skedaddle
New member
I am hoping somebody has already found a solution to this:-
I have a 230v Mastervolt Mass 24v 100Amp charger, charging 2 separate 24V 500AH FLA Banks.
This Charger has a Battery Voltage Sensor function. The Mastervolt Manual says:-
“3.5
COMPENSATION OF THE CABLE LOSSES
The Mass Charger can compensate the voltage drop
occurring over the DC cables. For this purpose the Mass
Charger is provided with terminals for sense wires. The
sense wires are connected closest possible to the
batteries in order to charge them with the right voltage.
When only the minus sense wire is connected only the
losses of the minus DC cable will be compensated.
Connecting both cables will give the best result, all losses
will be compensated until a maximum of 3V in total.”
The key words here is the quoted “maximum of 3V”
Looking at a 24V charging table for Traction Batteries from Rolls Batteries as an example. It shows a Bulk/Absorption charging voltage target for a 24V bank of 29.76V at 30’C.
At a 20% (ie down to 80% cap remaining) discharge on the bank you would have a battery voltage of ~ 24.91V when you start to charge the bank.
That means you have a voltage differential of 4.85V between the target voltage set in the Charger and the voltage shown to the Charger by the voltage sensing cable from the battery bank. Obviously that is well beyond the 3V limit quoted in the manual. The result is that you can only use the Voltage Sensing function in the latter parts of the Absorption phase and in the Float stage when the Charger Target voltage and battery voltages are starting to close to less than 3V differential. That almost completely negates its usefulness in reducing charging time.
If you attempt to switch on the Voltage Sensing function when the two voltages are beyond the 3V range. The Charger makes a squealing noise and if you persist it will damage the charger requiring repair. --- You don’t need to ask how I know that to be a fact!
Mastervolt seem to make themselves purposely un-contactable directly and direct you to their local agents. In what is currently my part of the world. Their local agents cannot/will not provide any technical assistance. They are simply retailers. They have no specific technical knowledge. My local Mastervolt agent’s support solution is to tell me to return the charger all the way to Holland, thru them of course not directly. That is a all bit hilarious as these units are built about 1000kms away in China!
Looking at the circuit board. It looks as if the 24V version of the Charger is built on the same circuit board as the 12V version. It seems possible, Mastervolt may have over looked the voltage differences? ie The 3V difference margin would probably just be appropriate for a 12V system. But is way short of what is required on a 24V system.
As a footnote, before anybody asks --- Yes the Voltages provided by the Sensing wires from the two battery banks to the Charger are correct having have been checked and double checked with a DVM, crimped, soldered and heat shrunk and anointed with holy water etc!
The question is- Is there a component on the board that can be changed? Is there any way to get around what appears to be a stupid flaw?
Mike
I have a 230v Mastervolt Mass 24v 100Amp charger, charging 2 separate 24V 500AH FLA Banks.
This Charger has a Battery Voltage Sensor function. The Mastervolt Manual says:-
“3.5
COMPENSATION OF THE CABLE LOSSES
The Mass Charger can compensate the voltage drop
occurring over the DC cables. For this purpose the Mass
Charger is provided with terminals for sense wires. The
sense wires are connected closest possible to the
batteries in order to charge them with the right voltage.
When only the minus sense wire is connected only the
losses of the minus DC cable will be compensated.
Connecting both cables will give the best result, all losses
will be compensated until a maximum of 3V in total.”
The key words here is the quoted “maximum of 3V”
Looking at a 24V charging table for Traction Batteries from Rolls Batteries as an example. It shows a Bulk/Absorption charging voltage target for a 24V bank of 29.76V at 30’C.
At a 20% (ie down to 80% cap remaining) discharge on the bank you would have a battery voltage of ~ 24.91V when you start to charge the bank.
That means you have a voltage differential of 4.85V between the target voltage set in the Charger and the voltage shown to the Charger by the voltage sensing cable from the battery bank. Obviously that is well beyond the 3V limit quoted in the manual. The result is that you can only use the Voltage Sensing function in the latter parts of the Absorption phase and in the Float stage when the Charger Target voltage and battery voltages are starting to close to less than 3V differential. That almost completely negates its usefulness in reducing charging time.
If you attempt to switch on the Voltage Sensing function when the two voltages are beyond the 3V range. The Charger makes a squealing noise and if you persist it will damage the charger requiring repair. --- You don’t need to ask how I know that to be a fact!
Mastervolt seem to make themselves purposely un-contactable directly and direct you to their local agents. In what is currently my part of the world. Their local agents cannot/will not provide any technical assistance. They are simply retailers. They have no specific technical knowledge. My local Mastervolt agent’s support solution is to tell me to return the charger all the way to Holland, thru them of course not directly. That is a all bit hilarious as these units are built about 1000kms away in China!
Looking at the circuit board. It looks as if the 24V version of the Charger is built on the same circuit board as the 12V version. It seems possible, Mastervolt may have over looked the voltage differences? ie The 3V difference margin would probably just be appropriate for a 12V system. But is way short of what is required on a 24V system.
As a footnote, before anybody asks --- Yes the Voltages provided by the Sensing wires from the two battery banks to the Charger are correct having have been checked and double checked with a DVM, crimped, soldered and heat shrunk and anointed with holy water etc!
The question is- Is there a component on the board that can be changed? Is there any way to get around what appears to be a stupid flaw?
Mike
