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Tending Dual Batteries

hotdaddy27

hotdaddy27

Well-known member
I winterized the Checkmate yesterday, and I was at a bit of a loss when it came to keeping the dual batteries charged.

The negatives are always "jumped", so I made a "jumper cable" for the positive sides on each battery. Then I hooked the battery tender (Pos & Neg) to one of the batteries assuming that the "jumper" cables will charge the second battery.

Is my thought process right, will this tend to both batteries?

All components are disconnected so the only thing I can hurt is the tender.

This is the first season that I have run dual batteries, so please forgive my incompetence.

Thanks in advance for the help. :bigthumb:

HD
 
Dual Output Charger

HotDaddy, that will keep both batteries charged. But if both batteries are not of the same type & size ( or health ) the weaker will always pull the stronger down. The ideal way would be to have a charger with multiple outputs and actually keep the batteries isolated.
 
Good point Enticer1!

Fortunately, the batteries are identical and were purchased within a few months of each other.

I think at some point I will just use two separate tenders just to be safe.

Thanks for the input guys, I really don't like guessing with electrical.

HD
 
"In Figure 9 we see a pair of 12-volt batteries connected in parallel. This 12-volt battery pack is connected to a single 12-volt charger. Note the blue wire designated W1. The purpose of this wire is to balance the voltage drop evenly across both batteries and each wire during charging. This is not critical for lower current chargers, but when you start to get into the 10 amp and above range, the voltage differential can be significant. The blue wire W1 must be connected to the opposite end of the battery pack as the black wire at the top of the battery pack."

Since the batteries are already charged and you're just maintaining them over the winter, you shouldn't have any problems. I wouldn't spring for the extra tender unless your wallet is getting too heavy.
 

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Where do you have both batteries mounted? Got any pics? Thinkin about adding another battery and a bada$$ stereo this winter...
 
ToP_Enticer said:
"Note the blue wire designated W1. The purpose of this wire is to balance the voltage drop evenly across both batteries and each wire during charging. This is not critical for lower current chargers, but when you start to get into the 10 amp and above range, the voltage differential can be significant. The blue wire W1 must be connected to the opposite end of the battery pack as the black wire at the top of the battery pack."
quote]

I think that a battery tender is only around 2 amps, so I wont use the W1 blue wire.

Besides the blue wire, that is exactly how my setup looks... COOL!

Thank a bunch TE.

HD
Click to expand...
 
BADBK said:
Where do you have both batteries mounted? Got any pics? Thinkin about adding another battery and a bada$$ stereo this winter...
Click to expand...

They are side by side (running front to back the long way) on the port side behind the rear bench.

My oil tank is on the starboard side in the same location as a reference.

I did it for my system as well.

HD
 
Really should try a on board dual battery charger most of them them will maintain the battery's also. Hooking them up on separate ones will be but it sure is nice to have just a extension cord going to the boat and not have to worry about them.
 
I had put a dual onboard charger on my starflite.It was sure nice to just pull the cord out of the splash well and plug in when I backed it into the garage(28ft deep). But it quit working after 5 or 6 yrs, pulled it and never replced it.The 28 ft deep garage is gone too!
 
28 Ft Garage

Merc245, my garage was only 23 ft but its gone just the same. My Ex lives in a new house that I paid for because I'm such a nice guy ( Not )
God I miss that garage !!!
 
wizard8575 said:
Really should try a on board dual battery charger most of them them will maintain the battery's also. Hooking them up on separate ones will be but it sure is nice to have just a extension cord going to the boat and not have to worry about them.
Click to expand...

During the summer my boat rarely sits long enough for the batteries to dip below 12V, so I don't have a regular need for the charger. Also, I have not been able to find a "real" charger that shuts off automatically like a tender does.

This is for winterizing only. I should have been more clear.

Thanks.

HD
 
hotdaddy27 said:
During the summer my boat rarely sits long enough for the batteries to dip below 12V, so I don't have a regular need for the charger. Also, I have not been able to find a "real" charger that shuts off automatically like a tender does.

This is for winterizing only. I should have been more clear.

Thanks.

HD
Click to expand...

Most of the marine dual bank chargers have trickle charge and maintenance cycles. The Dual Pro charger I used in my bass boat is exactly what I will be puttin gin my Convincor this winter. Here is a Linky

http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/DPPS2.html

I cant believe my 253 came with only one battery. Kinda goofy if you ask me.:eyecrazy:
 
This thread got me thinking about my battery. I just got a new one at the beginning of this season, and may as well make it last as long as it can. Any recommendations for good tenders?
 
For a single battery, any decent marine charger if you want it mounted, or any of the Battery Tender models if you want something portable or temporary. I have battery tenders on all my bikes and I put one on my boat when it sits for any length.
Dual batteries, a switch, onboard dual bank charger, and jumper posts are being installed this winter.
 
As a side note, I was wondering what the real cost of 'tending' a battery for six months would be... assuming 90% efficiency and 0.11/kWh, it looks like it'll cost about $5 to keep the battery maintained for six months. So... when batteries cost $80/ea it's obviously a good idea.
 
ToP_Enticer said:
As a side note, I was wondering what the real cost of 'tending' a battery for six months would be... assuming 90% efficiency and 0.11/kWh, it looks like it'll cost about $5 to keep the battery maintained for six months. So... when batteries cost $80/ea it's obviously a good idea.
Click to expand...

I have to run MERCURY (Exide) 1100 CA Batteries for warranty requirements. They run over $100/battery (more like $120). Times two batteries + tax is over $250.

Battery tender= $35
Juice= $5 (using your math)

NO BRAINER!!!!!!! lol
 
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