I learn from your articles even though I don't have an RV anymore..
In regards to the 50% discharge rule. Isn't that overstated?
• I agree that it maximizes life
• I've seen posts that suggest discharging to 20% is only somewhat more expensive per Amp Hour over the life of the battery. Maybe a 20% penalty in dollars/Amp Hour.
That seems a reasonable trade off for RV use with less battery weight, and less space usage per life time Amp Hours.
I haven't been able to find an authoritative source. This might be something for you to write about.
You use the turm 50% of battery that would tell me I can discharge battery to 6 volts is that correct? What is 50% of 12 volt battery? I need help. Looking forward to your next article.
I keep a 1.25 AMP Battery Tender charger maintainer connected to my house batteries when it's in storage. Every couple of weeks I disconnect it to draw the battery down then connect the Battery Tender again. Is drawing the battery down a wasted step?
Yes, there’s no need to draw down the battery. The Battery Tender will monitor the battery voltage and only provide enough current to keep it fully charged, without overcharging the battery.
What you didn't mention was the peukert exponent and the affect that cold weather will have on battery capacity. Those two affects can reduce the battery capacity significantly. It might be reduced by almost half in high discharge rate cold weather conditions like the ones discussed in the article. Then throw in the fact that unless the battery is brand new and well maintained and fully charged you probably don't have the rated capacity to start with.
So a 100AH lead acid battery might actually only have a 50AH capacity or less in conditions like the ones in this analysis.
All true, and I’ll cover those aspects of battery charging/discharging in a future article. But this is a 101-level post just to show readers the basics of battery energy capacity and usage. As you noted, there are lots of variables affecting actual battery performance.
I’ll post a more in-depth article next month covering RV battery chemistry (Lithium vs FLA or AGM) and charging rates.
Please Standby…
Really helpful for a subject that I find challenging to grasp.
Glad it helped.
Mike,
I learn from your articles even though I don't have an RV anymore..
In regards to the 50% discharge rule. Isn't that overstated?
• I agree that it maximizes life
• I've seen posts that suggest discharging to 20% is only somewhat more expensive per Amp Hour over the life of the battery. Maybe a 20% penalty in dollars/Amp Hour.
That seems a reasonable trade off for RV use with less battery weight, and less space usage per life time Amp Hours.
I haven't been able to find an authoritative source. This might be something for you to write about.
Thanks,
Irv
Mr Mikeee
You use the turm 50% of battery that would tell me I can discharge battery to 6 volts is that correct? What is 50% of 12 volt battery? I need help. Looking forward to your next article.
That’s s great question. I’ll post an article soon on measuring battery SoC (State of Charge) using a digital multimeter.
I keep a 1.25 AMP Battery Tender charger maintainer connected to my house batteries when it's in storage. Every couple of weeks I disconnect it to draw the battery down then connect the Battery Tender again. Is drawing the battery down a wasted step?
Yes, there’s no need to draw down the battery. The Battery Tender will monitor the battery voltage and only provide enough current to keep it fully charged, without overcharging the battery.
Thanks for clearing that up Mike.
What you didn't mention was the peukert exponent and the affect that cold weather will have on battery capacity. Those two affects can reduce the battery capacity significantly. It might be reduced by almost half in high discharge rate cold weather conditions like the ones discussed in the article. Then throw in the fact that unless the battery is brand new and well maintained and fully charged you probably don't have the rated capacity to start with.
So a 100AH lead acid battery might actually only have a 50AH capacity or less in conditions like the ones in this analysis.
LiFePo4 batteries would do much better.
All true, and I’ll cover those aspects of battery charging/discharging in a future article. But this is a 101-level post just to show readers the basics of battery energy capacity and usage. As you noted, there are lots of variables affecting actual battery performance.
Excellent analogy of a difficult process for many RVers to understand.