charging batteries

[mikietoo]

My new (to me) bass boat has 3 batteries. One for starting and accessories. Two for the trolling motor. The two for trolling are wired in parallel. Is it ok to put the charger on with both batteries connected or should I open the circuit between batteries and charge them separately?

 

[Home Cookin']

Re: charging batteries

sounds like a lot of batteries!

This is what I read--although I don't believe everything I read:

Don't charge or jump a battery while it is hooked to the outboard motor (a lifetime of doing just that with no problems says IGNORE)

Dual batteries need to be charged seperately. The charge does not fill the first one and pour over the second one, it was explained to me.

You should have battery cut-off switches to isolate each battery. Also since it's a new used boat, verify that they are hooked up correctly. We inherit the sins of our sellers with used boats.

 

[fishrdan]

Re: charging batteries

sounds like a lot of batteries!

LOL, I have 4 batts in my boat. :facepalm:

As HC said, I would break the parallel connection before charging the trolling motor batteries. I have charged batteries connected parallel before, and it works, it's just not the best way to do it.

Actually, I would ditch the parallel connection and put an A-B-Both-off switch in so you are only running from 1 battery at a time. Most likely, both of those batteries will not stabilize to the exact same voltage, and after charging, the better battery will bleed off and stabilize to the marginal batteries voltage. IE: good batteries 12.6V bleeds off to the 12.4V of the marginal battery, making them both at 12.4V. I ran a parallel setup for years, but when I installed a battery switch and ran the batteries separate, I had longer run times off the 12V trolling motor.

Also, in a parallel setup, if 1 battery goes bad it's going to eventually ruin the other battery.

 

[cyclops2]

Re: charging batteries

You do not know if both batteries are in the same condition. If not. A slight difference between them WILL DEFINATELY cause overcharging of the BETTER battery. It fully charges to a lower voltage. Older batteries DO HAVE HIGHER END OF CHARGE VOLTAGE. The better battery WILL ALWAYS NEED WATER....Until it becomes as crummy as the higher voltage one.

So. Put in good heavy duty selector switch to charge each battery SEPERATLY. It is cheap & beats to death ANY electronic gadget that may not work correctly after a few months. You may not notice it screwing up your batteries life spans.

The hand operated switch IS ACCURATE.

You may need 2 seperate switches. 1 switch for starting ON OFF... & 1 switch for each of the trolling batteries.

 

[fucawi]

Re: charging batteries

sorry cyclops you got that the wrong way around ..the worse battery will need water. Chargin g in parallel is fine ..its a long established commercial practice but the critical thing not mentioned yet is to get the batteries up to 14.4v ( or max specified if sealed) or you will not be fully charging them ... Dont leave them connected in parallel after charging ..Toyota had this on a 4x4 and the next model only had one battery as they had so much trouble...

 

[5150abf]

Re: charging batteries

Just get a 3 bank battery charger and be done with it.

I have 3 bats on mine, a starter and 2 house, the house are on a 2 bank charger and I manually charge the starter, stator bad and I don't want to come off on the $300 to fix it.

My house are wired into the boat but one is in the front and one is in the back although 13.8ish ois the highest I have ever seen my voltage even after leaving them on the charger for a couple days, it automatically goes to trickle after they are fully charged.

 

[cyclops2]

Re: charging batteries

The web site www.batteryuniversity.com will clear up everybodies misinformation about why batteries die so quickly.

Look at the bottom of the opening page & read.....Charging lead acid batteries........ The site also has information on other types of batteries.

Getting the most from ANY battery is not a simple matter if it has more than 1 cell being charged at a time. Series or parallel.

Enjoy

Rich

 

[cyclops2]

Re: charging batteries

Sorry fucawi. You do need to go to Battery University for a update on theory & modern chargers.

 

[cyclops2]

Re: charging batteries

A real problem with modern batteries is the constant use of recycled car battery Lead. It is NOWHERE close to being as pure as the VIRGIN out of the earth stuff. Visit a lead recycling plant or 4 of them. I had no idea how difficult the process could be to keep all cars supplied with working car batteries.

They are doing the best that they can, to supply the millions of 12 & 24 volt batteries changed every year.

Every battery has a little of a 20 year old Lead battery in it.

 

[Silvertip]

Re: charging batteries

Since a 12 volt battery has six cells, it is not possible to charge one cell at a time so this is a non-issue -- fine to discuss it iin theory but still a non-issue. It is all a compromise and charging effectivemess is based solely on the quality of the charger being used. Batteries can safely and effectively be charged in parallel and have been for decades. Over the road trucks can have six batteries in parallel and they live nicely. Battery manufacturers charge their batteries in "gang" fashion as well. Batteries in parallel are simply one giant battery as far as the charger is concerned. The "pack" will eventually equalize the state of charge and gradually reach the float condition. Yes -- the weakest battery(ies) in the "pack" will suck the life from the others until the "pack" is again equalized. But for charging purposes there is no need to disconnect them (from each other or the engine). You don't do that with your car and you don't need to do it with your boat. If one of the parallel batteries is weak it should be replaced anyway -- just as it would if it were the ONLY battery available.

 

[cyclops2]

Re: charging batteries

How do you know when 1 of the 2 batteries is going bad ? You are not seperating them at anytime.
The battery company HAS EQUAL CELL VOLTAGES .........Because the cells ARE brand new.
Have you ever looked into the cells of a charging older battery ? They start reaching the gassing stage at different times.

I have NEVER seen or heard of ANY electric fork truck battery company telling drivers to make up D I Y rigs to charge several at once. They have ALWAYS been charged seperately in every company I worked in. Some had 15 to 20 trucks.

Quicker & easier? Of course.
Longer life & safer, if 1 battery develops a shorted cell ?? NO WAY. People do not check battery gauges constantly. My Chaparral gauge reads high by 1.5 volts. How many people care if the volts are always a little high ? They simply do not know or care. Normal.

Charge them seperatly & you will notice 1 battery is taking longer always.

 

[John_S]

Re: charging batteries

Anybody I have known to run parrellel batteries was always seeming to be replacing more often than others. And if they replaced only one, it seemed to get worse. It has been my understanding as to what Cyclops2 is describing. I'd install the switch if you need the extra reserve capacity. I'd have them on seperate charger banks, too.

 

[Silvertip]

Re: charging batteries

You can tell when one battery is going bad because whatever it is you are powering does not perform as well as it did when both batteries were new. If you suspect a battery is going to battery heaven have it load tested. If you have the option to charge them individually and want to be bothered with the process of disconnecting them by all means do so. If you feel they should be disconnected from each other when not in use by all means do so. A dual battery switch makes this possible and painless. The fact remains, whatever process you use is compromise. Do what makes you happy but there is no MUST in this process. To get maximum life out of any battery proper battery maintenance requires a quality battery charger. If you have a cheap, non-smart charger and that's all you can afford it is still better than no charger and will probably work just fine if you understand how to properly use it. Yes I have looked at many batteries and noticed one or more cells gassing before the others. So what? Disconnecting one battery from a pack will not stop the gassing. On a single battery you have the same issue. How to stop gassing on one or two cells. Only reducing the charge rate will do that. Smart chargers know what the limits are for a battery with any number of cells. It cannot determine whether one cell is down 20% or two cells are down 10% each. The only way that can be done is with a balancing charginger such as those used with lithium batteries that have a balance connector. While I haven't seen every battery ever made, I have not seen a flooded battery with a balance connector.

 

[fucawi]

Re: charging batteries

Well said silver tip ....but of course " in theory" if they are gassing you have taken the voltage too high......of course we always use a hydrometer dont we ..I never buy a totally sealed battey..saved too many by levering the glued on tops off and topping them up ....Even car alternators are now 3 stage controlled by the main ECU .....