Too large a battery on Vitesse?

[daverclasper]

Hi. Running a dynamo and a Bosch 540(EN)60Ah battery that was given to me. It's physically larger and heavier than the usual size.

As well as struggling to charge properly, when using lights etc, will this also overwork and potentially harm the dynamo?

Thanks, Dave

[Pete Lewis]

6 minutes ago, daverclasper said:

As well as struggling to charge properly,

so what is the stuggle ????    is it going flat ??

wont affect the dynamo but lack of use with over capacity may reduce the battery life 

to keep a battery up to scratch they need a good level of balance charge /discharge  so battery is normally matched the the usage

sort of.... too small  lacks life  and too large never gets fully used 

but sally on and see how you get on its nothing to loose sleep over 

Pete

 

[johny]

I would have thought the energy to start an engine is pretty much fixed so the subsequent recharging of the battery used will be the same what ever its size is. Saying that perhaps the voltage fall will be slightly less with a bigger battery so the peak recharging current will be less but be needed for longer.

However I think the biggest difference will come if youre recharging a flat battery (for example after a bump start) as the dynamo will have to give a high output for longer with a bigger battery which may affect the operation of other equipment and overheat the dynamo....

[daverclasper]

Thanks. I think its charging ok, though haven't been using it with lights etc much, as only fitted it a few weeks ago.

I think I read on here that a larger than usual battery can struggle to get fully charged, that's why I asked. I do keep it charged when not in use.

Cheers, that's put my mind at rest, though not for wars and global warming, etc🙂

[Chris A]

16 minutes ago, daverclasper said:

I do keep it charged when not in use.

What you could do is when you get back after a good run, no lights etc, put it on charge and see how long it needs before fully charged. If the dynamo is in good condition I think you'll find it doesn't need long.

[daverclasper]

Thanks Chris, yes I do that with a small motor bike charger and it only takes an hour or so

[SpitFire6]

Hi,

 Generally if the volume of the battery (SLI) is larger, the capacity & resistance have improved.
I believe your cracking speed will increase vs OEM "Size".
Recharging time same.
Recharging from Zero SOC will not be high as Resistance of Battery High, so no problem.
A SLI battery has a < 100% SOH when DOD is more than 80%.

Cheers,

Iain.

[PeteH]

The "rule of thumb" used to be it takes around 1/2 an hour of brisk driving to bring a battery back after a Cold start.

[SpitFire6]

On 05/03/2022 at 20:17, PeteH said:

The "rule of thumb" used to be it takes around 1/2 an hour of brisk driving to bring a battery back after a Cold start.

I assume it takes one Ahr of energy to start a cold car engine. Probably a couple of brisk driving minutes & battery energy replaced?

[johny]

oooh could we say 400A for 3 seconds gives 1/3Ah which with the dynamo giving a maximum of 22A would take just over 7 minutes to make up (as long as engine revs are kept up sufficiently and other demand is low)? Alright a lot of guesstimation there so does anyone want to shoot me down😁

[PeteH]

I did say "rule of thumb" and we are talking old fashioned Motors here, it was perceived wisdom "back when". The old dynamo`s don`t charge well at low speeds, and short commute type journeys, like to work, where Killers. I well remember cranking the old side valve Ford for long periods before getting a start. That`s why we had Starting Handles as well!. And often 6volt systems.

Battery technology has moved on as has the starter tech: so moderns don`t have the same issues.

Pete

[johny]

yes I think it ties up pretty well cos of course the dynamo/alternator wont put out its max output right up until the battery is fully charged. It will progressively reduce output current as the battery voltage rises so increasing the recovery time...

[Chris A]

to come back to this question of a battery being too big (capacity not physical dimensions).

I run my 13/60 with the standard dynamo and a 540A/62ah battery.

The car was taken for a run, the actual state of the battery charge wasn't controlled before hand - yes bad scientific practice... The route was the 'pretty' route to town via rural 'B' roads through 2 small villages with 50kph limits, a 2Km section with a 70kph limit to the edge of town. Filled up with petrol and went into town for a 'pause café' with a couple of mates fro an hour or so. Total distance each way 15kms. Same return route less the petrol station stop. No stop start driving to speak of.

Car stood for 1 week. Connected battery charger and virtually immediately showed full charge. Didn't do a volt test but the charger does do its job.

OK, so not really scientific but does show that a dynamo is capable, certainly when the car is driven on open roads, of keeping a large capacity battery charged.

 

[SpitFire6]

Battery weight is pretty much equal to Ahr/Capacity within same type. it's not unusual for a battery to be taller (More Volume) yet contains the guts from a shorter battery.

Volume is a general indication of Capacity. 

Iain.