For a *good* charger (i.e. one designed to handle lead-acid batteries) you would expect that the automation includes the possibility to either automatic or manually select the needed equalization.
I have a pretty dumb charger (sorry Bycan folks) that consists essentially of a big ferro-resonant transformer and a small circuit board that has two timers, one level detector and a bit of logic. The first timer is the longest (supposed to be about 20 hours) to shut off the charger even if it does not detect that the pack is full (so it won't forever continue to murder already full cells that are too old or for some other reason fail to reach the end of charge threshold). The level detector finds the moment that the 120V pack reaches the 147V level indicating that charging is done (2.45V per cell). At that moment the second timer starts and continues the charge for a (user selectable) period, either 2 or 6 hours. Since the voltage is already high (around 150V) the current out of the transformer has dropped to a few Amps into the 250+Ah floodeds, so while they do gas, there is no excessive water loss - in fact, I am now watering my pack after using it for about 5-6 months (I bought the truck last May but have been traveling and had some down time when fixing the EV-100 controller) The truck has done over 2100 miles in that time which means about 100-150 full charges. Watering the 20 + 2 golfcart batteries (pack + aux) back to the 1/8" level under the opening seems to take about 3 gallons of distilled water. This means about 160ml (2/3 cup) per cell. I am guessing that the level was almost halfway down from the refill opening to the tops of the plates, but it is hard to judge due to the different angle of light below the fluid, it could also be only 1/3 of the way down. Certainly no exposed plates - that is what I have been monitoring carefully. Typically I run the charger on the 2 hours setting and from time to time I will flip the switch and run a 6 hour equalization cycle when I know that there is time to do so or when I think it might be necessary. The charger will turn off automatically at the expiry of this second timer, so I do not need to worry about over- or under- charging. I can plug in and walk away - even go on a trip of several weeks with the truck plugged in. There is also a second threshold: if the pack voltage drops below that while still plugged in, the charger will reset and recharge the pack. I would hope that smarter and more sophisticated chargers also do implement such simple controls to maintain your pack. Something to look out for when shopping (or designing) your charger / BMS combination! Regards, Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: [email protected] Private: http://www.cvandewater.info Skype: cor_van_de_water Tel: +1 408 383 7626 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of SLPinfo.org Sent: Monday, February 04, 2013 2:10 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] Elcon PFC-2500 Chuck, Well, that's essentially all I do now, and I'm fine with that as long as I can do some regular equalizing to help extend the battery life. As a non-engineer and non-hobbyist, my EV is my daily driver. I need it to be there for me, and I don't like to have to think too much about it - I actually got rid of my previous charger where I could set several different things, because I felt like it was smarter than me (I never felt like I fully understood what it was doing; my own limitations, not the charger's). Thanks for all the info. - Peter On Mon, Feb 4, 2013 at 10:51 AM, Roger Stockton <[email protected]>wrote: > SLPinfo.org wrote: > > > MY QUESTION WAS HOW WOULD YOU DO IT SPECIFICALLY WITH ONE OF THESE PFC > > 2500s? I GOT THE IMPRESSION THAT THERE WAS NOTHING MUCH BESIDES PICKING > A > > PROFILE THAT YOU COULD SET, SO WHAT WOULD YOU HAVE TO DO TO EQUALIZE WITH > > ONE OF THEM? > > The typical advice for an electronically-controlled/automatic type charger > is that to perform an equalise you let the charger run to completion, then > restart the charger and let it run a second time. > > Just how much additional charge this will deliver to the battery will > depend on the profile that the charger uses, but this is generally your > only option for an automatic charger. > > Cheers, > > Roger. > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... 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