Charger to trickle.

We have a forklift with 24 individual cells and totals 48v, We have just bought it recently to help out with our own 48v forklift. The m/c is 2007 but the cells are reasonably sulphated as the specific gravity l cannot raise above half charge. All 48v chargers these days l have been lead to believe do not have a `float` charge, as compared to many 12v chargers.
My question is, we have an old (not used now) forklift charger 48v 55a . Like all the old chargers they charge the battery to hell as it wont quite reach the shut of voltage and this leaves the battery cooked. Is it possible to bypass its circuitry and manually use it as a trickle charger (about 5 amps) and l can decide when to turn on and off. We still have another charger to use to bring up the bulk. I hope with using the forklift regularly and trickle charging we will slowly improve its capacity.

Without exact details of the charger circuit, there is no way to know. You could try just connecting a 12V bulb in series with it as a current limiter, eg. a car headlamp bulb.

The other simple solution would be four cheap 12V car chargers, one across each six cells.

If the cells are sulphated due to lack of use rather than just old age and over-use, an electronic "desulfator" may help - they are supposed to electrolyse the sulphate back in to the electrolyte, which increases its SG and to some extent restores overall capacity.

I've had mixed success with them on smaller lead-acid batteries from UPS units that have become unusable; some can have a lot of capacity restored, others do not change at all.

There are numerous DIY designs for the gadgets around, eg.

Or you can buy various kits and ready-built devices on ebay & amazon etc.


Regardless of any claims of battery voltage, again I'd suggest connecting one across six cells and move it to a different section of the battery every week or so.

Background info:

Hi. Many thanks for suggestions, I did wonder however if using large resistors inline with the charger would lower the current.. Im thinking this as we have 60 year old 24v charger that has a low, med and high rate of charge and this uses large wire wound resistors in the back of it?

That's what the filament lamp would do - it works as a low value high wattage resistor, at lower cost than a conventional resistor of the same power rating.