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Old 17-06-2014, 13:17   #181
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Re: Mixing Battery types in 1 Bank

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Originally Posted by sailinglegend View Post
Thank you for your inquiry here at the home office of Interstate Batteries, Inc. It is not advised to add an AGM battery to an existing flooded lead acid battery. The reason behind this would be the discharge and recharge as explained in the posting on the forum. Two different chemistries and two different internal resistances can cause a huge nightmare with possible out gassing, run times and recharge capability. Current travels the path of least resistance. Meaning, the battery with the least resistance (the AGM battery) will get all the current before it returns to the flooded batteries. This will increase the heat of the AGM bringing on out gassing and a shorter life span of both batteries.
I hope this makes sense. Let me know if you have more questions.

Thanks,
Jeff Barron

Engineering & Technical Service Specialist
Thank you Jeff Barron!
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Old 17-06-2014, 13:17   #182
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Re: Mixing Battery types in 1 Bank

Monte, I think your manual is wrong. They either made a mistake in full, or a mistake in translation.

I can only guess that "open type free electrolyte" refers to a constantly vented battery with access to the electrolyte - like you seem to have.

However, an absorption (boost) voltage of 14.1V is lower than any battery manufacturer's recommendation that I have seen. For example, Trojan recommends 14.8V. 14.4V is pretty much considered the generic "boost" voltage for non-sealed FLA's.

It is best to find out what Exide recommends for your batteries. I have not found much info on that model, but the following: http://www.exide.com/Media/files/Dow...0%205_9_13.pdf
shows that for their standard and "marine dual purpose" batteries, they want a boost voltage of 14.8-15.0V and a float voltage of 13.5-13.8V. The boost voltage is the same for their deep cycle FLA's, but the float is a bit lower at 13.2-13.4v.

My guess is that your manual is wrong here and meant to put the GEL type battery in the first box and move the others down.

Mark
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Old 17-06-2014, 13:28   #183
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Re: Mixing Battery types in 1 Bank

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Originally Posted by sailinglegend View Post
I reported you to the moderator for continually trying to make me look stupid with your misleading and incorrect postings.

…..

This time Andina you have pushed your 'commercial member' interests too far in trying to deceive us all, so I shall be reporting you to the moderator.
Wow, that is sad. And you are concerned about my comments making you look bad…

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Old 17-06-2014, 13:32   #184
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Re: Mixing Battery types in 1 Bank

So is Jeff Baron correct, or Dave?

Mark
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Old 17-06-2014, 13:45   #185
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Re: Mixing Battery types in 1 Bank

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Originally Posted by colemj View Post
So is Jeff Baron correct, or Dave?

Mark
Dave was correct that the SOC would vary between the batteries. Jeff is correct as to the mixing of AGM and FLA will cause the AGM's to charge faster, take most of the charge current and cause failure. That oddly enough is what I've been saying.

Please tell me your not going to argue with Interstate's battery engineer.
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Old 17-06-2014, 14:45   #186
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Re: Mixing Battery types in 1 Bank

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Originally Posted by sailorchic34 View Post
Dave was correct that the SOC would vary between the batteries. Jeff is correct as to the mixing of AGM and FLA will cause the AGM's to charge faster, take most of the charge current and cause failure. That oddly enough is what I've been saying.

Please tell me your not going to argue with Interstate's battery engineer.
+1
They (count it as most responding here) have said the same thing with different words constantly and you disagree becouse not using the same words or what ever..
And I continue repeating myself, wouldn't use ANY batteries (identical, same age included) paralled unless it were the lasts chance..
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Old 17-06-2014, 17:26   #187
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Re: Mixing Battery types in 1 Bank

Monte-
With the switches in the original positions, I would do as Don says and measure the actual voltage at the battery terminals while the charger is on.
Contact Exide, or find their web data, that says what the correct (optimum and maximum) charging voltages are for those specific batteries.

If the charger is not putting out the correct voltage, tell the boat maker they set I up incorrectly and ruined the batteries, which must be replaced.

In addition, if "reversing" the positions or using different settings cannot give you the correct voltages to match what Exide wants, tell them that the batteries and charger are incompatible, and you expect them to provide compatible batteries not just mismatched replacements.

Find out what's wrong (since they apparently are not capable of that), tell them what is needed to make it 100% right, and give them one chance to do so. One chance, and then pursue whatever your local warranty laws and consumer rights laws allow you to do.

We had a similar problem with an air conditioning system. The guys who installed it, left the switches all set to default "arctic" settings. One call to the maker, and they knew immediately what the problem was, and sent out the installers to correct it, without any argument. Anyone can make a mistake, but the guys who fix it fast and right, get extra credit.
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Old 17-06-2014, 23:02   #188
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Re: Mixing Battery types in 1 Bank

My previous posting was adressed to Mark.
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Old 23-06-2014, 01:58   #189
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Re: Mixing Battery types in 1 Bank

Thanks again for all the input. Just an update. All batteries have tested as OK however the smell remains. We believe it is coming from the starter battery. A technician has suggested that the starter battery shouldnt be connected as per the attached diagram from Lagoon.
One starter battery is connected to D terminal on one of the chargers, the other starter is connected to the BAT2 terminal on the other charger.
The pic of the charger manual shows that D (for Debut/start) is set to lower charging rates than the house batteries.
The technician suggested the second start battery should be on the D terminal of the second charger.
Is this a problem and the possible cause of the smell?
The Exide guy came and tested the batteries and said all was well, and he has agreed to replace the starter battery, but I want to make sure the same doesn't happen again.
Thanks again.
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Old 23-06-2014, 04:02   #190
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Mixing Battery types in 1 Bank

Quote:
Originally Posted by sailinglegend View Post







Thank you for your inquiry here at the home office of Interstate Batteries, Inc. It is not advised to add an AGM battery to an existing flooded lead acid battery. The reason behind this would be the discharge and recharge as explained in the posting on the forum. Two different chemistries and two different internal resistances can cause a huge nightmare with possible out gassing, run times and recharge capability. Current travels the path of least resistance. Meaning, the battery with the least resistance (the AGM battery) will get all the current before it returns to the flooded batteries. This will increase the heat of the AGM bringing on out gassing and a shorter life span of both batteries.

I hope this makes sense. Let me know if you have more questions.



Thanks,

Jeff Barron


[B]Engineering & Technical Service Specialist

This type of paragraph is typical of most battery manufacturers it contains truths half truths and some exaggerations.


I've explained why differing SOC s are the primary reason for advisng against mixing types ( and ages and capacities)

However the internal resistance issues quoteD in that paragraph are simply WRONG And can easily be disproved by anyone willing to put together a simple test rig.

What of course Mr Barron forgets is the EMF of the cell and the fact that internal resistance is a very complex factor in a LA battery.

During recharging , current will divide between the AGM and the FLA as appropriate to their respective instantaneous input resistance. That resistance will rise as the charge cycle continues with current proportions changing as each battery recovers it's SOC. Once the chargers does not exceed any of the limitations of either battery, then the various things Mr Barron alludes to will not happen.

As I explained absorption mode will be asymmetric resulting in one battery being subject to a longer absorption mode voltage then necessary. However this in itself is no cause for concern and often occurs in systems with load sharing

The simple fact is that in recharging, having a FLA alongside an AGM, is not much different to having a load in parallel with an AGM during charging , a situation very common in boats.

Dave



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Old 23-06-2014, 06:40   #191
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Re: Mixing Battery types in 1 Bank

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Boy's Boys.... Be nice.

I've never read Calders book, but being an engineer who wrote a hydraulic analysis program ages ago I know a thing or two about piping and hydraulics.

Piping like electrical cable has an internal resistance to flow based on the size of the pipe and flow rate through it. Pretty much just like electrons and wire, though without inductance.

Like electrons, water travels the path of least resistance. So you will get unbalanced flow between batteries with with conductors (wires) of different lengths. You will also get different acceptance rates based on the internal resistance to the batteries or tanks. Water tanks with internal bladders set at different pressures will accept water at different rates.

Nothing tells the electrons which battery to go to, except cable resistance and battery resistance. Thats why even with the same battery types as the OP was talking about, but of different ages, the internal resistance would not be the same. This as resistance rises as batteries age too.

OK that's a bit simplistic as there are other factors too with electron flow and battery aging too.
Your post raises a question: I decided this year to combine my bow battery (designed to feed the thruster and windlass) with the house bank, by keeping the combine switch closed. All batteries were replaced in April with identical deep cycle FLA types from the same mfr. batch date. The bow battery is connected by #4 AWG cables (approx. cable 20 ft away or 40 round trip from the house bank). My thought was that the bow battery is almost never used unless the engine/alternator is on, and is not really discharged much because it's mainly used as a cranking battery. So why not join it to the house bank instead of carrying that dead weight forward with little benefit?

So is there any reason not to do this?
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Old 23-06-2014, 08:22   #192
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Re: Mixing Battery types in 1 Bank

Quote:
Originally Posted by sailorchic34 View Post
Originally Posted by sailinglegend







Thank you for your inquiry here at the home office of Interstate Batteries, Inc. It is not advised to add an AGM battery to an existing flooded lead acid battery. The reason behind this would be the discharge and recharge as explained in the posting on the forum. Two different chemistries and two different internal resistances can cause a huge nightmare with possible out gassing, run times and recharge capability. Current travels the path of least resistance. Meaning, the battery with the least resistance (the AGM battery) will get all the current before it returns to the flooded batteries. This will increase the heat of the AGM bringing on out gassing and a shorter life span of both batteries.

I hope this makes sense. Let me know if you have more questions.



Thanks,

Jeff Barron

Thank you Jeff Barron!
Yes, boilerplate answer flavored to sell batteries unnecessarily.
I got just about the same response from the same question to Interstate batteries. I wrote back twice thanking them for the advise but asking why I should throw away a 6 month old lead acid battery just because it was being used in parallel with an AGM, assuming maximum charging voltage was set to satisfy the requirements of the AGM.

Finally on the second time asking for a reason for their statement they said they would pass my question on to a battery technician.

The technician wrote back and said that there was no problem putting them in parallel.

You are dealing with teenagers, probably in India, who are given some basic information and stock answers to questions. Ask them to justify WHY they said that and what would happen if you went ahead and did it.
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Old 23-06-2014, 09:18   #193
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Re: Mixing Battery types in 1 Bank

This is almost as much fun as the anchor wars!! I agree with Andina and Dave that Jeff Barron's words disqualify him as the 'expert from afar'.

Meaning, the battery with the least resistance (the AGM battery) will get all the current before it returns to the flooded batteries. This will increase the heat of the AGM bringing on out gassing and a shorter life span of both batteries.

If you want to believe Jeff's logic, just take the flooded battery out of the system--then AGM-only systems will take ALL of the current ALL of the time--leading to even further 'increase the heat of the AGM bringing on out gassing' and shorter life span.

My hard drive crashed and I lost the computer model, but I'm working on a improved version. To the person who said that modelling batteries is impossible, I would just say that engineering analysis is the art of approximating life by neglecting unimportant terms.

In the meantime, I came across an article from a real engineer which has a lot of good data on flooded battery performance. If anyone can point me to similar curves for AGM's I would appreciate it.

http://scubaengineer.com/documents/l...ing_graphs.pdf
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Old 23-06-2014, 09:31   #194
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Re: Mixing Battery types in 1 Bank

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This is almost as much fun as the anchor wars!! I agree with Andina and Dave that Jeff Barron's words disqualify him as the 'expert from afar'.



Meaning, the battery with the least resistance (the AGM battery) will get all the current before it returns to the flooded batteries. This will increase the heat of the AGM bringing on out gassing and a shorter life span of both batteries.



If you want to believe Jeff's logic, just take the flooded battery out of the system--then AGM-only systems will take ALL of the current ALL of the time--leading to even further 'increase the heat of the AGM bringing on out gassing' and shorter life span.



My hard drive crashed and I lost the computer model, but I'm working on a improved version. To the person who said that modelling batteries is impossible, I would just say that engineering analysis is the art of approximating life by neglecting unimportant terms.



In the meantime, I came across an article from a real engineer which has a lot of good data on flooded battery performance. If anyone can point me to similar curves for AGM's I would appreciate it.



http://scubaengineer.com/documents/l...ing_graphs.pdf

That article is quite good and non technic and illustrates the non-linearity of the situation quite good. Everyone should read it.

As to LA battery models. This is still doctorate level stuff. Even good second order models are quite deficient especially under dynamic conditions.

Modeling a battery of course is quite easy, the trick is that the modelling process is close to real like in al conditions , then it's gets tricky fast

Dave
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