Dual AGM Battery system

[Doug1]

I'm using Dual AGM batteries to have extra reserve electrical power but hooked them up in parallel temporarily until I could get a solid plan to make the best use of them. I've already had one instance where the Alt was not getting a good signal to charge the batteries and so I drove for a long time on just battery power. I don't have idiot lights so the volt gauge alone didn't show any issues.

I want to be able to run my AV, etc. at shows without killing my starting battery. I'd also like the ability to switch to the second battery in case my starting battery was low and would not start the car.

I think only a DC-DC isolator will take the AGM batteries up to 100%. Will they allow switching like I mention above or do I need to add a manual isolator switch as well?

[Doug1]

Anyone have any experience with this?

[Larry Callahan]

No experience but I plan on doing something like this. Check out this site for info. Some even will disconnect when the voltage drops to some low number that will start the engine.

https://www.waytekwire.com/products/1347/Battery-Isolators/

- - - Updated - - -

or

https://www.waytekwire.com/products?pSearch=low%20voltage%20disconnect

[TheJDMan]

I know that motorhomes and RVs use a system that will isolate the starter battery from the the coach batteries so you can always start the vehicle.

[Doug1]

I know that motorhomes and RVs use a system that will isolate the starter battery from the the coach batteries so you can always start the vehicle.

Here are a couple of short videos from a RV place that sells these type systems. In the DC-DC charger, it can charge an AGM to 100% because you tell the system it is an AGM. The one thing I am not sure about is the starting battery.

Does a standard alternator charge an AGM to 100% or not? Since most AGM batteries require a 4 stage charge to get to 100%, how can it get there with a standard alternator?

Smart Battery Isolator
https://www.youtube.com/watch?v=9jjh3Y4xIL8 (https://www.youtube.com/watch?v=9jjh3Y4xIL8)



BCDC charger
https://www.youtube.com/watch?v=0V2AfxKXHvg (https://www.youtube.com/watch?v=0V2AfxKXHvg)

Battery Management System
https://www.youtube.com/watch?v=Qgg9unSaXYk

[TheJDMan]

Does a standard alternator charge an AGM to 100% or not? Since most AGM batteries require a 4 stage charge to get to 100%, how can it get there with a standard alternator?

I suspect not 100%. The reason I say that is because every time I drive the car it charges and starts just fine but I always put a maintainer on the battery when it is back in the garage and it always shows the battery a bit low on the screen. I have no idea if this is a problem or not an issue. I also have a pair of Odyssey AGM batteries in my Silverado Duramax now for about 5 years with no charging or starting issues.

[Doug1]

I'm thinking the alternator would need a microprocessor to fully charge an AGM. In newer cars, it most likely has the capability but a stand alone alternator most likely doesn't get it there. To keep them topped off it looks like you need to hook up a smart charger / maintainer. Sort of a bummer that you constantly charge it to 80% and run from there, as the video seems to imply. That has to shorten the life of the battery.

[anguilla1980]

This is for sure the case with my Odyssey battery in my car.

[Doug1]

This looks like the proper solution but it is EXPENSIVE.

https://www.sterling-power-usa.com/sterlingpowerusa12volt-210ampalternator-to-batterycharger.aspx

[TheJDMan]

That is an interesting regulator. I wonder how much difference it would actually make. I mean I'm running Odyssey AGM batteries in two of my tractors the car and the pickup and none of them have had any starting issues over the past five years.

[Doug1]

That is what I am trying to figure out. I have two Odyssey batteries in the TA and want to use them more wisely than I have. I actually had to get a jump start last week because I drove it for a while and it wasn't charging, without me knowing it. The only way I found it wasn't charging was when it didn't start. It turned out the wire to activate the alternator had worked slightly loose. These are two pretty big batteries so starting should never be an issue if I get this set up correctly.

I ordered this earlier this week after the jump start and it should arrive today but now I am not sure if it is the best thing to use, since it doesn't do the 4 step charge.

https://www.amazon.com/Blue-Sea-Systems-Automatic-Charging/dp/B001VIXLRO/ref=pd_rhf_eeolp_s_cr_simh_0_2/133-0152951-1409133?_encoding=UTF8&pd_rd_i=B001VIXLRO&pd_rd_r=98e7f0e0-0ae9-457e-8cdf-5a085b3ec46d&pd_rd_w=p1rWo&pd_rd_wg=T4X51&pf_rd_p=67aa5820-8762-4202-90ba-881bb99c913c&pf_rd_r=TD7N2J8J62TMW1YKVRKP&psc=1&refRID=TD7N2J8J62TMW1YKVRKP


There is this for less money since it is not marine grade..
https://www.sterling-power-usa.com/proregd12volt24voltadvancedalternatorregulator.asp x

Also needs an isolator added like this...
https://www.sterling-power-usa.com/ProSplit-RZeroVoltDropMarineBatteryIsolator-7.aspx


Then there are things like the advanced charging regulator which does the 4 step charge itself but isn't set up for dual batteries that I can see.
http://www.balmar.net/?product=regulator-mc-614-h

Lot's of info to work through.

[Warthog5]

I have experience with this in the marine industry. It's designed for a boat....but is applicable to what your trying to do.
I do marine wiring......I've installed 40 of these now. It's clean and simple to use.

http://www.marinco.com/en/716-sq-140a-dvsr


You turn the House switch ON.....Turn the Start switch ON......Leave the Yellow /Combine switch in OFF.....Think of that switch as a built in jumper cables and only turn it ON if start battery fails to start it.

The relay is closed until it senses a major rush of current....as when starting your motor.....The alt then brings the start battery back to a set voltage and the relay closes...then charging both batteries.....Now lets say your at a show....you have the stereo playing.....or some kind of dancing lights.....You pull those loads off the house battery.......The relay is still closed and batteries are paralled together......So time marches on and you draw the house down...The relay will open.....Saving the start battery so you can start the car.

[Doug1]

That does look like a cool device to replace an isolator, though the amperage limit might be a bit low. I'
m not certain of that yet. The other thing it doesn't address is the multi-stage charging that AGM batteries should be receiving. I'll get it figured out eventually! lol Thanks for the information!

[Warthog5]

The other thing it doesn't address is the multi-stage charging that AGM batteries should be receiving.

That is not a concern. It's charging from your alt..... Now if you were using a battery charger....then yes.

[Warthog5]

I was on my other computer when I 1st jumped in here....This is a write up that I have to explain better.



BEP Cluster Switch.

You start your day by turning the Start switch and the House switch to ON.
At the end of the day you turn them both OFF.

It doesn't get any simpler than that. You don't have to remember to turn from Batt 1 when going out and switch to Batt 2 on the way back in. Just something else that you have to remember.

OK so what goes on with it is done all automatically thru the VSR [Voltage Sensitive Relay]

The Relay is in a closed position. As soon as you hit the key to crank the motor the relay opens, due to sensing a large surge of current.

Ok the motor is cranked and running now. The relay is still open. The Alt is charging the Start battery until it reaches a set voltage and charge.

Then the relay closes and is back charging Both the Start & House Battery.

Now another feature that happened when you hit the key is your electronics were ON and wired from the House battery. This will stop any spiking of the Electronics. They don't like to be spiked!

OK...Now your out sitting on the beach. The motor is OFF, but you have the Radio playing for hours. The Relay senses the drop and opens the relay again. The radio is still playing, but the relay just disconnected the Start battery out of the circuit so that it stays at Full charge to start the motor.

When you get ready to leave the beach and crank the motor the alt will charge the Start battery first and when it's back up, the relay will close and charge the House battery.

There is one more switch on the Cluster. It is the Combine switch. Think of that as Jumper Cables without having to dig them out and hook them up. This switch would normally be in the OFF position, until you need a boost on the start battery. Then turn it to ON. After the motor is running turn it back OFF.

Everything is all Automatic. No thinking about it. Your batteries will have a much better charge in them.

[Warthog5]

https://static1.pt-content.com/images/pt/2019/06/IMG_zpsepwrxgxh-1.jpg

[Doug1]

That is not a concern. It's charging from your alt..... Now if you were using a battery charger....then yes.

This is where there seems to be a lot of confusion. (At least for me. lol ) I keep finding documentation that states a standard alternator such as mine does NOT do multi-stage charging so essentially it is only getting the AGM batteries partially charged (80-85%), which is not ideal for the batteries. It specifically can't do multi-stage charging to get an AGM battery up to 100% without the use of an advanced regulator or a full on Alternator to Battery charging system like the one below. The cars we are building generally don't have an advanced regulator that I have seen. I have a 200 Amp alternator but its an old style regulator and not a smart regulator.

So I think we might not have the optimal setup in place but it works well enough we don't really notice over the short term. Long term is another story. But then again, do I buy an expense $600+ alternator to battery charging system or just buy another set of batteries in a few years when these fail?

Check this link out.....
https://www.sterling-power-usa.com/library/What%20is%20an%20alternator%20to%20battery%20charg er.pdf

This link is to the Sterling Advanced Regulator Owner's manual.
https://www.sterling-power-usa.com/library/PDARWInstructions.pdf
You have to take the alternator apart and wire into the brushes. Seems like a lot of effort that can be skipped by using the Alternator to Battery Charger.

Here a link to Sterling Power USA Alternator-to-Battery Chargers
https://www.sterling-power-usa.com/sterlingpowerusa12volt-210ampalternator-to-batterycharger.aspx

Here are the instructions for the Alternator to Battery charger that I am looking at. So far it seems to fit the bill and would handle my 200 Amp alternator charging two batteries.
https://cdn.shopify.com/s/files/1/0658/7343/files/AB12210.pdf?477

This Alternator to Battery Charging System is designed to be put between an Alternator and AGM batteries. Though I'm not sure how it can be switched to use the house battery as the starting battery without a switch. I think a combination of the two is probably the ultimate solution. Maybe this along with the isolator switch as well?

The Sterling Power Alternator-to-Battery Charger is a marine grade, high performance, four step, alternator powered battery charger. By monitoring and then controlling the voltage level of the alternator connected to the input side, the alt-to-bat is able to provide a charge rate that recovers your batteries up to five times faster than a standard alternator.
Has the ability to mix on board battery types.
Can charge GEL, AGM, FLA, Calcium and LiP04 Batteries.
Always ensures start battery is properly charged, but also prevents the starting battery from being overcharged and damaged.
Our 4 Step Battery Charging Profile extends the life of your batteries by ensuring a full charge & conditioning, as well as entering a float mode when charging is complete to protect against overcharging your batteries.
Installs in place of a standard alternator to battery isolator.
Available in 12 volt / 130 amp, 210 amp and 400 amp output models.

[Warthog5]

Doug......Your confusing yourself.

That alt.....is the charging system.

Now if you want to charge a dead or Low battery, then yes.....You want a multi stage charger as a battery charger.


Looking at the links you posted.....I've never seen or used anything like that...

I run AGM's in my John Deere garden tractor, My whole house generator, My '07 Mustang GT/CS and my '15 F150.....Never needed or wanted a system like that Sterling.

[Doug1]

Doug......Your confusing yourself.

That alt.....is the charging system.

Now if you want to charge a dead or Low battery, then yes.....You want a multi stage charger as a battery charger.


Looking at the links you posted.....I've never seen or used anything like that...

I run AGM's in my John Deere garden tractor, My whole house generator, My '07 Mustang GT/CS and my '15 F150.....Never needed or wanted a system like that Sterling.

I confuse myself often. Lol. Your newer cars have an advanced regulator built into them. The system I listed does two batteries on different banks.

So an old style alternator can charge an AGM battery but it is not capable of the multi stage charging required to get the AGMs fully charged. An advanced regulator, such as the one on your new cars, can do multi stage charging.

[MonzaRacer]

"SIGH" In a car the alternator RUNS the car and refills the battery and unless your battery is drawn down way low you do NOT need any off the wall alternator or anything.
As for battery isolator the ones at local part store/farm store work just fine. Allowing the accessory battery to charge and be part of system as the alternator charges.
When car is OFF it isolates the battery that is designated for starting so it does not discharge if your radio or lights stay on. NOW if you really run system battery down some require you to jump dead battery off the charged starting battery but I would just add in a simple underhood crank circuit with push button. IF necessary.
I run a blue top in my Caprice with zero issues and standard 10SI GM alternator.
I have ran blue tops in two different cars with zero issues in charging.
Basically an isolator lets one battery power everything except the start circuit.
Proper grounds, and a proper turn on circuit for the alternator.
OH and I always like upgrading the charge wire to 8ga with crimped and soldered terminals.
https://www.zoro.com/e-z-red-hammer-indent-crimper-tool-b790c/i/G6404706/feature-product?gclid=Cj0KEQjw3PLnBRCpo8PCoaGM99MBEiQAppRu C-GkzlxMRiRYCbDLFrbIQczwnKlkPAwn9Q5Jl9LxlHIaApHb8P8H AQ

One of these, my Power Probe soldering iron/torch and some shrink and seal shrink tubing. Also welders cable can be had from NAPA and tractor supply most times by the foot. Fine stranded 2/0 cable make starters sing even when batteries are lower than normal.

[Doug1]

Look, I’m not saying I’m right. I’m trying to learn how these AGM batteries get fully charged. If AGM batteries require multi stage charging to get to get to 100%, how do you keep them topped off with an old style regulator that has no microchip? Or, are we (cars with old style regulators) running around with batteries at roughly 80% charge that we don’t even notice because they still run the car fine? If we’re running around at 80% then we are shortening the life of an expensive battery. It’s more of a curiosity.

I’m going to contact Odyssey, Optima and XS and see if they have anything to add since they are the experts. I’f I get any replies, they will be added to this thread.

[Doug1]

As promised, I am passing on what I learned from the Optima tech support person. While we know that not all AGM batteries are alike, some use lithium ion technology, etc, it goes deeper than that. In fact, even using the same storage technology, the best way to charge and maintain them varies. Here are the main takeaways from Optima regarding their batteries.

1. If you have an Optima battery, you should have an Optima charger on hand. Just because a charger is designed to charge AGM batteries doesn't mean it charges an Optima battery the best. For Optima they only recommend charging when a battery is 20% discharged which they consider a deep discharge. For keeping the battery topped off they need a constant voltage of between 14.4 volts to 14.8 volts with 14.7 volts being ideal.

2. The battery should never really discharge while in the car if the alternator and regulator are working properly. The alternator should just do a topping off since the power to run the car is from the alternator while it is running. So it is important to start with a battery that has been charged with the proper charger to 100%. An alternator / regulator combination that supplies a constant 14.4-14.8 voltage at the battery is also needed to keep the battery in top condition.

2. The staged charging is more important if the battery is down to 80% or less and then you need to use their specific charger. The tech advised that on other brand of chargers, sometimes the Gel setting or the Flooded setting could be a better solution than the AGM setting! So they don't recommend using any other charger for that reason.

3. If you have two batteries then you should use a device that can make sure the batteries independently get exactly the 14.4 -14.8 volts each that they need. The tech stated she didn't have much expertise in this area but thought a DC-DC charger was a good idea if the alternator could support it.

4. If the car isn't driven regularly, an Optima maintainer should be connected to the car when it is not in use. This will pro-long the life of the battery.

So kudo's to Optima for addressing the question and limiting their answers to what they definitely know. So I need to find someone who is an expert multi-bank charging to address that specific area but the rest of the questions posed were well answered.

[Warthog5]

Everything You talked to them about was with charging the battery via a 110V Battery Charger.



So an old style alternator can charge an AGM battery but it is not capable of the multi stage charging required to get the AGMs fully charged. An advanced regulator, such as the one on your new cars, can do multi stage charging.

What alt are you running? Be specific.

No a alt. does not multi stage charge. But if the vehicle is run normal it's more of a maintainer.

[Doug1]

Everything You talked to them about was with charging the battery via a 110V Battery Charger.
What alt are you running? Be specific.
No a alt. does not multi stage charge. But if the vehicle is run normal it's more of a maintainer.

1. I thought it was clear in my posting that Optima recommended getting the battery 100% charged using an AC battery charger and then the alternator should keep it topped off after that as long as there was no parasitic loss. But if not, this should do that. If it drops enough from parasitic loss, the AC charger or a maintainer should be used.

2. CD130D upgraded to 200 amps. It's a Tuff Stuff model 8219.

3. It's my understanding that newer regulators can actually do multi stage charging/maintaining but I may be wrong. It would not be the first time. lol

4. The most important thing I have learned in all of this is that you need to get a charger and a maintainer to match your BRAND of battery. Just being AGM aware is still not specific enough because they are all manufactured to different specs. So one brand AGM charger my work poorly on another's AGM battery.

[Doug1]

Odyssey Batteries just replied....Good timing!

Basic takeaway, use THEIR charger to get it to 100% and then your alternator needs to keep it there. If it can't, or the car sits for any extended time, use one of THEIR APPROVED chargers or maintainers to keep it topped off.


Thank you for contacting EnerSys/ODYSSEY.

If the battery isn’t getting deeply discharged, then a conventional alternator should be able to maintain the battery. If the battery is discharged due to parasitic loads or auxiliary loads, then external compatible charger or a maintainer to prevent parasitic drain. We have a list of compatible chargers linked on the website Literature page. The following addresses proper maintenance.

ODYSSEY Battery basics. ODYSSEY batteries are an AGM Lead Acid battery however the TPPL (Thin Plate Pure Lead) technology requires that the batteries be charged at a higher amp than most batteries and maintained at a slightly higher voltage than other standard lead acid batteries on the market including some AGMs. They are also truly dual purpose batteries that can be used for both cranking and deep cycling. Due to the technology, proper charge maintenance is critical to maximizing the life and performance of the ODYSSEY battery.

Most conventional batteries are considered fully charged at 12.6-12.7V. The ODYSSEY TPPL AGM battery is not considered fully charged unless it has a resting voltage of at least 12.84V. The usable energy of the ODYSSEY battery is from 11.2V (0% state of charge) OCV to 12.84V OCV (Open Circuit Voltage should be checked 8 - 24 hours post charge with no loads). When the battery goes below 10.0V OCV it is over discharged and is getting into the chemical part of the battery and can cause permanent damage. At less than 10.0V the ODYSSEY limited warranty deems the battery over-discharged due to abuse or neglect (usually unintentional). The ODYSSEY charger/maintainer or any approved maintainer can maintain the ODYSSEY battery indefinitely in or out of the application provided it has enough charging current to counteract the parasitic loads of the application. If the battery becomes over-discharged (below 11.0V OCV) then the sooner the battery can be fully charged the better. If the battery remains connected to the application during storage or extended periods of non-use, to prevent over-discharge and maintain the battery at a full state of charge, an ODYSSEY program approved maintainer would be required and/or disconnecting the battery prevent over discharge. There is a link to a list of ODYSSEY approved 12V chargers located on the ODYSSEY website Literature page for your reference.

The list of approved 12V chargers is provided due to the many chargers that are programmed for the vast majority of batteries on the market that prefer low amp charging and lower float voltages that do not fully charge or maintain the ODYSSEY battery properly. The minimum recommended charging current for an ODYSSEY battery is 40% of the 10 hour amp hour rating of the battery for cyclic or deep discharge applications (for example about 6A for a single 16Ah rated PC680 for example), a constant float voltage of 13.5-13.8V and no constant voltages exceeding 15.0V in any kind of de-sulfation/reconditioning/equalize mode. At greater than 15.0V the battery can overcharge, overheat, and/or go into thermal runaway. Maintaining any ODYSSEY battery at less than 13.5V will bring the battery down and maintain it in an undercharged condition causing sulfation and premature failure. This would not be considered a warrantable manufacturing defect failure.

For seasonal applications (non-daily use applications that set for more than 3 days in a row frequently) regular use of an approved maintainer that meets the charge voltage requirements noted in the previous paragraph is highly recommended during the season and/or a disconnect switch. The preferred storage method is to fully charge the battery before storing and disconnect the battery from the application (shelf storage mode). Stored in or out of the application with no loads, the battery would not require charging for up to 2 years at 77°F or until it reaches 12.0V, whichever comes first before charging is required. The self-discharge rate increases significantly for temperatures above 25°C (77°F) and for every 10°C (18°F) temperature increase the storage time to recharge is decreased by half. Charge maintenance is critical to maximizing the life and performance of the battery. Freezing will not harm the battery and self-discharge rates reduce significantly at colder temperatures.

It is recommended that the ODYSSEY battery be charged if it is less than 12.65V (about 80% state of charge) when put into use as a cranking battery per the ODYSSEY Owner's Manual (link provided on website Literature page for your reference). Most standard alternators are meant to top off a slightly discharged battery and maintain a fully charged battery. Most standard alternators/stators are not meant to be deep discharge recovery chargers and can become damaged if consistently used like one as well as not fully charging the battery with limited use. A battery discharged to below 80% capacity may not reach a full state of charge, regardless of how long you drive the vehicle using a standard alternator. Typical alternators only run at full amp output for a very short period of time before reaching its charging voltage and dropping into a very low amp trickle charge. Luckily enough, ODYSSEY batteries are very efficient at accepting high amp charging for quick charging.

Low amp trickle "charging" a discharged ODYSSEY battery is very inefficient and also causes premature sulfation. With the use of a 6A or higher amp charger that does not exceed 15.0V, the PC680 battery for example, should charge to a high state of charge (at least 85% SOC) then, an approved lower amp trickle maintenance charger should be able to complete charging process without prematurely sulfating the battery. The Cyclic Charge Voltage range printed on the top label of the battery is the recommended voltage at the battery from the applications charging system (alternator or stator). At less than 14.1V the battery may not be getting fully charged for infrequently used applications. You can verify the battery voltage by checking the voltage at the battery at least 8 hours after application use (or off charge) and if the battery voltage is not at least 12.84V then the battery is not considered fully charged. Voltage readings taken right off charge or after use (alternator/stator charging) will be inflated and inaccurate so for a true OCV reading, you should wait at least 8 hours before checking the voltage (OCV) with 24 hours being preferred.

Any lower amp (less the 6A for PC680 for example) charger that floats between 13.5-13.8V at the battery and never exceeds a constant voltage of 15.0V in any kind of automatic reconditioning, equalize, de-sulfation mode can be used as a maintainer only provided the charging current is high enough to counteract the parasitic loads of the application and maintain the acceptable voltage in float mode at the battery. With proper charge maintenance, a comparable Ah rated battery should have a service life of 2-3 times that of the same sized (Ah rated) battery in the same application with the same usage. ODYSSEY batteries have an 8-12 design life and have been known to function successfully well past the design life of 12 years for UPS applications where the battery is maintained at all times. Here is the link to the program approved charger listing from the ODYSSEY website Literature page for your reference. http://www.odysseybattery.com/documents/ODYSSEY_approved_12V_chargers.pdf. Here is the link to the Technical Info page that contains the Procedure to Recover Deeply Discharged ODYSSEY Batteries and ODYSSEY Battery Reconditioning Charge Procedure.
Please contact me if you have any questions or concerns.