Ready to jump to Lithium... any advice appreciated!

[MitchB]

I think that one of issues that makes these batteries more challenging to use (but ultimately better) is that we're used to a dumb battery.  We expect that all the management of electricity has to be done by the charger and with these batteries that's just not the case.   Battleborn is saying that their BMS will protect the battery. Further, in your case they've tested it on your WFCO charger and say it's fine.  If that's part of their warranty then basically you're golden.  It becomes a matter of money and not technology.

As I'm typing I'm getting ready to send you the $300 you've requested, please furnish me with your name, address, mother's maiden name, name of your first child, first pet's name, last four of your SSN, favorite color, street you grew up on and name of your first elementary school.  As soon as I get all that I will commence mailing you small round copper (or copper looking) disks that maybe, perhaps, are legal currency in all 50 states, at a rate of 2 disks every three weeks until the total amount is fulfilled. 

[DavidM]

Well ok, so here are some facts and speculation.

Unlike FLAs and AGMs, Li batteries only have two charging parameters that have to be met: maximum charging current and float voltage. The batteries charge at either the max the charger will put out or at their maximum allowed charging current until they reach float. Then the charger switches to float and the batteries stay at the specified float voltage. I recall but I am not sure that Li batteries like a little higher float voltage and that is why one of your references said that the WFCO would switch to float too soon and not charge the batteries fully.

I don't think it matters. You might lose a bit of capacity but not the end of the world. The Battleborn BMS will protect the battery from all of the standard faults, no matter what the charger puts out. Plus the WFCO converter at what 45 amps, isn't too much for a 100 Ah Li battery.

$300 contribution, ha!!! I have been dithering for a couple of years whether to scrap my single 70 Ah battery and replace it with two GC batteries to triple my Ah capacity for about $200 total. So far the single battery has served me well.

MitchB: You are absolutely right. Our paradigm is dumb batteries. Li batteries have to be smart with a BMS built in or integrated into the whole system. The charger is just a source of current.

So go for it. But don't expect me to pick up some of the tab ;-).

David

[Steve Sanders]

@tbrady,

"Maybe if there was "something"  I could put between the WFCO and the battery to stop it from charging the battery..."

If you can find a diode or diode pack that can handle the current, it would do what you suggest. Put the diode between the battery and the WFCO and the special charger between the battery and the diode. That would stop current flowing from the WFCO to the battery while allowing current to flow from the battery to WFCO.

I don't know how the WFCO charging system would react to this scenario.

Sent from my SM-G950U using Tapatalk

[tbrady]

Thanks Steve!  I will do some research on that...   

[tbrady]

I've done a lot more research...  fortunately this is a very active subject over on the Airstream forum (airforums) and I have learned a ton from there.  Here are the key things I have learned-

1.  Battleborn seems to be the best option for a "drop-in" replacement even though it's not completely a drop-in replacement.  They support the widest range of chargers/converters and their support is outstanding.  They were very active on airforum answering questions etc.
2.  I could keep my existing WFCO power center and use it with the Battleborn but I will most likely only obtain 90% SoC with it.  Also, it seems that WFCO converts are notoriously hard to go in to "bulk mode" and they will take a lot longer to charge the lithium batteries than a charger meant for lithium.
3.  To get a better lithium charger (e.g. rapid charging) I could either put a converter between the WFCO and the battery or replace the WFCO power center entirely with a PD4045LIK (which I believe will fit in the access hole) The PD4045LIK is a complete power center is  $195 and a basic lithium charger is around $165.  The power center would make for a cleaner/simpler install but there is more labor involved.  If you had a WFCO 89xx series you can easily replace just the converter section but this isn't possible with the 8735.
4.  You would most likely want to add a Victron battery monitor (bmv-700) so you can see the current draw and SoC etc for your battery.  This is around $140.
5.  You would want to add a diode (or something similar) to prevent the TV battery from drawing down the TT battery while traveling.  This seemed to be a common occurrence so people are putting something on the line so that the current can only go in one direction.  I think this was about $20-50 depending on exactly what you got...

In reading dozens of pages on this most people were thrilled with the conversion to lithium even though it was more complicated and much more expensive.  Battleborn in particular was very well regarded due to how attentive they are and their commitment to being as much of a drop-in replacement as possible.

So... I haven't pulled the trigger on anything yet.  I'm going to pop the WFCO out and measure the hole to see if the PD one will fit.  And then decide if I want to tackle wiring in a new power center.  If I do I will most likely place the new battery in the back of the trailer in the void near the hot water heater (I have the 21BHS).  And would probably put the battery monitor above the heating thermostat. 

Any feedback/suggestions/warnings is greatly appreciated!

[MitchB]

That sounds like a good plan, I'm anxious to hear about the end result if in fact you do go forward especially rewiring to install a new converter. I have the PD 4045 and if a rewire is easy I'd consider swapping everything and getting a lithium battery myself.  The additional usable amp hrs would be really nice.

I am a bit unsure of why the TV battery would draw down the a new TT battery while traveling but not the old one. The TV alternator should take care of anything the TV battery needs if you're moving and the voltage of the lithium battery isn't really any different the SLA you'd be replacing.  Battery monitor is a good idea whether you change the battery or not in my opinion.  I used a $30 Drok unit and it seems to work fine.  If i were going to replace it with something a little fancier the Victron would be my choice.

Looking forward to hearing more.

[tbrady]

From what I read some alternators would decrease voltage below 14.4volts or something like that and if the lithium was fully charged the flow would reverse and the TT would be pushing to the TV battery.  Not sure how prevalent this is but it had happened to a few people and the fix seemed easy so I would probably just wire it in.

[tbrady]

More info...  I've been chatting with LifeBlue more and they said even on the WFCO 8735 it's possible to wire in a new converter relatively easy.  The main difference between it and an 8900 series is that the 8900 series is more modular with converter sitting in it's own little box below the distribution panel etc.  The hookup however, is pretty much the same. 

Remove converter AC power from breaker.
Locate new converter behind power center.
Connect new converter AC wire to breaker, neutral and ground.
Connect DC output from new converter to bus bar terminals in power center.
Done.

The tricky part is tying the DC output from the new converter to the DC side bar on the WFCO.  I'll need to take the back panel off it looks like to get to it...  Will let you guys know what I end up doing.   I did take a look at AGM batteries but heck, to get the equivalent of a 100Ah Lithium I would spend over $500.  I really need something I can put in the trailer as my tongue weight is already high because of all the bicyles we carry there.

[Popup2012]

I got a 100 AH AGM at Battery Plus for a little over 220$ about  18 months ago on sale.  I think you can get one now for about 259$.  The brand was  Duracell.

[tbrady]

The conversion is complete (almost!).  I ended up buying the LifeBlue 100AH battery and the IOTA DLS-30 converter with the LifePo4 controller.  I went with LifeBlue because of their warranty, the built-in bluetooth battery monitor and the outstanding support from Larry at Starlight solar who thoroughly answered the few questions I had.  I've not yet taken it camping but I've tested it at home thoroughly and the results are great.  Probably the number 1 advantage is that this battery can be recharged RAPIDLY.  I bought the 30amp converter since the WFCO it replaced was a 35amp, with this converter I can pump 30amps an hour back in the battery using my 2200 watt generator.  So with a full discharge I can fully recharge it in a little over 3 hours.   Another thing that is really nice is the built-in bluetooth, I installed an app on my phone which tells me the state of charge, voltage, current (in/out in amps) and the number of cycles the battery has been through.

The battery is now inside the trailer in some dead space where the water heater is along with the new converter.  The existing WFCO converter could easily put back in commission if needed, along with putting a battery back on the tongue if necessary. 

The only work left is I want to add a thermal controlled cabinet fan to the compartment all these components are in.  According to Larry at Starlight he's never had an issue and hasn't done this but I was testing yesterday with letting the inside of the trailer get hot out in the sun and doing a full battery charge, while doing so the compartment got up to about 101 after about 2hrs of charging. 

So, only time will tell if this is worth the high initial cost.  If I get as many years/cycles out of this battery as their testing data shows I should I will be thrilled.  It will definitely help with our primary mode of camping w/o any hookups.

[Merlin]

Sounds really great. Nice work. Report back on how it goes with camper use. I'm pretty sure I'll do this too in a couple years when my batteries have their 7th birthday.

[MitchB]

As Merlin said, sounds great! Look forward to more reports.

[Jason]

I'm glad you made the jump and I can offer my experience and research for others. When we got our trailer we wanted solar and knew we would only go with lithium. There are some aspect of lithium that I think are being missed.

For starters, 100ah Li is equivalent to around double or triple of your AGM. Much of this has to do with the ability to be able to discharge down to 0%. Some state that they prefer 20% and either way that's 30 to 50% more usability than AGM. Furthermore, the voltage doesn't drop over time, they recharge fast, and they have a cycle life of 5,000 to 10,000 cycles! So AGM batteries have a cycle of like 500 and a Li battery would pay for itself in the few times AGM were replaced. Yet they would still last 10 to 20 years! It's what they use in a Prius. You can ignore  the generator and buy a Li battery.

We went with 3 Renogy Li batteries, installed in the pass through with a fold down enclosure. We have a go power controller and 2000watt inverter. With this setup, all of our plugs are hot. We can plug anything in (yet we put in 12v/usb ports in a few places like the TV). The initial cost is higher, but it pays for itself quickly. You can do more, for a longer period of time, with Li. We would need a lot of AGM batteries to meet our demands (think of the weight!) Li batteries weigh 20lbs each!

It's hard to embrace these new smart batteries, but when you do the math, look at the cost benefit analysis, Li by far comes out on top. Plus, the prices are dropping fast.

[tbrady]

Thanks Jason!  Yeah, after researching going to dual 6v AGMs and the amount that would cost, plus the fact that I'll only  need to run my genny briefly now to stay fully charged made it an easier decision.

Here's a couple of pics, we didn't lose any storage space really.  Added the battery switch and the you can see the charging module LED that shows whether it is in bulk or float mode.

I added a piece of HDPE plastic board to have something firm to bolt everything to...

[Jason]

Very nice. Well done.