Broken charger

[aab1]

After all the nightmares with my bike, now it's the charger that's dead.

It's a 36 volt lead acid battery charger. It started by making weird buzzing sounds and working only when held at a specific angle, and then just gave out completely.

Is there any way I could find and replace the damaged components? Any idea what part failure may have caused this?

In the worst case I'll charge all 3 batteries seperately with my 12v charger.

Are there any cheap lead acid 36 v chargers? I'd rather move on to Nimh but this was raelly not in my planned purchases, especially after I JUST got braend new lead acid batteries!

Thanks

 

[flecc]

You could try Powerscoots or Powabyke, both probably reasonable. Powerscoots have a choice of them on the page I've given.

Query Powerscoots prices though, they show them as without and with VAT but the with VAT prices are very much more than the plus 17.5% they claim.

Looks like a bit like a con to make the net price look lower than it really is.
.

 

[aab1]

What is VAT? I keep seeing that on UK stores, is that what they call the tax there?

By the way I just got a 500mah charger for 12v batteries and am cahrging them individually now, but the charger says for 1-2 Ah batteries, mine at 7 Ah, will it cause a problem? Wouldn't it just take 7 times longer?

Thanks

 

[flecc]

I'm sorry aab1, I'd forgotten you weren't in the UK.

VAT is Value Added Tax, the European version of the US sales tax and whatever there is in Canada.

That charger would be very slow but should complete the charges with sufficient time.

I don't know who to recommend in Canada for SLA chargers, but in the USA Powerstream are a very good source for every type.
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[ITSPETEINIT]

Value Added tax

What is VAT? I keep seeing that on UK stores, is that what they call the tax there?

Thanks

VAT is a tax that prevails throughout the European Community and is charged on all "Taxable" goods by the supplier to his customer. If the customer is a retailer or wholesaler he must add VAT to the price that he charges HIS customer (probably the end user). The rates of VAT vary from one country in the EU to another.
Any VAT paid by a middle man who is registered for VAT (Input Tax) can be recovered by him from the VAT that he charges (must charge) to his customers (Output Tax) - he will remit to Revenue and Customs the Output VAT less the Input VAT every 3 months.
There are 3 rates of VAT in the UK: Standard rate = 17.5%: Special Rate (for Power supplies) = 5%: and the Zero Rate.
There is also an Exempt Rate which is applied (so to speak) to Goods and Services such as Insurance premiums (they bear a different tax under a different system). An Exempt rated organization (e.g. the Police) cannot recover Input VAT from Revenue & Customs.
The purpose of the Zero Rate, which is as much a RATE as the Standard Rate, is so that traders who deal with Zero Rated Goods (e.g. Fresh Food) can recover the Input VAT they pay on services and taxable goods provided to them, from Revenue and Customs.

The importance of understanding these rules is that:
1) If you buy goods for your business being conducted in the UK for resale or use in the business (Like an Electric Bike) you may recover the VAT charged on it by the supplier (through your quarterly return to Revenue and Customs).
2) If you are not resident in the EU and the goods are delivered to an address outside the EU you may ask the supplier (in the EU) to exempt you from any VAT payable. But of course you may have to pay a tax and/or duty in your own country,

There is one more important rule to understand: The VAT on a Purchase that is described as "Inclusive of VAT" is not 17.5% of the total price but is the fraction 17.5/117.5 of that price.
Peter

 

[aab1]

Thanks for the explanation.

I just got an idea, could I wire my 3 batteries in such a way that a switch could change them from being in series (to power the bike) to being in parallel (to charge all 3 with a 12V charger?) so that I could charge all 3 with a 12 volt charger with the batteries in parralel? It would act as a large 21 Ah 12 volt battery wouldn't it?

Thanks

 

[flecc]

I don't think there going to be a problem with doing that on SLA batteries if they are fairly equal in quality and age, and identical in size. That's not true for most other battery technologies though where parallel charging is potentially damaging. Instinctively though, I'm not keen on parallel charging simply because of a potential for trouble, which doesn't exist with them in series.
.

 

[aab1]

I would have thought there would be more risk with them in series than parallel, why is it the opposite?

I also just finished drawing a wiring diagram using a 4PDT relay which would automatically wire the batteries in series by default, and re wire them in parallel as soon as the charger is plugged in.

All there batteries where bought new togheter and used in series ever since until now, where I am charging them individually one after the other for now.

Thanks

 

[flecc]

As cells are charged in series the charge passes through all equal cells to charge them similarly. As an example only, the series columns in NiMh batteries for e-bikes are always assembled with cells from a single manufacturing batch to ensure the same characteristics.

When in parallel, one objection is that even if cells are quite equal, since perfection isn't possible, the pairs will not be truly identical, so one of a pair of single cells or columns of cells will always tend to charge first. Any single charge cutoff method will detect the one reaching full charge and cut charging before the other of the pair is fully charged. Cell types which can be damaged by overcharging like NiMh will also suffer if the charge is continued beyond one pair's full charge to complete charge of the other. Parallel cells are sometimes used in some equipment, but always with charge balancing circuitry to keep things equal, and ideally such circuits should be used with series rows, but rarely are.