Charging the starter battery "in situ"

[Hoges]

Is is reasonable to charge the starter battery in the vehicle...all connected... rather than remove it or remove the leads first ...with a couple of provisos.
There seem to be as many opinions as battery owners on the net!:eek:

I normally remove the leads and put the charger on... reason is that the P38 has been off the road for several months while I tinker. I've kept the battery on a charger for a couple of days then let it sit for a three weeks then top up the charge...

However I got the truck all back together the other day and gave it a run:D but have a few more jobs to do. I wondered about connecting the starter battery to an identical external battery as per jump start (neg to engine block), then charging both batteries in parallel via the external battery...using the external battery as a sort of "capacitor" to minimise the chance of voltage spikes. The charger is an intelligent 6 stage Projecta.

Thoughts pls?

[jx2mad]

Hi. I look at it this way (which may be wrong ). If the alternator charges the battery while it is connected I see no difference in using an external charger whilst connected. I do it this way without problems. Jim

[sheerluck]

Same point of view for me as Jimbo above.

Could just be that ignorance is bliss. I'm a blissful kind of guy :D

[Blknight.aus]

depends on the charger, I wouldnt want to hook up my battery toaster with th battery in situe but with a smaller 10-20a smart charger, sure leave it hooked up, connect up to the jump start socckets and you're good to go

[d2dave]

If using Ctek chargers it is fine to charge with everything connected. You can even connect disconnect when plugged in with no spark

[glenhendry]

+1 on what Blknight said. For a smaller AMP charger, that's fine, but not for a faster charger. Only in a well ventilated area. I think there is more risk causing sparks and spikes disconnecting and reconnecting batteries, and then all the ginning around with the P38 with radio codes and window setting, risking 'engine disabled' etc...

See this blurb (which seems comprehensive):
From: Charging car battery (http://www.rac.co.uk/forum/showthread.php?2233-Charging-car-battery)
E<Ed: Do I need to disconnect my battery to charge> I am afraid this is just not true and in fact, is a garage fabrication used when they do not know why the ECU is not working. There are millions of auto and marine installation all over the world, but particularly in USA, Canada, Norway and Sweden, where battery installations in cars, boats and light aircraft are floated across a standard proprietary battery charger. They have been doing this every winter since the first auto and marine engines became available. Most cars have a socket around the front bumper area, as soon as you get home you plug into your existing wiring that runs back into a battery charger, and your charger is floated across your car battery.
To suggest to this person (who is telling you in his request that he is without any electrical knowledge) that he should disturb the battery terminals, is certainly not best practice. There are basic skills that must be used in handling batteries, lack of these skills has over the years caused many injuries (some very serious). All garage mechanics are aware of these, however a rookie owner driver is not.
Modern electronics is digital and is far more robust that the electronics that appeared in the 70’s and 80’s generation of vehicles. Basically because the circuitry does not rely heavily on inductance and capacitance to process data. The digital subsystem relies more on data switching. When the old analogue circuits were connected and disconnected, at the battery, sparks could be seen. These sparks did the damage, as they are proportional to the rate the circuit is switch on or off . In other words someone with a shaky-hand disconnecting a battery could as the terminals parted cause sparking, as the circuit was made – broken –made- broken, many times in a fraction of a second, inducing through the inductive circuits voltages as high as 90 volts. Which was more than enough to see off the older generation of electronics.
This is no longer the case.
Connect you battery charger across your battery without disconnecting anything. Once you have the leads securely in place switch on the charger.
Albridge

[bigdog]

A bit of a hijack, but on a related note.....

Is it safe to start the engine whilst the battery charger is connected to the battery and still charging (assuming that all leads and connectors are safely routed away from moving/spinning parts) or will this cause damage to the Car electrics or to the charger.....???

I'm curious as I have heard different views on this (I am guessing this is not recommended practice)

[d2dave]

I am not an expert here and would not do it. It will not hurt the cars electrics and if your battery is in good nick and fully charged it would probably be ok.

However if the battery is not fully charged or crook you might find that the starter motor tries to pull currant from the charger.

This is just my theory and I might be wrong, but as it is so easy to either unplug or disconnect the charger why try.

[Davo]

+1 on what Blknight said. For a smaller AMP charger, that's fine, but not for a faster charger. Only in a well ventilated area. I think there is more risk causing sparks and spikes disconnecting and reconnecting batteries, and then all the ginning around with the P38 with radio codes and window setting, risking 'engine disabled' etc...

See this blurb (which seems comprehensive):
From: Charging car battery (http://www.rac.co.uk/forum/showthread.php?2233-Charging-car-battery)
E<Ed: Do I need to disconnect my battery to charge> I am afraid this is just not true and in fact, is a garage fabrication used when they do not know why the ECU is not working. There are millions of auto and marine installation all over the world, but particularly in USA, Canada, Norway and Sweden, where battery installations in cars, boats and light aircraft are floated across a standard proprietary battery charger. They have been doing this every winter since the first auto and marine engines became available. Most cars have a socket around the front bumper area, as soon as you get home you plug into your existing wiring that runs back into a battery charger, and your charger is floated across your car battery.To suggest to this person (who is telling you in his request that he is without any electrical knowledge) that he should disturb the battery terminals, is certainly not best practice. There are basic skills that must be used in handling batteries, lack of these skills has over the years caused many injuries (some very serious). All garage mechanics are aware of these, however a rookie owner driver is not.
Modern electronics is digital and is far more robust that the electronics that appeared in the 70’s and 80’s generation of vehicles. Basically because the circuitry does not rely heavily on inductance and capacitance to process data. The digital subsystem relies more on data switching. When the old analogue circuits were connected and disconnected, at the battery, sparks could be seen. These sparks did the damage, as they are proportional to the rate the circuit is switch on or off . In other words someone with a shaky-hand disconnecting a battery could as the terminals parted cause sparking, as the circuit was made – broken –made- broken, many times in a fraction of a second, inducing through the inductive circuits voltages as high as 90 volts. Which was more than enough to see off the older generation of electronics.
This is no longer the case.
Connect you battery charger across your battery without disconnecting anything. Once you have the leads securely in place switch on the charger.
Albridge

I don't know what this is about - most cars have a socket for a coolant heater for severe cold, not a charger. But the rest of it sounds pretty good.

[jx2mad]

Our Rural Fire Service trucks are plugged into external chargers whilst in the station so the batteries are always on float and are fully charged. HOWEVER, the truck electrics are disconnected from the battery via an isolating switch to prevent possible battery drain. So as the truck readies to roll the charger is unplugged and isolating switch changed back. Jim

[scarry]

I do the D4 all the time,don't disconnect anything, as it doesn't get a lot of use at times.
The charger actually charges the second battery as well.
Luckily both are AGM,so just set the smart charger on the correct setting and leave.

I have a plug sticking out of the battery cover under the bonnet that i use to connect to charger for ease.I don't want one poking out of the grill or wherever as it would be too easy to leave it connected and accidently drive away.

[Ferret]

I do the D4 all the time,don't disconnect anything, as it doesn't get a lot of use at times.
The charger actually charges the second battery as well.


I do this on my D4 equipped with a Traxide USI 160 dual battery management system but I charge by connecting the smart charger directly to the aux battery terminals.

Am I charging my main battery when doing this or are there some conditions where the USI 160 black box could be isolating the main battery preventing it from charging in this way?

[scarry]

I do this on my D4 equipped with a Traxide USI 160 dual battery management system but I charge by connecting the smart charger directly to the aux battery terminals.

Am I charging my main battery when doing this or are there some conditions where the USI 160 black box could be isolating the main battery preventing it from charging in this way?

I have the SC80,and always connect to the main battery as sometimes the light is flashing on the SC80,so it is isolated from the auxillary battery.Never tried doing it the other way,but i don't think it will work if the SC80 is doing it's job properly.

With a multimeter you would soon work out what is going on doing it the other way.

[PhilipA]

AFAIK all isolators sense the voltage of the starting battery, if fitted correctly LOL.
So if you fit the charger to the aux AND the voltage is lower than the drop out voltage you will only charge the aux.
If you have a controller which I have then you can link the two batteries regardless of the starting battery.
BUT why would you want to? As soon as you put the charger on the starting battery the voltage will go above the trigger voltage and join the two batteries.
BTW I charge my batteries while connected all the time with a 20 amp smart charger. No problems so far.
Regards Philip A

[drivesafe]

Hi Ferret and scarry, and as PhilipA posted, if the battery voltage at your isolator is below the cut-out level, and you connect to the auxiliary battery, you will only charge the auxiliary battery.

The big difference between my isolators and all others, is that the cut-out level is 12.0v on the SC80 and 12.0v or 12.6v on the USI-160.

All other isolators are around the 12.5 to 12.7v mark.

With the USI-160, the user can select between 12.0v ( SHARED Mode switch set away from the LED ) and 12.7v ( IGNITION Mode switch set towards the LED.

Scarry, how often do you drive your D4 for and how long do you drive when you drive.

The reason I ask is that with fully charged batteries, you should be able to leave your D4 for 3 to 4 weeks before the SC80’s LED starts flashing.

[scarry]

Scarry, how often do you drive your D4 for and how long do you drive when you drive.

The reason I ask is that with fully charged batteries, you should be able to leave your D4 for 3 to 4 weeks before the SC80’s LED starts flashing.

Hi Tim

7 to 10 days without using it and the light will be flashing and voltage on both batteries will be around 11.7 to 12.0 volts.I am sure the SC80 is OK and doing it's job.Had the main battery checked by dealer and they say they load tested it and was all OK.
The amount of use the vehicle gets is hard to know exactly,but some weeks it does less than 30k's,other weeks it may do 250k's.We have company vehicles we usually use.I feel the aux. battery may be a bit tired as it was accidentally completely flattened once,and the Cteck smart charger seems to think it could be not as good as it should be.The aux. battery is around 18months old.

I charge both batteries regularly using the smart charger.

Even with the green LED flashing,the vehicle has never not started.

What i should do is probably fully charge the batteries and then leave the car stand and see how long it will go before the green led flashes.

[drivesafe]

What i should do is probably fully charge the batteries and then leave the car stand and see how long it will go before the green led flashes.

Hi Paul and if you get a chance, do just that, charge and test your batteries.

Then, if you are interested in being a Guinea Pig, get in touch with me and I’ll supply you with a new experimental power low drawing SC80.

This is an experimental unit I have been working on for some time.

There is a problem, more so in the UK, where they do not drive their D3s and D4s all that often and while my isolators protect against the cranking battery being flattened while camping, the isolators, up until this new one, just used power for nothing if the vehicle is left for long periods with out use.

In 95% of uses, this is not a problem because most people use their vehicles on a daily basis, but there are more and more people operating their vehicles like you do.

So I have developed a new program designed to dramatically reduce the amount of power it uses between drives and it works in two way to reduce the power.

The new unit has replaced the two 45 amp relays with 3 lower power consuming 30 amp relays and while the motor is running, the new triple relay units use the same amount of power the twin relay units but when the motor is turned off, and the common battery voltage drops to 12.7v, two of the three relays in the triple relay units turn of, reducing the new units power consumption to less than half that of the old twin relay units.

The new triple relay units also has an automatic TIME-OUT function where it goes into Cut-Out mode 72 hour after the motor was last operated, whether the battery voltage has reached 12.0v or is still higher than that.

This new unit may help improve your low use voltages.

[scarry]

Tim,i will send you a pm.