I work with off-grid homes, and nobody splits the series connections to charge their batteries in parallel, not even the small systems with 4 - 6V batteries. The same is applicable here. In fact few if any use battery management systems, but for the series chargers we use a BMS is advisable. The weight for the 6 chargers I carry on board is maybe 6 lbs. The Soneil 1206 which charges at a 6A equiv. runs 14oz. They're small as well and can be tucked in where you have room.
Jeff On Thu, Mar 13, 2008 at 8:32 AM, David Herron <[EMAIL PROTECTED]> wrote: > When you put batteries in parallel they automatically balance each other > ... and they will automatically all be charged to the same level by the > charger. > > If you bank charge with one charger per battery how do you have any > gaurantee the chargers actually all behave the same way? Chargers are > analog devices and some of the components could be different from > charger to charger. > > One issue I haven't seen Andrew address is ... if you connect in > parallel two batteries who aren't at the same voltage.. clearly they're > going to try and equalize when you connect them, so there should be a > large spark. > > - David > > > > > Jeffrey Blamey wrote: > > If you do the one charger how will you properly charge all the > > batteries to the same level. It seems from watching this list for year > > that the best approaches are a.) one charger for the series string and > > utilize a BMS to ensure all the batteries are at the same level of > > charge, or b.) individual chargers and no BMS - I am charging 6A per > > battery at the same time and each charger goes into the final stage > > when the time is approriate. You are clearly making it harder on > > yourself to have to break the series connections between the > > batteries. > > > > Time for the series charge/BMS guys to chime in here. > > > > Jeff > > > > On Wed, Mar 12, 2008 at 9:50 PM, Andrew Wowk <[EMAIL PROTECTED]> wrote: > > > >> In concept, I have to disagree. It is simpler, cheaper, and less bulky. I > >> think in abstract terms, all we are really trying to do is break the > battery > >> pack which is really just one large battery by definition, into 6-cell > >> sections for charging. I don't see why one large 12v charger wouldn't work > >> well, if not better due to being simpler and easier controlled. > >> > >> However, there are some advantages to having individual chargers: > >> > >> ⚫ The maximum current should always be within a predefined limit. It may > not > >> be with the batteries in parallel & one large charger, due to variations > in > >> the batteries, battery temperature, and the variation in wire lengths > >> connecting them. > >> > >> ⚫ If the chargers check for battery problems and give some feedback, they > >> may not be able to do this properly w/batteries in parallel. > >> > >> ⚫ In the case of a battery w/shorted cell, the other batteries will be > >> charged properly. This may not be the case with batteries charging in > >> parallel. > >> > >> Andrew in NM > >> > >> > >> > >> On Wed, Mar 12, 2008 at 8:29 PM, Jeffrey Blamey <[EMAIL PROTECTED]> > >> wrote: > >> > >>> Sorry as far as the chargers go you can leave the normal series > >>> connections in place, and wire each charger to each battery. 6 > >>> chargers at 6 amps each running their own charging algorith based on > >>> each battery state of charge is preferable to one large charger trying > >>> to charge 6 batteries in parallel. > >>> > >>> Just imagine the series string is open, when it is charging it better > >>> be. I have left the chargers in the circuit when the bike was turned > >>> on but the chargers disconnected from their ac source. No appraent > >>> problems with the Electricross chargers. > >>> > >>> Jeff > >>> > >>> > >
