Mixing battery chemistry

S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
I have 4 new AGM house batteries (2 x 2 parallel) plus one engine starter. The starter batt is now needing replacing.

Since it is charged via an Echo charger can I use anything other than AGM? .... or will it influence the house bank?

2005 Hunter33
 
rgranger

rgranger

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Jan 19, 2010
12,926
Hobie 16 & Rhodes 22 Skeeter Charleston
If the batteries are isolated from each other... then it is okay but if they are not... then you need them to all be of the same type and age.
 
Charles Erwin

Charles Erwin

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Jan 30, 2012
1,154
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
The title suggests you are thinking about replacing a start battery that is a different chemistry than the house group of batteries.

If so then you need to consider whether the start battery has a different charge regime than the house bank. And this is not strictly a function of battery chemistry. Instead look at what the battery manufacturer tells you is the charge regime for its battery. AGM battery charge profile can be very similar to a flooded battery charge profile. If so the fact one set is flooded and the other is AGM makes no difference.

In addition, if you use the start battery to start the motor (otherwise as a reserve in case the house fails) the amount of charge you need to replenish is very small. Just like your car - the motor starts and the battery is replenished to full at a fixed voltage quite quickly. Likewise if the start is 100% kept in reserve - the house bank supplies everything including motor start - you don't need much to keep the start at 100% no matter the battery chemistry.

So find out what the charge regime is on your battery - no matter the chemistry.

By the way the echo charge is a battery charge follower and does not itself make any changes based on battery chemistry. The echo charge is limited to 14.4 v. and does not allow more than 15 amps.

Charles
 
S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
Many thanks Charles. I believe you have answered all my concerns .... fast too!
 
S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
rgranger said:
If the batteries are isolated from each other... then it is okay but if they are not... then you need them to all be of the same type and age.
Click to expand
As Charles below surmises, I will be using the house bank for everything, including engine start. The engine batt is for emergency only: so I will get an AGM starter batt to replace it.
 
capta

capta

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Jun 4, 2009
5,072
Pearson 530 Admiralty Bay, Bequia SVG
There may be some, but I know of no battery chargers that will charge batteries of a different chemistries.
I would never not have a completely isolated starting battery, on any liveaboard boat that one cruises on. I believe that Mainesail disagrees with me though.
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,338
Catalina 34 224 Maple Bay, BC, Canada
AGM and FLA batteries use almost identical charging regimens. You can check them out in any Balmar regulator manual (www.balmar.net). No need to buy an expensive starter/reserve AGM. Really.
 
Charles Erwin

Charles Erwin

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Jan 30, 2012
1,154
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Stu Jackson said:
AGM and FLA batteries use almost identical charging regimens. You can check them out in any Balmar regulator manual (www.balmar.net). No need to buy an expensive starter/reserve AGM. Really.
Click to expand
Affirmative on those charge regimes - but if a 12v AGM start is deep cycle then you will get a backup that can take some cycling which might be useful. So are there 12 v AGM that amount to deep cycle?

By the way - how is the Canadian food where you are?

Charles
 
NYSail

NYSail

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Jan 6, 2006
3,178
Beneteau 423 Mt. Sinai, NY
I have 3 group 31 agm house and 1 flooded that works thruster and windless. All batteries are you in excellent condition. According to Balmar they charge similarly. Has worked this way for years. Xantrex charger set to agm all good.

I left the flooded because it was 1 year old when I bought the three agms.....
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,338
Catalina 34 224 Maple Bay, BC, Canada
Charles Erwin said:
By the way - how is the Canadian food where you are?
Click to expand
Excellent.

My wife is a superb cook! :)

"She "approved" this message!":)

Using a deep cycle to start or use as a reserve bank is just fine. Maine Sail has discussed this many, many times.
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,338
Catalina 34 224 Maple Bay, BC, Canada
capta said:
I would never not have a completely isolated starting battery, on any liveaboard boat that one cruises on. I believe that Mainesail disagrees with me though.
Click to expand
Actually, he doesn't. He & I both promote what are called OPTIONS - and not the stock market kind. :)

The 1-2-B switch remains the simplest to use, but a three or two switch scenario would allow separate start and house sources, with the option of being able to easily switch from one to other of the the banks, as "Use" switches, without having to rewire anything.
 
Ken Cross

Ken Cross

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Oct 24, 2010
2,405
Hunter 30 Everett, WA
Interesting, my charger WARNS you to NOT connect flooded and AGM batteries, The manual says one or the other and the switch selections on the charger effect both outputs. There are some chargers that charge mixed sets however. Look in the specifications of your charger.

Ken
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,338
Catalina 34 224 Maple Bay, BC, Canada
Ken Cross said:
There are some chargers that charge mixed sets however.
Click to expand
If you use a combiner, ACR or echo charger, you only use ONE output of the charger to the house bank. Then the charger doesn't care.
 
S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
capta said:
There may be some, but I know of no battery chargers that will charge batteries of a different chemistries.
I would never not have a completely isolated starting battery, on any liveaboard boat that one cruises on. I believe that Mainesail disagrees with me though.
Click to expand
The starter batt will have its own switch, but I'm not sure if that means it is isolated completely as it charges through the Echo charger.
 
S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
Ken Cross said:
Interesting, my charger WARNS you to NOT connect flooded and AGM batteries, The manual says one or the other and the switch selections on the charger effect both outputs. There are some chargers that charge mixed sets however. Look in the specifications of your charger.

Ken
Click to expand
If the Echo charger for the starter batt does what I assume it does, and the starter batt switch is off, then surely I could use a different chemistry batt and it would not influence the house bank charger, But am I right?
Meanwhile I will look at the Xantrex manual (charger not installed yet)
 
capta

capta

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Jun 4, 2009
5,072
Pearson 530 Admiralty Bay, Bequia SVG
Stillatit said:
The starter batt will have its own switch, but I'm not sure if that means it is isolated completely as it charges through the Echo charger.
Click to expand
I do not use an echo charger. Each bank is completely isolated from the other unless I switch the three way to both. Each has it's own charging source.
 
Charles Erwin

Charles Erwin

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Jan 30, 2012
1,154
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Stillatit

Isolation means disconnecting one battery group from another. If your definition is different then we need to know that so as to redirect discussion.

To the point - the echo charge isolates the battery to which the echo charge is directed from the source battery that is supplying the charging current to the echo charge. When the charging source is less than 13 v there is no path between the two battery groups.

If your switching can create a separate path from one battery group to the other that switching arrangement defeats (bypasses) the echo charge isolation and the groups are paralleled. In that case the less well charged depletes the more well charged. So don't leave the switches in positions that will defeat isolation.

So you need to understand whether your switching can parallel the battery groups or not. If not the echo charge provides 100% isolation. A voltage sensitive relay does exactly the same.

Charles
 
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S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
Charles Erwin said:
Affirmative on those charge regimes - but if a 12v AGM start is deep cycle then you will get a backup that can take some cycling which might be useful. So are there 12 v AGM that amount to deep cycle?

By the way - how is the Canadian food where you are?

Charles
Click to expand
Certainly the 4 new AGM 12 v house batts are deep cycle. I am now leaning toward non AGM for the (emerg only) starter as there will be a cost saving .... especially on a batt that may never see any actual use.

We live in southern Ontario, Canada and the food this time of year is fresh and cheap: unlike in the Winter when we import it from your country and it is neither! We also grow some of our own ... yet another seasonal hobby conflict.

I really appreciate all the help from you and the other kind folks here.
 
S

Stillatit

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Sep 22, 2014
9
Hunter 33 Parry Sound
OK Charles, it finally seems clear to me that my echo charger really does isolate the starter batt from the 2 house banks. It sees no load when its switch is off. Consequently it must not need to be same chemistry or deep cycle.
When (if) I use the 1-2-B switch (usually left at B) I am only switching house banks, and they start the engine with no hesitation .... no surprise with 4 x 90 amp.hrs capacity in parallel.
Martyn (Stillatit)
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,338
Catalina 34 224 Maple Bay, BC, Canada
Stillatit said:
When (if) I use the 1-2-B switch (usually left at B) I am only switching house banks, and they start the engine with no hesitation
Click to expand
It appears that you have a split house bank, and use the switch to put them together. Why bother?

Wire them together for the largest house bank and use that same switch to control your reserve bank.
 
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