Lithium battery???

[MiniMe-TMO]

I have a 2010 TrailMini 18L. We need to replace the lead batteries and I'd prefer to get something where they can still be charged/topped off during storage with the shore power cable so that I don't have to pull the trailer out/open it to refill the water in the battery (read: maintenance free). I considered the sealed/gel type battery, but has anyone used a lithium RV battery? Pros/cons? What brand do you have?

Also, I noticed the lithiums are quite pricey, but if they perform better/last longer then it might be worth the cost?

Thanks!

 

[Bill]

Just as another thought, you might consider a battery maintainer. Note that this is not the same as a "trickle charger", which is something to be avoided. You would need to disconnect the TM battery from the TM connections, and connect it to the maintainer's small cable. The maintainer can be mounted inside or outside the TM, as is most convenient for your situation. I don't think it is rain-proof, though.

The most important thing is that you do not leave the TM's built-in charger powered up and connected to the TM battery. Over a relatively long period of time, this does not work despite the advertising.

Among battery maintainers, I've had good luck with a Battery Tenda (aka Battery Tender). I bought the smallest one - 0.75 amp - and it is quite adequate provided you start with a fully charged battery. If you can't start with a fully charged battery, you might step up to the 1.5 amp version, but nothing higher is necessary. The 1.5 amp version will slowly bring your battery to full charge, and hold it there.

There are number of other battery tenders on the market that also produce good results. They have been discussed at some length here on the Forum. Use the search tool to find the discussions.

Bill

 

[MiniMe-TMO]

Bill,

When you say the TM's built-in charger, are you talking about that T-handle knob that disconnects power from the battery and the outlets/appliances inside? When we recharge the batteries, we engage the T-handle so the batteries are "connected", and then plug it into shore power only for a day or two before unplugging it. We never leave it just plugged in otherwise and we disengage the T-handle to prevent phantom power drainage from the batteries. This is how the dealer told us to do it, but I just need a maintenance free battery.

Thanks!

 

[Bill]

I'm not familiar with the T-handle - apparently Minis have a somewhat different configuration. My bottom-line take-away is that for long-term storage (more than a week, maybe) do not leave the battery connected to anything in the trailer. Not the charger, not the load panel - nothing. From your description, the T-handle sounds like it accomplishes this, but I just don't know. To be sure about it, I would simply pull the cable off the battery's positive post. Once the battery is completely disconnected, you can attach the maintainer cables directly to the battery posts (assuming a maintainer is your choice of approaches).

Bill

 

[Larryjb-HILO]

Here's an interesting option. I'm not sure if anyone here has tried it, although I remember there was a discussion about the LiFePO4 batteries, which these are.

 

[Bill]

Now that is really interesting, Larry. I never thought of it or heard of it. If you can get actual medical-device batteries, they should be good for the purpose, and not beat to death.

Please straighten me out on one point. Each battery in the video had two black cables hanging out, and the guy just plugged them together. At first I thought these were the battery power cables, and he was connecting the batteries in series. But as the video went on, it became apparent that they are not power cables. Are they control cables that synchronize the Battery Management Systems built into each battery? oes every ium battery have one of these?

Bill

 

[MiniMe-TMO]

It is very interesting. I work in a hospital and will see if the engineering guys can hook me up with a couple . They look to be about the same size as the two 6V flooded lead acid ones the dealer sold me a few years ago.

and I just looked up their website: https://lithiumwerks.com/valence-batteries/standard-modules/rt-modules/

 

[Larryjb-HILO]

It is very interesting. I work in a hospital and will see if the engineering guys can hook me up with a couple . They look to be about the same size as the two 6V flooded lead acid ones the dealer sold me a few years ago.

and I just looked up their website: https://lithiumwerks.com/valence-batteries/standard-modules/rt-modules/

You LUCKY son of a gun!

 

[rickst29]

I use LiFePO4.

Your main consideration with LiFePO4 is the going to be the fact that they shouldn't be charged when temperatures are low (near or below freezing). OTOH, if you fully disconnect the batteries from the TM phantom loads, they WILL last the entire winter (with no need to re-charge).

"lithiumwerks" is selling a small battery pack at the wrong Voltage (25.6V, 25Ah). A bigger so-called "12V" battery, actually 12.8V, would be more appropriate and cost less.

 

[btheo_TrailMini]

Not sure if this is relevant, but I've been overhauling my Mini, moving to Lithium. (200ah Lifepo4). It is definitely a different beast, with pro's and cons. You won't be able to use the existing Powermaster system, as it doesn't handle the charge voltage and cutoffs correctly. (You'll damage the battery.) In my case I rewired from the ground up, (as part of a bigger system that integrates Solar and a 50A feed from the car's alternator.) You'll also need to make some small adjustments to be on Lithium's slightly higher voltage as well, like a 12v converter to your propane detector, which maxes as 12.5v. Though other things like the fridge actually run better on the higher voltage. Happy to elaborate as needed.

 

[Hotdam]

Not sure if this is relevant, but I've been overhauling my Mini, moving to Lithium. (200ah Lifepo4). It is definitely a different beast, with pro's and cons. You won't be able to use the existing Powermaster system, as it doesn't handle the charge voltage and cutoffs correctly. (You'll damage the battery.) In my case I rewired from the ground up, (as part of a bigger system that integrates Solar and a 50A feed from the car's alternator.) You'll also need to make some small adjustments to be on Lithium's slightly higher voltage as well, like a 12v converter to your propane detector, which maxes as 12.5v. Though other things like the fridge actually run better on the higher voltage. Happy to elaborate as needed.

Btheo - yes, please elaborate! I purchased a 200 AHr LiPO4 battery for my 2720 thinking that I could simply drop it in and switch the jumper on my newer, lithium-capable converter. Then I decided to add solar and an inverter. Been researching for a while now, and may have a case of ‘analysis paralysis’.
My understanding is that a fully-charged lead acid produces about 12.9V, LiPO4 tops out about 13.8. You’re saying that the propane detector is sensitive about its supplied voltage? How did you address this? (Not sure what you mean by “12v converter”) Any other components you found sensitive?

 

[btheo_TrailMini]

Btheo - yes, please elaborate! I purchased a 200 AHr LiPO4 battery for my 2720 thinking that I could simply drop it in and switch the jumper on my newer, lithium-capable converter. Then I decided to add solar and an inverter. Been researching for a while now, and may have a case of ‘analysis paralysis’.
My understanding is that a fully-charged lead acid produces about 12.9V, LiPO4 tops out about 13.8. You’re saying that the propane detector is sensitive about its supplied voltage? How did you address this? (Not sure what you mean by “12v converter”) Any other components you found sensitive?

Sorry I meant a DC 12v stabilizer…
For example:

DC-DC Stabilizer, DROK 9V-36V to 12V

Boost Buck Converter 5A 60W Waterproof Auto Step Up Down Voltage Regulator 12V Volt Transformer for Car Audio Solar Power System LCD Television LED Display Screen [URL deleted].

On mine, the propane detector was the only intolerant component. The fridge is actually much happier with the higher voltage.

I actually suspect that PowerMax now makes a Li version of the main system. Though if you’re also wiring for solar, there is likely more complexity in your diagram than the powermax will do.

In my case I’m using a Renogy 50 dual to handle all DC power sources, a Victron smart 30A IP22 to handle AC to DC shore charging,, a renogy 2000w pure sine inverter for AC on battery, and a cheap manual rotary switch to handle shore power to battery power changeover.

Hope that helps.
B

 

[rickst29]

resurrecting a 2-year old Thread ...

Not sure if this is relevant, but I've been overhauling my Mini, moving to Lithium. (200ah Lifepo4). It is definitely a different beast, with pro's and cons. You won't be able to use the existing Powermaster system, as it doesn't handle the charge voltage and cutoffs correctly. (You'll damage the battery.) In my case I rewired from the ground up, (as part of a bigger system that integrates Solar and a 50A feed from the car's alternator.) You'll also need to make some small adjustments to be on Lithium's slightly higher voltage as well, like a 12v converter to your propane detector, which maxes as 12.5v. Though other things like the fridge actually run better on the higher voltage. Happy to elaborate as needed.

I am familiar with "PowerMaster" as a manufacturer of auto and truck Starters and Alternators, but I didn't know that TM ever used a manufacturer other than WFCO (newer models) or Parallax (most models of 2006, and all earlier models in earlier years).

My own propane detector unit is an after market replacement, and I chose one with a higher voltage limit. The maximum operating voltage in my DC system is 14.2v, during short periods of "bulk" charging. My "float" charging voltage is 13.6v, and my converter switches into "storage mode" 13.2 volts after about 2 weeks of idle time. (There appears to be a bug in the microcode of that Converter: Even under load and reduced battery voltage, it stays in "storage mode" voltage unless I use the Charge Wizard override button to explicity choose a different mode.)

Unless you have replaced the OEM-supplied bargman cable and rewired your TV, the wires along the path for the "Trailer Battery Charge" circuit might be too small to support 50A without overheating.

In my own Tow Vehicle (an old 4Runner), I heavily modified the simple "TV Battery Charge" circuit (formerly a simple fuse followed by wires no larger than 14-AWG) to convert from engine compartment voltage to36.0 volts under the control of a dashboard switch. That provides power to the TM (through an MPPT solar controller) with only 1/3 as much current occurring on the long wire path.

In recognition of the limited current handling within the TM's bargman power cord, I replaced the 30A fuse on the circuit to be only 15A. That lower limit applies to both the default "engine compartment" Voltage setting and the high-voltage alternate switched circuit. At the MPPT, I further limit maximum output current to only 30A, yielding a maximum of slightly more than 400 Watts into my LFP battery string under the high-voltage option.

 

[rickst29]

Btheo - yes, please elaborate! I purchased a 200 AHr LiPO4 battery for my 2720 thinking that I could simply drop it in and switch the jumper on my newer, lithium-capable converter. Then I decided to add solar and an inverter. Been researching for a while now, and may have a case of ‘analysis paralysis’.
My understanding is that a fully-charged lead acid produces about 12.9V, LiPO4 tops out about 13.8. You’re saying that the propane detector is sensitive about its supplied voltage? How did you address this? (Not sure what you mean by “12v converter”) Any other components you found sensitive?

I will assume that you meant "LiFePO4", and I will refer to that as an "LFP battery pack.

Many "Lithium Capable Converters" are programmed to run at a single high voltage all the time, that fixed voltage value can be as much as 14.6 volts. In many cases, that will cause the built-in "Battery Management System" of a packaged "12v" to shut down charging and maybe discharging as well, due to reaching or exceeding over-voltage limits.

Correct charging of a "12v" LFP battery pack should be done in two stages. In the initial "Boost/Bulk" mode stage, there is no appreciable advantage in charging above a maximum voltage of 14.4V, and most experts use values of 14.2 Volts and lower (3.55 volts per cell). Many experts never use a "bulk" stage at all, instead floating at 13.7 volts (and even lower values) at all times. But these experts all have access to control parameters of their BMS units, and they make sure that "balancing" is initiated at a lower voltage. And, while providing a charging voltage of 13.7 volts, most will prevent charge current from being accepted after the highest cell within the pack reaches 3.50 volts , allowing only "balancing" to occur after that limit is reached.

When the "12v" battery pack reaches about 13.5 volts, the BMS should have already starting a process to balance the voltage among the 4 individual cells inside. The battery pack (per attached chart) is already above 99% State-of-Charge. Charging the cells to still-higher voltage provides you with almost no additional usable power, but tends to cause significant damage within the cells.

In my expert option, "Lithium-Capable" Converters which present Constant Voltage above 14.2 Volts are horrible products, which will tend to greatly damage the lifespan of the cells being charged at abusive voltage levels. My own power converter is such a model, I resolved the problem by setting the DP jumpers into the positions specified for "AGM batteries". That setting critically avoids high voltage "equalization" cycles, and also provides for nearly correct values "boost/bulk" and "float".

IMO, your LFP battery pack should never be charged to reach a balanced voltage above 13.5 volts. If your BMS is configurable from a bluetooth connection, I can advise you on its paramter settings.

 

[btheo_TrailMini]

Hey Rickst, Lots of good stuff in here, thanks, so breaking it up..

I am familiar with "PowerMaster" as a manufacturer of auto and truck Starters and Alternators, but I didn't know that TM ever used a manufacturer other than WFCO (newer models) or Parallax (most models of 2006, and all earlier models in earlier years).

I was referring to Powermax, who make WFCO compatible replacements. Thats what my TM Mini 18' unit had installed, likely after the WFCO died. I haven't heard great things about Powermax, though I think they do make a Li capable replacement. But as you said, the stage charging details matter for LiFePo4 batteries, and I suspect you can't tweak the float on the units.

My own propane detector unit is an after market replacement, and I chose one with a higher voltage limit. The maximum operating voltage in my DC system is 14.2v, during short periods of "bulk" charging. My "float" charging voltage is 13.6v, and my converter switches into "storage mode" 13.2 volts after about 2 weeks of idle time. (There appears to be a bug in the microcode of that Converter: Even under load and reduced battery voltage, it stays in "storage mode" voltage unless I use the Charge Wizard override button to explicity choose a different mode.)

Man, I wish I had known that existed. I only found the 12V products by SafeT. Great tip for anyone who hasn't already repurchased.

Unless you have replaced the OEM-supplied bargman cable and rewired your TV, the wires along the path for the "Trailer Battery Charge" circuit might be too small to support 50A without overheating.

In my own Tow Vehicle (an old 4Runner), I heavily modified the simple "TV Battery Charge" circuit (formerly a simple fuse followed by wires no larger than 14-AWG) to convert from engine compartment voltage to36.0 volts under the control of a dashboard switch. That provides power to the TM (through an MPPT solar controller) with only 1/3 as much current occurring on the long wire path.

In recognition of the limited current handling within the TM's bargman power cord, I replaced the 30A fuse on the circuit to be only 15A. That lower limit applies to both the default "engine compartment" Voltage setting and the high-voltage alternate switched circuit. At the MPPT, I further limit maximum output current to only 30A, yielding a maximum of slightly more than 400 Watts into my LFP battery string under the high-voltage option.

Thats super clever! I assume 36v was simply the upper limit of your MPPT tolerance? Or is there another reason for that number? To your knowledge are there any concerns (performance inefficiencies or safety) for using an MPPT as a regular ol' voltage converter? My next project was to rewire the whole power line with 8ga pure copper, including the car and both 7-pin sides. My "Renogy dual 50a" controller allows simultaneous solar and and alternator feeds, but caps at 16v. But for anyone reading this who's not already invested, take note!

Just curious, how are you handling shore power switchover? I'm planning on wiring through a manual rotary switch. But it sounds like you're a few steps ahead.

Thanks,
B

 

[Shrimpburrito]

Why are we thinking that some of the TM appliances won't be able to handle the slightly increased operational voltage of a lithium battery? The bulk charging voltage for flooded lead acid batteries (~14.7-14.8v) is even higher than the voltage of a fully charged lithium phosphate (and also no higher than the charging voltage for lithium), and so they obviously are designed to handle that voltage for extended periods.

Am I missing something?

Dave

 

[Wavery]

I recently built my own LiFeP04 230AH battery. I also added solar, inverter, automatic transfer switch etc. The total system cost me over $3K.

If I had it to do over again, I would buy one of these total 110V systems that you can simply plug your camper into and use it. It would give you 110V for your outlets and could be wired into your converter to charge a small 12V AGM battery for your lights & W/P. I would also install about 400W of solar panels.

This way, you could also run some of your home appliances, (like your refrigerator 24/7) from your portable generator. Then when you sell your TM, you don't have to include your expensive LiFeP04 set-up.

https://www.amazon.com/BLUETTI-Port...mzn1.fos.4dd97f68-284f-40f5-a6f1-1e5b3de13370

 

[Hotdam]

Hey Rickst, Lots of good stuff in here, thanks, so breaking it up..

…
B

Many thanks to btheo_TrailMini, and others who contributed to my understanding, as well. And, yes Rickst, I left the iron out of my battery abbreviation - I thought something looked off about it, but didn’t take the time to run it down.