Front wheel or rear?

[Sundsvall]

My winter bike has a 24v 250w mini motor at the front. The 250w motor is an EU-limitation and this is the last time I’ll follow this regulation, its ability to climb the hills are way too low. Front wheel drive is a must because I drive in deep snow occasionally and by pedalling I then have an AWD (which sounds better than 2WD). The front wheel motor has helped me a lot and the low weight is a great benefit too. Unfortunately the lead batteries didn’t worked to well when the temperature dropped to -25°C and they was quite heavy too. For the winter to come I’ve bought a frog style battery pack from GM which should be better to handle cold weather and is a bit lighter.

The negative thing with the front wheel drive is that it can spin when there’s gravel on the road or it’s icy, and a more powerful motor probably increase this problem. If this happens when you’re in a turn you will very likely hit the ground, I have done this a few times and it really hurts. So for my summer bike project there will be a Magic Pie rear wheel and the battery pack will be located somewhere in the triangle.

Peter

[Leslie]

My winter bike has a 24v 250w mini motor at the front. The 250w motor is an EU-limitation and this is the last time I’ll follow this regulation, its ability to climb the hills are way too low. Front wheel drive is a must because I drive in deep snow occasionally and by pedalling I then have an AWD (which sounds better than 2WD). The front wheel motor has helped me a lot and the low weight is a great benefit too. Unfortunately the lead batteries didn’t worked to well when the temperature dropped to -25°C and they was quite heavy too. For the winter to come I’ve bought a frog style battery pack from GM which should be better to handle cold weather and is a bit lighter.

The negative thing with the front wheel drive is that it can spin when there’s gravel on the road or it’s icy, and a more powerful motor probably increase this problem. If this happens when you’re in a turn you will very likely hit the ground, I have done this a few times and it really hurts. So for my summer bike project there will be a Magic Pie rear wheel and the battery pack will be located somewhere in the triangle.

Peter

You can keep the SLA's warmer on the float charge.   Charging SLA's in very low temperature you can go higher with the volts.  Almost to 16v.

If you can manage to get 16v on each SLA.  Recharge to 15v each SLA and keep on float charge, and before you ride top them up to 16v,  this will warm them up.


SLA's should be ok with the minimotor.  If you can program the controller to do 10 amps continuous and 12 amps max the SLA's may work better, I found 250 watt motors are really cool with a 20" or a 24" wheel, 20" rocks.  I own a 20" brushed bike and motor.  It goes about 30 kph and has no problems towing stuff around. . 26" wheel at 250 watts may have some problems when you need some guts.

[Sundsvall]

Ok, maybe a little bit off topic but I just gave the new battery a chance on the road. Despite I have the studded tyre on, it felt real well. I live in a very hilly area and there is almost no flat terrain at all. There’s a street beside my house the motor didn’t managed to climb by its own with the lead batteries, now it was no problem at all. I’m happy right now; let’s see how happy I am when the temperature drops to -25°C.

The old batteries were 2 lead-gel 12 V, 8 Ah, 7,4 kg.
The new a GM frog style 24 V, 10 Ah, 2,7 kg.
That’s 4,7 kg lighter battery pack with more power and better look.

It has something to do with the topic after all. Now I have to be more careful with the throttle when it’s icy.

Peter

[Leslie]

Ok, maybe a little bit off topic but I just gave the new battery a chance on the road. Despite I have the studded tyre on, it felt real well. I live in a very hilly area and there is almost no flat terrain at all. There’s a street beside my house the motor didn’t managed to climb by its own with the lead batteries, now it was no problem at all. I’m happy right now; let’s see how happy I am when the temperature drops to -25°C.

The old batteries were 2 lead-gel 12 V, 8 Ah, 7,4 kg.
The new a GM frog style 24 V, 10 Ah, 2,7 kg.
That’s 4,7 kg lighter battery pack with more power and better look.

It has something to do with the topic after all. Now I have to be more careful with the throttle when it’s icy.

Peter

Maybe keep that battery on the charger on cold nights and not let it stay discharged over night.  A while ago I was reading that charged batteries resists the cold better than a discharged battery.  And a battery on standby is better again.

Maybe worth taking it off the bike and bring it inside on real cold nights too.

The froggies look sweet.

Well done and god speed with the new pack,

[Sundsvall]

All my bicycles stays inside my warm and cosy garage all the time they're home.

I've now measured the batteries with and without load, both cold and warm. The lead batteries are a joke when they’re cold. I never understood why the motor stopped working just after a few km but now it’s clear that it was the LVP. Now I don’t understand why the LVP didn’t cut-off earlier because the voltage dropped significant under load when they were cold.

Oh, and the topic: Front wheel drive is best in snowy weather which makes the bicycle an AWD but this only apply to weak motors. The stronger motors should only be for rear wheel for safety reason but the rear wheel is more complicated to convert.

Peter

[Leslie]

All my bicycles stays inside my warm and cosy garage all the time they're home.

I've now measured the batteries with and without load, both cold and warm. The lead batteries are a joke when they’re cold. I never understood why the motor stopped working just after a few km but now it’s clear that it was the LVP. Now I don’t understand why the LVP didn’t cut-off earlier because the voltage dropped significant under load when they were cold.

Oh, and the topic: Front wheel drive is best in snowy weather which makes the bicycle an AWD but this only apply to weak motors. The stronger motors should only be for rear wheel for safety reason but the rear wheel is more complicated to convert.

Peter

Maybe controller isnt designed to switch off at the speed SLA's slump especially when failing.  They must of been up and down like a yo yo.  

I am using some cheap SLA's I got from Jay car om my 250 watts brushed bike atm.

My SLa have had problems.  Like I used a 24ah batt with the two 12ah slas and it discharged the 12ah batts a few times  to far and I forgot to hook up the charger.  They were like trashed. I seemed to loose a set amount of range and she would slow.  One SLA was really bad.

I got another 12ah SLA so now I have three 12ah in series. I lost no added range moving the three SLA's.  

To get my range back I fully charged each cell then  I left the string stay on a 1.2 amp 46v charge for about 2 hrs yesterday and the capacity has jumped through the roof.  I don't have cold weather problems like that though.

But I did a 15 km trip and brang back a big trailer of shop home after the 46v solar 2hr bulk charge.  Then charged it again the same and I did a 25km trip with no pedals and my bike survived a good hill climb without the pedals again.  If Ive fixed the batteries,  I will use them now and not push the long bulk voltage charges.  Try balance them without the shunts.  These on my 250 watt bike could last me a few more months.  

There is no reason you cant salvage your old SLA's and shelve them or make useful purpose from them.  Get a bigger 12v charger and leave them on for three days and discharge by 10% and do again.

[Sundsvall]

There is no reason you cant salvage your old SLA's and shelve them or make useful purpose from them.  Get a bigger 12v charger and leave them on for three days and discharge by 10% and do again.

There’s nothing wrong with my lead batteries. Lead batteries that can give enough current, especially in cold weather, are too heavy for a bicycle. I’ll hereon stick to LiFePo4 batteries because I couldn’t find any difference in my new frog style battery even if I had it in the freezer. But we have summer with 25-30°C so the charging can’t be tested in real life situation.

The lead batteries will be serving as start batteries in old style vehicles for the rest of their life.

Peter