Powermax 75 amp converter/charger

S Davis wrote:
it just seems the amp output is low.

It's my understanding the batteries themselves determine what amperage they will accept.

Good that it is 14.68 :) so see my note above re the 13 amps.

You can run more 12v loads as a test. If the battery is still accepting 13 amps on the battery monitor, and those loads are running ok, then the converter must be putting out more than 13 amps which the loads are using.

Sorry just caught my typo, it is putting out 14.68 not 12.68. I will try and pick up a hydrometer today.

And just for clarification this bank is used without the charger hooked up, so I get back home and hook up the charger. The initial readings are within a min or two of hooking up the charger so I thought at 30% discharge the batteries would be accepting more amps.

The unit is rated to lowest voltage at 13v, so the OP at 12.68 is odd.

Another thing to check is that the input voltage is above 105v loaded voltage to get the best results.

You can see lower amps than what the converter is putting out if there is another load on. EG, my 75 amper will show 75 amps to the battery on Trimetric monitor and when the furnace comes on that shows now as 68 amps on the Trimetric. The furnace gets the first 7 amps, leaving 68 for the battery. When the furnace cycles off, the Tri shows 75 amps again.

EDIT--you set the converter to 14.8 and when charging it will show less than that at first, but gradually rise to 14.8 . You will not see 14.8 until the batteries are full and no amps flowing. the amps make the voltage drop until then.

The 14.8 is for 25C/77F so if it is colder out, set that voltage higher or if hotter out, set it lower. there are temp comp tables for that. EG at 35F set it to 15.2 in order to be equivalent to 14.8 at 77F.

If amps are only 13 amps and tapering from there, it could mean the batteries were higher in charge than you thought at first. But then their voltage would have been higher. You need an hydrometer to get the truth here. Always believe the hydrometer if the voltage doesn't match. Then find out what's making the voltage funny.

2oldman wrote:

S Davis wrote:
The powermax is only putting out about 13 amps @ 12.68 volts, does this sound right for a 75 amp charger?

The voltage will rise, slowly, as the batteries charge, until the absorb setting is reached.

Yes I have set the voltage, the first time I set it to 14.82 The Trojan spec but was only getting 14.68 when hooked up and charging. I reset it to 14.96 to get 14.82 out when charging, it just seems the amp output is low.

Check voltage right at the converter. Voltage and current are low but could be restricted by the circuit if measuring at the battery.

Your 75 amps on 225AH will look a lot like this graph at 70.

You are starting at 12.38 which is 70% SOC as mentioned. So if the charger is set to 14.6 and doing 75 amps, you are already past the Bulk stage and amps will be tapering from the start.



I am not sure if the voltage will stay at 14.6 for the 30 minutes in "three-stage mode" even if you are already past the Bulk stage, but i think so. It will then drop to 13.6.

If you are in single stage at 14.6 it will stay at 14.6 the whole way, which is what you want until the batts are full (as seen by an hydrometer reading) Then you can adjust back to 13.6 manually for the float stage. Or leave it at 14.6 and you can safely move the other switch to the left for 3-stage and it will do 13.6. See para 10.

I suspect you may have put the unit in three-stage and then turned the pot. Big no-no. That screws up all three voltages in the 3-stage mode. You can fix that by starting over in single stage, set 14.6 and now switch to 3-stage like it says in para 10

You should have set it to 14.8 anyway since these are Trojans. :)

S Davis wrote:
The powermax is only putting out about 13 amps @ 12.68 volts, does this sound right for a 75 amp charger?

The voltage will rise, slowly, as the batteries charge, until the absorb setting is reached.

Voltage is below Trojan specs. See https://www.trojanbattery.com/pdf/datasheets/T105_Trojan_Data_Sheets.pdf