Battery Question

Yoshi_TAB

Hello Battery Gurus,

Looking for some input.  We gave a 2021 TAB 320S with stock  solar.  We have had it for about 18 months.  We have taken it  on many long weekend campouts along with a 8000 mile journey over 8 weeks this past spring.  We have a pretty good understanding of how things work, battery management etc.  90% of our trips have had shore power.

Next spring, we are planning another long trip with more (50%)  stays w/o shore power.  I'm looking for your  thoughts from those who have dry camped more than us about our battery situation.  When we bought our TAB, I did not understand the relationship between batteries and power usage.  Our dealer offered many battery options.  I chose  the option of two flooded batteries, one with 80 AH (their standard install) along with a group 31 flooded battery with 105 AH.

I do now understand that you do not allow wet cell batteries to be discharged below 50% ,  if  I'm able to keep my drain to above 50% and my batteries charged, I will always have about 92 ah of usable power.

I'm debating whether to upgrade to a 100 ah lithium or just keep what I have?   I do understand that with the lithium, I will not have to worry about going below the 50%, which I can see as a huge plus.

Thank you

Marceline

My first impression is that it's weird to have mismatched batteries. But if they're working, theoretically you would have just a little less usable capacity with them as you would with a 100ah lithium battery. If it were me, I would stick with the current batteries until they're wrecked and then make the switch. I'd install a Victron SmartShunt to accurately track power use.

dragonsdofly

@Yoshi_TAB if upgrading to a 100 ah LiFePO battery, you can discharge it 90%, using about 90 ah of power, which is essentially what you have available with your current set up. Not much gain there. However, a LiFePO battery has a much longer expected life and many more charging cycles available before it becomes necessary to replace. Also, we are speaking about LiFePO batteries. There are also LiOn batteries (Lithium Ion) available, so be specific about which you are referencing.

I can tell you that a good LiFePO system works flawlessly, nearly endlessly and provides worry free power. I am at this moment enjoying an autumn day in Michigan in our 30' Keystone Laredo travel trailer with a total solar set up. We have 1.4 k of monocrystalline on the roof, 2 50 amp charge controllers, 3,000 watt pure sine wave inverter and 600 ah of heated Battleborn batteries. The system is monitored by a Victron smart shunt with a Victron cerbo screen display and control panel. Installed in January of 2021, this system has never had a moment off. We have full timed since December of 2021 and have not had a moment of worry. Even in Michigan at this time of year we are at 100% SOC with only a few hours of angled sun. I feel this is a perfectly sized system for our needs. We have never plugged this trailer into shore power. It manages and monitors itself although it is capable of shore power connection.

Our t@b 320 S has a group 31, 110 ah wet cell battery. We can usually keep the battery charged using our 80 watt Zamp suitcase. Every 3/4 years it is time for a battery replacement. Not so flexible or as easily managed as the LiFePO system. And certainly not as capable, yet very doable for a t@b.
 
What do you hope to gain? Ease of use or  maintenance? Length of life? As previously explained, you will have no greater power availability. This is all dependent on your camping style and "hands on"  preferences.

Any questions? -Denise

Yoshi_TAB

Thank you for the answers. 

@Marceline Re: Mismatch; My dealer had about 6 options for batteries, the one I selected  was one of the choices.  It had the most Ah for wet cell batteries for an under $200 extra cost.  Not knowing how we would use our TAB, I selected it.

@dragonsdofly RE: What do I hope to gain?  I was just looking to others to help me confirm  my logic for the Ah was correct.  

I think I'll keep what I have until I know for sure my current set up no longer meets my needs or won't work, understanding the more maintenance  and headaches with the wet cell.  I may add a portable solar panel to help my chances of keeping the batteries charged.

dragonsdofly

@Yoshi_TAB adding a portable panel would be the most logical and probably most economical bang for your buck at the moment with regards to extending the life and usability of your battery bank. 

@Marceline you are correct about the unusual battery mismatch. I also wondered about that being a proverbial battery bank no-no.

rcuomo

Just replaced my second battery with Renogy LiFePO4 100AH battery connected to my 1500w inverter. Using 100w Renogy suitcase to recharge. Just finished 4 day trip in Montauk using new battery to power 12v portable Bodega fridge/freezer full time, CPAP during night and various charging cubes. Never dropped below 85% and fully charged during day in less than 4 hours. Huge improvement over the previous 80AH RV battery. Will replace ‘house’ battery when it starts to degrade with same battery and upgrade WFCO converter to charge LiFePO4 battery. 

WayneW

@Yoshi_TAB  we upgraded to a 100 ah Ampere Time lithium battery ($380) in our 2021 320 last year. We also have a 100 w Renogy solar suitcase ($270) in addition to the rooftop solar, a Victron Battery Sense ($40) to disable cold temp charging from the rooftop solar and an AiLi battery monitor ($40). We are very happy with this setup and just got back from an 11 day boondocking trip w no problems. A few things to consider:

Is your converter lithium capable? For your year, some were and some were not. Not a big deal, but good to know. Our is not, therefore it will only charge our lithium to about 85% or so. We bought a Victron battery charger to top it off at home. 

If you go lithium, you will need to change the battery setting in your Victron solar controller. Pretty easy to do. 

Lithiums cannot be charged if the battery gets below freezing. Depending on when/where you camp this may not be an issue. Some lithiums have a battery management system that disables low temp charging while others do not. Ours does not. The Battery Sense addresses this. 

For shorter dry camping the portable suitcase is probably not needed but for longer stays it is invaluable. A monitor of some sort, either the cheaper ones like ours or better ones like the Victron w Bluetooth, is quite important. You need to know where you’re at as far as available amp hours and it’s hard to do w/o a battery monitor. 

There are many advantages to lithium. They are lighter, can be pulled down to 10% or so and last much longer than a wet cell.  Cost has come down. We are glad we made the change. There are many options out there. We took a lower budget approach but you can get fancier. 

I hope this helps. 

AnOldUR

Admittedly a dumb question, but out of curiosity, are you sure you have flooded batteries and not AGM?

Yoshi_TAB

AnOldUR said:

Admittedly a dumb question, but out of curiosity, are you sure you have flooded batteries and not AGM?

Yes, 100%.

Thank you for everyones input.  It was very helpful.

MarkAl

For both @Yoshi_TAB and @dragonsdofly when discussing what size battery and charging work, it's important to understand the year and type of the trailer and the current draw. Denise is fine with her 2017 because the propane fridge takes little power and the remote panel can be set up for available sun. But the 2021 and on have a compressor fridge which (I've found) takes about 30 AmpHr a day. An 80 watt panel will be difficult unless in constant sun to keep ahead of the discharge. 80 watt probably at best is about 4 Amps(Hr) so this best case may return over 5 hrs or 20 AmpHr of charge. I know 5Hrs(?) but it's hard to achieve more unless you play with the panels all day. I assume your 2021 has the solar option but I've rarely found that enough as it's usually shaded or pointing the wrong way. It's good to have, but not sufficient in most situations to rely on. All the responses here come from good people with good information just remember the best solar management is useless in woods and rain.