Signs of Aging Batteries?

manyman297

We have a 2021 400 that's 2 1/2 years old.

This year we haven't done as much camping as we'd liked to. The first trip we took was for a week and always connected to shore power. The subsequent three trips we've taken have all been boon docking trips and I'm noticing the batteries don't hold up like they used to. 

By that I mean that they seem to drain faster than usual. Voltage wise they look healthy and can charge to 100% but it seems like we burn through 25% of the capacity within a day. I've never that aware about how much power we used prior but I definitely don't remember draining them to that degree within a 24-hour period. 

Because of that I've also wondered about the solar panels and if something could be wrong with them. I don't know that much about solar other than sunny days are best, the angle of the sun is important, etc. In my Victron app it shows that I'm getting the max wattage from the panels at times although it's VERY rare that I actually get that. 

At any rate, what are some telltale signs that the batteries are aging? Ideally it's the batteries and this gives me the excuse to upgrade to lithium. Worst case scenario is that something is wrong with the solar panels but I don't think that's the case. 

ScottG

Even though a battery will still take a charge, what you describe (faster discharging) is absolutely a sign that it is aging. Another subtle symptom is that the voltage at which the battery stabilizes a day or so after charging gets incrementally lower. For example, a new battery may "settle in" at 12.8V and hold that voltage for days, while after a couples years of use that resting voltage may be only 12.7V. It doesn't mean the battery is no good, but it is certainly not as good as it was when it was new.

If you keep milking all the life you can out of it, eventually a cell will fail and the battery will no longer take or hold a full charge.

The electrolyte in regular lead acid batteries (the type with removable caps that require you to add water) can actually be tested with a hydrometer or refractometer. That can be a good way to spot a cell that is declining more that the others. However, I think 400s are all equipped with sealed batteries.

Grumpy_G

2 1/2 years of frequent use can degrade lead-acid batteries but it sounds the trailer was only out a few times. How many days do you estimate you camped without shore power ? 

Your trailer should have the setup with 2 6V golf cart batteries which have over 200Ah of capacity, how did you determine you're using 25% of that in a day ? 

manyman297

Thanks @ScottG. I'll need to keep a closer eye on the resting voltage. For some reason my Victron historic data only goes back to August.

@Grumpy_G On average the trailer sees maybe 20 nights of use per year so far. So at this point we're maybe at 50-60 nights of use total. So it doesn't see a ton of use. We rarely are connected to shore power. We just had a week-long trip in July where we were always on shore power.

I was able to determine the use by using the Victron app for the shunt. In the "trends" section I looked at the % of charge.

Marceline

manyman297 said:

Thanks @ScottG. I'll need to keep a closer eye on the resting voltage. For some reason my Victron historic data only goes back to August.

@Grumpy_G On average the trailer sees maybe 20 nights of use per year so far. So at this point we're maybe at 50-60 nights of use total. So it doesn't see a ton of use. We rarely are connected to shore power. We just had a week-long trip in July where we were always on shore power.

I was able to determine the use by using the Victron app for the shunt. In the "trends" section I looked at the % of charge.

If you haven't been monitoring the shunt in the past it's going to be hard to make an apples-to-apples comparison. But you might want to keep a closer eye to see how many amps are going in and out of the batteries going forward. It could be that you're just not putting as much back in the battery because the weather hasn't been as nice as it was for some of your trips in the past.

I seem to recall that you have a 2-way fridge. Are you using it? If so, are you cooling it on shore power before you leave home and putting only cold stuff into it? How much is the compressor running? It's easy to draw down a lot of power if you don't start with a cold fridge.

manyman297

I do have the two-way. I need some hard data to really figure out what’s going on. I feel it’s either my batteries are aging or something is going on with the solar panel. But it does feel like the battery discharges faster than usual…but if the panel is defective it also might feel the same way since the panel isn’t producing the same amount of power.

pthomas745

You have a 400 with the dual 6v batteries, that have "about" 135 amp hours available.  Your 2 way fridge might use, on a good day, 30 amp hours, and the rest of your trailer would use up about 10-15 more.  45 amp hours would account for about 25 percent of your battery amp hours. 

If your solar isn't picking up the pace, you should watch that closely.  You should be able to see the solar putting in "positive" current via the Victron SmartController display.

And, another reminder: you should not take a voltage readout as "reasonably accurate" unless the battery switch is off, and no solar/shore power charging coming into the battery.

manyman297

Another thing I should mention is that around 60% of battery I started noticing the LED would just slightly flicker when the fridge compressor would kick on. And when I went to use the water pump the lights would noticeably flicker while it ran. Is this normal as the battery voltage reaches 50% capacity? 

And would this same thing happen on an lithium battery nearing 50% capacity?

AnOldUR

The voltage drop during discharge is one of the big advantages to lithium.

(edit to say that I mistakenly grabbed a lithium-ion chart, not LiFePO4, but the comparison is still valid)

Marceline

manyman297 said:

Another thing I should mention is that around 60% of battery I started noticing the LED would just slightly flicker when the fridge compressor would kick on. And when I went to use the water pump the lights would noticeably flicker while it ran. Is this normal as the battery voltage reaches 50% capacity? 

And would this same thing happen on a lithium battery nearing 50% capacity?

With my lithium battery, there’s a point where my lights still work but the fridge compressor won’t run. I don’t have the exact SOC for that, but it’s pretty low. Maybe 25-30%. If it ever happens again (which of course I try to avoid) I’ll try to mark it. 

manyman297

Thanks @AnOldUR and @Marceline

That chart makes perfect sense. I remember our old tent trailer's lights would start to pulse when the water pump would come on as the battery voltage dropped...so I assume I'm seeing the same thing here. 

Well, once I rule out the solar panels as the culprit then I guess I'll start saving some money to get lithium next spring. 200Ah would be perfect for our setup. 

Marceline

@manyman297 before you give up on your batteries- are you initially cooling the fridge on shore power? 

d_v

If you want a set of stock 6v to hold you over I am selling mine. They are from a 2021 400 as well but are holding 6.47v each and they have been off the charger for 3 weeks.

manyman297

@Marceline So I normally cool it maybe an hour before we leave...not on shore power but almost always the solar panels are helping out (doesn't take too much sun to make up for the 45w-ish draw from the fridge.

@d_v Thank you for the offer but we're just about done for this season. I think I'll do some testing of these batteries over the winter and then make a decision. If they are indeed aging then I think the obvious choice is 200ah of lithium. That would give us almost double the usable amp hours and based on the voltage drop-off that lead acid gives, we wouldn't be dealing with flickering lights and possibly having the fridge shut down. 

I was such a proponent of AGM batteries for "light duty" campers like us (mainly weekend warriors with the occasional week-long trip) but I'm starting to see the light when it comes to lithium. Having 224AH of AGM stock sounds like plenty but the 112AH of usable power AND the voltage drop off really can cause problems even on a weekend trip.

AnOldUR

manyman297 said:

Having 224AH of AGM stock sounds like plenty but the 112AH of usable power AND the voltage drop off really can cause problems even on a weekend trip.

You're echoing the voices in my head last year. We had 250Ah of AGM before switching to lithium earlier this year. My final justification was that I could use the aging AGM's as backup power for my sump pump (at least that's what I told myself ).

Marceline

@manyman297

I think that before you give up on the batteries you should try pre-cooling the fridge from shore power well before you leave (12+ hours). Especially if the ambient temperature is 75degrees or higher, it takes a considerable amount of power to get the fridge down to 40deg. People really underestimate this. This would go a long way toward explaining why you're burning through "25% of the capacity within a day."

When I've been in a situation in which I can't pre-cool the fridge from shore power, I've put a couple of pounds of dry ice in the fridge for the drive to wherever I'm going. I keep the food in a cooler for the drive. I use a bluetooth temperature monitor so I can constantly monitor the fridge temp. It takes a heck of a lot longer than one hour for the fridge to get down to 40 on a hot summer day.

Even if you switch to lithium batteries you're still going to be drawing down a considerable amount of their capacity on the first day if you don't pre-chill the fridge. So you'd still be starting your trip with a big power deficit. 

manyman297

@AnOldUR I'm trying to do the same thing....where can I use these 6v batteries? I bet I can find a use for them. 

@Marceline I agree that I should pre-cool the fridge earlier. But I guess that's the issue...with nothing in my prep changing I'm seeing the battery discharge faster than normal. I have a BT temp monitor I use in the fridge and yes, that fridge can run all day if it's 90+ outside. But this last weekend was in the low 80s and down to the 40s at night. So theoretically it should be using less power but I'm seeing it discharge faster. 

ColoradoJon

If you have the dual 6V battery setup then you have at least 200AH battery power.  2 1/2 years on a dual 6V setup is not long at all.  Those batteries should last you six years if they are a decent brand.  Sure, they are maturing, but if you have been taking care of them they should continue to provide plenty of power for many more years to come.  I have two Deka 6V batteries in my 320 that have been there since 2016.  Almost 7 years, and they are still going strong.

You are most likely using more power than you think you are, and it is most likely the fridge.  The fridge is where most unaccounted for power usage lies as it is difficult to quantify.  Anecdotal evidence notwithstanding.

MarkAl

I've 2 6V that have about 3 yrs on them with multiple discharges to about 70% so I figure I've got a year or so left at least. The biggest problem I have and do not understand why it's not talked about more is slow charging to properly top off the batteries.

With my 30 amp dc-dc car + 100 watt (7 amp) solar if using lithiums I'd be charging at 37 amps almost to full charge. With lead/acid, I'm lucky at 80% to get 7 amps and it goes down as I get closer to 100%. Yeah charges much higher at 50% but then slows.  When adding 2 remote panels in full sun I still need a lot of time to recharge because the Victron does pull the max capacity. Deeper safe discharge and quicker charging are my primary reasons to change to lithium. They'll be moved inside making wiring easier and warmer when using. Thoughts? Am I not understanding this correctly? 

manyman297

@MarkAl This has been something I noticed on a trip this summer where I was using the generator for AC several days. I’ve never used the generator to top off my batteries and assumed it would happen fairly quickly. What I saw was maybe 230w or so being pushed to the batteries and a very slow “fill up” happening. I was using a 2200w generator. AC used maybe 900-1100 watts so I had plenty of power remaining but I’m guessing the converter regulates the charge? 

MarkAl

Yes, my issue is with limited time before needing full capacity. I need them full... "make hay while the sun shines".

manyman297

I wish I would’ve been more mindful of collecting data before I noticed the issue. I feel like my batteries would recharge back to full within a day’s worth of sun. Now it seems like I maybe get back to 85-90% with a day’s charge. I realize it’s all dependent on cloud, angle, etc. but this is just anecdotal information.

Hammick

If lead acid batteries aren't kept at 100% SOC the majority of the time don't expect them to last more than 2 - 3 years.  Make sure your replacement batteries are LifeP04.  Storing them a 50% is ideal.  Storing them at 100% shortens their life.  Completely opposite of lead acid.

justdoit70

A lot of talk here.A little off topic but please answer this question. 21 400 boondock .when camping always on shore power  at home always plugged in  and in the barn. Is this bad for the Harris 6 volt Battery's ? Thanks

pthomas745

No.

justdoit70

pthomas745  Thanks for the reply