How does engine alternator charge house batteries?

[saflyer]

I am getting lithium (LiFEPO) batteries for the house. 4 12v 105 AH Lion UT1300s.  The engine alternator charges both the chassis and house batteries.  I have been told the alternator shouldn’t be used to charge lithium batteries as it is the wrong voltage, if I follow the logic.  If that is the case how are the house batteries charged by the alternator, directly or through some other charging system?  What will I need to disconnect to keep the alternator from charging the house batteries?  Actually I have always found it very convenient for the engine to charge them.  Is there a system I could add to make the alternator charge the house batteries properly?  Eventually I will get solar which should take care of this charging without the need of the alternator.  I planned to get the batteries after the solar installation but Costco had such a good deal I couldn’t pass it up.

 

Any suggestions for installing the batteries is appreciated.  They will be in parallel and I know the connecting cables should be the same length and gauge to keep the batteries balanced.  That’s about the extent of my knowledge.  I have a Magnum ME 2012 inverter/charger and Magnum tells me it has a charging program that is good for lithium.

Thanks,              
 Ed    
2005 HR Ambassador

 

[Guest Tim503]

What is the deal with lithium? Go back to flooded T105 or whatever your rig came with. I don't understand the move to lithium. Expensive learning curve.

[Guest Cruzbill]

This is what Battle Born uses for battery isolation. Replaces your Big Boy and BIRD. 

http://precisioncircuitsinc.com/wp-content/uploads/2019/10/00-10041-26x-Li-BIM-Rev1.pdf

 

As for Tim, Lithium is here to stay, Better than flooded lead acid in every way, including life cycle cost. They will put a dent in your wallet. 

[Joelsheriff]

Whats the avantage to using lithium when AGM won't require and special charging requirements p

[Guest Cruzbill]

Flooded lead acid, AGM and Lithium all have different charge characteristics.  Lithium will outlast an AGM by, I don't know, more than 10 to 1. Lithium = 3500 cycles. 1/2 the weight,  what's not to like? Price? 

 

 https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm

[Bob Nodine]

6 hours ago, Joelsheriff said:

Whats the avantage to using lithium when AGM won't require and special charging requirements p

It is my opinion that RVers who do a lot of boondocking (living off the grid) are attracted to lithium batteries because they can almost double the amp hours in the same cubic space as flooded or AGM.  If you do the majority of your camping connected to the pedestal then lithium is not practical from a cost standpoint. 

[Military RVer]

Lithium batteries are a great way to go and the Battle Born one's are the best money con offer. but understand they are not truly lithium batteries. They are LifePO4 which is lithium iron phosphate, which is a subset of lithium batteries. LifePO4 are very expensive and outlast lithium 4-6:1 and AGMs 40-60:1. If I had a choice between AGM and LifePO4, I would take LifePO4 every day as they are safer and more reliable. Yes they take a dedicated style of charging but 99% of all MPPT solar chargers are equipped to work with lithium. I use AGMs right now as I am cheap and I get them at a very discounted rate.  When I have the money, I will change over to LifePO4 for house batteries but for the mean time, I will be using AGM.

[wamcneil]

So... are we done debating the merits of the poster’s choice of battery technology??? 
Maybe get back to the question in his post????

[jacwjames]

Yes I agree, let's get back to the original question. 

Why can't the alternator charge lithium batteries.  I've read a lot of posts on IRV2 regarding lithium and do not remember anyone saying that they should not be charged with the alternator.  Seems counter intuitive. 

[wamcneil]

What’s the alternator’s voltage?  Lifepo4 has a charge plateau of 3.5v per cell.  (14v total). As long as the alternator isn’t much over 14v it should be fine as far as voltage, right? 
I can see how amperage might be a problem though.  If the batteries are low they would take everything the alternator can put out, which might be hard on the alternator or be over the max charge current of the batteries. 
Walter

[waterskier_1]

On 6/28/2020 at 7:49 PM, Cruzbill said:

This is what Battle Born uses for battery isolation. Replaces your Big Boy and BIRD. 

http://precisioncircuitsinc.com/wp-content/uploads/2019/10/00-10041-26x-Li-BIM-Rev1.pdf

 

As for Tim, Lithium is here to stay, Better than flooded lead acid in every way, including life cycle cost. They will put a dent in your wallet. 

I just check this device out.  According to the manufacture the way they attempt to handle the problem of overcharging a Lithium battery is by disconnecting it from the charging source when it reached close to full charge.  Then, as the battery is used, it lets it go down to about 80% SOC before it starts to charge it again.  This "disconnect"  applies to the Lithium batteries while going down the road with the alternator running (charging)  OR it applies to the chassis battery when being charged by Shore Power with an appropriate Lithium battery charger.  This allows for the case that when you arrive at your destination after driving, your house (lithium) batteries might be at only 80% to start with.  It also allows for the chassis battery to be at only 80% when you get ready to leave after being connected to shore power.   While that may be acceptable to some, it is really a band-aid to me.  The reason they disconnect while being charged by the alternator is because the batteries require a "float" voltage of no more than 13.6 Vlots (Battlebone Lithium Spec).   Instead of using some sort of Pulse Width Modulation (like very basic Solar controller do) or better a MPPT arrangement like better solar controllers do, to make a controller for the Lithium Float Voltage (reducing the incoming 14.2 -14.4 alternator voltage).   

To clarify the OPs question on the concern of using an alternator for charging Lithium batteries I'll offer the following:  Per Battleborn Battery's Spec's the Bulk and Absorption voltage should be  14.2 - 14.4 Volts.  This is just what an alternator is outputting; so far we're good.  But it then states that the Absorption time should be set to 20 minutes.  That's a really short trip for most of us.  But the real problem is that once the battery is charged, you must reduce the voltage to the Float voltage of no more than 13.6 volts.  This is where the problem with charging by an alternator manifests - the alternator does have a voltage regulator, but it isn't smart.  It regulates the voltage to 14.2 -14.4 Volts, continuously (within it's design capabilities).  So, what to do.  I discussed some methods above.  I believe the best solution, and I really don't think it's a far stretch, is to add solar.  I think most who are considering adding Lithium batteries already have or plan to add solar.  Most are doing this to enhance their dry camping abilities, and that would surely incorporate Solar.  If you have a reasonable amount of solar power, you would simply use that to charge your house (Lithium) batteries while driving down the road or while camped.  I currently do this even though I don't have Lithium house batteries.  I have Lifeline AGM batteries.  They are a bit more tolerant of seeing Absorption level (14.2 - 14.4+) volts over and extended period, but it doesn't do them any good.  So, I have disabled my Big Boy from charging the house batteries.  I've got it wired so I can still connect both the chassis and house batteries together with the the dash "boost" switch if needed.  This also keeps my chassis battery from being charged by the Inverter/Charger (or, in my case, the main solar systems (I have 3 - two for the house - the original controller could only handle 50 Amps so I had to add another, and one for the chassis).   So, my chassis battery is charged by the original 100 Watt solar panel Monaco provided.  The house batteries are charged by the remaining panels.   Using this system, I do have to be aware of solar availability.   If necessary, I can quickly re-engage the Big Boy system.

Sorry for the long post.  Hopefully if you understand the charging requirement, you can see the problems and then potential solutions.

[Guest Cruzbill]

I'm sure you are aware that solar is a very expensive trickle charger. Your 100w solar panel outputs 5amps on a sunny day at noon.  If you are connected to shore power, your inverter will top off the lithium (and chassis) batteries in short order. If you are dry camping, you'll have to run your genny sometime to replenish your batteries, or if you have enough solar and enough sunlight. Lithium really doesn't need any type of charge except bulk, no adsorption or float is necessary. You think the Precision Circuits device could just allow the house batteries to come up to 100%, then isolate to 80%. Repeat. Same for the chassis at the different, flooded voltage.  

 

Happy 4th!

[waterskier_1]

18 minutes ago, Cruzbill said:

I'm sure you are aware that solar is a very expensive trickle charger. Your 100w solar panel outputs 5amps on a sunny day at noon.  If you are connected to shore power, your inverter will top off the lithium (and chassis) batteries in short order. If you are dry camping, you'll have to run your genny sometime to replenish your batteries, or if you have enough solar and enough sunlight. Lithium really doesn't need any type of charge except bulk, no adsorption or float is necessary. You think the Precision Circuits device could just allow the house batteries to come up to 100%, then isolate to 80%. Repeat. Same for the chassis at the different, flooded voltage.  

 

Happy 4th!

The coach came with the 100W solar panel.  It is of a different design than the other 10 Panels that were installed.  Rather than take it down, or leave it disconnected, since it couldn't be incorporated into the house solar arrays, I connected it to the chassis battery.  That way, with the Big Boy disconnected, I still can maintain the chassis battery - all for free.  I would have to reconnect the Big Boy for the generator to charge the chassis batteries.  I didn't want to have to open the engine hatch and connect/disconnect the Big Boy every time I arrived at a campsite/or RV Park.  

I believe what you stated about the Precision Circuits device is exactly how it works.  The problem for me is that allows for an only 80% SOC condition when I stop driving, or stop shore power charging.  That is less than ideal to me.  It may be acceptable to you.  As an Electronics Engineer, I find it more of a bandaid than a true solution.  Ideally, I want all batteries to be at 100% SOC whenever I quit the charging process - whether it be from the Alternator, Shore/Genny Power or Solar Power.  I do realize that is not always possible, but that is what I strive for.

 

[Ivan K]

1 hour ago, waterskier_1 said:

The coach came with the 100W solar panel.  It is of a different design than the other 10 Panels that were installed.  Rather than take it down, or leave it disconnected, since it couldn't be incorporated into the house solar arrays, I connected it to the chassis battery..

 

Exactly what I have done with our factory solar system, isolated it from the house and added separate system just for the house. Works great for our needs. Our house batteries are still newish and good but lithium may be next, in time. By then you guys will have it all sorted out 😎

[dl_racing427]

14 hours ago, waterskier_1 said:

The coach came with the 100W solar panel.  It is of a different design than the other 10 Panels that were installed.  Rather than take it down, or leave it disconnected, since it couldn't be incorporated into the house solar arrays, I connected it to the chassis battery.  That way, with the Big Boy disconnected, I still can maintain the chassis battery - all for free.  I would have to reconnect the Big Boy for the generator to charge the chassis batteries.  I didn't want to have to open the engine hatch and connect/disconnect the Big Boy every time I arrived at a campsite/or RV Park.  

I believe what you stated about the Precision Circuits device is exactly how it works.  The problem for me is that allows for an only 80% SOC condition when I stop driving, or stop shore power charging.  That is less than ideal to me.  It may be acceptable to you.  As an Electronics Engineer, I find it more of a bandaid than a true solution.  Ideally, I want all batteries to be at 100% SOC whenever I quit the charging process - whether it be from the Alternator, Shore/Genny Power or Solar Power.  I do realize that is not always possible, but that is what I strive for.

 

From what I've gathered, it's recommended to not charge Lithium batteries above 80%, nor to discharge them below 20% SOC.  Doing so will significantly shorten their life.

They're effective capacity is only around 60% of advertised capacity.

[Harvey Babb]

I think you all are  making this too complicated. LiFePO4 batteries have BMS (battery management system) built in. When the battery reaches full charge it will disconnect itself internally. Likewise, when the voltage drops below safe minimum it will disconnect to protect itself.

I stopped using AGM's on my mobility scooter 4 years ago and installed USED LiFePO4's. (I have a spinal cord injury and can't walk at all, so scooter is in use 16+ hours daily) They are finally showing slight decrease in capacity (but are still better than NEW AGM's). With AGM'S I was replacing batteries two to three times a year and still putting up with sluggish operation. Only downside to lithiums is that they don't give any warning when going down. When you reach minimum safe voltage the battery disconnects and you STOP! 

I just got a new scooter and spent $840 for a new set of LiFePO4 batteries. I will never go back to lead!

 

 

[jreich888]

The alternator can charge the lithium batteries fine, in fact it is probably too capable. 

When the alternator is charging the house lithium batteries, the big risk is that the alternator can overheat.  The lithium batteries can charge much faster than lead acid (lower internal resistance), so with a traditional relay (i.e. BIRD, Big Boy) the alternator will provide all the power it can, which leads to overheating, reduced life, and eventual failure.  That's why Battleborn recommends the Precision Circuits LI-BIM.  When charging via the alternator the LI-BIM cycles 15 minutes on, 20 minutes off to allow the alternator to cool. 

Regarding maintaining battery charge (some of this topics posts' focus), note that the product description from Precision Circuits states: "The Li-BIM does not guarantee 100% battery charge, but prevents harmful battery charge levels."   The LI-BIM is not a battery maintainer for the chassis batteries, but does helps bulk charging at times.  Its focus is on protecting your batteries and your alternator.  If you don't have another solution for your chassis batteries, you may want to add a trickle charger or a small solar panel for the charge maintenance.  

References:
http://www.precisioncircuitsinc.com/wp-content/uploads/2017/06/00-10041-2xx-Battery-Isolation-Manager-Rev7-1.pdf
https://battlebornbatteries.com/product/lifepo4-battery-isolation-manager/

[waterskier_1]

On 7/5/2020 at 11:43 AM, jreich888 said:

The alternator can charge the lithium batteries fine, in fact it is probably too capable. 

When the alternator is charging the house lithium batteries, the big risk is that the alternator can overheat.  The lithium batteries can charge much faster than lead acid (lower internal resistance), so with a traditional relay (i.e. BIRD, Big Boy) the alternator will provide all the power it can, which leads to overheating, reduced life, and eventual failure.  That's why Battleborn recommends the Precision Circuits LI-BIM.  When charging via the alternator the LI-BIM cycles 15 minutes on, 20 minutes off to allow the alternator to cool. 

Regarding maintaining battery charge (some of this topics posts' focus), note that the product description from Precision Circuits states: "The Li-BIM does not guarantee 100% battery charge, but prevents harmful battery charge levels."   The LI-BIM is not a battery maintainer for the chassis batteries, but does helps bulk charging at times.  Its focus is on protecting your batteries and your alternator.  If you don't have another solution for your chassis batteries, you may want to add a trickle charger or a small solar panel for the charge maintenance.  

References:
http://www.precisioncircuitsinc.com/wp-content/uploads/2017/06/00-10041-2xx-Battery-Isolation-Manager-Rev7-1.pdf
https://battlebornbatteries.com/product/lifepo4-battery-isolation-manager/

After reading the battleborn description, I find this worse than a bandaid.  The precision circuits description did not disclose how it accomplished the switching to maintain 80% to 100% charge.  But the battleborn description of simply switching based on time is, to me, unacceptable.  It says that the alternator is connected for 15 minutes. then disconnected for 20 minutes. and then repeats.  If the Lithium batteries are quite depleted, they would destroy the alternator in 15 minutes when attempting to draw 100's of Amps.  

On 7/5/2020 at 7:01 AM, Harvey Babb said:

I think you all are  making this too complicated. LiFePO4 batteries have BMS (battery management system) built in. When the battery reaches full charge it will disconnect itself internally. Likewise, when the voltage drops below safe minimum it will disconnect to protect itself.

 

 

 

I'm sure there may be some Lithium batteries that have that sophisticated of a BMS, but it does not appear that the Battleborn batteries do.  While their BMS will prevent severe discharging, and operation outside certain temperature conditions, they clearly state that the Bulk & Absorption voltage should be 14.2 - 14.6 Volts, with an Absorption time of 20 minutes.  Then you should switch to Float at 13.6 Volts.  They do NOT have any overcharge voltage built in, or at least they don't state that is the case.  I doubt they do, or there would be no need to clearly specify the Bulk, Absorption and Float voltages.  

[Harvey Babb]

From battle born "BMS Basic Features"

"High voltage: > 14.7V 

If an individual cell voltage exceeds a prescribed threshold during charging, the BMS will prevent a charge current from continuing. ..... "

I have been living with these things literally 8 inches under my butt for years now and I can't run if they go Chernobyl. Believe me, I have researched them extensively and carefully!

I challenge you to break a Battle Born battery. They are, IMHO, seriously over priced, but as bullet proof as it gets.

 

[TomV48]

On 7/3/2020 at 1:23 PM, jacwjames said:

Yes I agree, let's get back to the original question. 

Why can't the alternator charge lithium batteries.  I've read a lot of posts on IRV2 regarding lithium and do not remember anyone saying that they should not be charged with the alternator.  Seems counter intuitive. 

I understand the issue to be that your alternator MAY not be able the handle the load of charging LiFePo.  Internal resistance of LiFePo is nearly non existent.  It will take, in most cases, all your alternator can deliver, and then some.  BattleBorn advocates a form of isolator BIM that only allows the load on your alternator about 50% to protect it from the possible overdemand by the batteries

[waterskier_1]

23 minutes ago, TomV48 said:

I understand the issue to be that your alternator MAY not be able the handle the load of charging LiFePo.  Internal resistance of LiFePo is nearly non existent.  It will take, in most cases, all your alternator can deliver, and then some.  BattleBorn advocates a form of isolator BIM that only allows the load on your alternator about 50% to protect it from the possible overdemand by the batteries

No, while that may be an issue, the main issue is that most lithium batteries want 14.0 - 14.6 VDC in Absorption mode for 20 - 30 minutes, and then drop back to less than 13.6 VDC.  Your alternator would have them at over 14 VDC for hours!  There are ways around that problem, as discussed above, but that is the main concern. 

 

[saflyer]

At the bottom of this page:

https://lionenergy.com/products/lion-safari-ut-1300
 

“Can I charge from an alternator?”

”Yes, the Safari UT will take too much current so you must limit it with the wire you use to charge it. For example, if you need 10-12 feet of wire, a 10-12 gauge wire will work to limit the current. Double check the actual current with a current meter and size the fuses appropriately. You may need to add fuses and other protective equipment to protect the system. To prevent possible damage to your alternator we recommend using the Redarc (Model #BCDC1225D), which is a DC-DC charger. It will safely charge your batteries while you are driving.”

The BCDC1225D and fuse should take care of your question.

Redarc and Renogy also have DC-DC converters that include 25-50 amp MPPT solar chargers .  I’d look into them.

On 7/3/2020 at 3:23 PM, jacwjames said:

Yes I agree, let's get back to the original question. 

Why can't the alternator charge lithium batteries.  I've read a lot of posts on IRV2 regarding lithium and do not remember anyone saying that they should not be charged with the alternator.  Seems counter intuitive. 

My understanding is the alternator will charge the lithium to a lower voltage, maybe 13.6, than they want, 14.6 I think, so they are not 100% charged from the alternator.  I think the bigger issue is that if the lithium batteries are depleted a significant amount, how much I don’t know, they will draw a larger current than the alternator can handle leading to it’s shortened life.  You can solve this problem with wiring that has a resistance that keeps the current in check or by using one of the devices I noted above.

Edited September 9, 2020 by saflyer
Add mor information

[wamcneil]

13 hours ago, saflyer said:

At the bottom of this page:

https://lionenergy.com/products/lion-safari-ut-1300
 

“Can I charge from an alternator?”

”Yes, the Safari UT will take too much current so you must limit it with the wire you use to charge it. For example, if you need 10-12 feet of wire, a 10-12 gauge wire will work to limit the current. Double check the actual current with a current meter and size the fuses appropriately. You may need to add fuses and other protective equipment to protect the system. To prevent possible damage to your alternator we recommend using the Redarc (Model #BCDC1225D), which is a DC-DC charger. It will safely charge your batteries while you are driving.”

 

Hmmm. Whenever I get around to lithium batteries... I think I'll go the route of DC-DC charger.

That approach of just using a length of 10-12 ga wire as a current-limiting resistor doesn't sit well with me...

Cheers,

Walter

Edited September 8, 2020 by wamcneil

[gofastnow]

""

“Can I charge from an alternator?”

”Yes, the Safari UT will take too much current so you must limit it with the wire you use to charge it. For example, if you need 10-12 feet of wire, a 10-12 gauge wire will work to limit the current. Double check the actual current with a current meter and size the fuses appropriately. You may need to add fuses and other protective equipment to protect the system. To prevent possible damage to your alternator we recommend using the Redarc (Model #BCDC1225D), which is a DC-DC charger. It will safely charge your batteries while you are driving.”

The BCDC1225D and fuse should take care of your question.

Redarc and Renogy also have DC-DC converters that include 25-50 amp MPPT solar chargers .  I’d look into them.

 

The above statement of using the battery wire as a current limiting resistor is dangerous!!!! A RECIPE FOR FIRE!!!!! This appears to have come from the battery manufacturer?? I would never buy from an organization that would would make such a reckless statement.

[waterskier_1]

24 minutes ago, gofastnow said:

I totally agree.  Even if super-heating the supply wire wouldn't be dangerous, it's a total waste of energy.  All that voltage being dropped is being converted into unusable heat.  We need to conserve as much energy as possible.  There are ways of accomplishing the charging, but this is NOT one I'd recommend, or use.  If an insurance adjuster found this as the cause of a fire, it would likely disqualify reimbursement.

For me, the easy answer, and I'm doing this now but without Lithium batteries, is to simply disconnect the alternator and use solar panels with a quality MPPT controller set up for the batteries you are using.  Solar would just fine going down the road, although most only think of it when boon-docking.  I have provisions to engage my chassis battery with my house battery both with the Boost switch and another switch I've added, which would allow judicial use of the alternator to charge the house batteries.  I've never found the need for it.  But, I have never taken off with fully discharged house batteries.  That can be very hard on the alternator and charging circuits with lead-acid batteries too.  I'll run the generator while getting stuff put away, pulling the slides in and hooking up the toad.  That will usually put enough charge on the house batteries that the solar can take over.  

  -Rick

“Can I charge from an alternator?”

 

 

The above statement of using the battery wire as a current limiting resistor is dangerous!!!! A RECIPE FOR FIRE!!!!! This appears to have come from the battery manufacturer?? I would never buy from an organization that would would make such a reckless statement.