parallax power supply 7345ru parts PWM
My 7345 is not charging the coach batteries but does supply 12power to all accessories. The transformer, fan and relays work fine. Think i need a PWM circuit for it. Contacted PP tec support and th...
Forum Discussion
If I were to mess with our 7345 converter's feedback loop, one approach I might use would be to bump up it's feedback reference voltage to only around, say, 14.4 volts and then move it's feedback sense point to the battery post.
That way one would get a solid 14.4 volts right at the battery for all the way up to a battery charge current acceptance rate of the maximum of the 7345 ... supposedly around 45 amps. However, one would have to be careful to only have the converter connected to the batteries for a few hours to prevent boiling away the battery water ... while also taking care of the safety factor via combining of cable fusing with not using too-small cabling ... so as to prevent cable over-heating. This is because a charger with a feedback loop sense point at the batteries will maintain it's voltage on the batteries with even a very small cable size running between the charger's output and the battery terminals - so in this situation the battery being charged could accept up to the charger's full current regardless of cable size - which could start fires.
That's why I mentioned earlier the "ultimate" charger being a multi-stage one with it's feedback sense point at the batteries to guarantee full spec stage-voltage right at the battery - if - there was adequate cable-path fusing and cable size to eliminate the heating danger.
I'm guessing -> but I'll bet most charger manufacturers in general do not use remote sensing for at least the three reasons of 1) the additional material expense, 2) the additional installation/hookup complexity for users, and 3) the danger liability introduced from users maybe using interconnection cabling too small for what the batteries are accepting due to the voltages that the chargers will guarantee gets established on battery terminals regardless of cabling size and current flow. Remember, there is no cable resistance voltage drop seen by the battery terminals with a charger utilizing remote sensing.
That way one would get a solid 14.4 volts right at the battery for all the way up to a battery charge current acceptance rate of the maximum of the 7345 ... supposedly around 45 amps. However, one would have to be careful to only have the converter connected to the batteries for a few hours to prevent boiling away the battery water ... while also taking care of the safety factor via combining of cable fusing with not using too-small cabling ... so as to prevent cable over-heating. This is because a charger with a feedback loop sense point at the batteries will maintain it's voltage on the batteries with even a very small cable size running between the charger's output and the battery terminals - so in this situation the battery being charged could accept up to the charger's full current regardless of cable size - which could start fires.
That's why I mentioned earlier the "ultimate" charger being a multi-stage one with it's feedback sense point at the batteries to guarantee full spec stage-voltage right at the battery - if - there was adequate cable-path fusing and cable size to eliminate the heating danger.
I'm guessing -> but I'll bet most charger manufacturers in general do not use remote sensing for at least the three reasons of 1) the additional material expense, 2) the additional installation/hookup complexity for users, and 3) the danger liability introduced from users maybe using interconnection cabling too small for what the batteries are accepting due to the voltages that the chargers will guarantee gets established on battery terminals regardless of cabling size and current flow. Remember, there is no cable resistance voltage drop seen by the battery terminals with a charger utilizing remote sensing.
