Paul, is it possible that last time you checked and the lead acid charger backed off quickly, you were using thinner cable temporarily, and now that it's wired in more permanently, the cables are thicker? The lead acid charger might have been getting a significant voltage drop across the charger cables, but now less drop?Paul9 wrote: No, not this time! This time the combined charge got up to 27.4amps and stayed there?
Chargers really should have four output cables: two thick ones to deliver the power, and two much thinner wires to accurately sense the battery voltage, without being affecI'mted by the voltage drops. This is often referred to as a Kelvin connection. Perhaps one sense wire would do, assuming that the voltage drop across both cables would be the same. Though in many EVs, this may not be the case.
Edit: a quick note on how this would work. Suppose you have a battery that rests at 100 V, and is full at 110 V. With thin cables from the charger to the battery, at 25 A the battery might rise to sat 102 V due to its internal resistance, but the charger output might be say 108 V. The extra 6 V are dropped across the thin charger cables. So the charger thinks the battery is getting close to full, so it cuts back the charge current. With thicker cables, the voltage at the charger might rise to only 104 V (one third the voltage drop), so the charger continues at full current.