Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 


Reply
 
Thread Tools Display Modes
 
Old 05-25-2021, 08:46 PM   #11
Member
 
Join Date: Mar 2021
Location: Boulder, CO
Posts: 99
Thanks I do have one and had left it home charging on that trip. Oops.

Clarkboulder is offline   Reply With Quote
Old 05-25-2021, 08:51 PM   #12
Member
 
Join Date: Mar 2021
Location: Boulder, CO
Posts: 99
Thanks Great info Makes a lot of sense. Might just leave the panels home. 29lbs and bulky is just not worth the value brought to the camp site.

The flat(ish) rectangular portion of my hood is 55'x20". Seemed like a good surface but I see that it may not be worth it according to your numbers. I have not used idling yet to charge as I sort of detest the idea but it may be something I need to get used to...occasionally. Thanks
Clarkboulder is offline   Reply With Quote
Old 05-25-2021, 08:54 PM   #13
Member
 
Join Date: Mar 2021
Location: Boulder, CO
Posts: 99
DIY Lithium battery?
Clarkboulder is offline   Reply With Quote
Old 05-25-2021, 09:58 PM   #14
Senior Member
 
simplesez's Avatar
 
Join Date: Aug 2015
Location: Golden, CO
Posts: 952
Quote:
Originally Posted by 86Scotty View Post



Yep, I'm blissfully out of touch as usual.



#tunedouttotrends
simplesez is offline   Reply With Quote
Old 05-26-2021, 05:53 AM   #15
Junior Member
 
Join Date: Jan 2021
Location: Fort Collins
Posts: 10
Yes. Check out electric car parts.com out of utah. I built a 4800 watt hour battery for my van using their fortune 100 amp hour cells and a bms from overkill solar. Pretty easy and it powers the loads in our van easily. We use the van in the winter here in CO. My other half is terrified of a chill so it will run a heating blanket all night in addition to the diesel heater. It also runs the coffee maker and microwave and electric cooler. A three day weekend of maximum use is going to use about half the capacity of my battery in those conditions. I built a much bigger battery for my travel trailer. 13000 watt hours. I can tell you more about the source of the cells (direct from China) but for reference it cost the same to build as the battery in my van.
cotrailhead is offline   Reply With Quote
Old 05-26-2021, 08:15 AM   #16
Member
 
Join Date: Mar 2021
Location: Boulder, CO
Posts: 99
Quote:
Originally Posted by cotrailhead View Post
Yes. Check out electric car parts.com out of utah. I built a 4800 watt hour battery for my van using their fortune 100 amp hour cells and a bms from overkill solar. Pretty easy and it powers the loads in our van easily. We use the van in the winter here in CO. My other half is terrified of a chill so it will run a heating blanket all night in addition to the diesel heater. It also runs the coffee maker and microwave and electric cooler. A three day weekend of maximum use is going to use about half the capacity of my battery in those conditions. I built a much bigger battery for my travel trailer. 13000 watt hours. I can tell you more about the source of the cells (direct from China) but for reference it cost the same to build as the battery in my van.
Thanks COTRAILHEAD! That sounds like a good option although I am a noob to all of this so I have a lot to learn. (I only know bikes!)
How do you initially charge those batteries? Is that charged via engine or solar or electric hook up?
I’d love to learn how this could replace the generator (as it seems it could) and how and what converting to this option looks like. I just have no idea where to start with it. I only ever really want to power the microwave and an occasional induction hot plate or other basic appliance or plug in lights. Lugging around a generator seems silly for that as does the heavy solar panels just to top off the two house AGM batteries. That combo is over 160lbs.
Clarkboulder is offline   Reply With Quote
Old 05-26-2021, 02:05 PM   #17
Senior Member
 
Join Date: May 2018
Location: Arizona
Posts: 642
FYI I have just been doing a little research on the cheapo DIY LiFePO4 batteries.


If you want to go the cheapest for DIY LiFePO4 check out Will Prowse's channel. In the link below he tests a 280 Ah setup.

The cells are $416 (including shipping and tax) and the BMS can be anywhere from $150-$200 depending upon features.

So for LiFePO4 you are getting 0.8*280=224 Amp-Hr for $600 ish or $2.7 / amp-Hr

Compared to cheapest deep cycle lead acid 80 amp-hr / $100 which is equivalent to only $100/40 amp-hr
$2.5 / amp-hr .

Super Start Marine #24DCMJ

https://www.oreillyauto.com/detail/c...per-duty?pos=5


So capacity wise these are as cheap as lead-acid (non-AGM) but with much higher rated charge/discharge cycles. So the lifetime will be much longer. The size and increased charging rates are the know benefits as well.

I think it is recommended that you go to a 24V system if you want anything larger than this for running microwaves and induction ovens. The cable sizes just get too large.





This is somewhat older but gives a good overview.



The main thing that I did not see covered in either video is the thermal control of the battery pack. Like most things, the batteries will generally work best in temperature-controlled conditions like 20 degC. But for Lithium you have low-temperature shutoff requirements; they do not like to freeze. They can tolerate high temperatures even into the 115 degF range. See some details here.

https://batteryuniversity.com/learn/...w_temperatures

You will want to get an electric heating pad.
These are easy solutions for heating. All you need is a switch (possibly a relay but it is only 5 amps) and the thing controls itself.

Facon 7-1/4" x 25" RV Water Tank Heater Pad with Automatic Thermostat 12V DC
https://www.ebay.com/itm/30172428306...pid=1682217542

Whether you want to do any cooling will depend on battery size. Pulling 5 amps off of a 100 amp-hr battery is pushing it for an all July 4th all-day cooling scenario. In this case, I would at least run fans ( for example I am putting two 50mm/0.1 amp fans on my charge controller; two are for redundancy). For example, I have a wireless router mounted in a storage room that is exposed to the outside temperatures here in Tucson. I noticed that the heat sink was getting pretty warm and I left the case open and used a 5V USB fan to push air over the heat sink. It stays much cooler just with the forced air flow.

If you have a large battery and then a Peltier like this (4.5 A rated) might be a good idea if you can arrange a heat sink and cooling fan in the battery enclosure. So this has a comparable power diip[nation to the heater. You would need some type of thermal switch.


Teyleten Robot TEC1-12706 12V 60W Heatsink Thermoelectric Cooler Cooling Peltier Plate Module (5pcs)

https://www.amazon.com/dp/B07YZQFH65...NsaWNrPXRydWU=

This is basically how you configure a Peltier with fans to move out the heat and move the cold.


WiMas DIY Peltier Cooler Kit 12V Semiconductor Thermoelectric Cooler Peltier Cooling System TEC1-12706 Peltier Heatsink Module kit+Fan

https://www.amazon.com/dp/B07X6DX97Y...dDbGljaz10cnVl

These things are cheap and seem to work well.

2 Pieces DC 12V Electronic Temperature Controller Programmable -50 to 110 ℃ Heating/ Cooling Thermostat Control Switch Module, NTC Waterproof Sensor Probe, Dual Color LED Display Monitor

https://www.amazon.com/Electronic-Te...2059403&sr=8-5
posplayr is offline   Reply With Quote
Old 05-27-2021, 01:36 PM   #18
Senior Member
 
Join Date: May 2018
Location: Arizona
Posts: 642
I "bit the bullet" and ordered the LiFe cells and BMS from Ali-Express for a pair of DIY 100 Amp-hr batteries.

https://www.sportsmobileforum.com/fo...ild-28632.html
posplayr is offline   Reply With Quote
Old 05-30-2021, 04:39 PM   #19
Senior Member
 
moorefc's Avatar
 
Join Date: Feb 2009
Location: PNW or maybe Baja Sur
Posts: 381
On the hood mounted solar cells, besides the heat issue may be a reflection issue while driving....ouch..


And for diy lithium conversion there are a lot of posts, but you need
batt cells
BMS
(for an E350) a DC-DC converter
Wiring etc.
The dc dc can be expensive $200-400 (there are less expensive hacks, but...)
BMS is ~$100 BMS discharge rates limit one to ~1.5Kw inverter unless going to a $$$ BMS.
Cells are quoted above


It is quite a project when you get into it, but does have huge capacity potential.
It also is electrically and thermally complicated (ie reliability) compared to heavy metal lead acid alternator technology. I have been playing with but am on the fence re installing LiFePo4 in the van...
diysolarforum.com/ has lots of information and opinions on this option....Will Prowse (video above) is definitely entertaining and has a big following...
__________________
Pac NW and warmer places
1995 E250 EB 5.8 2WD on to a new owner
2006 E350 EB Elect Top 2WD
moorefc is offline   Reply With Quote
Old 05-30-2021, 06:25 PM   #20
Senior Member
 
Join Date: May 2018
Location: Arizona
Posts: 642
Quote:
Originally Posted by moorefc View Post
(for an E350) a DC-DC converter
Wiring etc.
The dc dc can be expensive $200-400 (there are less expensive hacks, but...)
Yea this weekend I have been coming to grips with switching from lead-acid deep cell to LiFePO4. My C/10 charging rate setup goes out the window with LiFePO4. I just bought the Renogy 40 amp DC to DC for $169 no tax-free shipping.

https://www.renogy.com/12v-dc-to-dc-...ttery-charger/

This morning dealing with the alternator overheating issues. I'm working on building up a double rocker ON-OFF-ON to control 40A/20A with a temp sense at the alternator to shut DC-DC charger on thermal overload. Tentatively 80 DegC but will have to do some testing to finalize that.




Quote:
Originally Posted by moorefc View Post
It is quite a project when you get into it, but does have huge capacity potential.

It also is electrically and thermally complicated (ie reliability) compared to heavy metal lead acid alternator technology. I have been playing with but am on the fence re installing LiFePo4 in the van...
The tech is somewhat mature and there are multiple commercial and DIY alternatives. People are succeeding even if most have some issues (very understandable). As an EE this does not bother me as much. I can also tell you I have wasted just as much time with "known good " solutions as DIY. At least with DIY you generally know what you are dealing with. When a vendor is protecting their reputation by not telling you about "issues" you can waste even more time. In contrast, with DIY you have hundreds of people posting their results and problems and usually, if you scan this you can avoid their problems.

Quote:
Originally Posted by moorefc View Post
diysolarforum.com/ has lots of information and opinions on this option....Will Prowse (video above) is definitely entertaining and has a big following...
Yes been there and scanning threads which is where I'm finding the gotchas to avoid.
Attached Thumbnails
Renogy_DC-DC_ChargeControl.jpg  
posplayr is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Sportsmobile Registry

Behemoth

Besags

Agnes

ranchero
Add your Sportsmobile
» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 02:45 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.