Battery Discharging on Vehicle

[Sid___]

Hi,
My Peugeot Boxer 2.0L (X reg 2000) petrol based campervan has developed a problem. We were away last weekend and when I tried to start the vehicle after an overnight stay the battery was completely flat. I borrowed a charger from a person on the campsite, took the battery off the vehicle and charged it overnight after which time it was fully charged. I re-fitted the battery and it got us home.

As a bit of background, the leisure battery was less than optimal when we bought the vehicle back in March of this year but I persevered with it as we use electric hookup when we are away. However, the time before last it started to smell badly of rotten eggs so I switched off the battery charger. When I checked the 30A fuse that connects the cab battery to the habitation side I noted that it had blown. I have since replaced the old leisure battery with a new one but have not connected it to the campervan nor have I replaced the blown fuse.

I had the cab battery tested at a local garage and it showed to be good but in need of recharging, which I did. it shows 12.6 - 12.7V when off the vehicle. When connected to the vehicle with all electrics switched off (I know the digital clock will still take a small amount of power for instance) it was drawing 4.6 amps when I connected my multimeter to the battery negative terminal and black negative lead. I have removed each fuse in turn and have not been able to trace the source of the current drain.

Any thoughts on what to try next please?

 

[R-fur]

4.6 Amps will drain your battery, you have to find out where it is going. What you did with the ammeter is correct. If you have established that it is not a fused circuit it must be a unfused circuit disconnect wires from the positive post one at a time.

 

[Sid___]

Hi,
My Peugeot Boxer 2.0L (X reg 2000) petrol based campervan has developed a problem. We were away last weekend and when I tried to start the vehicle after an overnight stay the battery was completely flat. I borrowed a charger from a person on the campsite, took the battery off the vehicle and charged it overnight after which time it was fully charged. I re-fitted the battery and it got us home.

As a bit of background, the leisure battery was less than optimal when we bought the vehicle back in March of this year but I persevered with it as we use electric hookup when we are away. However, the time before last it started to smell badly of rotten eggs so I switched off the battery charger. When I checked the 30A fuse that connects the cab battery to the habitation side I noted that it had blown. I have since replaced the old leisure battery with a new one but have not connected it to the campervan nor have I replaced the blown fuse.

I had the cab battery tested at a local garage and it showed to be good but in need of recharging, which I did. it shows 12.6 - 12.7V when off the vehicle. When connected to the vehicle with all electrics switched off (I know the digital clock will still take a small amount of power for instance) it was drawing 4.6 amps when I connected my multimeter to the battery negative terminal and black negative lead. I have removed each fuse in turn and have not been able to trace the source of the current drain.

Any thoughts on what to try next please?

Thanks for your quick reply. The positive post only has 2 wires connected to it. The thick red lead and a thinner red lead which connects to the habitation side which has a fuse next to the battery under the bonnet which was blown and I have not replaced. What sorts of things have un-fused circuits?

 

[R-fur]

Starting and charging circuits tend not to be fused. A possible reason for your current drain could be a fault in the alternator. Try measuring the current as before but with the plug disconnected from the rear of the alternator.

 

[Sid___]

Starting and charging circuits tend not to be fused. A possible reason for your current drain could be a fault in the alternator. Try measuring the current as before but with the plug disconnected from the rear of the alternator.

Thanks. I disconnected the heavy red lead from the alternator and measured the current as before. Now it's only showing approx 160mA. So I suppose the alternator has been over taxed. Fortunately, it's something that I can change myself. I'll price up an exchange one.

 

[EricMark]

I was going to say 4.6 amp is around the field current used by the alternator, normally the diodes in the alternator will stop it discharging when engine is not running, however alternators do use varying methods of control.

French cars in the 80's used single phase alternators, and some odd methods to regulate including dark glass over the bulb as they always glowed a little, so dark glass stopped you realising.

The Lucas, Bosch, and Delco were all three phase, but Paris Rhone used single phase and three diodes instead of the six or nine, and used external regulators, the Japanese also used external regulators.

Today things have moved on, and I know the alternator charging is controlled by the engine management computer to ensure every so often the battery is fully charged, and we have moved to absorbed glass mat or valve regulated lead acid (AGM or VRLA) which can stand the charge/discharge cycles of the modern stop/start engine, and swapping a battery entails telling the computer new battery has been fitted.

So I am really not sure if an alternator change is still a DIY option or if you need to delve into the engine management or if the field current is controlled internally or from the engine management? It is likely it has returned to external control boxes to work the alternator.

The domestic battery charging with narrow boats, caravans and motor caravans has also changed, it started with blocking diode, never very good, then we got the split charging relay, less volt drop so did work better, even if simpler, then the voltage activated split charging relay, but because the battery is no longer charged all the time the engine is running moved to DC to DC inverters so all the time engine is running the domestic battery is being charged either with pulse charging or stage charging so it pushes more into the domestic battery.

Still not really enough, the narrow boats even with stage charging and engine running 6 hours a day have a problem pushing enough back into the domestic battery, even with 360 Ah worth.

There has been a move to abandon the idea of split charging and fit solar panels instead, and the narrow boat shore supply use a special duel output stage charger with fixed voltage to engine battery and stage charging for domestic.

I hope in your case you can do a simple swap of alternator, the bad eggs smell means a cell had gone short circuit and you were charging a 10 volt battery from a 12 volt supply, your lucky it did not explode.

 

[Strima]

This method is an accurate way of finding the culprit:

View: https://youtu.be/lRcj1fQcWwU

 

[Sid___]

I was going to say 4.6 amp is around the field current used by the alternator, normally the diodes in the alternator will stop it discharging when engine is not running, however alternators do use varying methods of control.

French cars in the 80's used single phase alternators, and some odd methods to regulate including dark glass over the bulb as they always glowed a little, so dark glass stopped you realising.

The Lucas, Bosch, and Delco were all three phase, but Paris Rhone used single phase and three diodes instead of the six or nine, and used external regulators, the Japanese also used external regulators.

Today things have moved on, and I know the alternator charging is controlled by the engine management computer to ensure every so often the battery is fully charged, and we have moved to absorbed glass mat or valve regulated lead acid (AGM or VRLA) which can stand the charge/discharge cycles of the modern stop/start engine, and swapping a battery entails telling the computer new battery has been fitted.

So I am really not sure if an alternator change is still a DIY option or if you need to delve into the engine management or if the field current is controlled internally or from the engine management? It is likely it has returned to external control boxes to work the alternator.

The domestic battery charging with narrow boats, caravans and motor caravans has also changed, it started with blocking diode, never very good, then we got the split charging relay, less volt drop so did work better, even if simpler, then the voltage activated split charging relay, but because the battery is no longer charged all the time the engine is running moved to DC to DC inverters so all the time engine is running the domestic battery is being charged either with pulse charging or stage charging so it pushes more into the domestic battery.

Still not really enough, the narrow boats even with stage charging and engine running 6 hours a day have a problem pushing enough back into the domestic battery, even with 360 Ah worth.

There has been a move to abandon the idea of split charging and fit solar panels instead, and the narrow boat shore supply use a special duel output stage charger with fixed voltage to engine battery and stage charging for domestic.

I hope in your case you can do a simple swap of alternator, the bad eggs smell means a cell had gone short circuit and you were charging a 10 volt battery from a 12 volt supply, your lucky it did not explode.

I had the alternator reconditioned by a local auto electrician. The diodes had indeed been fried. I've put it back on the vehicle now and all is well. I have learnt the hard way.