Charging Vehicle and House Batteries that are Different Types (e.g. FLA and AGM)

[ckent323]

I have been planning to install the Blue Sea ML-ACR in place of the Surepower 1202 already in my truck.

I was going to bypass the IOTA charger controller with IQ-4 and take the wires directly to my camper bank. However, a consideration is that my truck only has a voltage regulator, no smart charger.

Further, the truck battery is a NAPA BAT-7235 1125 cca FLA. The camper batteries are a pair of Lifeline 220 A 6 V AGM.

from Blue Sea:

An ACR does not direct the charge to the battery that “needs it the most” or has the lowest terminal voltage. If there is a charge present on either battery, indicated by a high enough voltage, the ACR will combine the batteries.

One ACR will manage the charge between two battery banks. but the batteries need to be the same type (and probably manufacturer) because the ML-ACR can only handle one type of battery in a system.

Today I came across the Balmar Duo Charge while searching for a way to Automatically charge vehicle and house batteries of different battery types.

It seems this Balmar unit is designed to accommodate that exact situation

"The Duo Charge is designed specifically to enable its user to control charging voltage output -- making it possible to safely mix house and starting battery technologies. The Duo Charge features four different programs based on four battery technologies: Standard Flooded, Deep Cycle Flooded, Gel and AGM battery types. In addition, the Duo Charge can be programmed for 12-volt or 24-volt operation. When used with an optional Battery Temperature Sensor cable (MC-TS-, the Duo Charge responds to a battery over-temperature condition by automatically discontinuing charging output."

http://www.balmar.ne...tal-duo-charge/

If anyone has experience with this device I am interested in reading your comments.


Craig

 

[ckent323]

I just received a reply to my inquiry to Balmar about charging vehicle and house batteries of two different types. Here is the reply:

"Craig,
We do have a device called a Digital Duo Charge (DDC). It goes between two battery banks and can drop the voltage to the secondary battery but it cannot increase it. So if the main bank is charging at 14.6 volts and the secondary want to be at 14.3 the DDC can reduce it down.

The DDC has a 30 amp limitation. If the secondary bank's demand is over 30 amps the DDC shuts down, waits a few seconds and tries again. If the demand stays over 30 amps the DDC won't turn on.

I think the 30 amps limit is going to be a show stopper. Your "house" AGMs will be discharged more deeply than the FLA start battery and require more than 30 amps to recharge them. I would like to make the sale but I don't want you to buy something that's not going to work for you.
I have included the DDC manual and quick start guide for you to review.

Best Regards,
Thomas Pusateri"


Nuts! I am still looking for a solution.

Craig

 

[ckent323]

Sterling Power makes a 12 V charge controller that will handle up to 60 Amps which may be enough given that the house batteries do have solar charging - but if deeply discharged I would have to wait for the solar to bring the house bank up before this would kick in - if I understand its operation correctly.

However, it is expensive and in order to work with two different battery types it requires an add on battery chemistry module which is also expensive.

For those of you going to LiFePO4 this will accommodate those batteries as well and allow you to use a different battery in your vehicle.

Here is a link to the 12 V 60 A controller

http://www.sterling-power-usa.com/sterlingpowerusaprocharge12volt60ampbatterycharger.aspx

and a link to the battery chemistry add on module:

http://www.sterling-power-usa.com/batterychemistrymodule-2.aspx


Unless I can get these at significant discount they are too expensive for me. I am now going to search on what Xantrex might have.


Craig

 

[pvstoy]

Thanks for more info. I still thinking of a dual battery isolator that has the didoes. I know there is a drop in voltage to the batteries but you would still have the amps. And the batteries would never see each other unless a "A" "B" switch was installed.


***Craig I posted this on the other post before you had it here.

Craig this company has a lot to sell for complete systems for marine systems and I'm a little confused on two things.

1) The wiring diagram has the alternator wire going to the house battery then to the DDC unit. But there is a "S" wire from the battery post of the house battery going to what I think is a regulator. Then after the DDC unit it connects to the starter battery.

2) It is a 30 amp system meaning that is what the battery will get. But adds "An optional solenoid control enables higher start battery charging output when required."
.
.

Digital Duo Charge: DDC-12/24
[SIZE=large]Multi Bank Charging[/SIZE]

• [SIZE=medium]The DDC is a Solid-State Battery Combiner[/SIZE]
• [SIZE=medium]Control Voltage and Current between House and Start Batteries[/SIZE]
• [SIZE=medium]Eliminates the Need for an Isolator, Relay or Manually Operated Battery Switch[/SIZE]
• [SIZE=medium]Used in Concert with Max Charge or ARS-5 Regulators[/SIZE]
• [SIZE=medium]Can also be Employed without a Balmar Regulator[/SIZE]
• [SIZE=medium]Works in Both 12V and 24V Applications[/SIZE]
• [SIZE=medium]House and Start Batteries can be different technologies[/SIZE]
• [SIZE=medium]Start Battery Temperature Sensing Available with the MC-TS-B Sensor Cable[/SIZE]
• [SIZE=medium]4 Battery Programs Supported for the Start Battery:[/SIZE]
  [SIZE=small] Standard Flooded, Deep Cycle Flooded, AGM and Gel Cell[/SIZE]

[SIZE=small]The Digital Duo Charge[/SIZE] (DDC-12/24) provides a “hands off” solution for charging two battery banks without the use of problematic isolators or manual battery switches. [SIZE=small]During charging the DDC-12/24 monitors voltage at the house battery. When voltage exceeds the set minimum (typically 13.2V in a 12V system and 26.4V in a 24V system) the DDC-12/24 automatically engages, providing up to 30A charge current to the starting battery. When no charge source is present, the DDC-12/24 separates the batteries so the starting battery won’t be accidentally discharged into the house battery. An optional solenoid control enables higher start battery charging output when required.

[/SIZE]

 

[ckent323]

Pvstoy,

The problem is that if your starting and house batteries are different types you may undercharge/overcharge one of them and prematurely reduce it's life.

Here is what happened to me: I had a Sears Diehard Platinum (old Deka model) AGM 1050 cca battery in my truck. My truck is a 1993 Dodge W250 Diesel and it does not have a smart charging system so the AGM was not being properly charged.

Over the summer I replaced the two 6 V 200 Ah Golf Cart FLA house batteries in my camper with two Lifeline 6V 220 Ah AGM batteries. I also added Solar and a Victron solar controller and battery monitor. This system works fine stand alone. I had never had my truck electrical connected to my camper.

This past summer just before leaving on a 5 week trip I decided I wanted to connect the truck charging to the camper to make sure I did not let the camper house batteries run down too far. My truck had a 1202 Surepower battery separator in it (not previously connected during the 19 years I have owned the truck) so I connected it with the primary side going to the truck battery (AGM) and the auxillary side going to the camper house batteries. I used 6 Ga wires to go to the camper (through the IOTA DLS-30 with IQ-4 smart charger.

During the trip my battery monitor showed that at best I was only getting around 7 to 10 amps to the camper batteries from the truck. I was not happy with that and also wanted the ability to jump the truck battery from the camper (I had a strange headlight switch malfunction during the trip in which one headlight turned off but the other stayed on - I did not notice it and in the morning I could not start the truck).

So I decided I wanted to install an ML-ACR which would allow automatic charging of the starting and house batteries as well as jump start the truck from the camper. Unfortunately, I did not realize that the ML-ACR only works if all the batteries are the same type.

Before I figured this out I replaced the AGM starting battery in the truck with a new FLA battery (NAPA BAT7635 1125 cca) because it died after 4 years and I realized (too late) that is because there is no smart charger in the truck so it was never getting properly charged - actually was probably being over charged and AGMs do not like that.

Edit: Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive.

Doh!


Now I am thinking I should have 1) bought a smart charger for the truck 2) bought a replacement AGM battery for the truck and I think that would have allowed me to use the ML-ACR by bypassing the IOTA DL-30 and connecting directly to the camper house battery bank.

The Sterling system would probably work but the best price I found for the Sterling Ultra pro 12 v 60 amp is $400 and the add on battery chemistry module is another $275. Ouch!

If I buy a smart under hood battery charger for the truck that will cost around $200 but a new 1050 cca AGM battery will cost around $250 (not to mention the $170 I just paid for the new NAPA battery).

The ML-ACR will cost about $175 in any event.

I have contacted Xantrex and Ctek to see what they may have before I decide what to do.

Dang this is taking a lot of time! The upside is I am learning a lot. ;-)

The bottom line for anyone running anything beside FLA batteries and in particular if the vehicle battery is different than the camper batteries BEWARE you may be prematurely killing your batteries by not using the correct smart charge controller set up.

Craig

 

[Stokeme]

Hey Craig ... you still may have the 30 amp problem with this unit, and mine is single lithium 100ah, but this was recommended by my battery manufacturer. How does your two 6V, with 110ah run in parallel, differ from my 100ah lithium, other than the available draw/cycle?

http://www.sterling-power-usa.com/SterlingPower12volt-12volt-30ampbatterytobatterycharger.aspx

 

[cwdtmmrs]

I've heard it isn't right, but I have had an Optima yellow top in the camper for 11 years now hooked to an Interstate FLA starting battery in the truck through just a HD relay. I am on my 2nd Interstate, but that is normal no matter what. It wasn't until last year that even checked the Optima, and it still load tested good.

Cwd

 

[ckent323]

Stokeme,

Not sure I understand your question. Sterling makes a 60 amp unit ==> BB1260 best price I have found is $400. The Sterling USA rep replied this evening to my inquiry and said it will work for my application but he did not mention the Battery Chemistry module so I sent a follow up question asking if it was actually needed.

So far my Lifeline 6V batteries are doing fine. The 200 W solar system is keeping them topped off in float mode nicely (I did program the Victron 75/15 with the voltages for my particular batteries).

I get a usable 110 Ah out of them if I take them to 50% SOC but usually I don't run them lower than 65% - 70% SOC. So similar capacity as your LiFePO4 at less cost but more weight and more space I suspect.

BTW: Be sure your system is properly charging and maintaining your expensive LiFePO4 batteries. I have read several accounts by commercial boaters who have had premature failure of their LiFePO4 batteries and it is my interpretation from their write-ups they did not understand the charging needs of the LiFePO4s and charged them like FLA or AGM batteries. Expensive mistake!


cwdtmmrs,

I think one of the reasons (and perhaps the primary reason) that auto and truck batteries don't last is that many vehicles do not have smart charging multi-stage charging systems and only rely on a voltage regulator. When voltage drops below 13.5 volts, the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 volts, the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery.

Depending on how often and how far the car is driven the battery is likely undercharged or overcharged and never charged optimally.

https://www.carparts.com/classroom/charging.htm

Lead acid batteries should be charged in three stages, which are [1] constant-current charge, [2] topping charge and [3] float charge similar to AGM and Gel batteries.

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

So vehicles without a smart charger system routinely undercharge or overcharge the battery resulting in premature failure. No wonder vehicle batteries only last 4 or 5 years! How many consumers know this???

Based on what I think I know right now I would put an under hood smart charger in my truck and then put an AGM battery in the truck to be same chemistry as my camper house batteries (which are AGM). That would allow use of the ML-ACR etween the truck and the camper batteries.

Of course if the truck and camper has FLA or both had Gel that would work too. The only problem using the Ml-ACR is if the starting battery and the house batteries have different chemistry.

So far if the truck has one chemistry and the camper has another the only solution for properly connecting the two is the Sterling BB1260 (can supply 60 amps). The good news is that the Sterling will charge LiFePO4 as well as FLA, GEL or AGM and may be the only charge controller that can do that (but that may require the optional battery chemistry module - I am still waiting to find out if this actually needed - stay tuned).

I am getting incrementally smarter about this stuff but unfortunately it is slowly and incrementally. ;-)


Craig

 

[ckent323]

Stokeme and pvstoy,

Follow-up on the Balmar Digital Duo-Charge. It may work with the addition of a solenoid.

I read the manual and noted the following:

"In applications where the Duo Charge is used to support larger capacity starting batteries (such as 4D and 8D models) or windlass and/or thruster batteries, there may be instances when the 30-amp capacity of the Duo Charge’s circuitry may not provide sufficient current to satisfy demands.

When used as a stand alone charge source, the Duo Charge is designed to discontinue charging when demands exceed its capabilities. At that point, the Duo Charge will wait for a short period and query if the demand has diminished to below its 30-amp capacity. If so, the Duo Charge will continue charging. If demand continues to exceed capacity, the Duo Charge will continue to shut down, while checking periodically to see if demand has diminished.

If your application requires frequent charging levels in excess of 30 amps, it may be necessary to add a solenoid as a method to manually bypass the Duo Charge’s internal circuitry. Keep in mind, the Duo Charge will not automatically activate the solenoid if the demand exceeds its capacity. As such, it is important to monitor charging voltage closely at the battery being charged by the Duo Charge.

To utilize the Duo Charge’s solenoid drive function, it will be necessary for the user to supply an appropriate-capacity solenoid and a toggle or other ON/OFF switching mechanism to control the bypass function.

Once installed, the Duo Charge will be in the Auto mode whenever the toggle switch is in the OFF position, and charging will occur via the Duo Charge’s internal circuitry. When the toggle switch is in the ON position, the Duo Charge will revert to manual mode, allowing the solenoid to control charge flow to the secondary battery bank.

Ref: http://www.balmar.net/wp-content/uploads/2015/11/PDS-DDC-1224.pdf

I am also investigating using a smart charging regulator between the alternator and thee batteries along with ACR between the batteries. If the smart charging regulator can adjust for whichever type battery the ACR allows to be connected then perhaps this is a solution path. That would be better than using a solenoid and manual switch.

Now that I am thinking this through, another (and perhaps best) option may to use the ML-ACR and put a smart charger between it and the AGM house batteries. The root issue is that the AGM batteries are sensitive to overcharging and most vehicle voltage regulators put ot too high of a voltage thus overcharging AGMs on a long drive. So this option may solve that.

I am waiting for the Balmer rep to respond to my question about using a smart charger with the ACR.


Craig

 

[Vic Harder]

Craig,

I wonder if you are over thinking this. (that's a rando line that he has used on me a few times - )

Because I have metering in my truck cab, and the remote switch for the ML-ACR as well, I can keep an eye on this when I drive. I also do have similar battery chemistry in truck and camper - both are AGM, but that does not mean they both want the same voltage/current. Only the battery spec sheet can tell you that.

I generally keep an eye on the battery voltages, and once the Victron 702 Bluetooth app tells me that my house batteries are at 95%+, I disconnect the alternator from the house batteries by using the remote switch for the ML-ACR. That said, I have seen times where a nice sunny day in Utah when the house batteries were at 98%, the ML-ACR had the two battery banks connected, and the solar panels on the roof were over-powering the alternator and sending current INTO the truck battery (and the house batteries).

It's complicated. Ideally, there would be a smart charger on both ends, and accepting raw power from multiple sources and conditioning for the batteries they are connected to. I have yet to see such a system.

 

[ckent323]

Vic,

Hah! I have been asking myself the same thing: "are you over thinking this"?

I have the house batteries instrumented with the Victron BVM-702 with bluetooth dongle and I will be installing a Bayrite volt/ammeter on the truck battery.

The ML-ACR would give me control, as you point out, and perhaps the most cost effective solution is the old school approach before the VSRs and ACRSs came on the market - pay attention and manually switch as required. But don't forget to switch!

Your comments are appreciated!

;-)

Edit: I just read your comment about overthinking this to Wendie, She immediately started laughing and said yup that sounds familiar!

Hah! We are all in agreement. Must be closing in on the solution then.

;-)


Craig

 

[klahanie]

Craig, I dug up this charging test for your further reading. I think these are the Lifelines you have but in the 12V version which I have.

https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/

 

[ckent323]

klahanie,

Thanks. Yes, I have been looking a lot deeper into this.

Here is my current thinking (pun intended):

I can install a ML-ACR and periodically check my Victron BVM-702 battery manager. Once the batteries move to absorption stage from bulk charging I would use the remote switch for the ML-ACR to disconnect the house batteries and just reply on the solar to finish the charging job. (Thanks to Vic for pointing this out).

The downside is that it is not automatic and idiot proof (I could forget to switch the house battery out of the charging circuit). But it is one heck of a lot cheaper and less trouble than the battery to battery chargers I discussed above. Further, it is not clear to me if the battery to battery chargers can support jumping the starter battery from the house batteries (still waiting for that question to be answered)

As for jump starting the truck diesel via the ML-ACR (or some other device) I got worried when looking at wire size charts and allowable current capacity of wires. My starter can pull from 450 - 700 amps while cranking. Even 4/0 wire is not rated for that amount of current

But then I realized the ratings are for steady state current.

So I found the following equation to calculate the wire size need for short term current.

S =( Ia.√t) / k

Where : S : Conductor cross section in mm2
Ia: Effective (rms/amount of DC current) value of current (A)
t: duration of hazardous shock current (sec.)
k: Cable Insulation Material Coefficient:
For PVC-insulated CU conductors : k=115 As/mm2
For PVC-insulated Al conductors : k=76 As/mm2
For rubber-insulated CU conductors : k=141 As/mm2-

Reference: https://www.physicsforums.com/threads/short-term-ampacity-in-cables.330713/

Also I think that the truck battery will be not too far below the starter threshold current need of 450 amps when it is too low to crank the starter so I probably don't need more than 400 amps during jump starting (assuming the truck battery still has 200 - 300 amps or so available).

My truck usually starts with 3 - 4 seconds of cranking but when it is very cold it can take twice that long. I did a calculation using 30 seconds and 400 amps assuming the CU PVC insulated wire and that resulted in a wire cross section of 19 mm2. 4 ga wire has a cross section of 21.1 mm2

My conclusion is that 4 ga would work but 2 ga gives me some margin. I like margin when designing things.

(now I understand why jumper cables which often only have 4 ga wire and are 20 feet long actually work)

P.S: for a non-diesel starter the current requirement is significantly less so my guess is that 4 ga and perhaps 6 ga might be adequate for gas engines.


I hope this is helpful to others following this as well. Also if anyone sees any errors here please comment.

Craig

 

[Vic Harder]

current thinking... LOL! I've never met you or Wendie, but like you both more with every post!

I like your refinement on my practice of manually switching = when the batteries move into absorb mode. The Victron 7x2 series has provision for a relay function.... or is that in the MPPT? (I'm traveling and don't have ready access to that info) If we could use this relay to flip the ML-ACR that would help make the system more idiot proof.

To continue the puns... I think the idea has potential!

 

[ckent323]

Vic,

Thanks.

I think you are thinking of the load output on the MPPT controller. The following is from the 75/15 manual section 4.3:

"For larger models without a load output, the load settings can be used to drive the TX pin in the VE.Direct port, which can then be used to drive a BatteryProtect relay or other load-shedding device. See chapter 4.4 Tx port function, option 5: Virtual Load output, for more information."

Hoping I don't have a "biased" perspective on this. (OK, that one is a bit of a reach for a pun).

Craig

 

[ckent323]

OK here is the latest on the Sterling Power BB1260 Battery to Battery Smart Charger (same as the Promariner ProNautic 1260P)I asked the following:


Can I reverse the charge and use this to jump start a low starting battery?





This is if the starting battery in the truck (FLA) runs down can I use the house batteries to jump start the truck battery with this unit. Like I could do with an ACR or VSR?

To which the Sterling rep replied: We don’t have a setting like that, but if you had the ability to do that and tie input and output together for emergency start it wouldn’t harm the sterling dc to dc charger.

I also asked:




The BB1260 will accommodate both the FLA starting battery (that is being charged by the alternator/voltage regulator) and accommodate and properly charge the AGM house battery bank without the need for the battery chemistry module.






Please confirm.

Confirmed.

So the only advantage here over using a Blue Sea 7622 ML-ACR is that the battery to battery charger will not damage the AGM batteries if it is left to just work automatically.

However, since I have a solar system that will charge the house batteries (see discussion in earlier comment above) then as long as I monitor the house battery charging state while driving (using my Victron BVM-7x2 and the Victron App on my smart phone or ipad and manually switch the ML-ACR when the batteries change from bulk to absorption mode, the ML-ACR 7622 Will work fine and it is cheaper. Further, the ML-ACR 7622 will allow me to flip a switch to jump the truck battery from the house batteries in the event I need to do that.

So I think this completes my research and decision making process.

Craig

 

[ckent323]

Summary for those wanting to connect the house battery bank and the truck starting battery::

1. [SIZE=10.5pt]If you do not have a smart charging system in your vehicle then stick with normal capped lead acid batteries (flooded Lead Acid - FLA).[/SIZE]
2. [SIZE=10.5pt]If you have or intend to install a smart battery charger in your vehicle then it may be appropriate to consider AGM or Gel (Gel for those driving a lot off road as they are less susceptible to damage from bouncing).[/SIZE]
3. [SIZE=10.5pt]If the house batteries are the same chemistry as the vehicle starting battery there is no issue using an ML-ACR and I think it is a sensible thing to consider installing. You will need to bypass the typical OEM 110 V to 12 v charge controller (e.g. IOTA DLS-30) and connect directly to the house battery bank - there would be no need to use the factory pigtail plug in this case and the only use of the built in charge controller would be for converting 110 shore power to 12v. This applies to the cases in 4 and 5 as well and the wiring is given in 6.[/SIZE]
4. [SIZE=10.5pt]If the battery chemistry of the vehicle and house batteries are different then[/SIZE]
   [SIZE=10.5pt]if you want automatic charging you will need to use a battery to battery (B2 smart charger such as the Sterling Power BB1260 or the ProMariner 1260P. However, you will not have flip a switch ability to jump start your vehicle battery from the camper battery and the current cost of the B2B snmart charges is close to 2x the cost of Blue Sea ML-ACR. (there may be other products out there but after checking with Blue Sea, Balmer, Ctek, ProMarine, Sterling Power and Xantrex these are the only two products which I think will work (due to the potential of a >30 Amp current differential).[/SIZE]
5. [SIZE=10.5pt]if you are willing to monitor your house battery charging and accept the need to manually switch off the ACR but have the ability to jump the vehicle battery from the house battery bank with the flip of a switch then the ML-ACR is the way to go, BUT you must also have a solar system with smart charging to adequately charge the house battery bank (or plug the camper into shore power everyday).[/SIZE]

[*][SIZE=10.5pt]For those who go on long trips or who want the security and piece of mind of knowing if you have good batteries and sufficient charge on the batteries ​I think it is important to be able to monitor the battery state of charge in both the vehicle and the camper. There are a number of products that will allow you to do this. The cheapest require running wiring to volt/ammeter in the truck cab and the more convenient Bluetooth equipped devices don't require running wire to the truck cab but cost more. [/SIZE]
[*][SIZE=10.5pt]If you want to be able to jump start your vehicle battery from your house battery bank I strongly recommend 4 ga wire for vehicles with gas engines and 2 ga wire for vehicles with diesel engines (see calculations for short term current capacity in an earlier comment above).[/SIZE]
Unfortunately, at this time there does not appear to be a product on the market that will allow automatic smart charging of two different types of batteries in your vehicle and camper AND also allow a simple throw of the switch jump starting of a vehicle battery from the house battery bank.

I hope all this will be helpful to other folks.

Craig

 

[Vic Harder]

Nice summary Craig

 

[philos65]

I'm confused by all the above. Is there something wrong with using a voltage sensitive relay - something like this?

https://www.amazon.com/gp/product/B0058SGDFK

Or am I missing something here - you want to do something other than use the alternator to charge both batteries, with priority being given to the truck battery, or use the auxiliary battery to help start the truck?

Thanks for any clarity as to purpose of what seems to me to be a very complicated way to do something simple. Or, I could just be showing my ignorance, which is pretty normal...

Jeff

 

[rando]

There is no problem using a VSR. I would probably go with a bluesea SI-ACR for a few bucks more, as they are known reliable option:
https://www.amazon.com/Blue-Sea-Systems-BatteryLink-Automatic/dp/B00BFVGVA6/ref=sr_1_1?s=automotive&ie=UTF8&qid=1521563486&sr=1-1&keywords=si-acr

There is not really any 'priority' given. The relay puts both batteries in parallel when either battery is charging, and isolates them when the charging stops.

As usual, we have done an excellent job obfuscating the solution to a simple problem.