Help in choosing a 48volt charger

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I have x4 12volt 7.2Ah battery’s in series to make 48volt to drive a battery powered bike, I need to choose a charger which can handle the charge, any help welcome .

Thank you
 
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I have x4 12volt 7.2Ah battery’s in series to make 48volt to drive a battery powered bike, I need to choose a charger which can handle the charge, any help welcome .

Thank you
I have a 500VA UPS that takes 4 7AH sealed lead acids which I used to use to keep car batteries in tip top charge. and run ex BT kit. It's been preventing a small patch of my floor flying up to hit the ceiling for a lot of years.
Yours if you want it.

OO I forgot it will also double as a UPS.
 
I have x4 12volt 7.2Ah battery’s in series to make 48volt to drive a battery powered bike, I need to choose a charger which can handle the charge, any help welcome .

Thank you
I have a 500VA UPS that takes 4 7AH sealed lead acids which I used to use to keep car batteries in tip top charge. and run ex BT kit. It's been preventing a small patch of my floor flying up to hit the ceiling for a lot of years.
Yours if you want it.

OO I forgot it will also double as a UPS.

Go on then
 
Shame you didn't ask a couple of weeks ago, I took my daughter and grandsons to Clacton for the weekend.
 
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They are clearly made, but since made in low quantity tend to be expensive, I wanted to charge 24 volt, and found 2 Lidi chargers at 12 volt each was the best option, charged as 2 x 12 volt used as 24 volt. The Lidi charger is similar to Ctek in that you can connect and forget. They auto switch once charge completed. This is assuming lead acid.
 
Toy cars, drones, and many other devices use 48 volt batteries, but today most are not lead acid. Lead acid even with valve regulated types take time to absorb the charge, near impossible to recharge a lead acid fully in under 12 hours, may be able to charge to 90% fast, but that last 10% takes time, and unless given the time the battery capacity with slowly reduce.

The mobility scooter still use lead acid, but ebikes tend to use NiMh, Lithium or other similar batteries, lead acid are considered too heavy, for some odd reason they seem to be rated in watt/hours, so a small 300 watt/hour 36 volt battery will have a 50 to 75 mile range with the larger 400 watt/hour 75 to 100 mile range with peddle assist, so 300 watt/hour = 300/36 = 8.3 Ah and 400 watt/hour = 11 Ah and they do go up to 15 Ah and that weighs 4.8 kg. A 7.2 Ah lead acid weighs 3 kg and you need 4 so 12 kg battery weight, easy to see why Lithium is used.

That does not mean lead acid will not do the job, one can likely do 20 miles without a problem and if you don't need to take the bike up or down steps then extra weight is not so bad, however finding a charger able to charge 4 batteries in series together not so easy, 24 volt there are loads, mobility scooters and stair lifts 24 volt, but although some are good, the mobility scooter lasted some 12 years on a pair of batteries, the stair lift needed the batteries changing every two years, it clearly was over charging the batteries.

Battery chargers don't always say how they work, the Lidi 12 volt 3.8A charger I bought has two settings one for under 12 Ah and one for over 12 Ah, when set for under 12 Ah it switches off completely at end of charge, and switches back on each time volts drop to 12.8 volt, normally for few seconds so without a power monitor would not know it had done it, over 12 Ah however even after complete it still charges at 0.1 amp switching to 0.8 amp each time it drops to 12.8 volt. So you need a charger designed for that size of battery. If it was me, I would charge as 12 volt and use as 48 volt as 12 volt chargers are cheap and easy to buy, think Lidi one was around £14 and you could simply connect them in parallel to charge. Even in parallel so 28.8 Ah within 2 hours charge rate will have dropped, so in real terms a charger each battery will recharge the batteries in 11 hours and one charger on all 4 will take 12 hours, as charge time is all about what the battery can absorb, not what charger can give when using lead acid. OK wife's bike with a 300 watt/hour 36 volt lithium battery can be charged with fast charger in an hour, and with slow charger she has only 4 hours, but that's lithium not lead acid.
 

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