I have a 20 year old powabyke with a hub motor.
The 36V lead acid battery is us and there are some problems with the power/speed controller. The batterry replacement was 200quid last time I looked 5 years ago.
As Powabyke don't respond to requests at present I was wondering about converting it to run off two 18V makita clone drill batteries.
Are there any likely drawbacks?
As long as you are somewhere near the voltage and capacity of the original battery I can't see it being an issue (with it not offering similar , if not better, deeper DOD on Nicad, MiMH or Lithium technology) performance).
Obviously you will need to use a suitable charger. ;-)
If that doesn't work, could you just mount 3 suitable LA batteries NP7-12) in a fabricated box on the rack or something? Some XT60 connectors and some suitable cable should do it (and you could use the std charger). ;-)
Does your battery case have an 3 pin XLR connector on it OOI?
Cheers, T i m
p.s. I had a similar issue with an old electric kids sized scooter (our daughters) that was equipped with a 24V / 4Ah LA battery. Because I can't find a direct replacement atm (I have seen them for sale in Taiwan for about £15 each but don't need 50 of them!) I was going to substitute it with 3 x 7.2v Nicad RC car packs, at least to give it a try.
I'm not sure what the batteries are in our 26" wheel, step through Powabyke but I don't think it's LA for some reason.
Yes the makita charger
wallwart charger that came with the bike fried itself
The case has sprung loaded pins that make contact with the bike electrics, they were always a problem so I was looking forward to replacing them with Anderton connectors.
I'm not really keen on using lead acid again as the lithium ion ones should be better and readily available plus I can use them in other things like drills..
That should do it. ;-)
As they often do (often destroying the battery before they go). ;-(
;-)
Sure, if you can make additional use of said batteries and don't damage them in the process (for their drill use etc).
But looking at any alternative to LA was just so expensive ... plus LA is very efficiently recycled so could be better for the environment (certainly over the heavy metal based alternatives)?
I think the source of the problem was the charger. I've just spent over £100 on a 12/24V Optimate charger to charge / maintain the two (24V LA) mobility scooters I'm sorting here. A worthwhile investment when compare with the cost of having to replace quality / AGM / sealed semi-traction batteries, ruined by poor charging or maintenance. ;-(
Cheers, T i m
Always make sure both batteries are charged the same - in practice both fully charged - or you run the risk of reverse charging the weaker one. I'd put a nice big diode in parallel with each battery pack just in case.
The batteries will be in series so what will be the effect of a diode across each pack?
Will the diodes from a car alternator do the job?
I believe the idea is that if one battery becomes discharged, the remaining battery(/ies) in the series link with then, though the load, try to reverse charge the flat battery. Putting the diode in parallel with the batteries will limit the reverse voltage across the battery to about .6V and so minimise any deeper / further damage (than may already be done by taking the charge to that low level).
AFAIK, the rating of the diode needs to be sufficient to safely carry the running current produced by the remaining batteries when delivering full (remaining-resultant) current to the load.
Cheers, T i m
I've never heard of anyone doing that. Either you've had a very good and original idea or you've had a daft idea.
Bill
Many, many years ago, at a boot sale, I bought a 12V pack of D-size 'Cyclone' batteries (6 x 2V sealed lead-acid). Each cell had a reverse diode soldered across it.
Which makes more sense of course because a 'battery' could have a weak cell and so you could still end up reverse charging one (or more) cells within it, even with the diode across the battery.
Cheers, T i m
The main issue is likely to be current draw. A drill under load has to push a small amount of (quite resistant) wood or plaster around. A bike has to push a ~100kg lump up to 15mph. Expect gulps of ~30A as it accelerates. If the bike is pure pedelec (ie no twist-and-go) it will be a bit easier as there is some human input, especially from rest which is the most taxing bit of the curve.
I'd check what current the drill batteries expect to deliver. You might be OK, but many 18650 cells aren't rated at that kind of current level. This is why many e-bike batteries put cells in parallel to carry the load. The parallel cells provide a higher capacity as well, compared with say a
18V 2Ah drill battery which is just 5 series cells (5S1P).You might find a 2P/3P/4P battery pack is better at delivering current, but that might not be something available in drill packs.
Also, be wary of the controller if it has any 'low battery' sensing. It might decide to cut off if it thinks its lead acid is too discharged. A quick sum suggests a 10S lithium ion bottom end would be about 32V, while a
18S lead acid bottom end would be about 33V. You might not get the last capacity out but it looks fairly well matched, although I couldn't speak for whatever your example actually does.No harm in trying it and see though. I have one of these power meters:
Theo
Just buy some lithium power packs for model usage. Or for car starting. They can handle enormous peak current loads. An electric bike normally is around 200W with peaks up to 400 or so.
36V is 10s LiPo or thereabouts. You probably want about 4Ah.Ok this looks close enough at at a fair price and in stock in the UK
It weighs less than a kg...
The charging will be something you will need to attend to with a special charger
The cells made for nicotine vaporisers are often rated for that kind of current (35A is about the heaviest). Around 500W is not an unusual peak draw for a power drill (almost stalling) so those cells should be good for peaks of 25A.
NP is the wrong type of lead acid, they don't last well in such use. OP would need to use something intended for golf carts or mobility scooters.
No way is the OP paying £200 for 7Ah of LA, unless they have no idea what they're doing. £200 for 3 lead acids would buy what... dunno but maybe 50Ah or so. Lithium is always going to cost more per Ah than LA.
NT
The Powabyke batteries can be opened up and the SLA batteries replaced (usually 3x 12V) - they're just regular Yuasa/etc. However an e-bike with a lead acid battery is a fairly dismal experience - lightweight lithium ion will make it much nippier and more manoeurvable.
Theo
Suitable for all recent models Suitable for older models as supplied with rail and base plate 40-50 mile range**
SRP £479 <=== nippier
Come to think of it, that's enough money to have bought my current (human powered) bicycle.
"When I grow up, I want to be a lithium battery merchant." Sees to be a fat profit available.
Paul
Yes the sla battery is rated at 12Ah and 36V with three in series so about £115. The biggest Makita drill battery is 5Ah and two of them come in about 100 quid. The Natural philosopher's link is a 36V battery and
4Ah for 75quid but I would need a separate charger.I'm not sure how one can relate the usable capacity of a lead acid to a lipoly i.e. how many Watt hours would I be able to draw out of either battery to a non damaging depth of discharge.
I dunno where you're getting those prices, they're way OTT. Shop around & avoid the non-buggy/mobility types.
For a ballpark I recently looked at 7Ah 12v at somewhere around £15-20 each. One can also find used lead acids at car boots for not much, if you're overly brave.
NT
On an automotive battery, to achieve a large number of charge/discharge cycles, you use about 1/4 of the amp-hours.
On Lithium, 100% of the rating is available.
The difference is the notion of safety. Lithium systems have onboard protection against overcharge and excessive discharge. As a consequence, the "fuel rating" in ampere hours, is a "fully usable" rating.
Whereas with Lead Acid, nothing bad happens in terms of fires or the like, if the battery is abused. If is for the notion of a "decent service life" that the user may wish to observe a "no more than 1/4 of rated ampere hours" usage. This reduces the depth of discharge and means you get more charging cycles from them. Maybe the full charge voltage is 13.8V, and then you stop using it at 11V. That sort of thing. The cutoff voltage would be different for each battery chemistry and discharge strategy.
Lead Acid Traction batteries on the other hand, are both more expensive, and are also constructed to be less affected by deep discharge. You can run them flat. But, if you were to take care of them, you could likely get a good service life from them. If your golf cart had some sort of undervoltage lockout, it might improve the service life.
The poor service life of my Black and Decker NiCd screwdriver, can be directly attributed to the horrible infrastructure support the packs received. If there was a bad design decision they could make, they made it. They might as well have designed the thing to use dry cells, for all the good that NiCd would do under those working conditions.
There was a time, when the area of the bicycle frame bounded by the two rising bars and the crossbar (a triangular area), on an E-bike, that area was completely filled with cells. By doing so, you could use any old crap technology you wanted, instead of some svelte cartridges that fasten to just one bar.
A few weeks ago, I started seeing Bird scooters littering the sidewalks here, in the downtown area.
Aha! And this is how they're getting charged. How horrible.
Paul
I had a feeling that something like this may be the case, hence wondering if a 4Ah lipoly or Liion battarry may work out cheaper and just as good in the long run.
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