Lithium Batteries (for the rest of us)

[S/V Alchemy]

And people ask me why I still keep my Atomic 4's hand crank...

[Cotemar]

I think post #15 took out the rest of us.

Maybe lead acid batteries are not so bad after all

[Maine Sail]

Originally Posted by Cotemar

I think post #15 took out the rest of us.

Maybe lead acid batteries are not so bad after all

Was not meant to "take out" anyone...

I just want folks to ask honest questions that really need to be answered before moving over to Li technology.

Recently two very well versed guys in the Li thread destroyed some cells $$$. Not the end of the world but still a quite expensive mishap.

One was because he accidentally left temp compensation for his charge source turned on. The temp dropped the charge source temp compensated or upped the voltage and bingo bulged over charged cells.... The other was a simple memory lapse and no mechanical/BMS or other means to stop charging... Expensive mistakes even by those who know this stuff very well.

Can it be done? Yes, absolutely, but it needs to be well thought out and complimentary pieces of the system chosen carefully..

[Cotemar]

Originally Posted by Maine Sail

Was not meant to "take out" anyone...

I just want folks to ask honest questions that really need to be answered before moving over to Li technology.

Can it be done? Yes, absolutely, but it needs to be well thought out and complimentary pieces of the system chosen carefully..

Wouldn't it be better if I just paid some smart LifePO4 guy like yourself to make me a house battery system just like the one you made for your boat.

http://www.cruisersforum.com/forums/...ml#post1157032

[ebaugh]

Originally Posted by Maine Sail

A more fair comparison would be the real usable capacity of LA batteries is about 30-35% or 50% SOC to 80-85% SOC due to acceptance current limiting.

Unless you are at a dock every day when you can "full charge" your LA batts then you're likely not starting out at 100% SOC where you would have 50% usable capacity.

On day two away from the dock your real usable capacity becomes about 30-35% because charging beyond 80-85% SOC becomes a time consuming waste of fuel.

With LiFePO4 you can charge right back to about 99% before the batteries begin "limiting" current or you've achieved a charging voltage that just won't push any more current into the bank. With LA batts this limiting can start as low as 70% SOC and as high as 90% for some AGM's. The last few % take hours and hours and hours....

I think it is important to ask a few questions before installing LiFePO4:

1- How am I going to charge the bank? Can my battery charger be custom programmed (most can not)?

2- How am I going to charge my bank via alternator? Do I have an external regulator that allows for full customization of the charging voltages?

3- Are my solar and wind controllers able to be fully customized for charging LiFePO4?

4- How do I plan to terminate charging when the bank is full?

5- Can I live without an alt sensed tachometer when the alternator charges the bank to full then cuts the field?

6- Can my alternator and belt system handle the massive current suck from LiFePO4, most can not?

7- What will I use to keep my alternator from melting down? Do I have temp sensing of the alternator?

8- Do my solar, wind, battery chargers or alt regulators have the ability to 100% disable temperature compensated charging (especially if "ambient sensed")?

9- How will I initially balance my pack? Do I have a bench top power supply to do so?

10- How will I keep my cells balanced?

11- What BMS system will I employ (it's looking like a BMS will be a "minimum" requirement)?

12- How will I terminate the alt regulator when the bank is full or an high voltage event (HVE) occurs? Regulator power feed cut, field cut etc. Balmar recommends a B+/power cut for the regulator power wire.

13- How will I terminate the solar or wind controllers in a HVE? Can my controller be "open circuited" without harm?

14- How will I terminate a shore charger in an HVE? What relay will I use?

15- What will I use for bank over current protection?

16- If a charge management device was used previously to keep "two banks" charged how will I now charge the second bank?

17- How will I "band" the cells.

18- How will I monitor cell level voltage?

19- How will I keep track or % of charge or "capacity"?

20- How am I protected against a low voltage event (LVE) situation? What relay/contactor am I using to disconnect the loads?

21- Will I employ a dual bus system, as in a charging bus and load bus??

There are many more that perhaps others will add, gotta run...

Can I use these questions in an added appendix to my DIY article, and give you credit for them? I will probably answer them in the context of my install, they are all good points for consideration.

[Maine Sail]

Originally Posted by ebaugh

Can I use these questions in an added appendix to my DIY article, and give you credit for them? I will probably answer them in the context of my install, they are all good points for consideration.

Sure, I'll probably use them at some point too.. Rattled them off in about 2 minutes after my third cup of Joe......

Got my bank installed into its new compartment today and just came in from the barn after working on the distribution board....

[ebaugh]

Originally Posted by Maine Sail

Sure, I'll probably use them at some point too.. Rattled them off in about 2 minutes after my third cup of Joe......

Got my bank installed into its new compartment today and just came in from the barn after working on the distribution board....

Wish I could type that fast. Nothing immediately came to mind to add, but Im sure there are a couple. Won't happen on my end immediately, so feel free to have another cup and keep going....

[nimblemotors]

You could ask most of those questions with a lead acid battery pack,
so quite frankly, looks like a bunch of FUD.

[FlyingCloud1937]

Originally Posted by nimblemotors

You could ask most of those questions with a lead acid battery pack,
so quite frankly, looks like a bunch of FUD.

Actually you should ask all of those questions, even for a lead acid bank.

Main...nailed it, because he's a professional. Would you want anything else. As professionals we are held to a higher standard, which is the way it should be.

Now if you're a diy'er then Main... has given you a very good road map no matter what type of bat bank you decide to install.

I say excellent job there Main Sail

Lloyd

[ebaugh]

Originally Posted by nimblemotors

You could ask most of those questions with a lead acid battery pack,
so quite frankly, looks like a bunch of FUD.

That's true. But many of the answers have different considerations.

I'd like to say don't overcharge or over discharge and your blessed, but it's really not that simple on a cruising boat. But the points make you think, and that's a valuable exercise.

[DeepFrz]

You could ask most of those questions with a lead acid battery pack,
so quite frankly, looks like a bunch of FUD.

FUD is stuff you throw at people who don't want to ask questions because they don't want to hear the answers. A list of questions to ask is just that and Maine Sail's list is a great guideline for anybody who is planning a marine electrical system; whether they are planning on DIY or having a pro do it.

[manitu]

If you're planning to charge directly from the alternator, make shure you have aCC-CV (constant current-constant voltage) circuit between the alternator and bank.

This will limit charging current until the battery hits the user set limit, then it will keep this voltage, while the current drops, because the battery is near full charge.

Ths can be set at 0,1v below the nominal charging voltage, and your battery will only reach about 90% charge.

.manitu

[boom23]

Can you elaborate on the circuit you mentioned?

Where can someone get it, etc.?

Originally Posted by manitu

If you're planning to charge directly from the alternator, make shure you have aCC-CV (constant current-constant voltage) circuit between the alternator and bank.

This will limit charging current until the battery hits the user set limit, then it will keep this voltage, while the current drops, because the battery is near full charge.

Ths can be set at 0,1v below the nominal charging voltage, and your battery will only reach about 90% charge.

.manitu

[CharlieJ]

An external alternator regulator; e.g., the Balmar MC 614, has this capability.

[sailorboy1]

I must be missing something. From reading this thread and a little of the other, near as I can tell it will cost 4 times the cost of a 6V LA house bank for the batteries PLUS you have to apparently change a lot about your charging system.

Just what is the big plus of these lithium batteries to justify such costs and efforts?