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Old 02-18-2008, 06:54 AM
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Default Mixing AGM & Lead Acid Batteries


I currently have 4, flooded lead-acid batteries on board my bay boat. Two are dedicated to the T-motor in a 24 V configuration, 1 is primary starting + "house" use and 1 is reserved as back up starting. I have a ProSports 20 Plus onboard battery charger (3 banks). The two starting batteries are connected to a battery isolator/switch and there are secondary alternator outputs connected directly to the reserve cranking battery to keep it topped off. I've attempted to sketch this all out here:



My question is this: after years of wrestling with battery issues related to the t-motor batteries (typically running group 31 units) and reading many positive reviews of the Optima AGM batteries for this application I am considering replacing the 2 trolling motor batteries with blue top optimas. However, my owners manual for the ProSports 20 Plus charger
( details here: http://www.promariner.com/productFea...oductNum=41220 )

emphatically say not to mix battery types. The charger also has a battery type selector though it seems that the selector mechanism lumps flooded lead acid and AGM together and it's only the gel type that is truly separate.

Will using the Optima AGM batteries for the T-motor power source with flooded lead acid for the starting batteries cause a problem with any of the batteries, charger or other equipment????

Thanks in advance for any help.

Tim
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Old 02-18-2008, 07:03 AM
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Default Re: Mixing AGM & Lead Acid Batteries

Look at other AGM's besides optimas - do a search here - some have reported early failure suddenly. A better choice is the sears maraine AGM or the PC1500 by odyssey...they are both the same.

There is a reason that yellowfin stopped using optimas and switched to Odysseys in thier boats....
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Old 02-18-2008, 07:54 AM
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Default Re: Mixing AGM & Lead Acid Batteries



I did search the topic here Glen and saw some threads where you and some others reported problems using Optimas as starting batteries with Verado & Optimax engines. Also saw other threads reporting good service from these products. All I can really say about that is that I have some personal acquaintances, who fish the way I do, using these batteries in the same general application that I would be, that have been using the blue top optima batteries for this application for several years now without a problem and with the Odyssey batteries priced at roughly 2x what I can get the Optima's for even if I only got 2/3 the service life out of the Optimas that I might with the Odyssey, cost wise I still come out ahead buying Optima.


Redirect back to topic: =>

Irrespective of brand can I mix the AGM and flooded lead acid batteries in the set-up diagrammed in my original post without damaging the batteries, charger or some other device? I see no reason to go to AGM for the starting battery as standard flooded lead cell batteries have worked fine there in my application and am just trying to improve the reliability of my T-motor batteries.

Tim
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Old 02-18-2008, 10:56 AM
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Default Re: Mixing AGM & Lead Acid Batteries

Quote:
BandDad - 2/18/2008 10:54 AM



I did search the topic here Glen and saw some threads where you and some others reported problems using Optimas as starting batteries with Verado & Optimax engines. Also saw other threads reporting good service from these products. All I can really say about that is that I have some personal acquaintances, who fish the way I do, using these batteries in the same general application that I would be, that have been using the blue top optima batteries for this application for several years now without a problem and with the Odyssey batteries priced at roughly 2x what I can get the Optima's for even if I only got 2/3 the service life out of the Optimas that I might with the Odyssey, cost wise I still come out ahead buying Optima.


Redirect back to topic: =>

Irrespective of brand can I mix the AGM and flooded lead acid batteries in the set-up diagrammed in my original post without damaging the batteries, charger or some other device? I see no reason to go to AGM for the starting battery as standard flooded lead cell batteries have worked fine there in my application and am just trying to improve the reliability of my T-motor batteries.

Tim
you sound informed and make a good arguement...as far as mixing, I have always been taught that you can.......they charge the same so I think it's a non issue...but I'd still bank the same type together if it was me....
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Old 02-18-2008, 11:03 AM
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Default Re: Mixing AGM & Lead Acid Batteries

Nice setup & nice diagram

The specs on your charger say to select Lead Acid or Gel. Most chargers use the LA setting for AGM's. I would check with the mfg to confirm

I like the simplicity of 1 type of batt & no maintenance. AGM is a great choice.

Although AGM's would work in all of your applications (starting, house, TM) my sense (not a batt expert) is that for optimum performance of your TM, deep cycle batts would be the choice.

The only improvement (slight) that I see is that you could add a combiner b/t batts 3 & 4 to allow the batt charger to charge both w/o using your batt switch

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Old 02-18-2008, 12:09 PM
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Default Re: Mixing AGM & Lead Acid Batteries

In answer to the mixing types question: I don't see why you couldn't, as the different types are isolated from each other.
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Old 02-18-2008, 01:43 PM
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Default Re: Mixing AGM & Lead Acid Batteries



Thanks for the feedback guys.

I don't think it should be an issue either since the only batteries not isolated from each other would both be AGM type and, apparently, AGM & flooded lead/acid charge the same way in combination with the "distributed on demand" feature of this particular charger. Point being that it's not going to overload the AGM's trying to bring up the flooded lead/acid. I'm just not a battery guru and didn't want to spend all that $ on AGM batteries and then either compromise them or some other device due to some unknown (to me) issue. I emailed the charger mfg today so hopefully we'll see what they have to say soon.

Interesting suggestion on the battery combiner thingy Elusive! Since I almost never use it and the motor is always charging it when it's running this battery seems to hold a charge well, but a good suggestion nonetheless.

Tight lines and fair winds all.

Tim
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Old 02-18-2008, 08:11 PM
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Default Re: Mixing AGM & Lead Acid Batteries

As Elusive posted, I like one bat per motor, isolated but with the ability to be combined for emergency starting. Battery combiners, however, may not work with motors with auxiliary charging circuits. Look at BEP website for ideas.
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Old 02-19-2008, 08:51 AM
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Default Re: Mixing AGM & Lead Acid Batteries



Here is ProMariner's response to my question:

AGM and lead acid batteries can be mixed, they charge at the same
voltage.


Robert XXXXX (name edit by me)
Pro Mariner service department

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