Charging 24volt system...

Salmonator · 08-08-2001, 10:18 PM

Is it possible to charge two 12 volt batteries while connected as a 24 volt system or do they have to be disconnected and charged separately? I have the heavy duty 100amp charger. TIA... Joe

willierower · 08-09-2001, 06:01 AM

Im almost positive the 2 batteries can be charged together. A frind of mine runs a 24 volt motor on his boat and has the batteries and a charger mounted in the boat. I think he has the positive side of the charger on one batter ad the negative on the other.
I will ask him how he does it and get back to you. He lives in Albany, Maybe you could swing by and check it out yourself.

FallRiverGuy · 08-09-2001, 08:30 AM

Joe,

You can but they have to be wired in series like willierower said. For example, the battaries that store the energy from my photovoltaic panels are 6V and my system is 24V. I have 4 battaries wired in series which equal 24V.

SureSet · 08-09-2001, 08:36 AM

I don't have one, but my basic electrical intuition tells me that unless you have a 24v charger, the batteries would need to be charged in parallel (negatives together positives together), not in series (negative to positive) as they are set up in a 24v system. Series gives you double voltage, parallel gives you double capacity/current. I know you can charge two 12v at once when they are in parallel, as long as they are close to the same basic size (otherwise you run a isk of overcharging the smaller one).

My 2c worth.

SureSet

O'City Fisherman · 08-09-2001, 08:59 AM

After working on tanks for 4 years the answer to you question is yes. Like everyone has said you would have to run neg to neg in a series and *** to *** in a series. If you could find one a busbar would be best.. Then you would always be in series.

FallRiverGuy · 08-09-2001, 09:04 AM

I was under the impression that the charger was 24V. If it is 12V then they will need to be charged in parrallel as SureSet said.

DK · 08-09-2001, 12:07 PM

if the batteries are run in parallel they remain the same voltage if run in series the become doubble what the batter voltage is you need a 24volt system to charge the batteries
or disconect and charge separate

Gizmo Man · 08-09-2001, 03:43 PM

As said, if you have them + to - when charging you need a 24v charger. These are available and sometimes if you check out the thrift stores you can find one. They are used to charge the batteries on the 3 and 4 wheel scooters that older and disabled people use.

You need more voltage, about 14v, to charge a 12v battery. If batteries are hooked up in series your 12v charger won't bring the charge voltage high enough to charge the battery. I would guess you might even burn out your 12v charger when you hit it with 22-25 volts if you should touch the leads of the charger to the batteries hooked up in series.

I assume you do not want to take the batteries apart each time you charge them.

Another solution would be to disconnect the motor then charge each battery separately. Takes twice as long but you will be doing it correctly.

One additional thought. i have been told by several battey type people that you want to charge deep cycle batteries slowly. Usually at the 2 amp mode to get the max. life out of them. I was told you never want to charge them above about 10 amps setting if you need a quick charge.

The Giz....

[ 08-09-2001: Message edited by: Gizmo Man ]

Vinny · 08-09-2001, 09:04 PM

The easiest way to charge without disconnecting, is to just hook up your 12 Volt charger to one battery at a time.
The only current flow will be through the battery which is connected to the charger. Remember to loosen the batt cell caps if you have them and refill cells with water after you charge (unless you can look inside and see that the electrolyte level is really low, then add some water first). If your charger doesn't reduce the charge rate to a trickle (or shut off) automatically, it's a good idea to use an outlet timer to shut it off to prevent overcharging (which will overheat and shorten the life of your battery). Also, 100 amps is too much for charging, that's used just for starting something with a dead battery. I rarely use more than a 10 amp setting. More current, more heat, shorter battery life.

[ 08-09-2001: Message edited by: Vinny ]

Salmonator · 08-09-2001, 10:17 PM

Vinny you are absolutely right. Went out to look at the charger and it is adjustable for 2amp trickle, 15amp deep cycle charge with automatic shutoff and 100amp vehicle start. Thanks to all that replied... Joe

Troutinator · 08-09-2001, 11:46 PM

Along this line, I have a neato Vietnam era 24DC output generator that was used on carriers to charge the starter batteries on aircraft. Fairly small, 2-stroke, ran good the last(only) time I fired it up. The output voltage meter is missing but it was outputting a clean 24V when I checked it. Bottom line: If anyone wants this thing I'd like to get it out of my garage.. I'll take darned near any offer or trade.

cosmofurball@yahoo.com