I've just been reading belfert's battery-or-generator thread, and the comments from windtrader and others about building a lithium house battery got me thinking.
I've some limited experience of building lithium packs as I've got a 36v lithium pack in my electric bike which I built myself from new-old-stock laptop batteries bought cheaply on Ebay. I've also watched Youtube videos of people building much larger Tesla Powerwall-type packs for their homes - so I've got an idea of what's involved and would have no fears about building a large capacity 24v pack for my bus, and I know that it could be done fairly cheaply and would greatly out-perform the existing lead-acid batteries
My question though is how you'd charge a lithium pack in the bus:- obviously the pack itself would have it's own BMS, but you'd still need a charger designed for lithium cells, and my existing Trace inverter-charger definitely isn't - and since that's an expensive bit of kit I'm not about to throw it away to replace it with something else
So my question is - is there some other work-around here? Perhaps some device that sits between the Trace and the lithium pack that will enable it to be charged safely without burning the bus to the ground?
Jeremy
How about turning off the charger in the inverter and using a quality charger like a Victron that can deal with lithium batteries? You would want the charger to only get power when the generator is running, or on shore power.
In the Lifepo4 battery system I am building I will using the Electrodacus SBMS0.
https://electrodacus.com/ (https://electrodacus.com/)
One of the issues I have is an outdated Aims Inverter/Charger, like you, this is an expensive piece that I don't want to rebuy if I don't have to.
The SBMS0 is an interesting piece of hardware that functions as a BMS, Solar Charge controller, Inverter and charger controller and wants to be in charge of any charge or drain on the system.
Due to the age of the AIMS PICOGLF30W24V120VR it does not have a lithium charging selection.
There is a rotary dip switch for the charging selections including an off selection.
I contacted AIMS and was told the Lead Acid selection (#4) would be best for Lithium, they also told me I could bypass the dip switch connections to turn the charger on and off remotely.
I opened the case and soldered wires to the switch board in parallel to the main on/off switch and the Dip Switch #4 selection, these wires will in turn be connected to the SBMS0 to turn the charger on/off giving it control of the state of charge, or turn the entire unit off to protect the batteries if the state of charge gets too low.
I am still waiting on my batteries to arrive from China, (has taken over 4 months) so I have not tested it out yet.
I am hoping that the 1500 watts of Solar I have planned will keep the batteries changed and I will not have to rely on the AIMS to charge them, but I can definitely see where I will need to on occasion and want the option.
I am no expert, this is the way I plan on doing it, use this at your own risk.
I have included a high level design of what I have planned.
Peter
Jeremy and Peterbylt!
We can start the lithium crowd; others do lithium like freds so we can make our own club here. LOL
SBMS0? Way to go. That is what is driving my DIY pack as a solar charge controller and BMS for the battery. Just about any 24v inverter/charger will work for charging the pack. I have both an older Vanner and a newer Victron inverter/charger in the bus. Just kept the Vanner in for backup purposes but may wire in parallel for continuous 7kWh use but even at max demand now I don't need more than 3kwh.
Your AIMS should work. Why would it not? I think it depends on the specific pack you make. 7S LiPo is 25.9v nominal, typically charged to 4.0 is 28vdc. LiFePo4 is 25.6v nominal, 28vdc max recommended.
The primary reason chargers have various settings is charge profiles. Different battery chemistry can be charged at different rates so the charger needs to know to feed current safely. In the case of lithium, all types in this specific use case, all that matters is the voltage and using a setting that maxes charge current as lithium can take it. Well, most should not charge at more than 1C, so just make sure you stay under that unless the specs allow for higher charge current.
Good luck there is a bit to learn but it is very rewarding to build lithium battery storage for $125/kW
Thanks very much for all replies, especially for the Electrodacus info and the circuit diagram (which I've saved to my PC for future reference!). I can see I have a bunch of new reading to do, but it's good to know that others have addressed the exact issue I was wondering about
I need to do some learning but at first sight I'm not sure how much I like the idea of an external BMS / charge controller being able to turn the big inverter-charger on and off:- for instance I'd be worried about damage being caused if the charge controller tried to rapidly cycle the inverter-charger on and off as the battery pack reached it's fully-charged state. Also - I understood that the inverter-charger would run a pre-set charge cycle program itself (bulk, absorption, float etc), and surely turning it on and off is going to mess with that completely - at best you'd presumably keep getting the maximum-output bulk setting, and at worse the charge controller might get horribly confused because each time it asked for current they'd be a delay whilst the inverter-charger turned-on and analyzed the battery state before deciding what output to provide.
The other thing that occurs to me after looking at peterbylt's circuit diagram is that I've not thought about the solar side of my installation at all - I've always had the vague idea that I would add solar eventually, but clearly it's something that really needs to be planned as an integral part of the house bank charging system, not just added as an after-thought later
Thanks again for the food-for-thought
Jeremy
Ive read that there COULD be a problem charging from the engine alternator in that lithium can take a charge much faster than SLA and could overheat the alternator.
Engine alternator is only connected to start batteries in my system. Lithium bank is charged solely off solar array or generator on occassion.
Quote from: windtrader on October 05, 2021, 09:34:05 AM
Good luck there is a bit to learn but it is very rewarding to build lithium battery storage for $125/kW
Can you give details on your battery bank please? I've read that large prismatic LifePO4 cells should not be used in RVs, but no explanation why. The larger cells are a much better value than the smaller cells.
Lithium batteries is something I am glad you guys buy from China ,I stopped this summer and saw how that stuff is mine,not a tree hugger myself but it is nasty and ugly on the environment for something "green"
The biggest environmental danger posed by lithium mining is the amount of water the process uses up: an estimated 500,000 gallons of water per ton of lithium extracted. This can endanger the communities where the lithium is being mined because it can cause droughts or famine if operations are not kept in check.
Only 2% is mined in the US in one state the rest is in Austrailia, south America, chilli. Portugal and Spain.
Quote from: Dave5Cs on October 06, 2021, 06:57:45 AM
The biggest environmental danger posed by lithium mining is the amount of water the process uses up: an estimated 500,000 gallons of water per ton of lithium extracted. This can endanger the communities where the lithium is being mined because it can cause droughts or famine if operations are not kept in check.
Only 2% is mined in the US in one state the rest is in Austrailia, south America, chilli. Portugal and Spain.
Yep and the Nevada desert has plenty of water :^,that water is wasted through the evaporation process to mine the stuff .The place had a recycle center and the guy told me only about 15% of the batteries ever gets recycled,The BLM approved another mine in Winnemucca (Thacker) NV for the same outfit
Quote from: luvrbus on October 06, 2021, 07:11:38 AM
Yep and the Nevada desert has plenty of water :^,that water is wasted through the evaporation process to mine the stuff .The place had a recycle center and the guy told me only about 15% of the batteries ever gets recycled
I'd venture to guess that that number is either # of batteries counting a phone the same as a car battery or is just wrong. Contrary to what a surprising number of Facebook posts have said The big batteries are far to valuable to be thrown away.
Here is link to one post where I show a picture and some specs of what was built\https://www.busconversionmagazine.com/forum/index.php?topic=34877.msg400816#msg400816
Quote from: Fred Mc on October 05, 2021, 07:08:56 PM
Ive read that there COULD be a problem charging from the engine alternator in that lithium can take a charge much faster than SLA and could overheat the alternator.
You can control the charge rate by varying the voltage supplied by the alternator. This is easily done with a modified alternator voltage regulator.
You can also use a DC to DC converter.
Quote from: luvrbus on October 06, 2021, 07:11:38 AM
Yep and the Nevada desert has plenty of water :^,that water is wasted through the evaporation process to mine the stuff .The place had a recycle center and the guy told me only about 15% of the batteries ever gets recycled,The BLM approved another mine in Winnemucca (Thacker) NV for the same outfit
I'm amazed at the BS on Facebook and social media in general that people believe. People with absolutely no technical background are domain experts on what can and cannot be done. Who needs engineers and scientists ? Apparently people who barely graduated from high school are suddenly the the experts. LOL.
I have three Battle Born 100amp/hr size 31 lithium batteries only being charged by the Magnum 2800 true sine wave inverter/charger. Battle born gave me the parameters to setup the Magnum for their Lithiums. No big deal. Good Luck, TomC
As to LiFePo4. It is actually most used in RV as it is has greater operating range of conditions. It has less energy density but in a bus application not a major factor. It also has more charge cycles and better handles deep discharge. My experience comes from LiPo and bikes, so I'm comfortable using it in the bus.
Cell size has very little, if any, affect on overall performance. There might be a very small increase in overall pack size when using smaller cells and more connections but there are plenty of sizes available to suit a large pack build. This criteria is very low on the list.
Quote from: TomC on October 06, 2021, 11:22:49 AM
I have three Battle Born 100amp/hr size 31 lithium batteries only being charged by the Magnum 2800 true sine wave inverter/charger. Battle born gave me the parameters to setup the Magnum for their Lithiums. No big deal. Good Luck, TomC
I would love to use Battle Born batteries, but the cost is so much more than other Lithium batteries. I do like that they are assembled in the USA and have a ten year warranty. They would certainly make things easy.
3-size 31 Battle Born batteries were $2,700. Good Luck, TomC
Quote from: TomC on October 09, 2021, 06:01:50 PM
3-size 31 Battle Born batteries were $2,700. Good Luck, TomC
There is 2018 Lady Liberty H-45 in the Toe Truck yard here the Lithium charging system went haywire and caught fire and burn almost to the ground.I didn't much detail on what brand of batteries looked to me like it had 10 batteries maybe 12 lithium batteries
Just to raise this thread about charging a lithium house battery again:- I've been doing more reading and thinking about this subject over the last week or so and am now wondering whether simple DC-to-DC charging of a lithium battery bank from a lead-acid bank is the way to go, at least when starting-out on the lithium journey
I expect that I'm the same as many others in that I'm attracted to the idea of lithium house batteries, but I don't (at least at first) want to get into the complications and unknowns of interfering with my existing inverter-charger or alternator etc etc. I also don't especially want to lay out the big chunk of money that would be required to entirely replace my existing lead-acid house batteries with lithium in one go.
So how is this for an idea? At the moment my 24v house bank is four 12v lead-acids in series & parallel, which I could reconfigure as follows:
1- Reduce the existing bank to two lead-acids in series, with the existing charging set-up left untouched
2- Install a 24v lithium bank into the space previously occupied by the two removed lead acids
3- Fit a 24v DC-DC charger between the two banks.
DC-DC chargers suitable for lithium cells can be bought fairly cheaply and this approach would seem to give me both the simplicity and reassurance of a conventional lead acid system plus the benefits of a lithium bank, albeit a lithium bank that is only half the size that it could be.
If the worst came to the worst you could connect different house circuits to the different battery banks in order to keep them entirely electrically separate, but I'm hoping that in fact the set-up could include a switch that connected both packs together in parallel when they are being used (ie. when they're not being charged).
Does anyone know if it's considered acceptable to connect lead acid batteries and lithium batteries in parallel? Obviously this is exactly what you do when (for instance) jump-starting a car with one of those lithium booster packs, but that's not to say that there may not be reasons not to do it for long periods of time. I'd welcome any thoughts on this
Jeremy
Quote from: Jeremy on October 18, 2021, 02:28:22 PM
Does anyone know if it's considered acceptable to connect lead acid batteries and lithium batteries in parallel? Obviously this is exactly what you do when (for instance) jump-starting a car with one of those lithium booster packs, but that's not to say that there may not be reasons not to do it for long periods of time. I'd welcome any thoughts on this
Jeremy
In your current setup, is there a separate alternator for the house batteries or are they charged off of the main alternator with a battery isolator or tie in relay arrangement?
IMO the only lead acid batteries that you should have are vehicle/generator start batteries.
While it might be desirable to charge while the coach is in motion from the main alternator.
If you are going to something modern it would be simpler to have the house batteries charged via the inverter when on shore power and solar at other times. Engine based charging would only be useful if you anticipate a high percentage of driving.
However that said Victron does make a DC to DC smart charger that has engine start detection built in. Though it tends be more used by the boating crowd who spend long periods of time cruising from place to place.
Thanks for your reply. My own set-up doesn't involve any alternator charging of the house batteries at all (shore power & inverter/charger only), but I mentioned alternators just now as I believe other people do have auxiliary alternators for their bus house banks - some of the earlier replies were from people who were reluctant to switch to lithium due to the potential damage that the high charging currents could do to their alternators
Jeremy
Quote from: Jeremy on October 18, 2021, 03:28:10 PM
Thanks for your reply. My own set-up doesn't involve any alternator charging of the house batteries at all (shore power & inverter/charger only), but I mentioned alternators just now as I believe other people do have auxiliary alternators for their bus house banks - some of the earlier replies were from people who were reluctant to switch to lithium due to the potential damage that the high charging currents could do to their alternators
Jeremy
My bus has a dual voltage system with a separate alternator for the house 12V bank.
The 12V system is used for:
1. House DC lights
2. Diesel generator starting
3. DC compressor refrigerator which is conversion of my dual door RV refrigerator that I installed.
Not sure my 12V alternator is functional, so been thinking of just pulling it out; however the bus manuals document it being there.
Diesel generator needs work so need to focus on that as a backup. However in the meantime I am expanding my Tesla based battery bank from two modules to five modules which will max out the available space.
Jeremy,
If you want to keep FLA and lithium battery banks electrically separate, i.e. so one cannot backfeed into the other, then do what I've done with my two entirely separate solar systems / charge controllers / battery banks. Each bank has a Cole-Hersee 250A Schottky diode at its output, then each bank contributes what it can to the main DC busbar. And for when I may ever need to charge my batteries from my Magnum inverter's 100A charger, I have a Blue Sea switch that allows me to bypass either or both of the diodes - obviously the diodes would ordinarily prevent the inverter's charger from charging the batteries! So far, so good.
John
Quote from: windtrader on October 05, 2021, 09:34:05 AM
We can start the lithium crowd; others do lithium like freds so we can make our own club here.
Don -If you haven't seen these already, or if you already have, you should enjoy how my friends Juan & Michelle put together their 4106's house battery system using a Nissan Leaf lithium battery pack:
https://www.youtube.com/watch?v=K47NLwHyZng&list=PLq1-J1YKxmjp5_TPV-qs70cisI9YypeLO
Enjoy!
RJ
I know one thing now for sure a 100 amp Lifepo4 will spin a 95amp starter under no load like crazy but will not spin the same starter under a load of 180 amps the BMS kicks out,lol I had to call to find out how to reset the damn thing
and you thought electronically controlled engines were the end of learning. Back to school. Oh, for points and condensers again...
Quote from: chessie4905 on October 20, 2021, 06:14:31 AM
and you thought electronically controlled engines were the end of learning. Back to school. Oh, for points and condensers again...
yep a feeler gauge and a screw driver was tough to beat ,if you got fancy high tech a timing light and a dwell meter .I saw one of the old Snap On tune up cabinets not long that had the spark plug cleaner and dwell and other stuff built in
had a spark up cleaner. pitched it when I bought a blast cabinet, which is one of the best investments ever.
What are your thoughts on the SOK brand batteries.
They have a max charge capacity of 50 amps.
Would that scare any of you off?
I'd get more details on the SOK. They are new to market and beating competition by 50%. I looked at their website and something is not right with those specs. They show the 200ah battery at 100ah max discharge, this is .5C. Maybe they just copied and pasted the web pages. They all can't have the same spec, even if they use the same raw cell, every single cell added in parallel increases current capacity. Will Prowse does a video review of them
Quote from: windtrader on October 20, 2021, 12:14:12 PM
I'd get more details on the SOK. They are new to market and beating competition by 50%. I looked at their website and something is not right with those specs. They show the 200ah battery at 100ah max discharge, this is .5C. Maybe they just copied and pasted the web pages. They all can't have the same spec, even if they use the same raw cell, every single cell added in parallel increases current capacity. Will Prowse does a video review of them
Yes. That review got my attention. He seems to like them but reacted to the 50 ah charge capacity.
That was all he mentioned. Didn't sound good or bad.