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Mastervolt 12-2500-100


frahkn

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My Mastervolt combi has a problem with the battery charger. It's a pre 2003 model so the only answer may be replacement but it may be worth running the problem by you folks first.

 

When on 16 Amp shore-power it always goes to float too soon but if I switched it off and on again, it got there eventually.

 

Now, it's allowing my batteries to discharge rather than charge. For example, last night my battery management display showed "0 Ah with 0.3A going in". This morning it showed "-6 Ah with 1.2 A" going in.

 

Is there a solution other than getting a new one?

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It may be that some of the components inside that are used to measure voltage have drifted over time, so it is measuring voltage wrong and coming to the wrong conclusion over how much charging to do. The difference between say 13.4 and 13.5V is only 0.7%, so it doesn't take much drift in a multiplier resistance value to significantly affect the voltage measurement. 

Is there a way to disable the charger side of the combi and just use it as an inverter? If so, then buying a new decent separate charger could be a way to go. Then, if/when the combi finally dies, you only need buy a suitable inverter. Separate inverters and chargers are a good idea anyway as a failure in any one item doesn't fail the other and replacing the failed separate is cheaper than a whole new combi. 

Jen

Edited by Jen-in-Wellies
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4 minutes ago, Jen-in-Wellies said:

It may be that some of the components inside that are used to measure voltage have drifted over time, so it is measuring voltage wrong and coming to the wrong conclusion over how much charging to do. The difference between say 13.4 and 13.5V is only 0.7%, so it doesn't take much drift in a multiplier resistance value to significantly affect the voltage measurement. 

Is there a way to disable the charger side of the combi and just use it as an inverter? If so, then buying a new decent separate charger could be a way to go. Then, if/when the combi finally dies, you only need buy a suitable inverter. Separate inverters and chargers are a good idea anyway as a failure in any one item doesn't fail the other and replacing the failed separate is cheaper than a whole new combi. 

Jen

 

That is a very useful idea, although I don't know if the charger element can be disconnected, I'll have to see.

4 minutes ago, Phil. said:

https://voltmastersystems.co.uk
 

the chap who runs this is very knowledgeable with mastervolt. He will give advice over the phone, before you have to spend money on a fix or replacement.

 

I will give him a go next week. Thanks.

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3 minutes ago, frahkn said:

 

That is a very useful idea, although I don't know if the charger element can be disconnected, I'll have to see.

Does a Mastervolt combi of this vintage do automatic switch over between shore mains and inverter, or do you have a manual switch to do this? The easiest way would be to just disconnect the mains input to the combi and connect the shore, or generator mains to the new battery charger. 

Jen

Edited by Jen-in-Wellies
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1 minute ago, Jen-in-Wellies said:

Does a Mastervolt of this vintage do automatic switch over between shore mains and inverter, or do you have a manual switch to do this? The easiest way would be to just disconnect the mains input to the combi and connect the shore, or generator mains to the new battery charger. 

Jen

 

The combi cannot be set to 'charger only' manually, it has one, three position, switch. The three positions are "off", "on" and "remote" but it (or the boat) did not come with a remote.

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2 minutes ago, frahkn said:

 

The combi cannot be set to 'charger only' manually, it has one, three position, switch. The three positions are "off", "on" and "remote" but it (or the boat) did not come with a remote.

That isn't the question I asked. When the mains supply from a bollard, or generator is disconnected, how does the combi behave? I have a Victron. On that, when an external mains source comes in, then it is automagically passed through to the boat and at the same times used as a source for battery charging. When the external mains source is disconnected, or fails, the inverter starts up and seamlessly takes over from the missing external source when in inverter mode. Is the "on" position on the switch of your combi similar to this, or does it do something else? 

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Apropos nothing, other than interest:

 

I bought a Sterling 2500W Pro Combi S Inverter charger in 2011, which it turned out has a high quiescent current of 4A!!.

 

After using it for a while I became concerned that, if I left it charging on shore power and left the boat for a few days and the shore power failed, it would revert to inverter and flatten/destroy the batteries.

 

I asked Sterling if there was a facility to set it to "charge only", and the reply was an emphatic "No!, but if you buy next years model, there will be".

 

I also discovered that many inverter chargers do have a facility to set to charger only - I recall the Victrons in particular, but I would guess that the latest Mastervolts also have this.

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3 hours ago, frahkn said:

My Mastervolt combi has a problem with the battery charger. It's a pre 2003 model so the only answer may be replacement but it may be worth running the problem by you folks first.

 

When on 16 Amp shore-power it always goes to float too soon but if I switched it off and on again, it got there eventually.

 

Now, it's allowing my batteries to discharge rather than charge. For example, last night my battery management display showed "0 Ah with 0.3A going in". This morning it showed "-6 Ah with 1.2 A" going in.

 

Is there a solution other than getting a new one?

 

Have you measured the battery voltsge with a known to be good voltmeter?

It may be that the display is lieing, and the batteries really are being charged.

 

I would check before deciding to bin it.

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4 hours ago, frahkn said:

My Mastervolt combi has a problem with the battery charger. It's a pre 2003 model so the only answer may be replacement but it may be worth running the problem by you folks first.

 

When on 16 Amp shore-power it always goes to float too soon but if I switched it off and on again, it got there eventually.

 

Now, it's allowing my batteries to discharge rather than charge. For example, last night my battery management display showed "0 Ah with 0.3A going in". This morning it showed "-6 Ah with 1.2 A" going in.

 

Is there a solution other than getting a new one?

I am only familiar with that Combi of around 2010 vintage, but that one has plenty of settings for the charger including the voltage in each of bulk, absorb and float and the current at which it changes from absorb to float. Perhaps you just need to check and perhaps adjust the settings?

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11 hours ago, Jen-in-Wellies said:

That isn't the question I asked. When the mains supply from a bollard, or generator is disconnected, how does the combi behave? I have a Victron. On that, when an external mains source comes in, then it is automagically passed through to the boat and at the same times used as a source for battery charging. When the external mains source is disconnected, or fails, the inverter starts up and seamlessly takes over from the missing external source when in inverter mode. Is the "on" position on the switch of your combi similar to this, or does it do something else? 

 

I suspected that I was answering the wrong question, sorry. The answer to your question is "yes", the on position will give a result similar to yours.

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15 minutes ago, frahkn said:

 

I suspected that I was answering the wrong question, sorry. The answer to your question is "yes", the on position will give a result similar to yours.

Apologies. I was a bit abrupt. The option exists to have a separate charger, but it might need a switch to move the mains to the boat from external shore bollard, or generator to the inverter. Victron do an external automatic changeover relay. Easiest would be either to get the existing Mastervolt combi repaired, if that is possible, or replace with another combi, but expensive. Cheaper, or spreading the cost would be a separate charger and retain the combi as an inverter till it finally dies, but would need some rewiring of the mains. This would make the system more resilient to a single gadget failing in the future. 

 

For repair, if the voltages for varying stages of charging can be altered, then any drift in the combis voltage sensing could be compensated for. Might be possible to do this yourself. So if a particular stage ends at say 13.5V, but the combi now measures 13.5V when it is really 13.3V, then up the stage end programmed to 13.7V to compensate.  Needs a known good voltmeter as @cuthound says and adjust as @nicknorman suggests.

Jen

Edited by Jen-in-Wellies
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2 hours ago, Jen-in-Wellies said:

Apologies. I was a bit abrupt. The option exists to have a separate charger, but it might need a switch to move the mains to the boat from external shore bollard, or generator to the inverter. Victron do an external automatic changeover relay. Easiest would be either to get the existing Mastervolt combi repaired, if that is possible, or replace with another combi, but expensive. Cheaper, or spreading the cost would be a separate charger and retain the combi as an inverter till it finally dies, but would need some rewiring of the mains. This would make the system more resilient to a single gadget failing in the future. 

 

For repair, if the voltages for varying stages of charging can be altered, then any drift in the combis voltage sensing could be compensated for. Might be possible to do this yourself. So if a particular stage ends at say 13.5V, but the combi now measures 13.5V when it is really 13.3V, then up the stage end programmed to 13.7V to compensate.  Needs a known good voltmeter as @cuthound says and adjust as @nicknorman suggests.

Jen

No apology needed.

 

I will ring Phil's guy and open the front of the combi to contemplate the innards but in the end, I suspect, I will get another one (or perhaps separate inverter and charger).

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