Help! Battery conundrum.

[1Ricker]

Hi all. I could really use some insight as to why my batteries will fully charge but then drain rapidly. The problem emerged for the first time on my last trip 2 weeks ago, and has gotten dramatically worse on the trip I'm on right now.

I have a '19 Kodiak Cub 175BH. When I got it in November 2019 it came with a 12v lead-acid marine battery and 100 watt solar panel. I added a Quicklynks BM2 Bluetooth 4.0 monitor that always indicated we would take the battery down to about 60% (12.2v) at night, then in the morning after sun came up above mountains would recharge back to 100% in about 1-1.5 hours.

We've boondocked 6 times since getting the trailer with this kind of performance. However, on my last trip two weeks ago things went south. My first night was normal, and the following morning I recharged to 100%. But when the sun started going down my monitor said I dropped to the 60% level in just 3 hours. At that time I was running nothing but one or two lights, occassional use of the water pump, and whatever (if/any) power the fridge/freezer draws when running on propane . I was not using the stereo like the day before b/c I couldn't connect via bluetooth, although the stereo seemed to be broadcasting a bluetooth signal even though I had the unit powered off.

For the rest of that trip the same thing would happen: I'd fully recharge to 100%, but come sundown the discharge rate of the battery would accelerate/worsen.

Because of this, when I got home I purchased and installed a 2nd 12v marine deep cycle battery and wired it in parallel.

Perhaps one important note: during this process I noticed a black, sooty-like residue atop the original battery. Over-boilage?

I'm now in the middle of a five-day trip in SW CO and the situation is getting worse, even with the new 2nd battery aboard. Yesterday we left camp and batteries had hit 100%, but when we returned around 4pm (with a decent amount of daylight left, though not direct) the batteries were reported to be at 30%. By 5pm they were at 20%.

So I prepared the kids for a cold night, assuming furnace wouldn't be able to run. We turned the furnace thermometer down to about 50-55 degrees, only used headlights, and no usage of the water pump.

The weird thing is: we made it thru the night with no power issues.

Did I somehow totally fry the original battery and now it is so dead it is sucking the life out of the new battery in order for them to equalize? Or do I have some bizarro parasitic load? Do I need to replace the original battery if it is now fried? Or can I top it off with distilled water? If my theory is correct, have I now gone and torched the new 2nd battery?

We are supposed to be out for 3 more days, so I don't want to hide tail and go home. But if I'm looking at getting one or two new batteries, so be it. If I do, is it worth the $$$ to go to AGM? I can't go to lithium right now b/c it'd require a fairly involved re-wiring process.

Any guidance folks could provide would be really appreciated. I rolled the 45 minutes into town to get signal to send this as I'm quite stumped.

Thanks in advance!

[1Ricker]

I'll throw into the mix the option of moving to a two 6v system. Just got off the phone with auto parts shop in Cortez, CO that has AGM in stock, but said they think the two 6v golf cart batteries in series-option is better for travel trailers with solar. Thoughts there?

[colokb]

The only concern I would have moving to 2 6v golf cart batteries, I believe if one goes down you lose power from both.

[dsol]

I think you might have a bad battery. Can you disconnect and check with no load? They have to be disconnected or you won’t get a true test. Check the water levels too. You might have boiled some water out or even have a bad cell. One bad cell in one battery and you are finished. The best way to really test is with a hydrometer ( I think that is what it is called) that measures the gravity of the water/acid and will relatively easily confirm a bad cell.

You shouldn’t need to enhance or upgrade especially since you had good history. It would be different if from day one you couldn’t go long enough between charges but you could.

If it is bad and you have to replace I would suggest you consider AGM but I wouldn’t do that yet if I was you as might not be necessary. Check the battery and be real careful dealing with battery acid and make sure to clean the tops well before opening as you don’t want dirt and dust getting in there.

Good luck.

[franktafl]

I may be wrong but I don't believe a 100 watt solar charger will recharge your batteries to 100% when you have a drain during the day with whatever vampire loads you have on during that time. Hopefully Persistent will be along shortly with the full technical explanation.

[CSCLARK]

To start with you connected the 2nd battery to the percieved bad battery in a 12 volt circuit it will suck the new battery down to its level. When you replace FLA batteries, you have to replace all at the same time and same type. You probably inadvertently killed both now.

If you do a lot of boondocking and plan on keeping your rig I would suggest you consider lithium as they are the best for the money, long term and you can add anytime within about the first year. Yes, expensive but with no maintenance full 100% usage and add on capable it's a great option.

As for the 100 watt solar, no way it charged your batteries to 100% in 1 or 2 or 4 hours from 60%, especially if there was any draw whatsoever.

If you are still out I would consider disconnecting the older battery and see what you get with 1 new one as it will probably get you through the end of your trip. Good luck, keep us posted.

[persistent]

“I could really use some insight as to why my batteries will fully charge but then drain rapidly. The problem emerged for the first time on my last trip 2 weeks ago, and has gotten dramatically worse on the trip I'm on right now.”

Possible reasons:
Battery has deteriorated and no longer has the same capacity.
Solar charging hours have decreased during fall season.
Other issues that decrease solar power generated like weather or shade.

“I have a '19 Kodiak Cub 175BH. When I got it in November 2019 it came with a 12v lead-acid marine battery and 100 watt solar panel. I added a Quicklynks BM2 Bluetooth 4.0 monitor that always indicated we would take the battery down to about 60% (12.2v) at night, then in the morning after sun came up above mountains would recharge back to 100% in about 1-1.5 hours.”

How many amp hours is the 12v marine battery rated for? I have two group 31 AGM batteries in my Cub that are 100 amp hours apiece. Your single may be 60 amp hours.

A 100 watt solar panel with a high quality solar controller will make approximately 8 amps for 5 about hours. That is 41 amp hours or 60% charge. So if your battery bank is down to 10% state of charge, the panel will bring it up to about 70% in one summer solar day.

I don’t know anything about a “Quicklynks BM2 Bluetooth 4.0 monitor ‘. It would be typical for a voltage based monitor to quickly show 100% when charging. Mine does. That does not mean the battery is charged to 100% state of charge.

Batteries basically have three voltage profiles. They are: Charging, Static, and Discharging. My state of charge meter is only accurate for Static. Static is when not discharging and not charging for a few hours.

The discharging profile is always lower than the static voltage for the same state of charge. The greater the power draw, the lower the voltage.

Charging voltage depends on the battery bank and charger combination. It always reads a higher voltage than static voltage for the same state of charge.

“We've boondocked 6 times since getting the trailer with this kind of performance. However, on my last trip two weeks ago things went south. My first night was normal, and the following morning I recharged to 100%. “
This behavior is typical for a charging profile using a voltage based monitor. It does not mean batteries are fully charged. As stated above, you may be at 70% at the end of the solar day.
But when the sun started going down my monitor said I dropped to the 60% level in just 3 hours. “


This is typical behavior when the charger stops charging. Voltage will drop to static level in as little as 30 minutes. The greater the power consumption, the quicker is will drop.

“Perhaps one important note: during this process I noticed a black, sooty-like residue atop the original battery. Over-boilage?”

This is typical accumulation when using a flooded cell type lead acid battery.

“I'm now in the middle of a five-day trip in SW CO and the situation is getting worse, even with the new 2nd battery aboard. Yesterday we left camp and batteries had hit 100%, but when we returned around 4pm (with a decent amount of daylight left, though not direct) the batteries were reported to be at 30%. By 5pm they were at 20%.”

I can’t say for sure, but this is likely behavior if you doubled your battery bank size. The solar panel is still generating 41 amp hours more or less. The charge is now split between the two batteries. Where you saw 60% before, you should now see 30% now. You would need to also double your solar power to get to 60%.

“The weird thing is: we made it thru the night with no power issues. “

This is also expected. You still have the same amount of power provided by the solar panel. It is just split between the two batteries.

“Did I somehow totally fry the original battery and now it is so dead it is sucking the life out of the new battery in order for them to equalize? Or do I have some bizarro parasitic load? Do I need to replace the original battery if it is now fried? Or can I top it off with distilled water? If my theory is correct, have I now gone and torched the new 2nd battery?”

You have probably not damaged the batteries. It takes 14 to 18 hours to do a full clean charge of any lead acid batteries. You should always store lead acid batteries fully charged. So it would take your solar charger three days in full sun with no appliance use to fully charge the battery. It would probably take your converter/charger no more than 18 hours connected to shore power. Your tow vehicle may also provide charge although it is unlikely you drove for 18 hours without using 12 volt appliances.

Storing below full charge will decrease storage capacity. The lower the storage voltage, the faster it will lose capacity. Did you store at full charge?

“We are supposed to be out for 3 more days, so I don't want to hide tail and go home. But if I'm looking at getting one or two new batteries, so be it. If I do, is it worth the $$$ to go to AGM? I can't go to lithium right now b/c it'd require a fairly involved re-wiring process.

Any guidance folks could provide would be really appreciated. I rolled the 45 minutes into town to get signal to send this as I'm quite stumped.”

Adding storage capacity will not help until you increase your charging capacity. You could add a second solar panel and larger solar power controller.

You could add a small gasoline generator (maybe 1000 to 2000 watts). Run the generator for 2 hours in the morning. It will power your built in converter/charger and probably add about 40 amp hours before the solar starts working hard.

I wish you good luck and happy trails ahead!

[kjlarson]

Persistent is right on. I installed three 100ah AGM batteries and a 2000 watt inverter as I draw a lot of power out of my batteries during the day. Coffee pot, toaster, microwave. Don't like running the generator all day, quiet and peaceful in the boondocks so I run off the batteries as much as possible. Each morning I power up my 1600 watt iPower generator which recharges the batteries in about 3 hours using the stock WFCO 55ah charger. Don't have solar yet, next year budget item. I strongly suggest that you upgrade the batteries to AGM; no maintenance and they last longer. Good luck with fixing your issues and happy camping.

[swixelann]

Since the problems first occurred two weeks ago and has progressed, don't overlook the obvious. Check any battery cables that run near framework.
I spent two days chasing an issue only to find the insulation on a battery cable had rubbed on the frame and finally wore through the insulation.
If cable insulation fails, leakage to ground can get ugly quickly.
Best of luck

Tow Vehicle: 2004 GMC 8.1L
RV: Dutchman 29RK

[rich2481]

I would guess,, that if your solar panel says 100 watts on it, that is a perfect world, perfect sun angle through out the day etc,,, a simple DMM ( digital multimeter) would tell you the voltage out of a panel, out of the controller and into the batteries,,

[Marv]

Your first mistake is using a battery monitor that is based on voltage readings. Voltage readings are very, very poor indicators of a battery’s state of charge. Your second mistake is not understanding how lead acid batteries are recharged. Meaning, knowing the various modes of recharging which I see someone else already explained. My suggestion is to do two things.
First get a shunt based battery monitor so you will know the true battery state of charge. Secondly, use a multi-stage charger to recharge your batteries.

[kimbo@alum.mit.edu]

I use jumper cables to charge in an emergency from my truck to the trailer battery. Let it charge for a hour or so. Those 7 pin connectors do a poor job of charging the trailer battery because the vehicle wire is small and new vehicles don't always put out full voltage from the alternator when running. With a new battery you should be able to easily last overnight using just LED lighting, occasion water pump, propane fridge, propane HW and heat. A 100 watt panel will give a max of 8 amp charging current.
I use a DC amp clamp meter to run down leakage current fast.