Search found 661 matches

by fatty
Jul 23 2021 2:13am
Forum: Battery Technology
Topic: 18650 vs prismatic - which is safer?
Replies: 5
Views: 104

Re: 18650 vs prismatic - which is safer?

As above, other factors predominate

But all else equal, cylindrical cells are safer
by fatty
Jul 23 2021 1:48am
Forum: Battery Technology
Topic: Charging an Electric Battery with Gas (a car does this)
Replies: 7
Views: 93

Re: Charging an Electric Battery with Gas (a car does this)

?? Would be way simpler than adding a generator and charge controller to the mix. Generator = motor, so this is added either way Direct DC generators are available with integrated chargers And it's MORE efficient. Gas engine -> wheel is way more efficient than gas engine -> generator -> charge cont...
by fatty
Jul 23 2021 1:29am
Forum: Battery Technology
Topic: Charging an Electric Battery with Gas (a car does this)
Replies: 7
Views: 93

Re: Charging an Electric Battery with Gas (a car does this)

austin2359 wrote:
Jul 22 2021 1:47pm
I wonder if I could find a 52v configuration like this, that would allow me to essentially not have to worry about range but not have a gas motor just a gas generator.
Probably not 52V, but plenty of 48V gas generators for charging
by fatty
Jul 22 2021 10:21pm
Forum: Battery Technology
Topic: Charging an Electric Battery with Gas (a car does this)
Replies: 7
Views: 93

Re: Charging an Electric Battery with Gas (a car does this)

JackFlorey wrote:
Jul 22 2021 3:54pm
Gas motor on a trailer is a lot easier. Trailer pushes you, and you don't need any extra connection to the battery. Regen charges the battery.
This would be terribly inefficient and subject to failure.
by fatty
Jul 21 2021 10:47pm
Forum: EBike General Discussion
Topic: Strategies to increase range while on road (you can't use a gas station)
Replies: 17
Views: 364

Re: Strategies to increase range while on road (you can't use a gas station)

As above,
-increase Wh
-decrease Wh/mile -- this varies by an order of magnitude
by fatty
Jul 21 2021 10:00pm
Forum: Battery Technology
Topic: 18650 fire!
Replies: 8
Views: 275

Re: 18650 fire!

So where did I screw up? Seriously? I changed out the battery.. to a larger capacity 52v 12ah chinese made aliexpress hard pack 18650 2+ years ago... Battery was dead but after plugging it into the charger for awhile, it seemed to come back to life and charge. -Aliexpress pack is invariably salvage...
by fatty
Jul 21 2021 5:42pm
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 32
Views: 643

Re: Low Speed, High Torque Hub Motor?

Thank you both for your replies!! I started looking for 48V, to be honest. By calculations, it seems my application could work with the 48V. I tried to use 7.5A for each motor as this is the highest amps I will be using on each one and I reduced the speed to 1m/s which is around 3.5km/h as this is ...
by fatty
Jul 21 2021 4:21pm
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 31
Views: 686

Re: How to charge bike battery to only 80% ?

Couldn't you say the same for docware's rigid cell tests? When talking about "capacity vs cell cycle life" isn't it OK to be as rigid as possible (minimize variables) when testing one cell vs say a LUNA 14s Shark pack (or 10s3p) with considerably more variables compared to the rigid deman...
by fatty
Jul 21 2021 4:07pm
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 32
Views: 643

Re: Low Speed, High Torque Hub Motor?

SlowCo wrote:
Jul 21 2021 6:30am
Not if you keep approaching the design and component selection backwards...
It's not at all backwards if he has existing design constraints.
He's obviously not designing from scratch...
by fatty
Jul 21 2021 10:59am
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 31
Views: 686

Re: How to charge bike battery to only 80% ?

spinningmagnets wrote:
Jul 21 2021 7:54am
Tesla and Chevy have VERY expensive battery packs, and they charge to 4.05V
Can you share a reputable source for this? Would be great to save for future reference on similar topics.
TIA
by fatty
Jul 21 2021 10:54am
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 31
Views: 686

Re: How to charge bike battery to only 80% ?

Yes percentage of voltage is virtually useless. High voltage is what ages cells, and percentage of voltage is used in the literature. Actual voltage limit as implemented by OEM is just an abstraction/application of percentage of voltage. Percentage of voltage is perfectly fine, if not ideal to use,...
by fatty
Jul 21 2021 12:07am
Forum: Battery Technology
Topic: good balance charger recommendations please
Replies: 11
Views: 193

Re: good balance charger recommendations please

I highly recommend exploring node charging as a better method of balance charging.
RCX BC168
by fatty
Jul 20 2021 10:51pm
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 31
Views: 686

Re: How to charge bike battery to only 80% ?

Charge percentage is based on controller LVC with 3.2v/cell/p-group in a 18650 pack as an acceptable LVC standard (IMO) ... 10s = 42v to 32v = 10v x 80% = 8v + 32v = 40v (80%) ... OR ... 10v x 90% = 9v + 32v = 41v (90%) 12s = 50.4v to 38.4v = 12v x 80% = 9.6v + 38.4 = 48v (80%) ... OR ... 12v x 90%...
by fatty
Jul 20 2021 6:05pm
Forum: Battery Technology
Topic: Hyperion Eos repair. anyone had success????
Replies: 4
Views: 70

Re: Hyperion Eos repair. anyone had success????

If the design is marginal, higher output fans w/o grills may help.

If you're already replacing FETs, uprated FETs direct from a reputable source.
by fatty
Jul 20 2021 5:54pm
Forum: Battery Technology
Topic: Shimano Steps e8000 - Battery recommendations?
Replies: 2
Views: 68

Re: Shimano Steps e8000 - Battery recommendations?

Replacement of the locked battery may not be possible, but it's always possible to parallel another battery of the same voltage.
by fatty
Jul 20 2021 3:01am
Forum: Battery Technology
Topic: 2/4 Turnigy battery packs suddenly died?
Replies: 11
Views: 215

Re: 2/4 Turnigy battery packs suddenly died?

The packs weren't bulk charged. They were balance charged with a hobby king dc-4s all to exactly 4.10V with splitting leads (all connected in parallel so exactly the same). :thumb: Good risk mitigation I think the graph posted by markz says it all... They fall off a cliff at 3.6V, whereas my 30Q pa...
by fatty
Jul 20 2021 12:53am
Forum: Motor Technology
Topic: Motor theory? Size/rpm, wattage.
Replies: 14
Views: 454

Re: Motor theory? Size/rpm, wattage.

This is not correct maths. Units. Man. Units. If you want to extrapolate Hp from Tq and RPM, I can do that for you. Gimmie some more math pls. So you converted to non-native units and think your math is better? That's not at all a refutation/correction. Learn how to do math in real units first and ...
by fatty
Jul 20 2021 12:48am
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 32
Views: 643

Re: Low Speed, High Torque Hub Motor?

Voltage is often easiest to adapt, so let's float voltage and fix wheel diameter to 13":

diameter 13" = 330mm
circumference = πD = π*330mm = 1037mm
rpm = 6,000,000mm/h / 1037mm*60 = 96rpm
96rpm / 2.39rpm/V = 40V

So a 48V system would bring these goals closer to reality
by fatty
Jul 20 2021 12:38am
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 32
Views: 643

Re: Low Speed, High Torque Hub Motor?

Hi, I have been looking around for similar specification but seems like with my required voltage and torque, I can't find anything suitable for me. any idea anyone? My requirements are as follows: Speed: 0-6 km/h (0-3.7mph) Suggested diameter: 8-13" Vehicle weight: 120-230kg Voltage: 24V Speed...
by fatty
Jul 20 2021 12:03am
Forum: Battery Technology
Topic: 2/4 Turnigy battery packs suddenly died?
Replies: 11
Views: 215

Re: 2/4 Turnigy battery packs suddenly died?

The other 2 packs had cells at 3.65V only about 1.5km before we'd stopped to measure the pack and had 59V implying 3.68 per cell. Not clear on this. 1.5km before power loss, pack was 59V (= 3.68V/cell average ), and the two sub-packs that turned out good were 3.65V/cell? If so, the other two sub-pa...
by fatty
Jul 19 2021 9:54pm
Forum: Battery Technology
Topic: 2/4 Turnigy battery packs suddenly died?
Replies: 11
Views: 215

Re: 2/4 Turnigy battery packs suddenly died?

mxlemming wrote:
Jul 17 2021 1:51pm
We measured the while pack at 65.5V before setting out... Indicating 4.1V per cell.
Strictly speaking, this (pack voltage divided by series = V/cell) is only true if balance charged.

It's possible that dodgy HK LiPo could have been or become imbalanced when bulk charging.
by fatty
Jul 17 2021 4:48pm
Forum: Battery Technology
Topic: 12V Battery system for Small Travel Trailer
Replies: 2
Views: 132

Re: 12V Battery system for Small Travel Trailer

For 12V, you might research some RV chat forums, and look for info on 4S LiFePO4 batteries. 4S is common because they are nominal 3.2V I agree and would exclusively recommend a 4s LFP (LiFePO4) for 12V automotive-related use, as it can be connected to the 12V automotive system: charge from alternat...
by fatty
Jul 14 2021 12:58pm
Forum: Battery Technology
Topic: Safe Lowest batteryvolyage
Replies: 8
Views: 269

Re: Safe Lowest batteryvolyage

After the idea was born for this adventure I contacted an acquaintance who is a Electrical Engineer who advised not to parallel the two battery banks Yeah, apparently everybody here has an EE friend that conveniently confirms their preexisting lay electrical theory :roll: how the  transfer switch b...
by fatty
Jul 08 2021 10:49pm
Forum: Battery Technology
Topic: paralleling different voltage packs
Replies: 2
Views: 109

Re: paralleling different voltage packs

As expected, and great to have documented for future reference :thumb: