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!

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 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

[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
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
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