why would you charge individually ? if theyre in parrallell the charge is nicely shared betewwen the batteries . Even if the batteries were of different capacities this still applies !
its if you have them in series that unequal charging can (does) occour.
to visualise the parrallel case imagine the analogy of many water tanks all linked by pipes at the same level above ground . the charger is like a water pump . You COULD fill up one tank and then empty it into the others but just as easy to fill all the tanks at once from equal pipes. the tanks will settle to the same level.
chris s
--- In electricboats@
>
> Therein lies my problem, lets say we start with new batteries that are pretty close to equal in all respects, they all feed to a common bus bar and this powers a pair or more of 12 volt to 120 volt inverters, trying to set up a cycle that as a single battery reaches the set low it is isolated from the group and is recharged to the ideal peak, it then goes back to the group in a fully charged state, as the next of the group reaches it's low state and starts being recharged. You always have a battery being cycled in a near perfect pattern, while the main collective supplies the load to the inverters.
>
> In a group of 12, you have 11 from fresh charged to fully discharged, with one being charged. Only the quality of each individual battery would cause this cycle to fail.
>
> I know this ideal world cannot be reached, but how close can we come? As I stated before, not much knowledge in electronics but I feel a solution is out there that can supply an automated system.
>
> Ron
>
> --- In electricboats@
> >
> > Oops, Chris is right. I was thinking of series connection.
> >
> > Charging batteries in parallel, though, means the batteries "sharing" the current may not get charged equally. I think the charger sees the average condition of the batteries; overcharging some and undercharging others. The potential for uneven charging increases with the number of batteries sharing the charger.
> > ----- Original Message -----
> > From: hardy71uk
> > To: electricboats@
> > Sent: Monday, February 22, 2010 5:47 AM
> > Subject: [Electric Boats] Re: Skeptical wife has question about SolidNav
> >
> >
> >
> >
> > At 1200Ah I guess you have them all in parrallel. Surely they will share all charge and so they will not need to be individually monitored . It is impossible to separately charge parrallel batteries without disconnecting at least one connection per battery. To charge such a bank overnight ( no need to make any disconnection) you would need a single 12 volt charger of around 120 amp rating . Obviously you can charge at a lower rate . a 12 amp charger, for example, would take some 140 hours .But that maybe too long for the long term health of the batteries.
> >
> > Chris S
> >
> > --- In electricboats@
> > >
> > > Ron, You can hook up the chargers without disconnecting the batteries. Of course you would need 12 chargers (or 3 four bank chargers) to do all 12 batteries at once. No manual work involved except plugging in the chargers to shore power.
> > >
> > > Pack Tracker makes a meter that monitors as many different batteries as you buy sensors for.
> > > ----- Original Message -----
> > > From: Ron
> > > To: electricboats@
> > > Sent: Sunday, February 21, 2010 10:49 AM
> > > Subject: [Electric Boats] Re: Skeptical wife has question about SolidNav
> > >
> > >
> > >
> > > Thanks Pat,
> > > Although I have messed around with batteries and motor/generators for a lot of years, I am still far short of knowledge in best practices of battery care.
> > > I have 12 deep cycle, 100 amp hr batteries (group 29 I think) and because of poor disipline and job requirements, have most likely lost them.
> > > I'm pretty much in the dark about electronics, but feel there has to be a way to have them as a group (12 volt X 1200 amp hr) and still monitor and charge them as individual batteries on an as needed basis without the physical disconecting of the wiring, I think it will involve some sort of rotating solonoid with push pull action, controlled by electronics.
> > >
> > > This time involvement to do things manually and often times improperly is I think the biggest cause of short battery life, so any information about proper hookups, is something I would like to see.
> > >
> > > Thanks
> > > Ron
> > >
> > > --- In electricboats@
> > > >
> > > > I'm not sure I would make such a general statement. Some chargers do connect the negative battery lead to ground and many boats tie the negative side of the battery system to the metal frame (if any) of the boat (commonly refered to as ground even though it isn't). However, in this case, it is true that chargers designed to charge multiple batteries in series do not tie any of the battery leads to each other or "ground". Each charger "floats" independantly and does not interfere with any other charger operating at the same time. You can buy dual or quad chargers that contain 2 or 4 independant chargers in one package. (Denny, I know you already knew all that, but I wanted to clarify for the newbies like me who read these messages). ...Pat
> > > >
> > > >
> > > > --- In electricboats@
> > > > >
> > > > > Yes, of course. There isn't a ground in a DC power system like there is in a house where all the neutrals are connected at the circuit breaker box.
> > > > >
> > > > > ----- Original Message -----
> > > > > From: KGB
> > > > > To: electricboats@
> > > > > Sent: Sunday, February 21, 2010 8:26 AM
> > > > > Subject: [Electric Boats] Re: Skeptical wife has question about SolidNav
> > > > >
> > > > >
> > > > >
> > > > > Hi Denny,
> > > > >
> > > > > A question on charging a 48V bank of four 12V batteries with four separate chargers: I suppose that is OK only if the chargers outputs are isolated from ground. OK?
> > > > >
> > > > > /KGB
> > > > >
> > > > > --- In electricboats@
> > > > > >
> > > > > > John,
> > > > > > The reason that 48 volts is a popular voltage is that it takes a certain power to push your boat. Power = volts times amps. Double the voltage, cut the amps in half. Resistance losses in the motor vary with the square of the current so a 24v motor at 100 amps is less efficient than a 48v motor at 50 amps. Also, the size of the components generally goes with the amperage, not the voltage so a higher voltage, lower amperage system can have smaller wire, smaller controller, etc.
> > > > > >
> > > > > > 12v systems are not used, except for the smallest trolling motors, because the current would be so high to get the required power.
> > > > > >
> > > > > > Charging a 24, 36 or 48v system is simple. If you do not want to get a high voltage charger you can use multiple 12v chargers; one for each 12v battery or pair of 6v batteries.
> > > > > >
> > > > > > You will want at least (4) 60 - 70# 12v batteries to get enough energy storage to have a practical range under power. (8) 65# 6v batteries would be even better. Starting with one 12v battery with the thought to add more later is not a practical option. 48v motors, chargers and controllers are readily available.
> > > > > >
> > > > > > I believe Compac has tried a few EPower pod drives from Kevin Plank. He is now out of business. You would be better off with an "inboard" electric motor or a Torqeedo outboard on a transom bracket.
> > > > > >
> > > > > > The electric system, including a decent bank of AGM batteries, should cost around the same as a diesel. The diesel will have more power to push the boat into adverse weather, have much greater range, be annoyingly noisy and require some periodic maintenance. If you can live with the range and max power limitations of electric drive and can recharge from shore power conveniently, electric may be for you. Cruising along in a flat calm at 5 kts in silence is sweet. A well engineered system with AGM batteries requires no more maintenance than your cell phone - just plug it in at night.
> > > > > >
> > > > > > You should try to get a ride in an electric boat before committing to diesel.
> > > > > >
> > > > > > Denny
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
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