Hawkers and the large batts, need a minimum of 13.6 volts to charge fully, or you will only charge the top half of batt with the small charger maintainer desulphators being used a lot , one finds the batts will not start these trucks in cold, Not a bad batt, just not a fully charged batt . it seems they are being brought back to life by charging them with the proper rate, but in actuality they are just fully charged for the first time. The chargers in the trucks are not smart chargers and only fully charge the first batt in line fully, The resistance when close to full on the others shuts charging down so not to over charge the first batt . These batts in series and parallel need to be pulled fully charged and rotated annually to get maximum life. The hawker company reps have told me this, Look up there web site and call a rep. Its easy and as for the Army having special chargers, It just means they are chargers that are adjusting the charge rate the batt needs from say 12 to up to almost 15 volts at times to fully charge the batts. that means they are " Smart chargers, Easily purchased by civilian's, This is the short fast answer on how to keep your batts running for up to 10 years like I have been doing since using the advise and knowledge of the company's who make em. Good luck . Oh one more thing, slow chargers suck on these big batts . One must fully charge with proper rate and then top off and maintain with the smaller desulphators maintainers. AFTER that
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