DIY Solar Generator

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Re: DIY Solar Generator

Postby friz » Tue Aug 20, 2019 3:08 pm

I hope I can find this thread in a few years when my agm gives out.

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Re: DIY Solar Generator

Postby John61CT » Tue Aug 20, 2019 3:18 pm

RJ Howell wrote:I've bought from them 3 times now. All 18650. # different types for 3 different reasons. All have tested out as advertised.
Thanks much
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Re: DIY Solar Generator

Postby John61CT » Tue Aug 20, 2019 3:20 pm

bdosborn wrote:I used a relatively large balancer that will balance at 6 amps or so rather than the milliamps the BMS conducts.
Could you link to the balancer please?
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Re: DIY Solar Generator

Postby RJ Howell » Tue Aug 20, 2019 3:25 pm

bdosborn wrote:Here's a link to the vendor I used:

Shenzhen Foxelion batteries Company Store

Bruce


I see some brand names I'm pleased with there. Seems they are a re-seller/promoter.. The GTX portable (water-proof case) I've watching is there in a 80ah version for $100 more than I paid for the off-brand I purchased and only get 30ah out of.. Close to nearly 3 times the usage for another $100, and not even during 'sale month'.. Wish I had known of them before! Then again.. pricing may be much better now.

Thank you! They are now on my watch list!
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Re: DIY Solar Generator

Postby RJ Howell » Tue Aug 20, 2019 3:34 pm

I've gone back through all the posts a few times now.

Can you confirm the ah of this pack please. You stated you built a 180ah for your camper, yet I don't see (or missed, 3 times now) the ah of this pack.
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Re: DIY Solar Generator

Postby retep » Tue Aug 20, 2019 4:37 pm

RJ Howell wrote:I've gone back through all the posts a few times now.

Can you confirm the ah of this pack please. You stated you built a 180ah for your camper, yet I don't see (or missed, 3 times now) the ah of this pack.


Hi RJ

Here is a link to a calculator. My results show 40 ah. Hope this helps

https://power-calculation.com/battery-s ... ulator.php


So my calc suggests 4 in series with 9 sets of batteries in parralel equals 36 batteries to get to 180 ah. LiFePo4 are not cost effective until you consider Total Cost of Ownership. What Bruce's solution brings to the table is to augment your current lead acid or in Bruce's case he wanted to power his cooler while traveling and not put demand on the vehicles battery. Either way its a clean solution. I used 2 small lead acid batteris for a power pack. I think i get about 15ah and it weighs about the same. Use it mainly to charge devices and power my ham radio without putting a demand on the vehicle when staionary But then again the batteries were free from bro in law so it was a why not do it.

Cheers
Peter


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Re: DIY Solar Generator

Postby bdosborn » Tue Aug 20, 2019 7:01 pm

RJ Howell wrote:I've gone back through all the posts a few times now.

Can you confirm the ah of this pack please. You stated you built a 180ah for your camper, yet I don't see (or missed, 3 times now) the ah of this pack.


Each cell is rated at 20 amp-hrs,two cells in parallel doubles the amp hours so the battery has 40 amp-hrs total. Here's how the cells are connected:
Image
In fact, I think the cells have more than that since I got 38 amp-hrs out of them and my voltage was still at 12.5V. Here's some links to everything I bought:

Meter

Case

PowerPorts

BMS

Charger

Balancer

20 amp-hr LiFePO4 Cells

Bus Bars This are for Headway cells and are a little too short for the cells I bought. I had to drill out the holes to get them to fit.

DC Circuit Breaker

jehugarcia This guy has a lot of good videos on DIY solar generators and power walls.

Bruce
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Re: DIY Solar Generator

Postby bdosborn » Tue Aug 20, 2019 7:07 pm

retep wrote: So my calc suggests 4 in series with 9 sets of batteries in parralel equals 36 batteries to get to 180 ah


I used 180 amp-hr CALB cells for the camper, here's the thread on it:

LiFePo4 Batteries

I don't think I would use the 20 amp-hr cells for anything bigger than 40 amp-hrs, too many cells that can fail.

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Re: DIY Solar Generator

Postby bdosborn » Tue Aug 20, 2019 7:12 pm

RJ Howell wrote:Does it also do cumulative readings?
I have two similar to these. One on my battery bank and the other on my solar panel.


Yeah, it reads current both ways, in and out, so you don't need two meters.
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Re: DIY Solar Generator

Postby bdosborn » Tue Aug 20, 2019 7:21 pm

RJ Howell wrote:I have a hard time walking away from the 18650's..

The 18650 are a different chemistry from the LiFePO4. I didn't want to risk screwing something up and having them catch on fire inside my camper, and I always do things wrong the first time I build something. LeFePO4 is much more forgiving of mistakes.

Bruce

P.S. 18650 cells are 18mm by 65mm. ;)
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Re: DIY Solar Generator

Postby bdosborn » Tue Aug 20, 2019 7:40 pm

If you build this DO NOT connect it directly to your car to charge it. The LiFePO4 cell has an extremely low impedance and draws as much current as is available when charging. It will burn out your car alternator, wiring and damage the cells. I plan to use a solar charge controller to limit the current when charging via PV and the charger I linked to when charging via AC or the car.

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Re: DIY Solar Generator

Postby retep » Tue Aug 20, 2019 8:55 pm

Agreed, one can't charge it directly from the alternator. I enjoyed the read from other thread, very good info. Unfortunately I don't think it would be the wisest choice for my trailer as my trailer will be sitting in the freezing temps frequently. But the power pack is still something i will create in the future.

Great read.

Thanks again.
Peter


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Re: DIY Solar Generator

Postby RJ Howell » Thu Aug 22, 2019 7:25 am

bdosborn wrote:
Yeah, it reads current both ways, in and out, so you don't need two meters.
Bruce


Maybe I mis-stated.. does it show usage of a period of time? Mine show usage since last reset. I check the panel for production against the battery for usage daily when camped. I like that part as I can figure average usage and production according to weather I have encountered.

My habit is to check Battery SOC prior to departure. Dis-connected (rested) for 24hrs and check voltage against my SOC chart. Always seemed like a good way to watch over the batteries.
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Re: DIY Solar Generator

Postby bdosborn » Thu Aug 22, 2019 7:03 pm

RJ Howell wrote:Maybe I mis-stated.. does it show usage of a period of time?


Nope, just the gozinzas and gozoutzas without any kind of timestamp.
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