Battery Vehicle Society

Would there be any problem with recharging a large 36v 550ah forklift battery with a rather small 15amp 36v battery charger?

Im guessing it will charge it just rather slowly!

tom192 wrote:Would there be any problem with recharging a large 36v 550ah forklift battery with a rather small 15amp 36v battery charger?

Im guessing it will charge it just rather slowly!

Lets see, 15amps * 36 hours = 540ah. So if 36+ hours for a recharge for a completely flat battery is o.k. with your needs then I don't see any other problem.

Might even do the battery some good, I'm always for a long slow charge rather than a short sharp one.

ChrisB

ChrisB wrote:Might even do the battery some good, I'm always for a long slow charge rather than a short sharp one.

ChrisB

Regarding Lead-acid battery, I would recommand charging time 8hrs to 10hrs. If quick charge of it, that voltage increases too quickly, batteries may not ready to receive which may non fully be charged. If batteries usually are under-charged, it will passivated which will affect the lifetime.

As for Lithimum, a shoter charging time is perfered.

tom192 wrote:Would there be any problem with recharging a large 36v 550ah forklift battery with a rather small 15amp 36v battery charger?

Im guessing it will charge it just rather slowly!

Hi, but I suppose it was not a suitable charger for you. Output current is too low. Please inform me how many cells in serial? What's the type of your battery? I can figure out a proper charger. You may need a 1.5KW or 3KW charger.

tom192 wrote:Would there be any problem with recharging a large 36v 550ah forklift battery with a rather small 15amp 36v battery charger?

Im guessing it will charge it just rather slowly!

Charging time should be 550ah/15a=36.6Hours
If Lithimum battery, add extra 0.5hour for full charging, so charging will be 36.6+0.5=37hrs above
If Lead-acid battery, add extra 2hrs for full charging, so charging time almostly 39hrs.

Really a long time. A higher power is required.

The maths in this thread is all straightforward, but I am concerned about Tom's real-life problem.

Will a 15A charger ever charge up a forklift battery? I fear the internal resistance (or some such characteristic) of the big battery will stop the small charger from doing it's job.

I don't have the knowledge to back up my worries, except that Halfords want to know the engine size of a petrol car before selling you a charger for a starter battery. I have tried to charge my Land-Rover starter battery with a small charger, and got nowhere.

Hopefully an expert will come along to correct me.

If the 15A charger WILL work, then a day and a half doesn't sound that bad to me, depending how often you use your forklift.

There is a minimum charge current, below which the battery won't charge at all, but this is pretty low. In effect, it's the battery's self-discharge current, which varies with capacity, temperature, battery condition etc.

For practical purposes this can be ignored for any charger that's able to put out an amp or more, as the self-discharge current of even a big fork lift battery will only be of the order of mA.

As has already been mentioned, slow charging does have some benefits, in terms of being kind to the battery. The only real disadvantage is the massively extended charge time.

As an example that I know about, it's common practice to keep microlight aircraft batteries on a very low charge all the time when not in use (particularly at this time of the year, when they are only being used very infrequently). All the evidence I have is that this massively extends battery life, over the alternative of periodic charging at normal rates. The only critical factor is to make sure that the end of charge float voltage is held down to a safe level, I've found that the small Optimate chargers are very good in this regard.

Jeremy

With modern electronically controlled chargers, if the battery voltage is too low they will not charge even if the battery is actually OK. The older non controlled ones will generally charge any lead acid battery that will take charge.
Its well worth having a simple non electronic controller for such uses.

Grumpy-b

Grumpy-b wrote:With modern electronically controlled chargers, if the battery voltage is too low they will not charge even if the battery is actually OK. The older non controlled ones will generally charge any lead acid battery that will take charge.
Its well worth having a simple non electronic controller for such uses.

Grumpy-b

Yep I'll go with that, I've got a lovely C-Tek charger, very nice it is too, but its a pain if a battery is really low as it wont touch it and refuses to start thus a couple of times I've had to kick start it with either another 12v or just charge the battery on an old fashioned charger to get the voltage back up where the c-tek can take over.

ChrisB