New build Battery help

[pbmzt]

hi folks i'm new here I just built a new 1000w rear motor kit, at the the minute i cannot afford a lithium battery so for now i'm running off 4 SLA 12v in series 7mah total when charged 57v,problem is the motor works ok but seems to lack power on hills im pretty heavy like 18stone and the bike feels like a ton weight lol,also when i give it full throttle the battery meter drops to one bar then snaps back up when i release the throttle is this battery sag as a result of running SLA batteries or is this a fault with the motor or controller setup ?........managed to get around 8 miles range but very sluggish and walking pace on hills...any ideas guys.......


battery
http://www.screwfix.com/p/sealed-lead-acid-battery-12v-7ah-100-x-65-x-151mm/38315#product_additional_details_container

kit
https://www.amazon.co.uk/Voilamart-Electric-Bicycle-Conversion-Cycling-x/dp/B06XXQK2MD/ref=pd_sbs_263_6?_encoding=UTF8&refRID=722QA276710AEZJ46DCD&th=1

 

[amberwolf]

I'm assuming you mean 7Ah, not 7mAh.

18 stone is 280lbs, which means that you plus your bike probably weigh nearly as much as my heavy-duty cargo trike SB Cruiser, which itself would probably have some trouble with hills using just one of it's two motors, each of which presently is around 1500w peak. Using both it would probably be fine, though.

So you may have two problems, the first being the SLA batteries, the second possibly insufficient power for the hills (or not going fast enough for the motor's particular winding vs wheel size to keep current low enough).





SLA that small are not really capable of putting out a lot of current without sagging in voltage a lot, which means the battery meter drops down low, and might sag so much that the controller would cut out, stopping the motor.

Larger SLA, like 12Ah, might do a bit better, but they'll be nearly twice as heavy and large as the 7Ah.

18-20Ah SLA would do better yet, but will be nearly three times as large and heavy as the 7Ah.

Also, the cost would probably be about as high as just getting a small lithium pack, which would probably perform better than any of the SLA options.



Another issue with SLA is that in this type of use, they will supply only about half their rated Ah.

 

[pbmzt]

Thx for the reply man yes the bike is heavy lol.....kinda figured the SLA batteries weren't up to much and they're really heavy too.......i noticed in the kit description that it was restricted to 250w instead of 1000w for UK road use is this set by default or do i need to reprogram something on the display to get the full 1000w or disconnect wires ?.....certainly felt like it was only 250w instead of 1000w...........


kit description
https://www.amazon.co.uk/Voilamart-Electric-Bicycle-Conversion-Cycling-x/dp/B06XXQK2MD/ref=pd_sbs_263_6?_encoding=UTF8&refRID=722QA276710AEZJ46DCD&th=1

 

[amberwolf]

Couldn't tell you how to remove the restriction, you'd have to ask the seller about that, if it's not listed in the manuals or on the seller's web page or the product web page.


If it's not there, and you can't get them to answer, you could always order an unrestricted controller from somewhere else, though I don't know if it would be stopped at customs or not. I also don't know what would happen if you ever got stopped and tested for power levels, though it's probably not a likely thing to happen.