Charging a lithium house battery

[TomC]

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

[windtrader]

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.

[belfert]

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.

[TomC]

3-size 31 Battle Born batteries were $2,700. Good Luck, TomC

[luvrbus]

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 

[Jeremy]

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

[freds]

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.

[Jeremy]

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

[freds]

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.

[Iceni John]

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

[RJ]

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

[luvrbus]

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 

[chessie4905]

and you thought electronically  controlled engines were the end of learning. Back to school. Oh, for points and condensers  again...

[luvrbus]

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

[chessie4905]

had a spark up cleaner. pitched it when I bought a blast cabinet, which is one of the best investments ever.