I have 3 batteries in my boat.
1 x 12v crank battery
2 x 12v batteries in series for my leccy
After every fishing trip, i currently disconnect all three batteries and then put them on the trickle charger.
Is there a way of not needing to disconnect these batteries all the time for the need of charging them?
i find it a PIA, and woudl rather flick a switch or something so i don't drain the batteries whilst still connected sitting at home in the garage....
splash
Splash....Are they not getting charged whilst your motor is running?.....What is daring them in the garage....I certainly give my batteries (2) a trickle if I know I am not likely to use them within the next month or two, but otherwise they hold their charges.
Sorry if I am missing something here....I actually do take the positive terminal off but only to eliminate the electrolysis effect causing corrosion not to stop the batteries from going flat which they don't.
Gotta Love Maroochydore.
Charge them one at a time and you won't have to disconnect anything.
BEP do a range of switches that will do the job. Have a read of the docco on their site. A simple setup would be the use of a couple of 1/2/both switches, one for the levy pair to allow isolation for charging and a bridge to the main to allow for emergency starting.
If the charging system is up to it, you could expand with VSR's.
The batteries for the leccies are still likely to need trickle charge after an outing if you don't travel far to get back to the ramp. The amp hours consumed with a leccie would require time to bring them back to fully charged.
Cheers
Thy
thanks.
the batteries are holding charge and they do get put on the trickle charger as soon as i arrive home.
to me it is a pain having to undo the connections all the time before i put the trickle on. i guess i thought i had to do this because i thought leaving the connections on, charge woudl drain out of battery.... perhaps i am wrong..
i once left the 2 x leccy batteries connected for a week without a trickle charger attached, and both batteries were nearly shot in terms of charge.
if i charge 1 of the 2 leccy batteries at a time without disconnecting anything, will this be ok?
i will have a look at the bep range.
splash
Ideally you should have isolator switches on all batteries and a charging relay between the start battery and the auxillary batteries. So in that case when charging you have all your batteries switched off via their isolators and when wired correctly you put your charger on to battery 1 (start battery) and when it is up to charge the relay should switch the other batteries in to charge state.
I am not a fan of trickle charging continuously long term although it is done all the time in many systems OK but I think that you want a quality charger to manage this properly. I just hook mine up for 24 hrs if I think the batteries may be getting down a bit or the boat has sat for a few weeks unused.
I put mine on last night actually due to the crappy weather not getting out much. I was interested to see what the system did so hooked it all up with voltmeters, ammeters and observed.
My charger is a basic 10amp automatic charger so it regulates the voltage output to control the charging current. So I have two batteries paralleled for starting and two house batteries also paralleled. They have isolators and a charging relay (VSR or ACR) in between both banks. Observing the chargers voltage and current showed that the start battery charged alone for about 2 hours and when the voltage increased to about 13.7 volts the relay switched in the second battery bank for charging which then ran overnight charging all 4 batteries at about 6 amps.
This current will usually drop away over 24 hrs to either nothing or a couple of amps when I disconnect the charger.
Yes mate, keep it simple unless you have a need to recharge the leccy batteries overnight.if i charge 1 of the 2 leccy batteries at a time without disconnecting anything, will this be ok?
thanks johncar.
do i need to disconnect the batteries before i put on the trickle charger?
Splash
If the batteries are going flat while connected there must be some load on them, maybe just the leccie controller, but you need to consider that a 6w load draws .5 AH, OR 12 ah per day. 1w will draw 2ah per day, so 4 weeks is a minimum of 56ah, and possibly much more as the voltage drops, the current increases. Ohms law applies. Isolation switches can stop this.Originally Posted by Splash
There is no issue with wiring a charging plug from the battery side of the isolator to make it easier to charge.
Maintaining charge with a battery minder style charger is a good idea for extended periods of non- use. But up to three weeks probably doesn't require this.
We run 2 batteries, 1 for start, 1 for house, with a Vsr. If the isolation switches are not used, the Vsr relay runs the start battery down in just three weeks. I can testify that the switch to bridge both batteries is a bloody good idea, saved me much embarrassment at the ramp on the day with more than 30 boats lined up in the queue.
Our boat is stored down the coast, so trickle charging is no an option, and neither is solar. Ensuring the Isolators are switched off is now a mandatory checklist item before tarping up.
Reducing the Voltage increases the current... Georg Ohm will be rolling over in his grave.
The VSR runs the start battery down in 3 weeks... It must be faulty.
do i need to disconnect the batteries before i put on the trickle charger?
splash
120w at 12v = 10amps draw
120w at 10v = 12amps draw
120w at 8v = 15 amps draw
My understanding is that Ohms law is "watts divided by volts equals amps". Happy to be corrected.
Old George has no need to roll. It is for this reason that cable size over long runs becomes important, as voltage drop can result in current exceeding cable ratings.
As for Vsr, it is a powered relay in normal operation, "sensing" voltage still has a current draw associated. In hindsight, ignition may have been on and contributed heavily, must admit focus was on clearing the ramp. Not experimented sufficiently to say what current it draws. Intent was to convey the importance of isolating batteries when not in use to avoid small loads over time draining the batteries.
Not if they are isolated. Assuming your leccie batteries are in parallel, it is ok to charge them in parallel but there is a risk that if one is in better nick than the other that the better one will accept charge to a point where the regulator on the charger switches it down/off before the second is fully charged.
Here you go thylacene.
http://en.wikipedia.org/wiki/Ohm%27s_law
Use Ohms Law to get a resistance value for your first example.
120w at 12v = 10amps draw = 1.2 Ohms
Then use Ohms Law to apply that resistance value to the other two examples and you will see the Amps drop in proportion to the drop in Volts.
1.2 Ohms at 10 Volts = 8.33 Amps
1.2 Ohms at 8 Volts = 6.66 volts
Consider Voltage drop to be nothing more than an added resistance in a circuit which means less current flow not more.
It will all fall into place once you follow the Wikipedia link.
Key left on sounds like it, let's face it no one would buy a VSR if their draw was any more than negligible.
Splash...
No need to disconnect anything, just charge them one at a time.2 x 12v batteries in series for my leccy
Posting Permissions
Reply With Quote
