Connecting LifePo Batteries to Delco Remy 50dn Alternator...

[mqbus767]

In reviewing what I've done, I think I may have purchased the wrong relay. I've installed the "Cyrix-ct" combiner and I think I need the "Cyrix-Li-ct" combiner. I must have just clicked on the wrong thing in Amazon.

https://www.victronenergy.com/upload/documents/Datasheet-Cyrix-ct-120A-230A-EN.pdf

vs

https://www.victronenergy.com/upload/documents/Datasheet-Cyrix-Li-ion-230-A-EN.pdf


I also think that I've wired it incorrectly with the voltage sensor on the start battery instead of the Lithium side of things. It's possible that the BMS on the batteries (Yes, each BB battery has an integrated BMS) is cutting in and out with the voltage regulator causing the cycle that I described above. I'll play around with it a bit and report back here.

[luvrbus]

I saw a 2.5 mil Prevost they changed over to AGM from Lifepo the charging rate was killing all the electronic for the house system I am guessing the Crestron system didn't like it ,shouldn't be problem without all the electronics

[fortyniner]

Right you cannot just ADD lithium to existing system. It really requires a rethink/redesign with current limiting alternator for sure.

Cost no object would have LTO start batteries with LifePo4 house batteries.
LTO can handle any temp and can be 100% discharged without damage.

Plus the top and bottom charge limit can be higher than LifePo4. Finally LTO cranking amps are several times higher than FLA.

But LifePo4 is incredibly high density power source requiring less babysitting than AGM/FLA hence it popularity with the offgrid solar group.

[buswarrior]

Voltage sence line choices...

How are you going to protect the start batteries from over-charging, when the Lithiums are still calling for a charge?

Mixing battery types with one charge source has always been a devil...

Keep your money in your pockets!!!

Happy coaching!
Buswarrior

[windtrader]

Here's my experience on this.


Last year I started doing a Li-Ion house battery upgrade. The starts are two Group 31 24v. They got a bit abused so were pretty pokey so I figured I'd explore using the house bank, alternator, and PV as sources to keep Group 31 happy.


I experimented with connecting the start battery to the house bank then tested charging from the alternator (DN50 gear) to the starts then to the house battery. The first thing I noticed is the wiring (jumper cables) between the house and start getting hot. The current meter was showing over 200 amps @ 24v. That experiment stopped and time to ponder.


After some research, I decided it was not very smart to connect Li-Ion to LA bank which was connected to the alternator. These batteries have are very different technical specifications. And as was pointed out unless you monitor and control the flow of current between the house and starts you are completely exposed to overcharging and draining your precious and expensive li battery bank. Maybe the BB battery with internal BMS can do the job but I'd not trust it.


After much more pondering where I went was based on my own goals and that is to be 100% self-sufficient off-grid with supplemental external power only in worst-case, emergency scenarios.


I'm using a PV system to fully charge the Li-Ion 24v 480aH bank each day, no other charging source at the moment. The PV generates over 50Ah @ 26v or about 1500 watts of the rated (1800). This is more than adequate to run everything the same as in your home residence.


However, recent trials have shown that the Norcold 3-way absorption refrigerator is a massive energy hog, over 4kWh per day. By the afternoon with the house bank full, it will draw down several thousand watts overnight, so around 70% SOC in the morning. The system can easily handle this but it is disturbingly excessive energy to keep such a small cooler going. I'm planning on swapping out with a small apartment unit that will use much much less energy.


The other huge hog is the electric water heater. It draws thousands a day too as seen in the diagram. Each regular rise is about 450 watts and lasts for some time, around the clock. I called Sure Marine about this and he did not seem to know it cycled in this manner. Maybe the thermostat needs replacing? Meanwhile, when not lazy I manually switch on the hot water heater for an hour during the day and shut it off. The water stays plenty hot so it works as an interim solution.


The backup plan on the electric refrigerator is simply to switch to propane. It works fine, just uses propane. Part of getting totally off-grid self-sufficient includes ditching propane and 100% self generating electricity.


Long story short, I started down your path but as you see my journey went off on a totally different path. One last piece of the story which is coming next. There is a huge diesel generator taking up half a bay and weights a lot. I want that gone! I'll get a small quiet portable generator to supplement charign the house bank when extended days of lack of sun power. Based on my planned daily consumption a couple hours on a 2kW should be fine to top off the battery bank.


Finally, they may say you can do what you want but just the basic mismatch of LA and LI connected together is generally not the optimal configuration and incurs some real risk with respect to keeping both banks in their happy zones.

[mqbus767]

Thanks for the info WindTrader.

I watched this video some time ago and it provides some interesting information on the challenges and possible solutions for sovling this:

https://www.youtube.com/watch?v=dzU_pQFa19s


The real stuff starts around the 9 minute mark.

[windtrader]

OK. Got to 18 minutes. Had enough of the marketing of Victron products to solve charging paths that are not typically done. OK, so sure you can do this sort of stuff and Victron more than happily will offer up some product to solve that niche integration issue.


I'm still on the side that this is not an option unless you are forced into or don't have other options. This video convinced me charging via alternator to house bank is not the preferred method.

[fortyniner]

Voltage sence line choices...

How are you going to protect the start batteries from over-charging, when the Lithiums are still calling for a charge?

Mixing battery types with one charge source has always been a devil...

Keep your money in your pockets!!!

Happy coaching!
Buswarrior

This is very interesting indeed. I'm trying to integrate my big LifePo4 pack into the vehicle charge system too.

What I found is the LA start batteries max charge voltage actually exceeds the LifePo4 safe limit and would potentially degrade/destroy the expensive Lithium house pack.

If the 50DN (or other big alternator) charge profile is set for LifePo4 the LA start batteries will slowly degrade due to never being run through the full three state LA charge cycle.

I'm tired of baby sitting LA batteries though so I've been considering a design that replaces the LA start batteries with Lithium Titrate Oxide (LTO) pack. LTO is too expensive for house batteries but are ideal as start batteries
for the following reasons:
1) permissible upper voltage is higher than LifePo4
2) can be 100% discharged without damage
3) very wide temperature range
4) Ultra high safe discharge capability  (cranking duty)
5) Unlimited cycle life! (for our purposes) 

A relatively small LTO pack could replace a couple of 8D starts. An intelligent battery combiner can be used to charge the LifePo4 house when LTO pack voltage high
enough and optionally back charge the LTO starts from LifePo4 bank when needed.

A REAL current limiting alternator regulator is still needed and so far I have not found any that offer that feature yet.

That said the premade Lithium packs usually have protection circuits integrated into the pack to help protect them as a last line of defense.

I think its worth mentioning that LifePo4 cannot be charged below 32F! For that reason they are usually located within the living space or some other temperature controlled area.

-----

[windtrader]

Why you "baby sitting" LA batteries?


I confess the same past concern. That is now resolved and no longer any concern. As my electrical system supplies all the energy today, I just flip a switch or plug in a device.  What I now do is whenever it seems like the starts might need a bit of TLC, I just plug in the small charger and starts are happy again. so easy - no muss - no fuss.

[freds]

Here's my experience on this.

However, recent trials have shown that the Norcold 3-way absorption refrigerator is a massive energy hog, over 4kWh per day. By the afternoon with the house bank full, it will draw down several thousand watts overnight, so around 70% SOC in the morning. The system can easily handle this but it is disturbingly excessive energy to keep such a small cooler going. I'm planning on swapping out with a small apartment unit that will use much much less energy.

I switched my NorCold over to a DC compressor setup and it works great for me!!! Which I got from:

https://jc-refrigeration.com/

More detail is on my build thread:

https://www.busconversionmagazine.com/forum/index.php?topic=34318.msg405259#msg405259

Like you I do have electrically driven water heaters as part of my hydronic system. However my hydronic system makes use of a diesel boiler as it's main heat source. I only use the electric water heaters to dump power too when I have too much solar input or when I have shore power available.

[windtrader]

Hi Fred,
Sill playing tag - I think you're it! LOL.  one day we'll connect


I have explored products from this same company. They seem very knowledgeable and will gladly provide adequate support both pre and post-sales. The brochures are in the tickler file but I've since decided if going to this amount of effort, I may as well get more space, as it just doesn't support the sorts of stuff we put in the refrigerator. Stuff always not fitting or banging into something else. And that is with not many items at all. Like a two liter soda bottle won't go in upright and needs to lay on the side on a shelf. does not fly in my bus.


Two options - slide in a 10 cf small compressor-based apartment style refrigerator if it fits through the door. Or custom build an insulated storage box then run the compressor from a bay. 120v of course. Need to do calcs on actual efficiency before running down that path.


The hot water system does have a webasto loop but that uses diesel. Yeah better than propane but still non-renewable energy source. There is a small inline pump. The webasto control has two on states - one is labeled exchanger and the other is burner. I use burner for interior heating. I think the exchanger setting is for block heating and the water heater loops.


This is a timely topic because I'm needing to get the mini split installed and need space for the condensor/fan unit. Where I'd like to place it is where two 5 gal propane tanks live. I think an earlier measuring confirmed it would fit with the tanks. If that is not right then just one more reason to dith propane now.

[fortyniner]

Why you "baby sitting" LA batteries?
....

Just that traditionally they are problematic requiring periodic replacement and "special" charging regimes. Plus full of acid, gives off hydrogen, dies when discharged 100% etc.

Currently I just ignore start batteries special needs and periodically put them on a charger to keep them happy.

[windtrader]

Currently I just ignore start batteries special needs and periodically put them on a charger to keep them happy.

Is that not good enough? Just curious for taking time and energy on this

[fortyniner]

Is that not good enough? Just curious for taking time and energy on this

I think so since converting the 4106 to 24v. With 12v everything had to be 100% or it would struggle.

With 24v even a couple of car batteries will easily start it.  I will revisit LTO batteries when  replacement time comes.