Help w/ charging trolling motor batteries pls

[Gemrod]

Hello,
I just purchased a Marine Maxx 29 60 pound battery from Wal mart. It says 125 amp hours I think. I don't care what the Marine Crank number is, or the cca.

The salesman told me to only charge it on trickle charge...thats 2 amp manual on my little charger. So I never will know when it is fully charged. he said NOT to charge it on 10a automatic because it is designed differently than a starting motor. I don't get it. So what?

Guess two questions. What is a good amp hour rating for a trolling motor battery to use?
And how does one maintain the charge in a trolling motor battery?

I recently capsized my little 8' Pond Hopper boat and lost my battery.

When I went back out to look for my gear in another boat my battery went dead and the wind blew me to the far end of the lake and the wrong side as well.

So I bought two 75 amp hour btty's..thinking will take boaf on my boat. When one goes dead I will know where I stand and have the back up. Total weight 80 pounds!

My friend told me to take them back and just switch to the Marine Maxx 29 they have which weighs 60 pounds. I thought Group 24 size was all that was necessary for trolling but I really do not want to have a dead battery on board anymore. That experience was not fun.

I am not an experienced boater or battery charger. I wish I had asked for a battery recommendation on here before I purchased the battery.

Any comments and/or suggestions would be appreciated.

[Jeremy]

When I used to charge up my two deep cycle batteries for my boat manually, I used a standard 10 AMP charger w/a timer and set the timer for 8 hrs to fully recharge 'em. I have a Dual-Pro system now so it's not manual anymore.

A trickle charge won't drive the charge deep enough into the cells to fully get them set. You'll get ALL KINDS of advice on this and I might be wrong but since it's been working for me for over 20 years I'll go with what I've done.

The batteries (both) usually last around 5 yrs B/4 needing to be replaced. I had two batteries b/c I have a 24 volt (two 12v's) trolling motor that can pull a 17' Ranger fiberglass rig around all weekend. It does me well!

[Normand]

http://forums.iboats.com/showthread.php?t=66169

[Silver Creek]

http://www.windsun.com/Batteries/Bat...ery%20Charging

[Gigante]

for several years and always used a trickle charge. The battery last longer when pushing around a small craft like that. I used that battery with 30 40 and 50 lb transom mount trolling motors on both an 8' bass buggy and a 16' canoe. 8 hrs is a good starting point for charing. I have cheap charger that does 2 and 10 amp and automatically turns off when the battery is charged. Look into that. I think I only paid $20 for it.

[DaveP63]

Yup...You can find all kinds of chargers that shut off automatically. That's what I've used for the last five years on my battery.

[Terry Lightle]

I have charged mine like Jeremy for over 35 years with no problems.

[Gemrod]

Thanks for the charging information. I think I know and remember the precise formula. And that is for example if your battery says it is a 100 ah (amp hour) battery.....to fully charge it.....at one amp per rate it would take 100 hours to charge it. Therefore it is considered a battery with 100 ah capacity.....and is rated a 100 amp hour battery.

But first...I was told yesterday to only charge a deep cycle battery on the trickle charge setting. NOT to switch it to 10amp! I don't buy that...but generally try to follow good advice. I don't think this man knows as much about charging batteries as he thinks he does.

You guys are telling me you charge deep cycle batteries at 10a all the time. And your batteries have lasted for years. I think I need to follow Jeremy's formula. My little charger will only do 2a on manual and will only do 10a charge on automatic. Therefore...I cannot calculate the ampere hours to charge it precisely in hours...because as it charges it slowly drops down in the amp hour charge rate. It is not a fixed 10a charge....it automatically drifts down to 2a.....and when it thinks the battery is fully charged it will still set and run at 2a charge. I wish it would just shut off. I might go to the trouble of getting a hygrometer and taking a reading to know when it's fully charged. Since my little charger is not precise enough for me. I do not want to overcharge, or undercharge my battery but going by calculated ampere hours won't work with my charger because it is not constant.

I just don't remember what a fully charged specific gravity should read. Can't remember if it is supposed to .1230 .....or if for example 1237 indicates an over charge and stop charging. Don't remember the recommended specific gravity for correct charge.

Thanks everybody. I was told to get the Ever Start Maxx 29 from a fellow who did some research...not necessairly scientifically....but came up with that battery as best one to get for trolling in our neck of the woods. And he stated it was rated the best in Consumer Reports.

As someone mentioned above.....different manafacturers make a list of batteries. Hopefully I interpret his comment correctly in that the Maxx29 is made by Johnson. Back a kazillion years ago when I took care of batteries in power plants....the EXIDE batteries were the worst by far. We had to change them out more than any other brand. Plates sulpherized, got cat eyes...swelled up and popped the top of the batteries up! I hope I never buy an EXide unknowningly.

[tailingloop]

I use an automatic charger designed for deep cycle batteries. In automatic mode it varies from 12 to 2 amps, reducing the current as the charge on the battery builds up. I have never seen it start 12 amps, only 10. After the battery reaches a full charge it changes to a trickle charge mode, automatically turning the trickle charge on or off as needed. I think I paid about $40 for the charger at Wal Mart 15 years ago. My batteries have lasted for years.

I put the batteries on the charger at least once a month whether I used them or not.

[Gemrod]

Thanks Tailingloop

I think that is what I should do. Look for a new and appropriate charger.

Again tks