ElectroDacus Lithium Battery Charger

[adam88]

I am surprised no one has talked about this much on here. There was a kickstarter a while ago for a new unit Battery Management System for lithium ion batteries. As everyone knows lithium ion requires a proper charging scheme and BMS (battery management system). This unit is an all-in-one unit that replaces a lot of different units. It is basically a solar controller and battery monitor (like a trimetric) in one unit. Looks really neat. It is a bit expensive $239 for 60 amp and $276 for 100 amp but you get what you pay for I guess.

http://www.electrodacus.com/

 

[adam88]

 

[adam88]

The big downside I see about this (I am just reading about it now) is that it is a PWM unit and not MPPT.

The maker of it argues that MPPT is "dead" because solar cells are so cheap now. Why bother buying MPPT and just add another solar panel is the argument I guess. The problem with this argument is that RV's require everything to be as efficient as possible because there is limited space on the roof. A house has unlimited space to put solar panels but an RV does not. Also, our panels are flat and not tilted at the sun and so every bit helps.

Going to keep reading but lack of MPPT is disappointing. Is MPPT overrated???

 

[Haf-E]

MPPT is not dead - the reasons you state are all very valid. In addition, an MPPT makes a big difference in winter when the battery voltage is low and the solar panels are cold. Under those conditions the output can be increased by as much as 50%. The limited space on an expedition / RV vehicle is probably the other significant issue.

 

[LeishaShannon]

Its really well designed and built hardware, but his refusal to accept MPPT as a valid technology choice makes it difficult to impliment in an RV. (He lives in an off grid cabin where adding panels is easy)
MPPT really benefits Lithium systems because the average charge voltage is so low (13.2v) and most "12v" panels have a Vmp of 17.8v so 35% is a huge amount of power to be throwing away at STC (ie. when its cold) by using PWM.

 

[Semi-Hex]

I think we are a whole are so used to excess that never have to suffer the lack of space, panels or etc. Make your usages and systems as tight and energy efficient as possible, use what it takes to get there.

 

[Haf-E]

The other benefit of mppt is that it can allow use of larger/cheaper 60 cell or 72 cell "24v" solar modules with a 12vdc system. Solar panels made for 12v are usually more expensive as they are smaller.

 

[ajmaudio]

Both technologies have their place...one thought to consider: there are several long term time proven reliable pwm controllers out there that are about as bulletproof as anything electronic can be....that in my research is much harder to find in mppt. If reliability is paramount I would argue that a pwm had its advantages in this area. You cab build an effective system both ways..pick what's importent to you and go with it

 

[Rando]

I have a home built 100Ah LiFePO4 pack, and looked into using an ElectroDacus system, and came to the same conclusion - without MPPT it is not a good option for me. Instead I have a simple low cost balance/protection board on my pack, and plan on primarily using a Victron MPPT controller, programmed for 14.4V single stage charging to charge the pack.

My vehicle will be weight limited - so the LiFePO4 pack is a great option for me.

 

[snare]

Looks like the Victron MPPT controllers have a LiFeP04 setting .

 

[jonyjoe101]

this is a good option for those with large systems and the price isnt bad for the amps it can handle. I'm also surprise that there arent more of these lithium solar balance chargers available. This is a true lithium charger very similar to the ones use in the RC world.

In my use of lithiums (3s 11.1 volt 94 amp hour battery) , I notice the best way to protect your battery is to make sure the pack has a good built-in BMS that monitors the battery and shuts off all charging as soon a row of batteries reaches max voltage. It is very possible for a lithium battery to go out of balance and that is very bad. Most chargers even the ones that say lithium capable, monitor overall voltage and might shutoff charging or it might not.

With a good BMS that you actually tested, you can use any charger mppt or pmw and just rely on the BMS to shutoff the charging. On my battery I also have a failsafe relay that will shutoff the solar panel when the battery it self reaches max volts, just in case. Even with this Electrodacus charger, I would use a relay to shutoff the solar panel at a certain voltage. With lithiums you need to have that failsafe. The reason to shutoff power at the solar panel, is that the BMS wont turnoff completely, it wont let any more power into the battery, but the controller will still read voltage and will try to charge it.

And one more discovery that I've made using lithium as stated by others, is that they do benefit from mppt, I've been using my ecoworthy 20 amp mppt connected to a 240 watt solar panel for almost 4 years. With an agm battery I never got more than 12 amps of charging power, with lithium at max sun I can get up to 15 amps and it actually peaked at 17 amps for a few minutes (which I verified with a dc wattmeter). 17 amps is about the maximum output the panel can produce according to specs.

 

[pdxfrogdog]

FWIW, it looks like ElectroDacus now has a model that supports MPPT.

 

[pugslyyy]

very interesting! I'm going to go with lithium for my van build so this is useful.

 

[dwh]

And one more discovery that I've made using lithium as stated by others, is that they do benefit from mppt, I've been using my ecoworthy 20 amp mppt connected to a 240 watt solar panel for almost 4 years. With an agm battery I never got more than 12 amps of charging power, with lithium at max sun I can get up to 15 amps and it actually peaked at 17 amps for a few minutes (which I verified with a dc wattmeter). 17 amps is about the maximum output the panel can produce according to specs.

Um, just being picky here...but that's not "the lithium battery benefiting from the MPPT". That's "the MPPT benefiting from the lithium battery".


But you're right, harvesting power from a solar panel is going to benefit from the MPPT regardless of what sort of battery is being charged, and the lower the resistance of the battery, the more it will benefit.

 

[DiploStrat]

Um, just being picky here..
and the lower the resistance of the battery, the more it will benefit.

Ding! Ding! We have a winner.

One of the (many) BIG differences between lead acid and lithium is the fact that a lithium battery has a very flat voltage curve. This is good and bad.

Put a lead acid battery on charge and the internal voltage starts to rise immediately. As this voltage rises, the charge rate drops, the charge rate being partially dependent on the difference in voltage between the charge source and the battery. As a result, even with massive alternators and properly sized wires, I never see the sustained charge rates that 250A of alternators would lead you to expect. (The problem is made worse as some of this is "surface charge", but that is another discussion.)

A lithium battery typically sits at around 13v until it either pops up to full charge or drops down to dead. This means that once you put it on charge, it acts a bit like a black hole - it simply sucks amps until it is about 90% charged. This has good points (faster charge) and bad points, but in the instant case, might will explain why the original poster is seeing a higher charge rate from solar array with lithium than he ever saw with lead acid - the lithium battery is staying at a lower voltage, longer.

Those with fertile imaginations can now turn these facts to the challenges of charging from your vehicle's alternator. :Wow1: