Battery bank question

[Jon Elliott]

Hello everyone. I have a Pearson 36.2 with two Deka Marine dual purpose / deep cycle batteries connected in parallel for charging purposes (one for engine starting, one for a house bank). They’re both old and need to be replaced. I’m looking for suggestions on replacements while adding solar. My understanding is that you don’t mix a starter battery with a deep cycle…or can you? Should you? Or, can I just use two deep cycle AGM batteries and still be able to start the engine under normal conditions (not deep winter). I’ve looked at Renergy Batteries but they don’t recommend theirs as a starter. Any help, guidance or suggestions is really appreciated.

 

[Davidasailor26]

Starting a small marine engine with deep cycle batteries is just fine. It would be better to have a small engine battery separate from your house bank, just so you don’t need to worry about draining the house bank too far to start the engine. Some people just keep a jump pack for those emergencies too.

To size your bank consider what your expected loads and durations are. There are amp hours calculators to help with that. You want a bank large enough that you don’t need to go below 50% state of charge.

Also consider whether AGM is really best for your use case. We have them and like them, but they’re not for everyone. They don’t tolerate staying below 100% state of charge for long, so unless you have shore power or really good solar traditional flooded lead acid could be better.

 

[Maine Sail]

a pair of deep cycle batteries will easily start your engine.. Renogy is not quality battery manufacturer and their customer support is horrendous

Renogy reviews

The below capacity test was on a brand spanking new Renogy Deep Cycle 100Ah AGM... 72.27Ah.......!! Even when brand new these cheap Chinese AGM'S can't deliver...FWIW this was for a follow up article for Practical Sailor to the 2015 article "Fighting Sulfation in AGM Batteries". we could not find a single off-shore made AGM battery(Other than Rolls & Fullriver) that could meet its rated specification. In the end the article had to be scrapped.. Be very very very careful sourcing your AGM batteries off Amazon etc.

 

[Maine Sail]

If you insist on AGM (a waste of $$ now with LIFEPO4 kicking AGM butt).. there are only a few manufacturers worth buying from.

Reputable AGM BATTERIES
Lifeline
Odyssey
Northstar
FullRiver
Rolls


The above list is from years of experience and many many hundreds of capacity tests of AGM, GEL AND FLOODED DEEP CYCLE BATTERIES..

 

[Tally Ho]

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

 

[Bob S]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

 

[DayDreamer41]

We have had 6 Volt Trojan T105's on our Sapphire now since spring launch 2017 their state of health is 91% according to the battery monitor Balmar SG200, I leave them in place during the winter (ensuring full charge before diconnecting them), keep the electrolite levels as required. I have not equalized them since new, these batteries according to my research are the absolute best bang for the buck, at around $200 per plus jumper cable to allow series parrallel connection, I anticipate these batteries to last at least another 3-5 seasons. They are true deep cycle batteries that offer 225 Ah, contained in the correct orientation and secured perferably down low on the centerline of the boat. They weigh 62# per which makes them easier to carry as compared to a couple of those 12 volt 8D's.

 

[NYSail]

I had a 36-2 also with a 3HM35F. I added a 3rd battery aft of the batter compartment where the old waste bladder was. I had 3 deep cycle group 31 agm. 2 house one start. The battery aft I had on its side as the height was restricted. Lithium are nice and will be going there next change.

good luck
Greg

 

[Jon Elliott]

Starting a small marine engine with deep cycle batteries is just fine. It would be better to have a small engine battery separate from your house bank, just so you don’t need to worry about draining the house bank too far to start the engine. Some people just keep a jump pack for those emergencies too.

To size your bank consider what your expected loads and durations are. There are amp hours calculators to help with that. You want a bank large enough that you don’t need to go below 50% state of charge.

Also consider whether AGM is really best for your use case. We have them and like them, but they’re not for everyone. They don’t tolerate staying below 100% state of charge for long, so unless you have shore power or really good solar traditional flooded lead acid could be better.

Great information and thank you. My alerts didn’t notify me of any replies so I’m a bit late responding. My boat will be on shore power which begs another question. Do I allow the shore power charger to charge the batteries and shut the solar panel charger down or let both chargers run? I am by the way going with deep cycle AGMs. Thank you again for the response.

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

Thank you Bob and you’re right. There’s a dizzying amount of information to consider so I’m taking my time, trying to avoid an analysis paralysis moment as I tend to do.

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

I think my needs are similar to yours. A low voltage fridge, speed and wind instruments, my auto pilot on occasion (but rarely) and the ability to charge a tablet now and then.

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

a pair of deep cycle batteries will easily start your engine.. Renogy is not quality battery manufacturer and their customer support is horrendous

Renogy reviews

The below capacity test was on a brand spanking new Renogy Deep Cycle 100Ah AGM... 72.27Ah.......!! Even when brand new these cheap Chinese AGM'S can't deliver...FWIW this was for a follow up article for Practical Sailor to the 2015 article "Fighting Sulfation in AGM Batteries". we could not find a single off-shore made AGM battery(Other than Rolls & Fullriver) that could meet its rated specification. In the end the article had to be scrapped.. Be very very very careful sourcing your AGM batteries off Amazon etc.

I have decide to go with dual deep cycle and a solar solution. I think you’re right, a starter battery is probably not entirely necessary for my purposes. Particularly with the ability to isolate both batteries from each other.

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

a pair of deep cycle batteries will easily start your engine.. Renogy is not quality battery manufacturer and their customer support is horrendous

Renogy reviews

The below capacity test was on a brand spanking new Renogy Deep Cycle 100Ah AGM... 72.27Ah.......!! Even when brand new these cheap Chinese AGM'S can't deliver...FWIW this was for a follow up article for Practical Sailor to the 2015 article "Fighting Sulfation in AGM Batteries". we could not find a single off-shore made AGM battery(Other than Rolls & Fullriver) that could meet its rated specification. In the end the article had to be scrapped.. Be very very very careful sourcing your AGM batteries off Amazon etc.

If you insist on AGM (a waste of $$ now with LIFEPO4 kicking AGM butt).. there are only a few manufacturers worth buying from.

Reputable AGM BATTERIES
Lifeline
Odyssey
Northstar
FullRiver
Rolls


The above list is from years of experience and many many hundreds of capacity tests of AGM, GEL AND FLOODED DEEP CYCLE BATTERIES..

Yes, I saw Odyssey and Northstar in most of the top 5 or so reviews. Great information and thank you.

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

a pair of deep cycle batteries will easily start your engine.. Renogy is not quality battery manufacturer and their customer support is horrendous

Renogy reviews

The below capacity test was on a brand spanking new Renogy Deep Cycle 100Ah AGM... 72.27Ah.......!! Even when brand new these cheap Chinese AGM'S can't deliver...FWIW this was for a follow up article for Practical Sailor to the 2015 article "Fighting Sulfation in AGM Batteries". we could not find a single off-shore made AGM battery(Other than Rolls & Fullriver) that could meet its rated specification. In the end the article had to be scrapped.. Be very very very careful sourcing your AGM batteries off Amazon etc.

If you insist on AGM (a waste of $$ now with LIFEPO4 kicking AGM butt).. there are only a few manufacturers worth buying from.

Reputable AGM BATTERIES
Lifeline
Odyssey
Northstar
FullRiver
Rolls


The above list is from years of experience and many many hundreds of capacity tests of AGM, GEL AND FLOODED DEEP CYCLE BATTERIES..

We have had 6 Volt Trojan T105's on our Sapphire now since spring launch 2017 their state of health is 91% according to the battery monitor Balmar SG200, I leave them in place during the winter (ensuring full charge before diconnecting them), keep the electrolite levels as required. I have not equalized them since new, these batteries according to my research are the absolute best bang for the buck, at around $200 per plus jumper cable to allow series parrallel connection, I anticipate these batteries to last at least another 3-5 seasons. They are true deep cycle batteries that offer 225 Ah, contained in the correct orientation and secured perferably down low on the centerline of the boat. They weigh 62# per which makes them easier to carry as compared to a couple of those 12 volt 8D's.

Thank you, are they on a solar charge, shore power or both?

 

[Jon Elliott]

Be careful choosing a battery as their height plays a big role. Spend some time on Maine Sail’s How To website. Pay particular attention to fusing. There is a lot to learn if you want to take the time to.
Good luck!

I replaced 2 deep cycle (so called) Group 27 batteries with 2 6-volt Golf cart batteries. These are wired in series to give me 12 volts, and about 215 (maybe 230) amp hours capacity.

I use this bank to start my engine, and provide power for the house.

My needs are pretty simple, but I do have refrigeration. i day sail mostly, but have used this set-up for a long weekend on the hook.

Greg

a pair of deep cycle batteries will easily start your engine.. Renogy is not quality battery manufacturer and their customer support is horrendous

Renogy reviews

The below capacity test was on a brand spanking new Renogy Deep Cycle 100Ah AGM... 72.27Ah.......!! Even when brand new these cheap Chinese AGM'S can't deliver...FWIW this was for a follow up article for Practical Sailor to the 2015 article "Fighting Sulfation in AGM Batteries". we could not find a single off-shore made AGM battery(Other than Rolls & Fullriver) that could meet its rated specification. In the end the article had to be scrapped.. Be very very very careful sourcing your AGM batteries off Amazon etc.

If you insist on AGM (a waste of $$ now with LIFEPO4 kicking AGM butt).. there are only a few manufacturers worth buying from.

Reputable AGM BATTERIES
Lifeline
Odyssey
Northstar
FullRiver
Rolls


The above list is from years of experience and many many hundreds of capacity tests of AGM, GEL AND FLOODED DEEP CYCLE BATTERIES..

We have had 6 Volt Trojan T105's on our Sapphire now since spring launch 2017 their state of health is 91% according to the battery monitor Balmar SG200, I leave them in place during the winter (ensuring full charge before diconnecting them), keep the electrolite levels as required. I have not equalized them since new, these batteries according to my research are the absolute best bang for the buck, at around $200 per plus jumper cable to allow series parrallel connection, I anticipate these batteries to last at least another 3-5 seasons. They are true deep cycle batteries that offer 225 Ah, contained in the correct orientation and secured perferably down low on the centerline of the boat. They weigh 62# per which makes them easier to carry as compared to a couple of those 12 volt 8D's.

I had a 36-2 also with a 3HM35F. I added a 3rd battery aft of the batter compartment where the old waste bladder was. I had 3 deep cycle group 31 agm. 2 house one start. The battery aft I had on its side as the height was restricted. Lithium are nice and will be going there next change.

good luck
Greg

This would be a perfect solution for adding a third to ours as well since we have a Natures head on board. I like this idea a lot. I’d love to add lithium but man, the initial cost hurts. Maybe once I get the myriad of other projects done.

 

[kappykaplan]

Do I allow the shore power charger to charge the batteries and shut the solar panel charger down or let both chargers run?

I let the solar panels do most of the heavy lifting and rarely use the shore power charger - but my batteries are all FLA.

 

[Scott T-Bird]

Yes, I saw Odyssey and Northstar in most of the top 5 or so reviews. Great information and thank you.

I just bought a Group 27 AGM deep cycle from Batteries Plus. It is labeled X2Power. It is made by Northstar and is the exact same battery as the Odyssey and Northstar label only it is a new label exclusive to Batteries Plus. Of the 3 identical batteries, I found the best price (and most convenient outlet) at Batteries Plus. They were within 30 to 40 $ for a $400 battery.

 

[Jon Elliott]

Yes, I saw Odyssey and Northstar in most of the top 5 or so reviews. Great information and thank you.

I just bought a Group 27 AGM deep cycle from Batteries Plus. It is labeled X2Power. It is made by Northstar and is the exact same battery as the Odyssey and Northstar label only it is a new label exclusive to Batteries Plus. Of the 3 identical batteries, I found the best price (and most convenient outlet) at Batteries Plus. They were within 30 to 40 $ for a $400 battery.

Very helpful I’ll check them out!

 

[Scott T-Bird]

I use my new AGM battery exclusively for the windlass and starting.

Great information and thank you. My alerts didn’t notify me of any replies so I’m a bit late responding. My boat will be on shore power which begs another question. Do I allow the shore power charger to charge the batteries and shut the solar panel charger down or let both chargers run? I am by the way going with deep cycle AGMs. Thank you again for the response.

To fully understand your system, please explain. It appears that you have just 2 batteries. What kind of selector switch do you have? I'd assume that you have the ubiquitous 1+2+B switch. If that is the case, do you switch between 1 & 2 for starting and house bank use respectively? This kind of operation makes no sense since the output for starting and house bank is on a common output post. To get the most efficient use of your batteries, you are better off cabling them in parallel to double the capacity for house loads and don't bother with a separate start battery - your engine will start just fine on the house bank. The best thing you can do is double your house bank capacity and if you need an auxiliary, get a 3rd battery and just consider it auxiliary (not start).

If you really want a dedicated start battery, then we're talking a whole nuther system that actually makes some sense if you want to go that route.

 

[Scott T-Bird]

Very helpful I’ll check them out!

To clarify, Enersys acquired Northstar. So basically Odyssey, Northstar and now X2Power are under the EnerSys corporate umbrella, among other battery brands ...

EnerSys Acquires NorthStar

www.northstarbattery.com

.

Here is another article that I found to be interesting.

Should You Buy an X2 Power Battery - PowerUpTips

The name “NorthStar Battery” may sound familiar to you. Yeah, this is another name for the X2 Power battery since the NorthStar Company is the manufacturer of the product. A pure lead battery, the X2 Power comes in a thin, flat plate. It’s most likely that you’ve heard a lot about the benefits...

poweruptips.com

In some of my readings, I heard it mentioned that the price for X2Power is substantially less than Odyssey but I didn't find that to be the case. Perhaps when 1st introduced they had attractive rebate offers to promote the Batteries Plus brand, but I found the current pricing to be fairly similar. It was really convenient for me to hop down the street to a local Batteries Plus so that is what ultimately sold me on it when I found that it is a TPPL manufactured battery.