Are 12v to 36v step-up transformers available?

[Thaddeus]

I am building an electrically powered recumbent trike.

It has a 36 v motor.

I ALMOST bought 3 12v batteries to wire in series last night. But I realized the charging and maintenance of them (unhooking them so i could attach a 12v charger) would be a huge pain, and the turnaround time would be 3 times longer unless I bought 3 chargers.

So I was thinking, has anyone run a small deep-cycle 12v battery with a step-up transformer to get 36v output? If so, where could I get one? What are the cons (besides the fact the transformer uses some power when it changes the voltage)?

It would be nice to just have one 12v battery that could be charged with an ordinary car charger...

thanks

Thaddeus

 

[knoxie]

Hi

Just buy 3 x 12V SLA wire them in series and get a 36V SLA charger! job done, you dont need to balance them as such although making sure they either all flat or all charged first is a good idea.

You can get 3A switched mode 36V chargers at a number of places, will charge them all in 4 hours.

Dont use a car charger to charge SLA batteries as they are mostly constant current chargers.

Good Luck

Knoxie

 

[Thaddeus]

The other consideration here: i was looking at Werker SLA 12v 12ah batteries, which people recommended elsewhere on this board. the battery store guy told me I should not charge them at greater than 1 amp. At that rate, it would take 24 hours (he said) to bring them to full charge. that's too long, to my way of thinking: I don't want to have to take my buggy out of service for a full 24 hours from 'flat'.

Is there a more sophisticated charger that will pump up those batteries in less time without risking damage to them?

thanks

 

[fechter]

Step up transformers really only work with AC. What you are looking for is called a DC-DC converter.

I am not aware of any converters that would be suitable for what you are talking about. To work at that power level, the converter would be fairly large and expensive. Much more than a couple of chargers.

One way to use a single 12v charger is to find a big plug with at least 6 pins and have all the batteries come out to the plug. To charge, you unplug from the vehicle and the charger plug is wired to put the batteries in parallel.

The mating plug on the vehicle is wired to put the batteries in series.

Plan B is to find a huge switch that can do the series parallel change.

 

[D-Man]

I use a 36 volt soneil 2 amp charger for my 12v-12ah sla's and it works great. Not too expensive either. Usually only takes 4 hours to charge for a complete discharge. You can get them at electricrider.com. Beware of dumb sales clerks everywhere. Get your stats and charging requirements from the battery manufacture's data sheet. They list them at electricrider also.(for B&B battery, PDF's)