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diy solar

Lithium retrofit into lead acid battery power pack w/ inverter

ryukin2000

New Member
Joined
Feb 6, 2021
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5
Location
Calgary
Hello, total noob here with lithium batteries and solar power. I would love to learn how to build my own solar generator one day. But for now I'd like to start small and ask for some suggestions. I have a Motormaster Eliminator Powerbox 800 w/ inverter. It has a 28 Ah AGM sealed lead acid battery inside. Its been more than 10 years and doesn't really hold a charge that well anymore as. My father in law gave it to me recently. It loses 20% within 8 hours from full charge. Id like to keep it instead of junking it as it has all the other features like 3 AC outlets, a 12V DC socket and built in radio. It also has booster cables. It charges with a wall adapter and barrel connector @ 13.8DC-1A. I know the easiest & cheapest option is just to replace the AGM battery with the same rating.

For weight savings though and more power, I'd like to look into lithium battery options. Not sure if switching to lithium will retain/or lose the boosting ability of the unit but either way, it's not a big deal to me.

Would the current charging specs work with it? Do I need to upgrade the inverter too? Any suggestions are welcome. I have looked at the jackery's so i might consider that if the cost of retrofitting is close to it. Thanks.

AGM replacement battery
https://www.batteryspecialist.ca/motormaster-eliminator-power-box-800-battery-sw12280/








 
lithium chemistry requires a different (higher) charging voltage to “fill it up”. 2 stage charging (bulk, absorb) or 3 stage (bulk, absorb, float) are options for lithium charging profiles. Do not use chargers in equalization mode on lithium batteries. There are posts on the forum that explain why. With that said, you may be able to perform a (or several?) equalization cycles on your existing battery to bring back some of its life. Discuss this with someone knowledgeable on the subject before you try it, though.

You may end up being able to reuse the inverter in that unit (if you decide to swap in lithium), but...well ymmv. There may be other approaches or hacks (boost converter), but I will leave that to EEs to discuss.

What’s your end goal? Is this a project for you to cut your teeth on? How do you plan on using it?
 
equalization cycles on your existing battery to bring back some of its life.
Not supposed to equalize the AGM batteries, only FLA.

Honestly, recommend replacing with like AGM batteries if you want to keep it.

Start looking at a solar generator you’d like to build. I found that solar generators did not make a lot of power for my modest needs in my fifth wheel, and decided instead to install solar on the trailer.

I do have a solar generator which is a PWM charge controller that I can hook to four 100 watt of panels and then hook to a battery, and then I have a 400 watt inverter. Really is that simple to make. Never use it though.
 
Not supposed to equalize the AGM batteries, only FLA.

Honestly, recommend replacing with like AGM batteries if you want to keep it.

Start looking at a solar generator you’d like to build. I found that solar generators did not make a lot of power for my modest needs in my fifth wheel, and decided instead to install solar on the trailer.

I do have a solar generator which is a PWM charge controller that I can hook to four 100 watt of panels and then hook to a battery, and then I have a 400 watt inverter. Really is that simple to make. Never use it though.
details details...
 
details details...
Have you had success in equalizing AGMs?

Every Deep cycle AGM battery I looked at had this comment I got from the Trojan Battery User Manual:

”W A R N I N G! Deep-cycle AGM or gel batteries should NEVER be equalized.”

There are some web reference to equalizing batteries, but I tend not to go against the owners manual. Especial since those batteries aren’t designed to vent. They actually are, but the bubbling you get when you eqaulize is electrolytes off gassing, and you have no way to add these liquids back into a AGM battery. AGMs may vent at the end of their life cycle as the electrolytes tend to break down.

I do equalize the Flooded Lead Acid batteries I bought, but that’s different than AGMs.
 
lithium chemistry requires a different (higher) charging voltage to “fill it up”. 2 stage charging (bulk, absorb) or 3 stage (bulk, absorb, float) are options for lithium charging profiles. Do not use chargers in equalization mode on lithium batteries. There are posts on the forum that explain why. With that said, you may be able to perform a (or several?) equalization cycles on your existing battery to bring back some of its life. Discuss this with someone knowledgeable on the subject before you try it, though.

You may end up being able to reuse the inverter in that unit (if you decide to swap in lithium), but...well ymmv. There may be other approaches or hacks (boost converter), but I will leave that to EEs to discuss.

What’s your end goal? Is this a project for you to cut your teeth on? How do you plan on using it?
my end goal is to just use it for small power draws for camping and mainly save it from waste(even if I can't reuse the battery). You're right, I would get a dedicated charger should I convert it. It has been great for boosting my vehicle when needed. While nice to keep that feature, the smaller lithium booster units I see for sale nowadays is way more portable and lighter. I barely used the other features but I do plan to do more car camping eventually. I guess I just got an itch after watching some YT videos of people making their own power packs/solar generators. It's nice that everything is easy to follow. I feel confident I could make one. Integrating solar panels/charging is not a high priority as my camping trips are short. Too bad shipping costs to Canada for lithium battery's is nuts.
 
my end goal is to just use it for small power draws for camping and mainly save it from waste(even if I can't reuse the battery). You're right, I would get a dedicated charger should I convert it. It has been great for boosting my vehicle when needed. While nice to keep that feature, the smaller lithium booster units I see for sale nowadays is way more portable and lighter. I barely used the other features but I do plan to do more car camping eventually. I guess I just got an itch after watching some YT videos of people making their own power packs/solar generators. It's nice that everything is easy to follow. I feel confident I could make one. Integrating solar panels/charging is not a high priority as my camping trips are short. Too bad shipping costs to Canada for lithium battery's is nuts.
I know there is lynax [ `lie-nax] (not sure spelling is right) and canbatt (these are both Canadian battery dealers). I can’t speak to their reliability or price. I have just seen some youtube vanlifers using them.

As for building a solar gen, I say go for it! Geek out on it, man. That’s what that itch is! Before you dive in and start spending money, first hang around here reading threads and chatting. You’ll pick up what you need in no time. Explore the threads. You’ll learn a lot and find a lot of neat ideas. There’s a beginners corner, too (guilty of not having spent enough time there myself, probably).
 
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