I have a single 12v battery in my 5th wheel. AT night when I go to bed, I have a full charge on the battery, by morning, the battery is drained. There are no lights on, and only the refrigerator running on propane. I have to run the generator in the morning to recharge the battery so I can turn the lights on. I have it at the repair shop now and they say there is no "parasitic drain". I'm getting a second battery installed but would like to resolve the battery drainage issue. Any ideas? Thanks.
Overnight Battery Drain
- Thread starter MrGriz
- Start date
Dahillbilly
Well-known member
have the battery load tested this will tell you if it's worth keeping. A good battery should last longer under those conditions
I know from experience, even with the battery switches to the off position there were parasitic draws on every one of the four fifth wheels we have had. Never measured how much, cause I was always on shore power. Did you run your heat? Cause running the furnace will draw ton of juice for the brain box, and the fan. Having a second battery will give you twice the ampacity, but if your not on shore juice its a loosing battle.
How I test a battery is charge it up fully. Let it set for 24 hours not connected, and measure its no load voltage. It should be 12.6 or higher. Buying a battery off the shelf, if its not up the 12.6 or higher, I dont buy it.
How I test a battery is charge it up fully. Let it set for 24 hours not connected, and measure its no load voltage. It should be 12.6 or higher. Buying a battery off the shelf, if its not up the 12.6 or higher, I dont buy it.
taskswap
Well-known member
I'm confused about the "no parasitic drain" because almost every camper in the world has SOME. Your CO2 detector draws power and that's certainly on, and almost all coaches have clocks or radios that have standby power. Your TV has standby power so you can turn it on with your remote, and most aux devices like USB charging ports have some small internal loss even when nothing is plugged in.
Draining overnight... the responses above are probably still more likely about a possibly bad battery. But I'd love to hear something more scientific / objective than "no parasitic drain". Unless they tell you they disconnected your CO2 detector and everything else, maybe they had their high school intern "check something" but nothing really got measured at all...
This is my opinionated opinion but I think no coach "emergency toolbox" is complete without a multimeter. It doesn't have to be a good one. Harbor Freight or Amazon both have $10-$20 options that would easily measure this for you. Make sure you read the instructions and configure your meter for ammeter/current mode (usually you have to change what the leads are plugged into). Disconnect your negative battery cable and with everything you can think of off in the coach, connect the meter between the battery and negative cable. Be prepared for a small spark but it shouldn't amount to much - best to do this with the negative cable hanging out of the compartment in clear air just to be safe.
Every camper I've ever owned had about a 250mA - 750mA "house load" depending on what devices it had.
Draining overnight... the responses above are probably still more likely about a possibly bad battery. But I'd love to hear something more scientific / objective than "no parasitic drain". Unless they tell you they disconnected your CO2 detector and everything else, maybe they had their high school intern "check something" but nothing really got measured at all...
This is my opinionated opinion but I think no coach "emergency toolbox" is complete without a multimeter. It doesn't have to be a good one. Harbor Freight or Amazon both have $10-$20 options that would easily measure this for you. Make sure you read the instructions and configure your meter for ammeter/current mode (usually you have to change what the leads are plugged into). Disconnect your negative battery cable and with everything you can think of off in the coach, connect the meter between the battery and negative cable. Be prepared for a small spark but it shouldn't amount to much - best to do this with the negative cable hanging out of the compartment in clear air just to be safe.
Every camper I've ever owned had about a 250mA - 750mA "house load" depending on what devices it had.
“Test for parasitic drains on battery with everything off drawing .3 adc with disconnect shut off pulls 0 adc no issue found no excessive draws battery test ok recommend disconnecting fully for storage and add second battery”. This is the report from the tech. Thanks for the follow up.
CoveredWagon
Well-known member
Is you converter turned on, is it charging your battery. It converts AC to dc but also charges your battery
taskswap
Well-known member
300mA is actually enough to draw down a battery a fair bit, especially if it's small and there's only one.
A 100% charged SLA should be just under 12.7V. To get amp-hours of usage (not actually the best measure but it's what the industry uses) you do 0.3A * 12.7V and get 3.8Ah. That will change as your battery drains (because your voltage will drop - which is why this method is so coarse) but it's a good place to start. So in 24h you'd "use" a bit over 91Ah.
Even if you knock this number back a bit, that's still a lot of draw every day, and it's a lot "overnight" too if you aren't 100% charged to begin with. You don't have to have a bad battery for that to flatten one, especially if it's not that big. Bear in mind with a lead acid battery you're only supposed to "use" 50% of its rated capacity if you don't want to damage it over time, so even if it's something like 170Ah that's still enough daily draw to kill it.
There was a previous thread recommending a solar battery tender. That would help you a lot. Otherwise, even doubling up the battery is probably just going to buy you another day. If you don't have an alternate power source, you need to use your disconnect religiously.
A 100% charged SLA should be just under 12.7V. To get amp-hours of usage (not actually the best measure but it's what the industry uses) you do 0.3A * 12.7V and get 3.8Ah. That will change as your battery drains (because your voltage will drop - which is why this method is so coarse) but it's a good place to start. So in 24h you'd "use" a bit over 91Ah.
Even if you knock this number back a bit, that's still a lot of draw every day, and it's a lot "overnight" too if you aren't 100% charged to begin with. You don't have to have a bad battery for that to flatten one, especially if it's not that big. Bear in mind with a lead acid battery you're only supposed to "use" 50% of its rated capacity if you don't want to damage it over time, so even if it's something like 170Ah that's still enough daily draw to kill it.
There was a previous thread recommending a solar battery tender. That would help you a lot. Otherwise, even doubling up the battery is probably just going to buy you another day. If you don't have an alternate power source, you need to use your disconnect religiously.
Thanks for the info.
david-steph2018
Well-known member
What size is the battery? Is it a Group 27 or Group 29 or group 31.
batteryglobe.com
Read this as well
batterygroupexpert.com
Group 27 vs. Group 29 vs. Group 31 Battery – Which One Is The Best?
Need a new battery for your car, RV, camper, but unsure which one to get. This article shows you how to decide between a Group 27, Group 29, or Group 31 battery.
batteryglobe.com
Read this as well
Group 31 Battery - List of Best Deep Cycle Batteries, Dimensions, Reviews
If you need The Best Group 31 Deep Cycle Battery you should have expert opinion how to find the best battery you need
batterygroupexpert.com
Last edited:
david-steph2018
Well-known member
When you go to get new batteries, decide which one and type you required for your use. Take care going to an auto parts store, or a camper store because that person behind the keyboard might had been asking last week "You want fries with that?"
Go in well-armed with knowledge and know which battery you need.
Go in well-armed with knowledge and know which battery you need.
david-steph2018
Well-known member
Before you buy new batteries, physical measure the storage area for the batteries. As you see, Group 27 is the smallest battery compared to a Group 31, in regard to capacity/recover. It sounds like you have decided to install a 2nd battery, so consider jumping up to Group 31 if they will fit in the space. In the articles, you can see that Group 31 are more durable. but the tradeoff is in the size and weight of the batteries. In my opinion, Group 31 would be better for your requirements.
mlpeloquin
Well-known member
Never add a new battery to a battery with problems. It will drain down and ruin the new one. If you want two, get two new ones. Purchase a load tester from Harbor Freight. They are cheep.
Bogie
Well-known member
In your original post, your problem is killing the battery overnight with only the refrigerator running on LP. Your parasitic drain has been measured at 0.3 amps. I don't know which refrigerator you have, but my Dometic with aux cooling fan has a 3 amp DC fuse. So it uses something less than 3 amps when on LP gas. But let's use 3 amps to stay on the long side.
So at night you are drawing down the battery at a rate of 3.3 amps (3+ 0.3) for approximately 10 hours. Or, 30.3 amp hours.
The specification for the battery you pictured (when new) indicates your battery should be able to produce a reserve capacity of 160 min (2.7 Hrs). The industry standard for reserve capacity measurements is at 25 amps. So... 2.7 Hrs X 25 amps = 67.5 amp hours of capacity.
As an aside....This was probably the cheapest (and lowest Amp Hour) battery the dealer could have installed.
Flooded lead acid batteries become damaged when fully discharged. My personal view is never draw one down below 50%, but some use 80%.
So lets go long and say that if you draw the battery down to 80% you will have used 54 amp hours. This is still considerably less than the 30.3 amp hours necessary for overnight use. In fact only 56% of what should be available to you.
So, it is highly probable your original battery has experienced damaging sulfation and isn't capable of holding a full charge any longer. If you are interested in learning about what happens when sulfation occurs, you can read this article. https://www.power-sonic.com/blog/what-is-a-sulfated-battery-and-how-do-you-prevent-it/
My recommendation is to ditch the old battery and also add battery capacity. You can have two 12 volt batteries in parallel, or two 6 volt golf cart batteries in series (many use two Trojan T105 batteries which have 186 Amp Hour capacity). Which ever way you decide to go, I would recommend looking for batteries with higher a reserve capacity than what you have. If they don't list Amp Hour Capacity they will surely list Reserve Capacity in minutes. Just divide that number by 60 and then multiply the result by 25 amps to get Amp Hours.
Though these days I use lithium, in the past I have had both two Interstate SHM-24 batteries (81 Amp Hour each) as well as a pair of Trojan T105. In either case performance has been good.
I hope that helps.
So at night you are drawing down the battery at a rate of 3.3 amps (3+ 0.3) for approximately 10 hours. Or, 30.3 amp hours.
The specification for the battery you pictured (when new) indicates your battery should be able to produce a reserve capacity of 160 min (2.7 Hrs). The industry standard for reserve capacity measurements is at 25 amps. So... 2.7 Hrs X 25 amps = 67.5 amp hours of capacity.
As an aside....This was probably the cheapest (and lowest Amp Hour) battery the dealer could have installed.
Flooded lead acid batteries become damaged when fully discharged. My personal view is never draw one down below 50%, but some use 80%.
So lets go long and say that if you draw the battery down to 80% you will have used 54 amp hours. This is still considerably less than the 30.3 amp hours necessary for overnight use. In fact only 56% of what should be available to you.
So, it is highly probable your original battery has experienced damaging sulfation and isn't capable of holding a full charge any longer. If you are interested in learning about what happens when sulfation occurs, you can read this article. https://www.power-sonic.com/blog/what-is-a-sulfated-battery-and-how-do-you-prevent-it/
My recommendation is to ditch the old battery and also add battery capacity. You can have two 12 volt batteries in parallel, or two 6 volt golf cart batteries in series (many use two Trojan T105 batteries which have 186 Amp Hour capacity). Which ever way you decide to go, I would recommend looking for batteries with higher a reserve capacity than what you have. If they don't list Amp Hour Capacity they will surely list Reserve Capacity in minutes. Just divide that number by 60 and then multiply the result by 25 amps to get Amp Hours.
Though these days I use lithium, in the past I have had both two Interstate SHM-24 batteries (81 Amp Hour each) as well as a pair of Trojan T105. In either case performance has been good.
I hope that helps.
