Battery Charger question

[Seven Spades]

I have just returned to my boat and found that I have left the fridge on all week. Thankfully I have a keel cooler so it has not run the batteries flat but they are now low and need re-charging. I have plugged in the shore power and they are getting 2.2A. If I start the engine the alternator will give them around 30A at this level of charge.

My question is why does the shore power take so long to re-charge the batteries compared to the alternator, is it being kinder to the batteries by "trickle" charging them or is it likely that the batter charger is at end of life?

 

[pvb]

Impossible question. The charger could be faulty, could be on the wrong setting, could be badly wired, could be under-specified, etc, etc.

 

[prv]

Impossible question. The charger could be faulty, could be on the wrong setting, could be badly wired, could be under-specified, etc, etc.

+1

However, whatever the reason, no it's not right that it's only putting 2A into low batteries. Depending on the charger it should be in the region of ten times that.

What's the charger?

Pete

 

[Seven Spades]

It is a Guest Charge Pro 30 AMP Model 2630, 3-Bank Battery Charger, well that's what it says in the leaflet. Sorry for the delay I had to dig it out.

It looks like this:

I believe newer versions are available with a similar name.

 

[Seven Spades]

I have just looked at the charger and the meter in that window is reading 6A but the e-xpert lite battery monitor I use says that it is only 1.8-2.1A

In the last 2 hours the e-xepert Lite reports that the batteries have gone from -111A to -106A so it is charging slowly. Just for clarification the charger seems to be producing 6A and I am using 4A with the lights so that's how I get to a net 2A but isn't 6A still really low?

 

[RAI]

One would expect a 30 Amp charger to offer flat batteries a bit more than 6 Amps. Have you seen what the engine alternator will do at about 1500 revs?

 

[Seven Spades]

I can't at the moment I am on the hard, but I have noticed that there is a significant difference between the alternator and the battery charger. I wasn't sure if the charger was operating "as designed" or if it is poorly optimised or faulty.

I doubt that there is anything wrong with the installation, it is a really neat job.

 

[LittleShip]

Check your cables, joints and that the wire size is correct.?

Tom.

 

[Seven Spades]

Yes I am sure the cables are correct. If anything I would say that the location of the charger is further fro the batteries than it should be. I would say that it is probably 5m as the worm crawls. However it say 6A on the charger it self.

I now know from the answers here that the charger is not performing as well as a modern charger would, but I do not know at this stage if there is anything wrong with it, it might have always worked this way.

 

[dk]

Check the manual - is it a multi-stage charger? Does it have a boost phase? It might need you to reset some switches inside to suit the batteries. If not I'd update it - judging by the analogue meter I guess it's at least 20 yrs old anyway.

 

[GHA]

what's the voltage at the batteries?

 

[Iliade]

I would guess that it has sensing wire(s) and charging cable(s). One could run a temporary sensing wire direct to the battery bank. Also do check, clean and grease all battery terminals.

 

[Seven Spades]

The manual says:

Total current output

Maximum 30 amps at 12V DC

"float" mode 0.1 to 0.3 amps at 13.6 vDC

It is currently reading 13V -64.4 amps, so overnight it has changed from -106A to -64A so I guess about another 24 hours will see the batteries at full charge.

The boat is 19 years old this year so I guess the charger is a 20 year old design.

I have looked in the manual and I don't understand the wiring, there is no sensor wire but it says that:

The simplest way to connect the 2630 to your batteries is to run one red DC wire from each of it's three DC positive outputs posts to each battery. Then connect the negative to the common ground. Alternative methods... attach the positive outputs of the charger to the battery connections on battery switches or outposts of your battery isolator. This method is only recommended if your 2630 will be mounted much closer to your battery switches or isolator.

I have a BEP Marine VSR which sends all the charging to the engine battery first and once that is full it directs all charging to the house batteries so I assume that it has been wired using the latter method. The charger is about 15 feet from the batteries which is at the lower end of the scale in the manual which goes from 10-50 feet.

 

[prv]

I have noticed that there is a significant difference between the alternator and the battery charger.

That's normal. I have a 115a alternator and a 40a mains charger. I guess the thinking is that we (ideally) only run the engine for short periods, whereas if we have shore power it will typically be connected at least overnight. So no need to cram charge in so fast.

Pete

 

[GHA]

It is currently reading 13V -64.4 amps, so overnight it has changed from -106A to -64A so I guess about another 24 hours will see the batteries at full charge.

If that's the voltage coming out of the charger then it sounds like the charger might have lost its' oomph. Below is a voltage graph of a sterling 20A set to agm on fairly well charged batteries, 225Ah. Shame the amperage isn't on there as well but it's easily enough to drive the voltage up straight away. Sounds like yours might not be putting out enough current, thus the charging voltage is low. Old cliche I know, but have you tried turning it off and on a again a few times in case it's stuck in some float setting? (that's what caused the spike at the end of the graph, off and on forced the charged back into absorption)

 

[titian]

I wonder if you only have 1 output connected? If there are 3 o/p posts @6A that might explain it.

 

[VicS]

The manual says:



It is currently reading 13V -64.4 amps, so overnight it has changed from -106A to -64A so I guess about another 24 hours will see the batteries at full charge.

The boat is 19 years old this year so I guess the charger is a 20 year old design.

I have looked in the manual and I don't understand the wiring, there is no sensor wire but it says that:



I have a BEP Marine VSR which sends all the charging to the engine battery first and once that is full it directs all charging to the house batteries so I assume that it has been wired using the latter method. The charger is about 15 feet from the batteries which is at the lower end of the scale in the manual which goes from 10-50 feet.

It could be wired with separate outputs connected to the two battery banks in which case both batteries will be charged initially, as they would be without a VSR. Or the outputs might be commoned and the full output directed to the starter battery, the house battery being connected by the VSR when the starter battery voltage reaches the VSR operating point.

It would be sensible to trace the wiring so that you know how it is wired and then know how it will operate.


The figures you quote suggest that there is something wrong . Your battery monitor is indicating only 40Ah worth of charging overnight when you expected a much higher rate. It is however difficult to be sure without knowing the full characteristics of the charger.
Perhaps as Titian suggests only one output is connected, or only one working, limiting the output to 1/3 of its normal full output

My little Lidl charger is currently charging an old car battery at 0.05 amps at 13.2 volts. That is because it has already gone through its full charging cycle and has now cut back to a maintenance charge rate of 50mA.