40a MPPT controller preventing charge from shore power?

[viola33]

Hi all,

I plan to dig out my old 30a PWM controller and try connecting it to test this, but here is my experience:
On my old campervan, I had a 2000w converter/charger wired into onboard converter. I had three 100w panels mounted on roof, a 30a controller, and 200ah gel battery (actually two 6v wired in series). I could charge the batts by plugging into shore power with 30-amp connector, or into genny with 20a adapter.

I swapped out the 30a PWM controller for a 40a MPPT controller and saw the expected efficiency charging through panels. Charging with 30a shore power also worked fine. However, plugging into genny with 20a, my AC power in the van worked fine, but the batts would NOT charge.

I now have a new Winnegabo Solis pocket, with a 170w Zamp panel mounted on roof, a triple port that I plug additional panels into, a 40a Zamp MPPT controller, 200ah AGM batts. I am noticing similar behavior to old system with the MPPT controller: Panels work fine. Plugged in with 30a connection is fine, charges batts. Plugged into genny with 20a adapter does NOT charge batts. Just tested plugging into pedestal with 20a outlet/adapter. Batts do not charge, though again, AC outlets work fine.

Does MPPT controller prevent 20a connection from charging batts? If so, why would this be?
Please and thanks!

 

[sunshine_eggo]

Likely dealing with battery voltage and wiring inefficiency issues.

Once absorption voltage is reached, current becomes limited to that which is needed to hold that voltage. You might have 2,000A available, but if it only takes 20A to hold absorption voltage, you only get 20A.

Some chargers refuse to charge if the battery voltage is not below a certain level, e.g., if the battery is already at float voltage, the AC charger may decide it doesn't need to charge it.

Thin wires, long runs, and poor connections all contribute to premature charge termination. when a charger is operating at max current, measure voltage at the battery and at the charger terminals. A notable voltage drop indicates one or more of the three contributors are present.

Best way to test total charging capability is with applied loads, e.g., apply loads that are greater than your total charge capability. Once battery voltage drops below 12.5V, initiate all charge sources. Provided each charger reads < absorption voltage at its terminals, you should see maximum possible current.

 

[Jorge33165]

Hi all,

I plan to dig out my old 30a PWM controller and try connecting it to test this, but here is my experience:
On my old campervan, I had a 2000w converter/charger wired into onboard converter. I had three 100w panels mounted on roof, a 30a controller, and 200ah gel battery (actually two 6v wired in series). I could charge the batts by plugging into shore power with 30-amp connector, or into genny with 20a adapter.

I swapped out the 30a PWM controller for a 40a MPPT controller and saw the expected efficiency charging through panels. Charging with 30a shore power also worked fine. However, plugging into genny with 20a, my AC power in the van worked fine, but the batts would NOT charge.

I now have a new Winnegabo Solis pocket, with a 170w Zamp panel mounted on roof, a triple port that I plug additional panels into, a 40a Zamp MPPT controller, 200ah AGM batts. I am noticing similar behavior to old system with the MPPT controller: Panels work fine. Plugged in with 30a connection is fine, charges batts. Plugged into genny with 20a adapter does NOT charge batts. Just tested plugging into pedestal with 20a outlet/adapter. Batts do not charge, though again, AC outlets work fine.

Does MPPT controller prevent 20a connection from charging batts? If so, why would this be?
Please and thanks!

I have a similar concern. The MPPT controller output is not pure DC. It has spikes that may prevent the AC Charger from detecting the real battery voltage and make it switch to floating mode

 

[pollenface]

Some chargers refuse to charge if the battery voltage is not below a certain level, e.g., if the battery is already at float voltage, the AC charger may decide it doesn't need to charge it.

That is true for the DC-DC charger in my vehicle. I have separate scc with 130w panel and if the battery is already in float (13.7v) the DC-DC charger won't even kick on when I start the engine.

 

[viola33]

Likely dealing with battery voltage and wiring inefficiency issues.

Once absorption voltage is reached, current becomes limited to that which is needed to hold that voltage. You might have 2,000A available, but if it only takes 20A to hold absorption voltage, you only get 20A.

Some chargers refuse to charge if the battery voltage is not below a certain level, e.g., if the battery is already at float voltage, the AC charger may decide it doesn't need to charge it.

Thin wires, long runs, and poor connections all contribute to premature charge termination. when a charger is operating at max current, measure voltage at the battery and at the charger terminals. A notable voltage drop indicates one or more of the three contributors are present.

Best way to test total charging capability is with applied loads, e.g., apply loads that are greater than your total charge capability. Once battery voltage drops below 12.5V, initiate all charge sources. Provided each charger reads < absorption voltage at its terminals, you should see maximum possible current.

Thanks for this. It took some messing around, but I figured out I had two simultaneous problems. One is apparently the 30a -> 20a adapter I was using, and the other was something you noted, a charger that doesn't really do deep-cycle charging (tops out at 13.6v). Your hint helped me figure out that part of it. Gracias.