Charging Li batteries

[Daveh]

I would explore more. Right now you are hearing "Yea, you F-150 will pull that Mobile Suites just fine"

[hemsteadc]

Yep, that's why I'm here. But I'm not going to flat out dismiss what he's saying either!

[Daveh]

Well, lets just focus on the charger for a minute and see how their recommendation holds up. They want to give you a four bank 15 amp charger which retails for 600 bucks. Look at their list of chargers they also sell a 15 amp charger for one bank which is what you would want, IF you wanted a 15 amp charger, which you don't. 15 amp is ridiculously slow and you lose one of the biggest benefits of Lithium of charging fast. So they are recommending the wrong kind of charger, 4 bank and too low of amperage. The only unit on their 12 charger list that makes good sense IMO is the Magnum 2800, although I would get the 3012. Regardless, check their price on the Magnum 2800 for $2,000.00. You could get it much cheaper elsewhere. Here is the Magnum 3012 which has 125 amp of charging, as opposed to 15, and is a hybrid inverter allowing the batteries to supplement the AC charge when you need more Amps or if the AC voltage is low. A HUGE difference for $1,667.00. Again their is really no benefit to the lithium unless you have a an inverter charger that can utilize their advantages.

 

Ask them, why would I want a 4 bank system?

[Daveh]

Oldman read this from Technomadia especially the part about float charging. http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/ At least check out AMSOLAR as they discuss. You will not get a better reputation and cutting edge advice.

[hemsteadc]

 

Ask them, why would I want a 4 bank system?

I run a 48v system.

[hemsteadc]

Oldman read this from Technomadia especially the part about float charging. http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/

Excellent.. thank you.

[Daveh]

I run a 48v system.

Ohhhhhh, I see. I am not familiar with those. Don't you want a 48 V charger then? You will be connecting your batteries in series to make 48 volt pack? I don't see how you would do that with four 12 volt chargers? How do you do it now?

[Daveh]

before I put my Lithiums in series configuration to 48 volt I would want to make sure they were balanced. This could be achieved by connecting them in parallel, charging them to about 13.8 or even higher for the initial charge and then letting them rest and for a while connected in parallel. Once you separate them to configure in series, put a multi-meter on them to make sure they are indeed balanced. If not, repeat procedure. You would then put them in series and charge to 48 volt. Adjusted the max voltage for your batteries would be about 54.4 using the more conservative numbers I proposed. In addition to the extension of battery life the other reason to go with lower settings is you are not pushing one of your 12 volts too hard if they get out of balance. You do not want one pushing In the high 14 volt area while the others are still getting in the low 13's.

[Ronbo]

The reason they want to sell you a 4 bank charger is to charge each bank in your 4 bank 48 volt system. You can charge each bank without separating the system. But, I would not go this route. I would get a 48 volt charger.

[hemsteadc]

Perhaps it's the balancing issue with Li's that is critical. Hence the '48v charger' which is 4 12v chargers. I use a 48v charger, sometimes 2 and two Hondas if I really wanna blast it.

[Daveh]

Perhaps it's the balancing issue with Li's that is critical. Hence the '48v charger' which is 4 12v chargers. I use a 48v charger, sometimes 2 and two Hondas if I really wanna blast it.

Perhaps. I see they have the 4 bank 12 volt system listed under 48 Volt chargers. I honestly don't know how that would work as you need an actual 48 volt charger. Love to hear the explanation. Can you adjust settings on your current charger?

 

I do see this in the product description:

 

Quad Pro PS4 Four 15 Amp Banks 60 Amps 12V, 24V, 36V or 48V

 

So that answers one question you would have 60 amps total rather than the 15. Better not great.

 

I know the cruiser's forum link had chatter about running 4 separate 3.6v chargers to the cell rather than using a single 12 volt charger but that got knocked down. I cannot recall the details. I would certianly want to know the benefits of this system compared to a single 48 V system.

 

So in addition to settings I think you have the separate question of best charging method.

 

Curious, why are you not looking at the 48 V packages?

[Daveh]

Oldman this may interest you. This is the place I purchased my Lifepo4 charger from for my 3.6 volt cell initial charge. Look at the specs. They charge a 48 volt pack to 56.8V and then shut down. That corresponds to to a 14.2 V charge on a 12 volt battery. Again I think new consensus is that this is too high but these designated LiFePo4 are interesting in that they go to the designated level and shut down. No absorb or float. http://www.batteryspace.com/Smart-Charger-15-A-for-51.2V-16-cells-LiFePO4-Battery-Pack.aspx

[Daveh]

Oldman, Sorry to keep writing. I find this stuff quite interesting. I looked at their battery internals and it is all quite impressive. One other thing I found is their battery charge curve and I think it goes a long way to answering what voltages you should be shooting for. Almost all the capacity is between low 13 volts and about 12.4. Or for 48 volt packs 52V and 49.6. That is the sweet spot----going over or under just begs for trouble and shortens battery life. This is their own data sheet and the curve looks just like all the other LiFePo4 out there. http://www.lithiumion-batteries.com/uploads/files/14975/large/SB100%20Data.jpg

[hemsteadc]

 

Curious, why are you not looking at the 48 V packages?

Packages.. meaning a 48v battery/charger? The battery won't fit and it's too heavy. I will investigate the charger. Love the advice.. thanks.

[hemsteadc]

Oldman read this from Technomadia especially the part about float charging. http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/ At least check out AMSOLAR as they discuss. You will not get a better reputation and cutting edge advice.

Very informative.. especially the part about high temps in the battery bay.

[hemsteadc]

This charger may be what I'm looking for. One voltage. Can be wired in series, or possibly factory-set for higher voltages.

 

Also some good info on that page... including a discussion of how internal balancing works, and that having a separate charger/battery can result in faster charging times. Boy, this technology is really something!

 

It is beginning to appear that charging 4 batteries with a single 48v charger may take much longer due to this balancing act. It's a bit misleading for SmartBattery (or any Li battery seller) to describe these as 'plug and play'. That said, perhaps the balancing doesn't have to occur that often. I'll ask.

[hemsteadc]

Also note he says no battery management system. That is one of his quirks. This gets very confusing because BMS is used to refer to battery management system and battery monitoring system....

 

Again, the consensus in the RV and Sailboat community has become don't charge to such a high level but stop around 13.6, since you get very little extra capacity and all the risk. If you look at the charge curves contained at this link you will see what I mean. http://evtv.me/2012/07/calb-ca180fi-new-lifepo4-cell/ I

He also says not to connect those batteries in series. I guess it's just "those" batteries.

 

The chart shows a steady charge voltage of 14.4. Question: Does a regular LA charger rise in voltage as the Li is being charged, or do they simply rise to 14+ due to the characteristics of the Li batteries?

[Timon]

Keeping LiFePo4 batteries safe and well maintained is the function of the BMS. If you don't have a god BMS you WILL kill your batteries. With out a BMS any charger you use even a fully programmable one is going to kill your batteries. As long as your BMS has the ability to start and stop the charging and has the ability to disconnect all the loads your fine. The charger becomes nothing more and a source of bulk charging power. You don't need any of the other settings, just bulk as the BMS handles the rest. If your chargers malfunction the BMS will disconnect them thus protecting the batteries.

 

In addition the location of your LiFePo4 batters is important. You really don't want them in an area of your RV that sees extreme temperature extremes. To some this may sound strange but the best place for them is in the conditions space of your coach not out outside where the heat can reach over 100 or more and the lows can be below freezing. Since LiFePo4 batteries don't vent they are totally safe inside your coach. My plan when we get our 5th wheel is the batterie and BMS under the bed with the Inverter and charger equipment in the garage just underneath it.

 

As far as plug and play LiFePo4 that look like standard batteries, I'd stay away from them.

 

IMHO

[hemsteadc]

As far as plug and play LiFePo4 that look like standard batteries, I'd stay away from them.

Any particular reason?

[Daveh]

oldman . I wrote you a long response and then accidentally deleted to both your question and Timons statement. Argh. Will write tomorrow. By the way, look at this from progressive http://www.progressivedyn.com/lithium_battery_charger.html. Does away with the absorb and float but still at 14.4. To high? Many existing users think so and have research to back it up. Why are the big companies doing this? Don't know. Do they know something existing users don't? Could be but they need to explain it. The short answer to Timon's statement is that right now the plug and plays are the unproven lithium technology and come at a much higher cost.

[hemsteadc]

Yes, I posted a link to the same charger above. I find it difficult to believe the big companies are providing false information on purpose. Unproven, yeah, I can buy that, but it's very common to mistrust anything new.

 

I'm not liking the temperature sensitivity of these batteries, especially 90 and over. I don't do it often, but my battery compartment can easily get that hot. I could possibly mount them in my cooled basement.

[Smitty77_7]

I followed Paul & Nina's (Wheelingit) install. One of the reason Nina 'graciously(?)' gave up some of her storage, was so the bank could be installed inside the coaches living area (Rear bedroom area.). This was so they could help control the temperature as they maintained their own temperature comfort zone.

 

I've also seen one install where the battery basement area was sealed up from the outside, and a duct was spliced into to feed AC/Heating to the basement area. Each install could be different, due to differences in coach or trailer configuration.

 

One other thing I believe I've picked up from reading threads like this one, as well as talking with installers and owners of lithium battery banks. And that is to not cut corners on the BMS. Different price points, can bring different levels of management sophistication. At the price of these banks, yes coming down - but still pricey, cutting corners on less sophisticated BMS's, could be a short cut that will eventually be regretted.

 

We hope to have another 4-6 years out of our X's 4 L16's Lifelines:)! But when they go, we'll make the shift to a lithium bank. Came close to installing them 4-5 years ago, but just too new, not as many options for components - and I frankly wanted things to mature in the boating and RV'ing communities on someone else dime:)!

 

Best to all,

Smitty

[Timon]

Any particular reason?

See Daveh following post as he goes over the basics.

 

oldman . I wrote you a long response and then accidentally deleted to both your question and Timons statement. Argh. Will write tomorrow. By the way, look at this from progressive http://www.progressivedyn.com/lithium_battery_charger.html. Does away with the absorb and float but still at 14.4. To high? Many existing users think so and have research to back it up. Why are the big companies doing this? Don't know. Do they know something existing users don't? Could be but they need to explain it. The short answer to Timon's statement is that right now the plug and plays are the unproven lithium technology and come at a much higher cost.

Right, in addition you have no information from the BMS, such that it is, in the "all in one" batteries so you have no idea what's going on. A good BMS will have a display so you can monitor the condition of the batteries. The one 12V LiFePO4 battery that has an internal BMS that works very well is Vectron however they are quite expensive compared to other good LiFePO4 with external BMS solutions. AMSolar is a source for Vectrons excellent system.

 

As far as a PD LiFePO4 charger I'll have to look it over. You still need to be able to have the BMS shut it down when a full charged is reached as I don't want the charger doing that.

 

Yes, I posted a link to the same charger above. I find it difficult to believe the big companies are providing false information on purpose. Unproven, yeah, I can buy that, but it's very common to mistrust anything new.

 

I'm not liking the temperature sensitivity of these batteries, especially 90 and over. I don't do it often, but my battery compartment can easily get that hot. I could possibly mount them in my cooled basement.

This is why the best place for LiFePO4 is inside the conditioned space of your coach and not in hot compartments. Even during outdoor storage you can run your ventilation fans which should keep the inside of your coach in a range that the LiFePO4 can handle.

[Timon]

I think the PD LiFePO4 chargers would work out just fine. What I really like is that you can run them is series or parallel configurations. I don't see using a series configuration but parallel is a no brainer. This should allow one to keep one charger always connected when on a 120VAC 20A service and then kick the others in when running or 120/240VAC 50A service. They still require the BMS to disconnect them from the battery bank when fully charged.

 

Many BMSs will disconnect both the load and charge side as they only have one disconnect output so these will work best with ones that allows disconnecting the charging and loads independently. This also works best with Inverters only not Inverter/chargers such as the Magnums. Magnum doesn't have a good way to disable inverting and charging from a BMS so if using them I'd use an external charger and disable the internal one completely. I might change my mind if they could offer a connection which allow for independent disabling of charging and inverting using a two contact closures.

[hemsteadc]

They still require the BMS to disconnect them from the battery bank when fully charged

 

 

 

I don't understand why a BMS needs to be involved with both a charger that knows when to stop, and a battery that has built-in protection. The SmartBattery site doesn't list such a product. Is it because you think 14.4 is too high? Or because you want it to disconnect?

 

I understand the need for a monitor to know what the SOC is.