Charging/Maintaining Motorcycle Batteries in Solar Shed

[mheitt]

I just tried posting this but I don't think it worked so I'll try again. I want to charge and maintain two motorcycle batteries in a shed over the winter. I bought the Harbor Freight 45 watt solar kit which comes with three 15 watt cells, a controller and some DC lights. I'm thinking I want to by one or two Battery Tenders for the motorcycles, but am not sure how to hook things up. Below is a post I put on a motorcycle forum. What are your thoughts???

You can read the whole post from the start at: http://www.motorcycleforum.com/showt...50#post2098650



Here are some ways I figure I could hook up the Battery Tender Solar Charger (DC to DC):

1) HF cells through HF controller to backup battery and to BT as the load:


2) HF cells through HF controller to BT as the load with no battery backup:


3) HF cells through controller to bike as the battery backup with no load:


4) HF cells directly to BT as the controller to bike:

I'm thinking #1 is the way to go. Not sure how things will work with one controller (the BT) hooked into another controller (the HF) though.

[Mike90250]

Hi and welcome
Is your battery tender a 12v or 120VAC appliance ? It may be the simplest thing is to remove the 3 batteries from the bikes for the winter, and connect them in parallel to the HF controller and treat them as (1) battery.
I suspect however, the HF controller is not the best controller and may overcharge the batteries. Is it listed as a 3-stage charge controller ?

[mheitt]

The Battery Tender I'm thinking about getting is the 12v DC model, not a 120v AC model (there's a link near the top of my original post). I don't want to remove the batteries from the bikes because I want to be able go for a ride when there's a nice day mid-winter without having to reinstall and remove the batteries. I'm not sure if the HF controller is three stage, but I think it is. This doesn't answer your question, but this is the most info I got from the user manual:

The Charge Controller provides the following protection while charging:

a.Over-discharge Protection: When the electricity level of the battery goes too low (below 11 volts) from product usage, the Charge Controller will automatically shut off the power output to prevent damage to the battery. If this occurs, stop using the battery and charge it until the Voltage display shows 13 volts.

b.Overcharge Protection: If the electricity level on the battery goes too high (above 14.5 volts) the Charge Controller will automatically shut off power input to prevent damage to the battery.

c.Overload Protection: If the output current exceeds 4 amps the fuse (see Figure 6) will blow to prevent damage to the controller in the Charge Controller. If this occurs, have a qualified service technician replace the fuse.

[Mike90250]

Well, you either have to take a chance and hook the battery tender to the PV panels and see if the 25V at the panel will smoke it, or get an ADDITIONAL 12V battery for the HF panels to charge, and hook the BT to that for a stable 12V. This additional battery should be about 20 or 30Ah (another motorcycle battery) Using a larger battery will quickly ruin it, as the HF panel cannot supply enough power to charge anything much larger. You may need a real (not a Harbor freight looks like tools parts) solar panel and a real charge controller to do this properly.
Remember the 3 battery tenders will pull power from the battery all night (19 hours) to charge "their" battery and daytime (5 hours) the 45W panel has to recharge and power everything. The HF almost solar panel may not be up to the task.

[mheitt]

Sounds like you don't love the HF kits. I was just looking for a low cost way to charge the bikes' batteries. I don't think I need to have two BTs going at the same time; I can alternate one BT between the two bikes (e.g., one week on bike A and one week on bike B). So if I keep the HF kit it sounds like option #4 is the way to go: hook the panels directly into the BT with no additional controller, backup battery, etc. If this is the case I should probably just return the HF kit and get two "all in one" BT units that have a small panel and built-in controller... something like this: http://www.batterytender.com/Solar/5...ontroller.html

[Logan5]

HF solar kit's are over rated junk. even their fancy looking controller that comes with the deluxe kit is unstable at 12 or 24 volts and not worth risking my sensitive electronics much less my heavy and expensive battery.I saw the junky plastic panels. I did not buy the kit, but I had to have that fancy looking controller with all the USB out lets and super cool display and switches, 25 bucks from ebay. I have totally gutted and rewired it. I do use HF tools and consumables, even their 35 AH AGM battery for my porta power.