Thread: Battery Charger Question

three bank each lead connected to a battery...10 amps plus each lead...charge faster. I have an older three bank Charge Pro that has two ten amp circuits and one 5 amp circuit. The theory was back then the starter battery had the motor alternator that kept that battery up and it was more than likely a 24 class starting or dual purpose battery.

But a lot of boats pull auxiliary power stuff from the starting battery (livewell pumps,radio,nav lights etc.) so it is best to put in the best dual purpose in the largest size in the starter position if that's the case. Especially if you don't run your main motor a lot but fish all day.

Throw the juice to them...do not leave the batteries in any state of discharge any longer than absolutely necessary. You want to bring them back fast ...then a low amp charge to maintain or as they reach peak voltage is okay...charging all the way from deeply discharged to full at a low rate is not ideal unless you have a small battery with low amp reserve.

You leave everything connected...parallel batteries are going to balance out...important you keep both batteries at very close to same performance capability. Both mules pulling evenly at the yoke.Or the other gets tired faster. You can unhook them occasionally from each other and check them for peak voltage and charge time...or use a specific gravity tester to see how they are doing.

My frustration is my condo docks don't have power and my battery charger doesn't give indication of where they are so I am always guessing. my son bought a solar for TM because of it but it isn't much and read you shouldn't leave them overnight as they will discharge battery. new to boat ownership and very frustrated. Now Cranking battery which has always been no problem as it is recharged by running suddenly was dead and it's two years old. it is a battery tender plus and supposedly is good but never indicates battery is charged and have no idea where I am in process.

any brands or suggestions would be helpful thanks.

Originally Posted by hdhntr

My frustration is my condo docks don't have power and my battery charger doesn't give indication of where they are so I am always guessing. my son bought a solar for TM because of it but it isn't much and read you shouldn't leave them overnight as they will discharge battery. new to boat ownership and very frustrated. Now Cranking battery which has always been no problem as it is recharged by running suddenly was dead and it's two years old. it is a battery tender plus and supposedly is good but never indicates battery is charged and have no idea where I am in process.
any brands or suggestions would be helpful thanks.

First...get a digital multimeter. Most of even the budget models have very accurate DC voltage measurements. You can get one at Lowes or one of the auto parts stores. Generally steer away from the bargain bin ones....just a decent multi meter you can use all purpose.

Always double check them occasionally no matter what charger you have. As an all around rule of thumb...if you have around 12.7 volts you have a fully charged battery. 12.4 or so will act okay at first but you will notice you run out pretty fast,it's either a battery getting weak or ...your charger is shutting off before it's fully charged.Anything less.. considerably undercharged or bad cell or cells.

Put any battery you want to test on a charger first. When the charger shuts off...(if it doesn't your battery is probably definitely bad) and the see what voltage you have. You should have 12.7 or better...some chargers will leave a slight over charge of 13.1 volts or so. Put a small load on the battery for 20 minutes or so like a nav light. Then check to see if you have 12.7 or more...if you don't weak battery.

Generally speaking don't expect a lot from a 24 or even a 27 class battery. If you seriously need to power a troller and a multitude of devices...start with at least a 29 class or parallel smaller ones or multiple batteries for different loads . If you are going to stay on a budget with flooded cell batteries in the 100 dollar range...get the highest reserve capacity and best warranty you can. Wal-Mart batteries are not bad...it has a lot to do with treating them right. You will kill any of the low end batteries with incorrect maintenance . Three to five years tops out of them typically even when you treat them right.

centage of Charge	12 Volt Battery Voltage	24 Volt Battery Voltage	Specific Gravity
100	12.70	25.40	1.265
95	12.64	25.25	1.257
90	12.58	25.16	1.249
85	12.52	25.04	1.241
80	12.46	24.92	1.233
75	12.40	24.80	1.225
70	12.36	24.72	1.218
65	12.32	24.64	1.211
60	12.28	24.56	1.204
55	12.24	24.48	1.197
50	12.20	24.40	1.190
45	12.16	24.32	1.183
40	12.12	24.24	1.176
35	12.08	24.16	1.169
30	12.04	24.08	1.162
25	12.00	24.00	1.155
20	11.98	23.96	1.148
15	11.96	23.92	1.141
10	11.94	23.88	1.134
5	11.92	23.84	1.127
Discharged	11.90	23.80	1.120

Monitoring and Maintenance
The battery voltage should be kept at or above a 50% state of charge for maximum battery life. Keep the battery's electrolyte level to the indicated level and never let the plates be exposed above the electrolyte. Use only distilled water - not tap water, when refilling the batteries. Water is the only element used by your battery. You should never have to add acid to your battery. Do not overfill or fill when the batteries are discharged. Over-watering dilutes the acid excessively and electrolyte will be expelled when charging.
Equalization
Equalization is the controlled overcharging of a fully charged battery. This overcharge mixes the electrolyte, evens the charge among varying battery cells and reduces permanent sulfation of the batt

I would recharge that battery and then have it load tested at auto parts store
You might have left something on in the boat that drained it down
Like key lights fish finder pump etc
Don't know about solar panels but I would think they would have a diode in them to keep them from discharging battery at night
There are lots of them in use that are hooked up all the time


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Originally Posted by hdhntr

My frustration is my condo docks don't have power and my battery charger doesn't give indication of where they are so I am always guessing. my son bought a solar for TM because of it but it isn't much and read you shouldn't leave them overnight as they will discharge battery. new to boat ownership and very frustrated. Now Cranking battery which has always been no problem as it is recharged by running suddenly was dead and it's two years old. it is a battery tender plus and supposedly is good but never indicates battery is charged and have no idea where I am in process.

any brands or suggestions would be helpful thanks.

If you can leave it in the boat and charge the batteries while docked or at home ... I suggest a onboard charger, with enough leads to connect to all batteries separately, and 10amps per lead. A digitally controlled unit is also a plus factor.

Then again, if you're like me and have to take the batteries out of the boat to charge them at home (apt complex, etc) and you have more than one battery ... the onboard chargers work in that scenario, too.

I wouldn't suggest a "cheap" battery charger of any type ... so if you only need to charge one battery, then you still need to get a good quality deep cycle charger that puts out 10amps and has some type of gauge or dial showing where your battery is at during the process.

The lower amp chargers will charge the battery, but from what I've read ... the higher amp chargers help keep the sulfate from hardening on the plates (causing the battery to not take a full charge). But, I would defer to the battery guru "CatFan" for confirmation or clarification on that. I just know that I've always used a 10amp charger (or onboard charger with 10amps/lead) and my Wal-mart deep cycle boat batteries have always lasted around 5yrs.

Thanks for all of the feedback guys. Yet another reason I love this site.


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gotta say...doggone gave you great advice

agree KF, this site IS the best, so much specific advice that you can use! Thanks so much guys i really appreciate the information.