24v charging

[fivebucks]

I've been going thru deep cycle batteries too fast so I started to do some research and think I might need a 24v charger instead of a 12v charger. I never knew there was a 24v charger. Some boat background. It is a Lund 1800 and has a 3 prong male plug in with a 3 way switch. The positions are "charging", "12v", "12v/24v run". I have a female plug that plugs into the above and has 2 battery terminals to accept the clips from a charger.

I have been using your basic deep cycle automatic 12v charger and it doesn't quite work right (ie: green light does not come on indicating the batteries are fully charged) when I try to charge the batteries thru the 3 prong deal. The batteries charge just fine when I take them out and charge them individually. Any ideas? An on-board charger is not an option as the boat stays at the lake over the summer with a solar trickle charger hooked up, unless on board chargers can be powered by a trickle charger and not 110 current. Is this as simple as getting a 24v charger? Thanks for your help as I need to get some things bought as opener is just a few days away.

[jtroop]

I don't know specifically about your Lund but on my old boat the switch needed to be set to "charge" to send 12VDC to both batteries simultaneously. You didn't say if you were doing that.

Do you have a voltmeter ? Sounds like you need to verify that 12VDC (actually something over 13VDC) is getting to each battery from the charger.

Maybe someone else will have an answer but I don't know how charging at 24VDC (in "series") could be better than 12VDC (in "parallel") - all else being equal (sufficient current).

[JohnMickish]

Personally, if it where mine I'd go the on board charger route and run a GFCI protected extension cord down to the dock and charge the batteries. I think that's what it's going to take to do it right.

[fivebucks]

Jtroop,

I do switch it to "charge" when charging. I haven't run a voltmeter on it yet as I am not sure just how they work. They have a bunch of switches and I did not want to fry myself. I will read the instructions carefully and try that tonight. I got to thinking that maybe my switch went bad because a few years ago it worked fine and then one time the plug in got really hot and melted itself a little bit and hasn't worked right since. Thanks.

Mnfishingguy,

My cabin has no electricity yet so unless there is a charger that will charge in a short period of generator run time, I'll need to stay with the current setup.

Is there an easy way to test the switch?

[jtroop]

Melting electrical parts rarely helps but here's where I'd start: Take voltage reading on each battery independently - for example, lets say they're both at 12.3. Hook up your charging system and take readings at each battery again. You should see each of them slowly increase (to something over 13 VDC depending on charger) if the batteries and charger are doing their jobs. If the reading on one of the batteries doesn't move you likely have a wiring and/or switch problem.

[fivebucks]

Thanks, I'll be doing some testing tonight.

[Juan Grande]

Not to hijack this string, but I have a charging question of my own. I have a dual bank charger and two deep cycle batteries that run my trolling motor and electronics.

I hooked up the batteries this spring using a photo of the configuration from last fall so I'm pretty sure it's correct.

I left the charger plugged in all night so I know it was fully charged. Took the boat out on Saturday and the trolling motor does not seem to be running at full power. It's a 70lb motor and I had it on max speed and couldn't keep up with the waves. Some times I would turn the motor left with the foot control and the motor would turn all the way, even though I released the pedal.

Also, my Lowrance was acting goofy and was giving the wrong depth at times. I know it has acted weird in the past when the batteries were about to die.

Does this sound like a battery issue? The batteries are only a year old so I shouldn't need new ones.

[theoilman]

In most boats with 2 batteries in normal run mode you have some things running off 12V (just one battery) and some running off 24V (both batteries in series) the batteries will always be at different charge levels. Because of this charging with a 24V with the batteries in series will not bring both batteries back to full charge. Most boats have the "Charge" battery switch position that disconnects all the uses, reconnects the batteries in parallel (12V mode only) to charge with a 12V charger, and normally will bring both batteries back to full charge even though they were at different levels from use.

Fivebucks I suspect you have a wiring problem and the 'charge' position of the switch has something wired wrong.

Juan Grand, I suspect either you didn't get one of your batteries recharged as well as you thought, or you have a battery that has gone bad.

[fivebucks]

OK, I did some testing and here is what I found. First off I looked at my batteries and they are 5 years old so they might be worn out. I thought they were only 2 years old but that was my starting battery. Anyhow, I hooked up two other batteries and the voltmeter measured about 12.4 on each battery. I then hooked up the charger thru the 3 prong adapter and it went up to about 14.0 or so on both batteries. I think that verifies my charging system is working OK right? I am going to buy 2 new batteries tomorrow and re-test again. Thanks for the helps!!!!!!

[Whoaru99]

Sounds about right to me.

However, I think the advice about getting a dedicated OB charger is sound.

OTOH, if your batteries are lasting 5 years with the current setup, I'd think it hard to justify an OB charger unless, maybe, you need faster cycle time.

[BobT]

There's something else to keep in mind. When wiring multiple batteries in series or parallel the circuit power is limited by the weekest link. If both batteries are not at the same physical condition, you will not get peak performance.

My diesel truck has two batteries parallel wired to deliver the current necessary for handling the glow plugs and the starting motor. I had one battery develope a short-circuit which destroyed both of them.

One advantage to series wiring and using 24v is that one shorted battery only reduces the output voltage and is not likely to damage the other battery. A shorted battery connected in parallel has the same effect as putting a jumper across the terminals of the good battery.

Bob