Monday, December 31, 2012

Final (hopefully) Chargers have been ordered

And the charger saga continues.

There seems to be a charger theme as of late. But I plan on getting it right, so I shall continue this theme for a little while, anyway.

My recently purchased six individual chargers are a temporary solution to avoid murdering my brand new batteries. Series charging my pack was doing just that - undercharging some and overcharging others - because of varying internal resistance within my pack.
According to Canadian Tire's website, the return policy for these charger is "90 days in the original packaging". So I have 82 days left.

These chargers are old school transformer based chargers. Very very inefficient. So inefficient that I am embarrassed to enter fuel log data.

During the bulk charge when batteries resistance is low:
Input power: 160W
Output power: 10A*12.8V=128W
Efficiency: 80%
Once the battery voltages go up and resistance increases, the charger output current drops significantly while input current drops much less:
Input power: 125W
Output power: 5A*13.5V=67.5W
Efficiency: 54%

Since the current slows down at higher charging voltages, most of the charging time is spent in this stage, where efficiency is quite low.

But I knew it would be like this with these chargers, and I have to keep reminding myself that this is temporary.

So....for my [hopefully] final charging solution I have ordered.....(insert drumroll).....THIS:
Six of them. 12V/10A. Configured for 14.4V max output to match my AGM battery constant voltage charging spec of 2.30-2.43 VPC. Tiny (170mmX90mmX50mm) and light (1kg). PWM controlled (instead of transformer/resistance "controlled"). I really really hope they work!

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