11 volts under moderate load indicates a battery that is close to dead.

That being said, a starter battery in your application will not last long. If you have been using it for a while (say a year) then pat yourself on the back for getting so much life on it, and get a deep cycle battery.

[Sunking]

but the performance of the leisure battery is exceedingly poor. It can have a charge of 13.9V from a good day of charging, and once I begin using it it will drop down to 12.7 within a minute.

So how is that a problem? 12.6 to 12.8 volts is 100% SOC or full charge voltage of a rested battery. Now if the engine is running, and the voltage drops when you put a load on it is not a battery problem, that is an alternator or charger problem.

How old is the battery? If over two years is due for replacement soon. But for now what you describe is not a battery problem. A battery problem is where you measure say 12.7 volts when rested and not charging, Apply a load and the voltage collapses.

Additionally a Starter Battery is NOT A LIESURE BATTERY, it is a SLI battery. (Starting Lighting & Ignition). Leisure Battery is a Brit marketing name for a Hybrid Deep Cycle Battery. It is neither a SLI or a true Deep Cycle Battery. It tries to be both. Forcing a SLI battery into cycle service is a recipe for a dead battery.

[lucas]

Thanks for the replies everyone! Interesting.

I bought the battery 9 months ago. And it has been in use for 5 of these months. I knew I shouldn't have let it get below 25%, but it happened only once by mistake.

12.6 to 12.8 volts is 100% SOC or full charge voltage of a rested battery.

This is a problem because there is such a huge difference in performance after that one incident. It would not drop the voltage nearly as quickly, and if I am to avoid the 12.5-7 line where my charger says it's at 50%, it only lasts about a fifth as long as before.

I guess I will continue to use it until it dies and then get a deep cycle one. My only fear is that it will overwhelm the car alternator again if I use it too heavily.

On top of that issue you are finding that solar will not charge a battery anywhere as good as that alternator.

If I am to trust the charger, solar is doing a great job! (I'm in Greece at the moment ) And actually, when the alternator broke, that was the only thing keeping my car electricity going until I found a mechanic (in Ukraine haha)

[jflorey2]

This is a problem because there is such a huge difference in performance after that one incident. It would not drop the voltage nearly as quickly, and if I am to avoid the 12.5-7 line where my charger says it's at 50%, it only lasts about a fifth as long as before.

If, when your battery is DISCHARGING, the voltage is 12.5 volts and your charger says it is 50% discharged, your charger's display is broken. 12.5V while discharging is pretty much fully charged.

[SunEagle]

Thanks for the replies everyone! Interesting.

I bought the battery 9 months ago. And it has been in use for 5 of these months. I knew I shouldn't have let it get below 25%, but it happened only once by mistake.




This is a problem because there is such a huge difference in performance after that one incident. It would not drop the voltage nearly as quickly, and if I am to avoid the 12.5-7 line where my charger says it's at 50%, it only lasts about a fifth as long as before.

I guess I will continue to use it until it dies and then get a deep cycle one. My only fear is that it will overwhelm the car alternator again if I use it too heavily.




If I am to trust the charger, solar is doing a great job! (I'm in Greece at the moment ) And actually, when the alternator broke, that was the only thing keeping my car electricity going until I found a mechanic (in Ukraine haha)

That is good news your solar panel is doing the job. I just wanted to let you know that depending on how it is; angled, pointed, shaded, etc. the output could end up being much less then what you need to recharge the battery.

Usually an alternator will do the job in about 1/5th the time due to the high amp output it can produce as compared to what a solar charger can produce.

[lucas]

If, when your battery is DISCHARGING, the voltage is 12.5 volts and your charger says it is 50% discharged, your charger's display is broken. 12.5V while discharging is pretty much fully charged.

I wonder if we're talking about different types of batteries... When I purchased this battery the salesman said that its voltage is around 14V when fully charged. And when at 50% it's about 12.8V. He suggested I avoid going under that, but that a few times won't hurt. The readings on my solar charger support these stats.

[jflorey2]

I wonder if we're talking about different types of batteries... When I purchased this battery the salesman said that its voltage is around 14V when fully charged. And when at 50% it's about 12.8V. He suggested I avoid going under that, but that a few times won't hurt. The readings on my solar charger support these stats.

Then it's not a six cell lead acid battery. A lead acid battery's open circuit voltage is approximately 12.5 volts when full, 11.7 volts when dead. Variations in design will skew these by a few hundred mv's but not significantly.

That being said, if you are seeing these voltages DURING CHARGE they are perfectly normal. Most batteries float charge at around 13.8 volts and will do absorb charges around 14.2-14.8 volts. So if you are seeing those voltages DURING CHARGE then all is well. That is very different than open circuit voltage though, That's why I was very clear about seeing those voltages during discharge rather than charge.