# Question about matching batteries



## tom1s (Oct 4, 2007)

My moms boat, a bayliner 4788 had one battery hit the shi**er. Twin hino 310 hp turbo diesels. 

The good battery is a gel cell "sonnenschein" GF 12 160v made by exide. The Bad battery is a LifeLine GPL 8-D, also gel. 

At the shop I work at I ordered in an Interstate SRM4D. Its a standard deep cycle, not gel cell but the batteries are comparable in size and power. 

The problem is that the on-board battery tender (110 volt) stopped working at the same time that battery ate it, and it has settings for 12v gel or 12v regular deep cycle. I don't know if its cooked or if it just wont kick on with one bad battery and a dead system....If i put one gel cell and one regular deep cycle in a synchronized system, will it screw up the 110 v charging system, or how do i set it...to gel or regular deep cycle?


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## tom1s (Oct 4, 2007)

and I don't know if they are in series or parallel. I just pulled them and tested them and charged the good one.


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## hymarkdot (Nov 13, 2010)

*dont mix!*

Be careful mixing batteries. You must check the chargers owners manual to see if the charger has the capabillity to charge batteries of different types. Xantrex has a model that will do this and another brand i cannot remember. This has not been an option just a year or so back. One of the batteries will be ruined and the charger will most likely not rest and also burn up. The manufacturers tech lines for chargers are amazing for assistance.


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## tom1s (Oct 4, 2007)

I don't know who made the battery tender, its yellow and looks pretty fancy but my big ass cant squeeze past the riser to replace it. I know i can read the brand name or get it out of the survey. I just don't want to burn up a battery, charger etc. 

I'm getting the interstate SRM 4d's for 180$ each, so I might just tell my parents to get two regular deep cycles and keep the gel cell on board and charged as a back up for the engines or generator.


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## hymarkdot (Nov 13, 2010)

AGM (absorbed glas matt) batts are almost identical to flooded cell batteries and can be placed in the same location (no charge output voltage change needed)usually. Gell batteries on the other hand are at a different voltage(charge output) This is the problem you have . Im not sure but it seems you do not know for certain what the charger is set for gel or flooded. But at least you know they cannot be mixed (and stay fully charged with a useful life). Sorry if i have confused you. I think West marine has a guide printed in the middle of the catalog it is helpful and accurate. If not check the port supply catalog.


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## tom1s (Oct 4, 2007)

thanks for the input. The good battery is a GF and doent slosh, I presume thats gel filled....the battery tender is set to "gel" as of now but the batteries are out and all the breakers are off. 12v system is dead, that needs to change...blowers and pumps are 12v.


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## hymarkdot (Nov 13, 2010)

Lead acid(flooded) and agm's are @ the same voltage and can many times be charged by the same output type for example :

The battery charger output switch set to flooded 13.2vdc. Although you still should not mix battery types series or parallel.

The gel cell batteries must be charged by a different voltage output for example:

The battery charger output switch set to gel-13.4vdc.

I cannot remember the actual difference between the two and always refer to the manual to make the setup correct. Dont let anyone guess you the wrong answer. That is the point i am trying to make, none of us can afford to keep replacing batteries


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## tom1s (Oct 4, 2007)

I think il just recommend that she replace both of them with matching regular deep cycles and keep the gel cell as a back up. 180$ each commercial price isnt bad...and keep the gel one as a back up. The boats not a fixer-upper...its got back up filters x5, impellers, raw water pumps, back up about everything stored away. I guess its time to suck up the extra 180$ and have a back up battery too.


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## tom1s (Oct 4, 2007)

Holy Sh*T, west marine just quoted me 579$ to replace the 4d gel battery. I was talking to a friend at work about mixing one gel and one lead acid and he thought it might be dangerous to have a lead acid battery charging under the deck....it may release hydrogen and become an explosion risk. 

Do I really need to worry about this? The engine room and back where the generator is is pretty open...I'm not sure I can see enough hydrogen leaking from it to saturate the area but what do I know? advice?


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## X-Shark (Oct 3, 2007)

A common thing that I've seen now a days is people calling a AGM battery, a Gell battery.

Please do NOT do that. It is very confusing and they are in fact different. Gell batteries are becoming more and more less popular.

The word Gell is used generically to describe anything that is not a standard lead acid battery.

Same thing with the term Bearing Buddy. 

Know what you have and say exactly what it is. It takes so much confusion out out the equation.


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## hymarkdot (Nov 13, 2010)

*batteries*

Sealed batteries are basicly a new thing. Although they were designed many years ago ,it is the latest tech to hit the market in many versions. 
I dont know the exact situation you have but most vessels that needed a cranking battery used a vented battery for a hundred years or so. The vessel should be manufactured in accordance with ABYC standards with allowance for proppper battery ventilation. Both gasoline and diesel applications are produced with either vented or sealed battery groups.
The off gasing of hydrogen should not be taken lightly but it is possible that the vessel came with flooded batteries that have been upgraded to gel. Take alook @ the marina at 300 hp and bigger diesel vessels and you will see mostly 4d and 8d lead acid flooded(vented) batteries


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## woody (Oct 17, 2007)

I doubt that your onboard charger will effectively maintain two different types of batteries. 

Do a little reading here: 
http://www.windsun.com/Batteries/Battery_FAQ.htm#Battery%20Voltages


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## tom1s (Oct 4, 2007)

Thanks for the input everyone. Pops has gone threw many marine service manuals and Iv done some reading. I'm getting a second interstate 4d lead acid battery dropped at the shop in the AM and going down to put them both in Friday afternoon. 1330 cca each run together should do it I hope. 

I guess I'll use the left over gel cell as a back upon the boat...and use it to power a flounder or crab'n light for about three days straight


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## X-Shark (Oct 3, 2007)

Careful you don't strain your back installing the 4D's. Some of the places batteries have to go can put your back in a bad predicament.


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