Feasible Idea: Bicycle Trailer full of SLA Backup Batteries

[chopper_elec]

Hey all.
I've been converted to Lifepo4 before even trying out the 4x 12v 12ah SLA batteries that were just bought the other week for a Electric Shwinn Stingray Chopper style bike and i've got an order for a 48v 10ah Lifepo4 battery on the way from China.

I was thinking I would keep the 4x 12 12ah sla batteries for my long trips as a spare/backup set which would be stored in the trailer behind and I would use my 48v 10ah lifepo4 for the majority of the trip.

Mind you this trailer would be around the 15-18kg mark with the weight of the trailer and batteries.

Am I better off just returning the batteries? They only cost me $125US for all 4.

I'm guessing there is only a good 8-9ah usable in the batteries, but if it gets me another 15-20km on my 48v 24" front wheel hub motor that would be a great addition.

I'm guessing for the times that I would be pedalling with the motors off, i'm going to struggle big time.

 

[mikebikerad]

I put lead acid batteries in a trailer once for extended range and it was not worth it.

 

[Lessss]

If no steep hills go for it.

 

[chopper_elec]

I put lead acid batteries in a trailer once for extended range and it was not worth it.

Thats what I was worried about, I think the weight offset would just wreck anytime I was pedalling for a bit of extra range which i'd end up using by having to use the motor to power my movements.

If no steep hills go for it.

I will have to carefully map my trip better I think, the one path I found was hills up and down most of the way lol. Good some bits, not so good other bits.

Out of curiousity I wonder how far i'd get on flat ground with a mix of pedalling and power on using a 48v 500w conhis 24" front wheel with a 48v 10ah battery?

 

[ddk]

my trailer and sla batteries weigh in at 45kg (36V@36A)
-hardly notice the trailer until I hit the first 3-4% grade...

 

[chopper_elec]

my trailer and sla batteries weigh in at 45kg (36V@36A)
-hardly notice the trailer until I hit the first 3-4% grade...

Interesting..... I wonder how much 4 car batteries would weigh.. lol 55ah

The brakes would be under a fair bit of pressure i'd imagine, with just on 160-170kg pushing the bike forward.

 

[ddk]

my trailer and sla batteries weigh in at 45kg (36V@36A)
-hardly notice the trailer until I hit the first 3-4% grade...

Interesting..... I wonder how much 4 car batteries would weigh.. lol 55ah

The brakes would be under a fair bit of pressure i'd imagine, with just on 160-170kg pushing the bike forward.

lol-don't use car batteries unless you're willing to kill them quickly.
Deep-discharge rv or marine batteries would work but I wouldn't use a wet cell with a bike just because...
I'm using 9 each 12Ah AGM batteries until I can procure my preferred lithium batteries (currently not in stock)
'''as for brakes, my bike is a trike where I've added additional brakes.
I've considered putting hub motors on the trailer if only for having regen braking for those long downhill runs where I live, but it all becomes moot once I have the lithium batteries, as I won't need the trailer for those.

 

[Chalo]

Hey all.
I've been converted to Lifepo4 before even trying out the 4x 12v 12ah SLA batteries that were just bought the other week for a Electric Shwinn Stingray Chopper style bike and i've got an order for a 48v 10ah Lifepo4 battery on the way from China.

I was thinking I would keep the 4x 12 12ah sla batteries for my long trips as a spare/backup set which would be stored in the trailer behind and I would use my 48v 10ah lifepo4 for the majority of the trip.

Mind you this trailer would be around the 15-18kg mark with the weight of the trailer and batteries.

Am I better off just returning the batteries? They only cost me $125US for all 4.

I'm guessing there is only a good 8-9ah usable in the batteries, but if it gets me another 15-20km on my 48v 24" front wheel hub motor that would be a great addition.

I'm guessing for the times that I would be pedalling with the motors off, i'm going to struggle big time.

I suspect it depends somewhat on the qualities of the trailer and its tires. A well aligned trailer with good fast smooth tires with pressure appropriate to the load can be very efficient. I carry hundreds of pounds of groceries and the occasional adult person on the trailer I built. It's not easy to tell it's there except on acceleration or climbs/descents (when it can be a real chore sometimes).

If you carry a big fat load of batteries, you'll get better range by having them in parallel with your usual batteries. The lower the amp load, the less Peukert effect loss you'll get. So it's better to discharge whatever batteries you carry simultaneously rather than sequentially, as long as they all share the same chemistry. That would also keep your batteries to the same depth of discharge so that none get disproportionally beat down.

Chalo

P.S. -- It's easy to find out how your rig would ride when not on the juice. Just load the batteries in question into your trailer but don't hook them up to anything, and go for a spin without power.

 

[ddk]

...

P.S. -- It's easy to find out how your rig would ride when not on the juice. Just load the batteries in question into your trailer but don't hook them up to anything, and go for a spin without power.

:lol: don't need batteries, just add a few cases of your favorite beverages and the snacks to support said beverages.
In this way you''d have something to look forward too after the test.

 

[neptronix]

Another alternative, which would cost quite a bit more $, is some thundersky/sinopoly batts. You could later use them in a solar panel buffer array, if you got yourself a few kilowatt hours.

At about $350-$400 per kilowatt-hour, they are pretty reasonably priced.

They would be about 1/4th the weight per kilowatt hour, maybe better after you consider the peukert effect.

http://evolveelectrics.com/Sinopoly.html

 

[amberwolf]

I'll ditto what Chalo said above.

I'd also add one caveat--if your trailer hitch is not rated for the load, or if you are close to the rating, or it's old and with plastic parts, Id' highly recommend some sort of backup chain or cable to tie it to the bike in case the hitch breaks or comes loose for any reason. It's rare, but it happens, and if it does so a couple things could happen--the trailer could just fall off and be left behind, or (if it is a type that connects anywhere forward of the back edge of the rear tire) it could have it's hitch pivot inward toward the wheel, and end up in the spokes, taking you down. If the cable or chain is tight enough around the stays or wherever so it can't do that, then you should be ok, as long as nothing else goes wrong before you can stop and deal with the hitch failure.


It also keeps the trailer from just falling off and getting run over by cars that are behind you.

 

[chopper_elec]

Thanks for the heads up everyone.

I am absolutely over the moon with all these ideas. I have so much to think about.

I'm tempted to try out some solar panel action, i'm not sure if I could get one to suit a 48v system. If I went out for a full day, i'd get a fair bit of recharge from the process.

If I am able to position the batterys as close to the axle as possible I have less chance of the hitch getting the full force of the weight.

 

[Chalo]

I'll ditto what Chalo said above.

I'd also add one caveat--if your trailer hitch is not rated for the load, or if you are close to the rating, or it's old and with plastic parts, Id' highly recommend some sort of backup chain or cable to tie it to the bike in case the hitch breaks or comes loose for any reason. It's rare, but it happens, and if it does so a couple things could happen--the trailer could just fall off and be left behind, or (if it is a type that connects anywhere forward of the back edge of the rear tire) it could have it's hitch pivot inward toward the wheel, and end up in the spokes, taking you down. If the cable or chain is tight enough around the stays or wherever so it can't do that, then you should be ok, as long as nothing else goes wrong before you can stop and deal with the hitch failure.


It also keeps the trailer from just falling off and getting run over by cars that are behind you.

Yeah, I guess I should have mentioned that one of the factors in making a bike with trailer ride sweetly is keeping the tongue weight low. You do want a little tongue weight to minimize porpoising and/or frequently reversing forces on the hitch, but keep it modest. I shoot for about 10% of the whole trailer's weight.

chopper_elec: You can use 12V solar arrays hooked up to each battery individually. As long as they are mounted on the same flat surface, and none of them has even a little bit of shadow falling on the PV cells, they should all charge about the same amount.

Chalo

 

[chopper_elec]

Thanks for the heads up.

I am still debating whether to return the SLA batteries now. I have my lifepo4 48v 10ah battery on order but i'm still tempted to give the trailer idea a go with those sla batteries.

 

[dogman dan]

Well, you couldn't pay me 125 bucks to tow the lead. But I live at the top of a large hill. If you can return the lead, I would.

But that's me. Towing the lead might work great for you. Bear in mind that if it's flat enough where you are, a lot of starts and stops can be just as bad. Keeping that weight going is not so bad on the flat. But getting it going again every block will not be fun.

BTW, a 5amp charger for the lifepo4 you have coming will just about fully charge it in one hour. So for some trips, you might be able to just charge up some more, like a 30 min zap while you eat for instance.

 

[SamTexas]

I would give away any lead acid batteries intended for ebikes or etrikes. If no one wants them, I will pay people to take them away. In the past 6 months I have given away 4 good working big, heavy AGM batteries, each costing at least $200 new.

 

[The fingers]

I have considered a low tech heavy battery trailer to extend range, but if I had the money I would go for a lighter/longer solar panel trailer instead.

 

[ddk]

I would give away any lead acid batteries intended for ebikes or etrikes. If no one wants them, I will pay people to take them away. In the past 6 months I have given away 4 good working big, heavy AGM batteries, each costing at least $200 new.

I promise I'll put them 'near' my trike :lol: :lol:

 

[ddk]

I have considered a low tech heavy battery trailer to extend range, but if I had the money I would go for a lighter/longer solar panel trailer instead.

...have to be a pretty big trailer

 

[John in CR]

If you do use the lead anchor trailer, don't use the lead as backup, but instead run them in parallel. As soon as the lifepo4 is within a half volt of the lead pack, switch the lead on too. You'll get a lot more capacity out of your lead that way, which practically speaking isn't much over 50% of their rated capacity. For more info check out Peukert Effect.

If you can return them for credit, that's the best option, though in the hobby lead batts can be useful around the house, not so much so on wheels unless you need the weight for stability such as something for the kiddies.

John

 

[cal3thousand]

...

P.S. -- It's easy to find out how your rig would ride when not on the juice. Just load the batteries in question into your trailer but don't hook them up to anything, and go for a spin without power.

:lol: don't need batteries, just add a few cases of your favorite beverages and the snacks to support said beverages.
In this way you''d have something to look forward too after the test.

I like your style... the dude abides.

 

[Out-Spokin']

I've been using my SLA battery trailer for a year now, even through the Winter. I love the thing because it keeps the weight off the bike and lets it feel more responsive. It also allows me to find a compromise between $$$$$ LiFePO4s and $ SLAs. This trailer has 36 Volts at 18 AH. I did change out the ugly box a few times for appearance, but it is what it is. Very handy to go to the grocery store too because I can bungie some packages on to it (a la Beverly Hillbillies).

Here is a short description of the Trailer and a link to a youtube if you like

http://www.youtube.com/watch?v=rkbPCcPHigs

This IS a kid's trailer. I got it at a "Side-of-the-Road" sale for $30. It HAD all the covering and seats (pretty colors) and all. I ripped all that stuff off and made a Buckboard out of it. The brand of the trailer is, "Safety-First." I liked the Mag Wheels, although I am sure ones with Spoke wheels would be rugged enough.

The Box is one you can get at Staples for putting office supplies in. It is the sturdier one of the two. It rests on 1/2" PVC piping that is hose clamped down - rather crude I know but it works. Also, some cheap Hold-Down Straps from Pep-Boys works to hold down the box from moving Fore and Aft. Battery operated lights clamp right on the back bar as though they were made for it. I have three flashers.

I have pedaled it up hills without nudging the Throttle because I wanted to see if I can do it. It rolls nicely along even in low gear.

Safety-First has a caution to limit the weight to 100 Pounds. So I keep it under that. The 18ah SLA battery weighs about 45 pounds in its plastic Marine Battery Box. Here is a link to the exact battery - I have 3 wired together to make 36Volts

 

[dogman dan]

I'm sure that works good for you. But unless that lead is free, or close to it, you are paying more per mile than you would if you just bought a good 15 ah lifepo4 pack. And losing about 30 or more pounds, well, priceless.

 

[REdiculous]

lead batts can be useful around the house

That's what I was going to say.

A 100w inverter and a CFL will light up the kid's treehouse (/other) pretty nicely. Add a solar panel and you're set.

 

[amberwolf]

And when they die they are good for holding things down, or using as lifter blocks to hold your bike up to work on. (I do this a lot with CrazyBIke2, piling them up under the cargo pods to hold up the back of the bike)