Dead Batteries- how bad?

[danhannah]

I hope this is on-topic. I accidentally discharged my 2 - six volt trojans in the MH below 10.4 volts.

They are about a year old. Does a one-time 100% discharge shorten their life considerably? I mean, did it take years off their life?

I usually quit discharging at 50%, trying to take good care of them.

Thank you for the comments.

[Morich]

It's not a one and done thing as there are lots of different things that change how batteries work. Temperature, how long, what minerals are in the water used and design are some.
That leaves me to not worry the issue too much when I find I have performed "less than perfect". I'm kind of using to finding out I've messed up the small points, so I just tell myself to do better and keep watching the bigger issues.
I find battery expense just gets fit into the overall question and it's often not one of the big ones. I'm losing far more value from the RV setting out in the Texas sun than the batteries cost me.

[creativepart]

Dan, I moved your post into its own thread. It’s always better to start a new thread for a new topic rather than post on an existing thread on another similar, but different topic.

Hope this helps.

[al1florida]

Originally Posted by danhannah

I hope this is on-topic. I accidentally discharged my 2 - six volt trojans in the MH below 10.4 volts.

They are about a year old. Does a one-time 100% discharge shorten their life considerably? I mean, did it take years off their life?

I usually quit discharging at 50%, trying to take good care of them.

Thank you for the comments.

If the battery was left for many weeks (months in storage) in the dead battery state, then probably quite a bit of damage was done.
If it was a couple of days and then charged, then probably not much damage.

Do you boondock/dry camp for several days, or do you mostly travel from shore power to shore power and just depend on the battery to get you from location to location?

[danhannah]

Not a lot of boondocking, we are usually plugged in. The batteries self discharged over 5 days, I guess from the inverter on standby and other very small loads.

It's the first time I've had them below 50%, but they were completely discharged for a day or so.

[Topsail]

Maybe you took off one of its nine lives and maybe not. If it continues to take a charge just keep an eye on it and have a back up plan (toad battery) just in case.

I thought I killed my start battery when I ran it way down under dead. The battery was right at a year old and took a charge. It's still performing as it should, therefore I must have caught it just in time.

[al1florida]

Originally Posted by danhannah

Not a lot of boondocking, we are usually plugged in. The batteries self discharged over 5 days, I guess from the inverter on standby and other very small loads.

It's the first time I've had them below 50%, but they were completely discharged for a day or so.

Chances are you won't see any affect.

If you have a battery monitor which shows the AH (Amp Hours) used and the battery voltage, you would most likely see that there is a little less battery capacity available. You would have had to have experience with dry camping and monitoring your battery capacity to have something to compare to.

[Morich]

We are probably looking too critically at something that happens pretty often in real life. There are several ways to damage batteries over the lo9ng run but the worst is letting them run dry, as that exposes the plates.
Killing a battery by running the voltage down has two things to make me feel better. One is that the voltage reading is also a surface reading, not a true reading of the total charge left in the battery. This is one of those which I think most will not understand as voltage seems so simple but it is not on batteries. Batteries are not a single cell but several connected together, so when a meter looks at the voltage it is often looking at the points where the posts are connected and those are also where the charge is changed first, either when using or charging. Given time, the charge in the first cell and all the others will reach a "stable", somewhat even, reading as the chemical reaction happens. But it's a slow process, often taking days to complete.
So that slow change is often making the voltage reading look far more radical than if we take a longer look at things. One it shows we have drained the battery far more than other tests will show but on the flip side it also makes us think thirty minutes of driving or running the generator does us more good than real testing might show.
The second thing that comes from experience tells me it is not fatal to run a battery completely down!
A large number of us are probably old enough to remember what happened to the battery when we forgot to turn the lights off when we parked the car? Come back the next morning and the lights were so dim they barely glowed but the battery lived for years after being charged, right?
I'm thinking it was not good for the batteries but not all that bad either.

[creativepart]

Originally Posted by Morich

We are probably looking too critically at something that happens pretty often in real life.

I'm with you on this.

We haven't heard back from the OP but I hope he set about getting a good charge on those batteries ASAP. Because, it's not only how low did they go but how long they stayed there.

[danhannah]

Thanks for all the replies. I feel much better about this error. I did get them charged back up the same day - and maybe I have been being TOO gentle on them, they are probably tougher than I think


THANKS

[Morich]

I used to know a girl who liked to listen to music on the car radio while laying out in the sun. did the dead battery about three times before her dad figured out why the car wouldn't start!
Never said anything about it killing the battery but he did have to jump it to go to work!

[al1florida]

Interesting the comments about "starting" batteries for starting an engine, versus the deep cycle batteries we use in RV's to provide our daily power requirements.

There is a really big difference between using the battery system to power our RV's off the grid and a starting battery to start an engine.

First, as long as the engine you are starting, starts right away, you are unlikely to ever notice the damage done by draining the battery to the point of close to dead, UNTIL it finally dies months or years later.

HOWEVER, when we are using our batteries to dry camp or boondock we will soon realize the damage done by running the battery down to dead a several times.

Assuming a 400AH battery set up (200AH usable) and a measured RV power usage of between 125AH and 175AH on a daily basis, we will realize we have a problem after killing the battery system times.

The problem happens because we are depending on our RV batteries to produce a set amount of power every day. Start draining the battery to far and the 200AH capacity we planned for is no longer there. As it drops to 175AH capacity, or 150AH capacity we really begin to notice.

Now because we no longer have the 200AH capacity we have to start taking the battery down below the 50% full, to give us the 175 we need today. This speeds up the loss in capacity. Soon we are needing to replace the battery bank.

Some more things the experienced dry camper/boondocker learns:
-- There are a lot of times we don't get our battery pack back to 100%. So the 200AH capacity we planned for just isn't there. Maybe only 150AH capacity to the point of 50% full. And I am thinking of new or relatively new batteries. So if it is a day were we need 175AH and we only have 150AH to reach 50% we are again stressing the battery bank.
-- While we plan for a normal usage of 125AH to 175AH a day, there are days we will use more.
-- Then there are days when the sun is not as bright or it is a cloudy day and we don't get the charge we planned for back in the battery.
-- Additionally we learn that we will not leave our generator running for the 4-6 or 8 hours or more to get our batteries completely back to 100%. This is an additional stress on the life of our batteries.

Bottom line it is not practical to compare starting batteries used to start an engine to deep cycle batteries to provide our daily power requirements in an RV.

[creativepart]

We don't dry camp a lot - but we have done more every year and last year we got our feet wet by moving from a full hookup site we didn't like in Flagstaff 8-miles up the road to a great National Forest campground with no hookups for 4-days. Bonito Campground.

We have 400 aH of House battery storage, a 5.5K genset, 300w of Solar Panels, and a Magnum BMK.

What a great learning experience. The weather was great. Cool sunny days and cold nights. We needed power for all of our devices and TVs, plus we have a residential fridge and we needed some LP Heater each night.

When planning trips now, my wife encourages me to find more dry camping NFS campgrounds along our routes.

One day these four 3-year old (in July) AGMs will need to be replaced - I'm kind of looking forward to that day. I know we could replace them now but, we certainly don't need to.

[Topsail]

Originally Posted by al1florida

Interesting the comments about "starting" batteries for starting an engine, versus the deep cycle batteries we use in RV's to provide our daily power requirements.

There is a really big difference between using the battery system to power our RV's off the grid and a starting battery to start an engine.

First, as long as the engine you are starting, starts right away, you are unlikely to ever notice the damage done by draining the battery to the point of close to dead, UNTIL it finally dies months or years later.

HOWEVER, when we are using our batteries to dry camp or boondock we will soon realize the damage done by running the battery down to dead a several times.

Assuming a 400AH battery set up (200AH usable) and a measured RV power usage of between 125AH and 175AH on a daily basis, we will realize we have a problem after killing the battery system times.

The problem happens because we are depending on our RV batteries to produce a set amount of power every day. Start draining the battery to far and the 200AH capacity we planned for is no longer there. As it drops to 175AH capacity, or 150AH capacity we really begin to notice.

Now because we no longer have the 200AH capacity we have to start taking the battery down below the 50% full, to give us the 175 we need today. This speeds up the loss in capacity. Soon we are needing to replace the battery bank.

Some more things the experienced dry camper/boondocker learns:
-- There are a lot of times we don't get our battery pack back to 100%. So the 200AH capacity we planned for just isn't there. Maybe only 150AH capacity to the point of 50% full. And I am thinking of new or relatively new batteries. So if it is a day were we need 175AH and we only have 150AH to reach 50% we are again stressing the battery bank.
-- While we plan for a normal usage of 125AH to 175AH a day, there are days we will use more.
-- Then there are days when the sun is not as bright or it is a cloudy day and we don't get the charge we planned for back in the battery.
-- Additionally we learn that we will not leave our generator running for the 4-6 or 8 hours or more to get our batteries completely back to 100%. This is an additional stress on the life of our batteries.

Bottom line it is not practical to compare starting batteries used to start an engine to deep cycle batteries to provide our daily power requirements in an RV.

That is a great write up on power consumption. Thanks for some specific information that we can all use. Measurable is the key.

[al1florida]

Originally Posted by creativepart

We don't dry camp a lot - but we have done more every year and last year we got our feet wet by moving from a full hookup site we didn't like in Flagstaff 8-miles up the road to a great National Forest campground with no hookups for 4-days. Bonito Campground.

We have 400 aH of House battery storage, a 5.5K genset, 300w of Solar Panels, and a Magnum BMK.

What a great learning experience. The weather was great. Cool sunny days and cold nights. We needed power for all of our devices and TVs, plus we have a residential fridge and we needed some LP Heater each night.

When planning trips now, my wife encourages me to find more dry camping NFS campgrounds along our routes.

One day these four 3-year old (in July) AGMs will need to be replaced - I'm kind of looking forward to that day. I know we could replace them now but, we certainly don't need to.

OH, NO another convert to dry camping to take up the NF campgrounds we love!

Here is a great website with great info for every NF campground you can drive an RV into: https://www.forestcamping.com/

[bill06447]

I work for a company that sells and services industrial equipment, including electric pallet jacks that use the Trojan T105 and equivalent wet cell batteries. The programming shuts off all functions except traction (to get you to a charging station) at 1.7 volts per cell which comes out to 10.2 volts. The batteries routinely last a minimum of five years at this cycle rate so you have no worries.

[danhannah]

Originally Posted by bill06447

I work for a company that sells and services industrial equipment, including electric pallet jacks that use the Trojan T105 and equivalent wet cell batteries. The programming shuts off all functions except traction (to get you to a charging station) at 1.7 volts per cell which comes out to 10.2 volts. The batteries routinely last a minimum of five years at this cycle rate so you have no worries.

Thanks Bill. Much appreciated info!

[JoeC]

Originally Posted by danhannah

Not a lot of boondocking, we are usually plugged in. The batteries self discharged over 5 days, I guess from the inverter on standby and other very small loads.

It's the first time I've had them below 50%, but they were completely discharged for a day or so.

Take a "selfie" and put it on a poster with your story. You could be the "poster person" for battery monitoring products. I don't mean this to be harsh in any way. Hopefully you learned a lesson here that when you have more than a simple RV battery system with tiny loads and little boondocking (you added an inverter), you need, as in not optional, quality battery shunt monitoring. It will pay for itself in just an episode or two like the one you experienced, plus you will know what's actually left on your battery bank for planning purposes and help you plan ahead in future expansions. As we all know, RVing is usually an evolving process, not a stagnant event.

[danhannah]

I don't know how a better battery monitor would have helped. I parked the rig with the inverter on, and left it for 5 days unattended. I guess a bluetooth type low battery alert system would have alerted me. Thanks!

[cj_calva]

Yes you have shorten your batteries' life. But how bad? Well charge the batteries well and then you will see. My wife's old english car lives with two 7 years old 6V batteries which are down after every ride in the dark or in the rain (dynamo delivers a maximum of 128W, front H4 light need 2x50W /high beam 2x75W, then there are rearlights too, wipers, etc)... well the batteries with 75ah are more or less always down at 9V after a journey with rain. But at home the batteries are connected to a smart charging/maintain device and so it's no worry until the next ride....