# Battery questions - Need an electronics whiz



## ElLobo (Sep 14, 2020)

So I recently moved my starting battery to the front hatch of my boat. Ordered 2 new Relion Lithium RB52's for the TM. Can I wire all 3 batteries (trolling and cranking/house) in parallel but have house to position 1 on selector switch, lithiums to position 2 and both lithium and house also connected in 1&2 position? 

My thinking is with a 12v TM I can pull power from all 3 batteries when needed in the combo position and also charge them from the alternator without needing something like a power pole charge. Then when not needing a TM just use position 1 and maybe use position 2 when trying to save the cranking battery power when using the TM.

If this is doable, can someone mock up/draw a diagram of how to wire all 3 in parallel but also to different battery switch positions?


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## DuckNut (Apr 3, 2009)

I do not know. But if you wire it up sitting on saw horses you can test your plan with a voltmeter to find out.


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## rspehL (Feb 23, 2015)

ElLobo said:


> So I recently moved my starting battery to the front hatch of my boat. Ordered 2 new Relion Lithium RB52's for the TM. Can I wire all 3 batteries (trolling and cranking/house) in parallel but have house to position 1 on selector switch, lithiums to position 2 and both lithium and house also connected in 1&2 position?
> 
> My thinking is with a 12v TM I can pull power from all 3 batteries when needed in the combo position and also charge them from the alternator without needing something like a power pole charge. Then when not needing a TM just use position 1 and maybe use position 2 when trying to save the cranking battery power when using the TM.
> 
> If this is doable, can someone mock up/draw a diagram of how to wire all 3 in parallel but also to different battery switch positions?


Are all 3 batteries lithium? I would not mix different battery types.


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## Vertigo (Jun 3, 2012)

If you wire three batteries together in parallel, if one goes bad it will draw down the others. If one goes bad, the others will probably not charge from the alternator. Once wired in parallel to the battery switch I can not envision how switching to a different setting would keep the batteries from being wired in parallel. To make your scheme work you'd probably need three battery switches and a technical manual to refer to for switch positions. The best idea is to have the two TM batteries on a separate circuit from the starting battery. Carry jumper cables to make alternative or emergency connections.


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## Smackdaddy53 (Dec 31, 2012)

I think one of these is something you could incorporate to have the desired effect. I had one on my last boat with a trolling motor and the switch will swap charge to the battery bank that needs it. 



https://www.bluesea.com/products/7622/ML-ACR_Automatic_Charging_Relay_with_Manual_Control_-_12V_DC_500A


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## ElLobo (Sep 14, 2020)

This is what I’m going to try to run. Lithium’s are wired in parallel and house is not. They share a ground though. Will go to a 4 positions battery switch. Pos 1 will be house/cranking only. Pos 2 will be TM lithium’s. Pos 3 will be both. Engine should be able to charge the batteries depending on the position when running and when in Pos 3 get extended trolling life and ability to start the engine incase house battery is too low in emergencies. Pos 3 will be hardly used 99% of the time.


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## Steve_Mevers (Feb 8, 2013)

Smackdaddy53 said:


> I think one of these is something you could incorporate to have the desired effect. I had one on my last boat with a trolling motor and the switch will swap charge to the battery bank that needs it.
> 
> 
> 
> https://www.bluesea.com/products/7622/ML-ACR_Automatic_Charging_Relay_with_Manual_Control_-_12V_DC_500A


I am using something similar on my Action Craft and rarely even have to plug in the AC charging system


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## emptysea (Jul 14, 2019)

Do not mix battery types on the same bank


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## ElLobo (Sep 14, 2020)

emptysea said:


> Do not mix battery types on the same bank


As in the charging system?


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## emptysea (Jul 14, 2019)

lithium and lead acid shouldn't be wired in series or parallel together at all. Currently the only really safe lithiums with normal charging systems currently are LIPO type. Lithiums dont like to be overcharged and often times end up exploding when this occurs. I wouldn't use a non LIPO battery or one without some integrated Management system within the battery


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## GitFishin (May 10, 2019)

If you want an out of the box solution this is Power Pole Charge's wheelhouse


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## mro (Jan 24, 2018)

Steve_Mevers said:


> I am using something similar on my Action Craft and rarely even have to plug in the AC charging system


I hadn't planned to use my outboards charging system (60 HP merc) because I thought that it could overload trying to charge two (lithium 100 amp) deep cycle batteries. Think I'll contact Mercury and ask. Burnt up alternator would ruin my day.


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## attitudeindicator (Sep 8, 2020)

Look at a Yandina troll bridge for lithium. It’s similar to the ACR from Blueseas but it’s designed to charge lithium from a lead acid battery.

I agree with everyone you don’t want to wire in parallel with different battery types. The Yandina will control the charge rate of the lithium.

plus it’s only $100ish


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## mro (Jan 24, 2018)

attitudeindicator said:


> troll bridge







__





Yandina Trollbridge 12X24 Volt Battery Combiner - e Marine Systems


Yandina Trollbridge 12X24 Volt Battery Combiner TD 1224 is suitable for installations with alternators up to 100 amps and 24 volt trolling motors up to 85 amps.




www.emarineinc.com





While I still have some reading to do
(don't think my outboard has a 100 amp alternator) ,
thanks for the info about this product as I want a way to charge the batteries while on multiday trips
Mike


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## attitudeindicator (Sep 8, 2020)

mro said:


> __
> 
> 
> 
> ...


most skiffs are less than 20amp alternators


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## mro (Jan 24, 2018)

attitudeindicator said:


> most skiffs are less than


 I was being a little facetious as to an outboard and 100 amp alternators...
My GMC 3500 trucks and diesel van didn't have 100 amp alternators either.

What I've been looking into is how I could charge the batteries on my trips to the mountains without having to bring a generator. So far solar panels to charge the batteries is possible but doesn't look to be practical. Most trips are only 3 or 4 days fishing. The trollbridge includes a solar element. I've read that lithium batteries "require" a slightly higher voltage to charge properly than traditional deep cycle batteries so I'll be looking to see something like the trollbridge can change my mind although my problem with the solar idea is that it might require to many panels to get the job done in the amount of time available.


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## Steve_Mevers (Feb 8, 2013)

They also have troll bridge type devices that not only direct voltage from your outboard to charge the trolling motor batteries, but have an option to also connect to your tow vehicle so it charges while you are towing the boat. I have not looked it up in a long time so I don't remember the brand, but the bass fishermen use this setup a lot.


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## ElLobo (Sep 14, 2020)

UPDATE* So I connected the TM lithiums in parallel and grounded them to the ground on the house battery. Hot from position 1 on the battery switch goes to the house/cranking. Hot from Position 2 goes to the TM lithiums. 1+2 position turns both circuits on and the alternator charges both. Doesn't seem like there will be any problems that I've noticed so far. Added a NOCO 2 bank 10 amp battery charger to the front hatch to charge and maintain the batteries from shore power when the boat is stored. This setup essentially allows me to run the TM on both if needed for extra juice and I can charge them when the boat is running. Who needs a power pole charge!


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