Lithium install

[Mpk200]

I got a LCD meter with my lithium kit which has really small gauged wires positive and a negative.
Ideally it should be wired to a on and off on the key switch.The guy i ourchased from has said it would be better wired that way.
The original meter has 3 wires in a harness clip.

At the minute ive wired the meter straight from the batteries positive and negative.Im getting some strange readings from it around 70% until i turn the key on and press the gas pedal the meter then reads 100% and volts 58.8.
Anyone know if i can wire into the main harness?
Thanks

[Eco Battery]

Originally Posted by augiedoggy

Another option depending on use, I have a 36v cart im building and will be installing a 200ah lifepo4 battery. instead of or in addition to the traditional charger route I purchased a 44"x66" 355w 39v solar panel to use as a roof panel and a $60 boost mppt charge controller. This will charge my 42v battery pack with roughly 12amps while in the sun. I know this isnt the best solution for everyone but being mine is mainly used at a campground this will keep the battery topped off and extend battery life in my situation plus I wont have to worry about being stranded anywhere on a sunny day as 30 mins in the sun will give me a couple miles of extended range. These large panels are available pretty cheap as many remove and replace them with newer more powerful panels..

If you have a 42V pack then it needs to be charged at minimum of 46V. So theoretically the best you can get is 355W/46V=7.7A charging, however with PV panels you are typically going to get 80% of the rated watts, so around 5A-6A max will probably be more realistic. 6A is still solid for extending run time if out in the sun all day.

[augiedoggy]

Originally Posted by Eco Battery

If you have a 42V pack then it needs to be charged at minimum of 46V. So theoretically the best you can get is 355W/46V=7.7A charging, however with PV panels you are typically going to get 80% of the rated watts, so around 5A-6A max will probably be more realistic. 6A is still solid for extending run time if out in the sun all day.

Fair point about the panel putting out slightly less. It's a 36 V Battery pack but due to the cells being optimally charged at 3.6 V I assumed I only needed to charge it at 43 V Give or take This is how I have manually charged and equalized other lithium battery packs in the past off of a power supply

[Pat911]

Are you sure about that 46v charging voltage EcoBattery? I think Augiedoggy’s battery is 42v maximum, not nominal. 46v would be way too high for a 36v nominal 12s LiFePO4, it’s 3.83v/cell. I would have thought that a maximum of 43.8v should be used but typically 42.6v (3.55v/cell).

Cheers
Pat.

[Eco Battery]

Originally Posted by Pat911

Are you sure about that 46v charging voltage EcoBattery? I think Augiedoggy’s battery is 42v maximum, not nominal. 46v would be way too high for a 36v nominal 12s LiFePO4, it’s 3.83v/cell. I would have thought that a maximum of 43.8v should be used but typically 42.6v (3.55v/cell).

Cheers
Pat.

I was just going off his statement saying “my 42V battery pack”. There are some guys over-volting their 36V carts with either 7X 6V FLA’s or 13S LFP packs. I misunderstood his statement if he only has standard 36V FLA pack.

However the voltage doesn’t really change the output current much. A 355W PV panel charging at 42V-43V still only has a theoretical max of 8.2A and a realistic max of 6.5A so it doesn’t change much. I bet real world it averages 3A-4A for most of the day.

Not trying to be argumentative, just saying 15A isn’t feasible on 355W.

[Eco Battery]

Originally Posted by augiedoggy

Fair point about the panel putting out slightly less. It's a 36 V Battery pack but due to the cells being optimally charged at 3.6 V I assumed I only needed to charge it at 43 V Give or take This is how I have manually charged and equalized other lithium battery packs in the past off of a power supply

At 42V charge output, it is still only 8.5A theoretical max. 3A-4A charging is my guess on what you see on an average sunny day.

[Pat911]

Originally Posted by Eco Battery

Not trying to be argumentative, just saying 15A isn’t feasible on 355W.

Oh, definitely not being argumentative and I agree with 15A not being feasible. I just didn't want augiedoggy, or anyone else reading this thread, charging their battery with too high of a voltage. I've seen some suppliers wrongfully describing their 12s or 16s LiFePO4 batteries as 42v or 56v to get a marketing edge, not Eco Battery of course

Cheers
Pat.

[augiedoggy]

Yes its a 36v 12 cell diy pack made with 200ah 3.6v cells so the actual voltage at full charge is more like 42v. and yes I misread the solar panel sticker... The max fuse was 15a not output.
The amp specs stated on the panel is IMP-8.99a and isc-9.48a... the vmp is 39.5 and voc-47.7v I am going to be using the green mppt boost controllers which are popular for this on youtube.

[Eco Battery]

Originally Posted by augiedoggy

Yes its a 36v 12 cell diy pack made with 200ah 3.6v cells so the actual voltage at full charge is more like 42v. and yes I misread the solar panel sticker... The max fuse was 15a not output.
The amp specs stated on the panel is IMP-8.99a and isc-9.48a... the vmp is 39.5 and voc-47.7v I am going to be using the green mppt boost controllers which are popular for this on youtube.

The VOC and IMP are important for selecting the proper charge controller, but wont necessarily indicate how many amps your battery will get charged with. It’s all about watts. The math is watts/battery charging voltage 355/42=8.45A which gets you the theoretical max. Then for real world you have to reduce by ~20% for panel inefficiency and other losses. So on a clear day with sun directly overhead you may see 6.7A charging. This will further reduce based on sun angle and cloud cover. 3A-4A should be expected.

Don’t get me wrong, I love the idea of a PV panel roof, and already have carts with them, I just don’t want the expectations to be unreal.

[Eco Battery]

Originally Posted by Pat911

Oh, definitely not being argumentative and I agree with 15A not being feasible. I just didn't want augiedoggy, or anyone else reading this thread, charging their battery with too high of a voltage. I've seen some suppliers wrongfully describing their 12s or 16s LiFePO4 batteries as 42v or 56v to get a marketing edge, not Eco Battery of course

Cheers
Pat.

No worries! I think we are both on the same page, looking out for other members best interests.