upgrading to Lithium batteries

[ekgflashnet]

Just a brief update on the direction I took using much of the feedback from the group.  I decided to go with the Weize Lithium battery.  The review on youtube was thorough and confirmed the capacity was true along with the specified features (low and high temp protection plus the usual other protections).  One thing I like about this battery was its auto-balancing feature.  With other batteries, before you hook them up in parallel you need to first ensure the voltages are nearly identical between the two banks.  With auto-balancing, this is now done by the BMS.  200AH for $700 on Amazon.  I did go ahead and remove the Big Boy BIRD like others suggested.  The dc-dc charger which is only active when the alternator is running charges the house battery when travelling.  The only real loss is the ability to charge the chassis battery using the inverter/charger (when the house batteries are full).  However, charging at 14.4 volts (what the inverter/charger is configured for with lithium batteries) to the chassis battery is pushing it, so this seems like the safer way to go.  I did go ahead and install a temperature controlled heater in the battery compartment which will turn on as needed when the battery temperature is below 40 degrees.  This way I can charge the batteries with the generator in colder weather.  It is a rather small space, so I don't think too much energy is required to keep this space above 40.

Batteries were delivered free and quick in just 3 days.  Should be done with the install by tomorrow.

steveg 2005 ddiv

[wamcneil]

That's great! They sound like really good batteries. I hope they work out. If they live up to the specs for continuous output amps of 100A each you should be good. 

Running my microwave draws about ~165A from the batteries. The refrigerator and other base loads add at least 15A.  So with a TV on and other loads it's pretty easy for my system to pull 200A when running on the inverter. The magnum specs for 2000w inverters say maximum continuous power draw 267A. 

So, if it were me... I'd beat on those batteries mercilessly and try my best to break them before the amazon return window closes. If they survive a torture test, they should be good for a long time!

Cheers,

Walter

Edited April 29, 2022 by wamcneil

[timaz996]

12 hours ago, ekgflashnet said:

Just a brief update on the direction I took using much of the feedback from the group.  I decided to go with the Weize Lithium battery.  The review on youtube was thorough and confirmed the capacity was true along with the specified features (low and high temp protection plus the usual other protections).  One thing I like about this battery was its auto-balancing feature.  With other batteries, before you hook them up in parallel you need to first ensure the voltages are nearly identical between the two banks.  With auto-balancing, this is now done by the BMS.  200AH for $700 on Amazon.  I did go ahead and remove the Big Boy BIRD like others suggested.  The dc-dc charger which is only active when the alternator is running charges the house battery when travelling.  The only real loss is the ability to charge the chassis battery using the inverter/charger (when the house batteries are full).  However, charging at 14.4 volts (what the inverter/charger is configured for with lithium batteries) to the chassis battery is pushing it, so this seems like the safer way to go.  I did go ahead and install a temperature controlled heater in the battery compartment which will turn on as needed when the battery temperature is below 40 degrees.  This way I can charge the batteries with the generator in colder weather.  It is a rather small space, so I don't think too much energy is required to keep this space above 40.

Batteries were delivered free and quick in just 3 days.  Should be done with the install by tomorrow.

steveg 2005 ddiv

Would love to see pictures of it when done.

[ekgflashnet]

I have a wiring question so I can ensure I'm doing the right thing.  I'm in the process of removing the big-boy BIRD.  My question is should I jumper the house side of where the big-boy was to the chassis side?  If I don't, I don't have alternator power going to the house batteries where the dc-dc charger is located in my setup.  (see photo of the schematic for my coach below).  If I do jumper the two sides, I think this means that the house and chassis batteries are permanently linked together.  So they will charge together and discharge together (basically what the big-boy does when it senses voltage from one bank higher than 13.2v).  I wanted to minimize wiring changes, so perhaps my solution is to run a power wire from the alternator connection at the coach battery directly to the dc-dc charger.  Thoughts?

I'm still looking for a way to charge the chassis batteries when the coach is not used, but plugged in.  Perhaps a Trik-L-start. This should keep the chassis batteries charged while plugged in.

[wamcneil]

Ok… so you’re removing the relay in order to isolate the house batteries from the alternator and chassis batteries. Right?  
Jumpering the chassis batteries to the house batteries defeats that purpose.  
The dc/dc charger will siphon some current from the chassis batteries and alternator and give it to the house batteries when the engine is running (assuming you connect an ignition wire to make it active only when engine running).

And you’ll need some way to keep the chassis batteries charged while parked. I have a small 10a permanent mount battery charger in the engine compartment for that purpose. Plugged into the non-inverted. block heater outlet.

cheers

Walter

 

[ekgflashnet]

Thanks for the clarification.  Makes sense.  I was also thinking the same thing about the block heater plug.  Any concerns that if running the generator while travelling that both the alternator and this small charger would be charging the chassis battery at the same time?

 

steveg 2005 ddiv

[wamcneil]

I wouldn't expect any problems. The battery charger will see the elevated voltage like a fully charged battery and should just sit there at its float voltage (which should be below the alternator voltage so producing no current). 

Also, there should be a switch on the dash to turn off the block heater outlet and power down the charger. 

Cheers,

Walter

[ekgflashnet]

I've got everything up and running.  I do still though have some questions on some observations I've made.  My charger has been reconfigured for the lithium battery profile.  I have 2 options for the charging profile - 3 stage or 2stageNoFloat.  Any suggestions out there?  I've also set absorption and bulk voltage to 14.2v.  I have notice something I don't understand though.  The Inverter/charger remote display shows it is charging at 14.2v.  I take a reading at the inverter/charger posts itself and it reads 14.18v.  That seems good.  But, if I take a reading at the battery itself, it reads 13.55v.  The Victron smart shunt reads 13.75v.  Why would the voltage at the battery be about 0.5v lower than at the charger?  Long run from charger to rear run bay back to the batteries?  To test this, I first disconnected the coach from the inverter/charger.  I hooked up a 12v FLA battery directly to the inverter/charger and took the same readings again.  I get the same nearly identical readings.  (14.18v at charger posts, 13.52v at the battery posts).  So, seems the coach wiring is not at issue.  Is this normal?? Since the lithium batteries are specified to be charged at 14.2v, should I increase the inverter/charger setting to a higher voltage so that the batteries themselves see this higher voltage?  Your opinions?  (as a side note, the readings on the amount amps being pushed are the same at all the measuring points)

thanks

steveg 2005 DDIV

[timaz996]

This forum has excellent information on charging Lithium batteries. Look around and you will learn a lot.

https://diysolarforum.com/

Tim 

[Rocketman3]

It is probably the amps (heat being generated) going through the wires. 
 

I noticed when I run the microwave (large amp draw) the inverter sees over a volt less than the batteries are producing. I have found an area in my wiring where Monaco used copper bus bars - and half my voltage drop is in that one area. While running the microwave that buss bar gets warm (warm not hot).  I am planning on changing the fuse area so I keep it all in 4/0 wire.   I noticed the same thing happening when I charge at a high rate - voltage drop. 

If I am inverting or charging at low rates - there is practically no voltage drop. 

[Ivylog]

I was able to reduce my voltage drop from a little over 1V to 0.4V by tightening the multiple of connections. This was when drawing 100+ amps which I rarely do as anytime I’m inverting that many amps, I crank the generator if quite hours allow.

Yes, it helps when charging but by the time the battery voltage gets above 14, the amps have decreased to where there’s maybe 0.1V difference. Contrary to many, Lithiums can be charged using a AGM setting…they are not that picky and 13.4V is 99% charged.
 

[Ivylog]

Decided to build my own Lithiums so order 8 280AH cells from AliExpress… $914 total and they arrived this week. All 8 voltages were at 3.31. About to leave on a trip so not going to get around to building them. 2 BMS for $120 and another $100 in cables and lugs should do it for a cost of $1134 or $2/AH.

Edited June 3, 2022 by Ivylog

[timaz996]

On 4/21/2022 at 1:53 PM, Tim-AZ said:

I replaced my AGMs with two 200ah lithium Lossigy batteries as I already have the BMV-712, and a Victron 3000w multiplus inverter and it all works great. I didn't have room in my bay to fit the Multiplus II our I would have gone that route. my Lossigy 200ah batteries cost 659 each...669 on Amazon. Look up Will Prowse on YouTube, he takes them apart and shows you how all of the different lithium batteries are built and rates them. Mine don't have blue tooth but with the BMV-712 I don't need it. A friend just put in two 400ah Lossigy batteries in his bay because the 200ah battery you are looking at is the same size as his 400ah batteries, that cost him 3000 for his two.

I would call your thoughts a good way to go.

Tim  

Update, Three weeks ago I found out the dimensions I had for the Multplus II were incorrect and I changed out my Multiplus standard for the II. I love how the Victron equipment works together.

Tim 

[Ivylog]

Finally finished up my two 280AH Lithium batteries…used plastic strapping to band the cells together and then a wooden box making it one unit that will fit where I removed 8 AGM batteries. Already built 600 AH 2 years ago so 1160 AH. Did a 2 day test run at the Tampa Super RV show and the only issue using the AGM2 setting was until I drew them down to 40%, the charger thought they were fully charged… wouldn’t start charging. I do have an additional 100A charger that will. While my box is not pretty, it’s a good fit in the compartment.