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Topic: Lead Acid Lithium hybrid battery system (Read 427 times) previous topic - next topic
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Lead Acid Lithium hybrid battery system
In the quest for more amp hours we added a lithium battery to two standard 6V flooded lead acid batteries.

The side advantage is the lithium can bring the lead acid batteries up to 100% when the solar system cannot.

The lithium battery is indoors so no temperature problems.

The lithium charges much more quickly than lead acid ever will.

The link is to a Class B forum but the install is on a 2006 RB Lazy Daze. Testing is still ongoing but it looks like a success.

Field Test: lead acid and lithium hybrid battery system - Class B Forums
Harry 2006RB
Re: Lead Acid Lithium hybrid battery system
Reply #1 –
The link above has evolved into an excercise to double and eventually triple the battery capacity of an RB. Generator run time is reduced by 1/2 to 1/3.
Harry 2006RB
Re: Lead Acid Lithium hybrid battery system
Reply #2 –
An interesting electrical system experiment.
How much more efficient is it compared to installing 4-AGMs batteries and a larger converter? It's an upgrade that has been done successfuly on many LDs.

While lithiums can absorb huge amounts current efficiently, so can a 440-amp/hr AGM battery pack which can easily absorb more current than any converter and/or solar panel system can supply.
A four AGM battery pack, with bigger converter, would cost a lot less and is less complicated to install and operate.

Replacing the converter with a 2000-watt inverter, one with a built-in 100-amp charger, would provides a superior source of A/C power, when needed, plus a very large charger.
Prosine 2.0 Inverter | Flickr

Larry





Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lead Acid Lithium hybrid battery system
Reply #3 –
May be. My guess is that 2 100 amp hour lithiums and two 6 volt lead/acid would equal 600 amp hours of lead/acid. I'm finding there is a lot of capacity in the 80% to 100% of lead acid that heretofore was difficult to access 'cause it takes so much time to charge to 100% and when you don't have enough solar you never get there. It certainly is not worth a generator run.

I'm not arguing the cost issue. Inverter chargers aren't cheap either. Lithiums are a better battery, it seems. At 50% lithium 90% lead acid switching from lead acid to lithium the furnace fan speeds up. Too bad they have such temperature sensitivity. This is a way to get around that sensitivity. Morning generator runs used to be an hour and a half and solar may or may not bring things to 100% Now generator runs are around 30 minutes. If solar doesn't do it the DC to DC charger will but I haven't had to do that yet. Lithium charges at full current right up to 100% full. Lead/acid does not, and that is the major difference.

This is what I'm doing to increase battery capacity. Not trying to convince anyone to do it. It is a new approach and you should know about it. A total lithium conversion with battery heaters is much more expensive than this. No changes in RB structure are required. I don't know about the other models. Just drop a lithium battery in with a charger, add the switch and you are done.
Plenty of room in an RB under the dinette next to the battery box.
Harry 2006RB
 
Re: Lead Acid Lithium hybrid battery system
Reply #4 –
While it is complicated, I see how the hybrid system can minimize generator run time, especially in cold conditions.
Full timers, who dry camp, would benefit from it primarily during the winter, the time of year where solar isn't sufficient.
The hybrid system has too many pieces for the the average RVer to deal with,  you obviously like to tinker with things, a psychological condition I'm familiar with.
Do you plan on staying with the system long term or will you make the jump to full lithium, when the AGMs wear out?

Lithium batteries are delicate creatures that need a temperature controlled climate for maximum efficiency.
If I ever make the switch, it will probably be with a total package, probably Victron, wanting a matched and proven system.
http://shop.pkys.com/assets/images/Lithium%20Drawing-3000.jpg
The battery, charger and BMS would be mounted inside a cabinet that can be ventilated and heated.
Lithiums definitely need to be mounted inside the coach and not in the conventional exterior battery box.

While at Home Depot today, I saw a display for a Tesla Power Wall, it sure looks like a solution looking for a problem.
So many ideas, so little time and money.

Larry


Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lead Acid Lithium hybrid battery system
Reply #5 –
"...you obviously like to tinker with things, a psychological condition I'm familiar with."
---
Oh, yeah!  ;)
2003 TK has a new home
Re: Lead Acid Lithium hybrid battery system
Reply #6 –
Quote from: Larry W  - 
Do you plan on staying with the system long term or will you make the jump to full lithium, when the AGMs wear out?

I like it like it is. I would already have the second lithium battery except I'm on the road. Shipping a high value, hazardous material battery to your home is pain enough. You have to be there when it arrives on their schedule or they send it back. I'm not even gonna try on the road. I can get it around June 1. Might as well keep the lead/acid batteries out in the cold tray. Lithiums can't go there which is the beauty of the whole system.

I don't like AGM batteries. I'm using Trojan flooded. AGMs are fine under the hood. Everybody I know has ruined a set of AGM deep cycle batteries as they don't tolerate inadvertent abuse. Just a personal bias.

I don't need the second battery but I want it. Now that I have more power I'm coming up with ways to use it. Sure would like to have my mattress pad heater back, only 120 watts. The 1500 watt whole house inverter and second charger is waiting at home. I'm $1300 in now, not counting the DC to DC charger which isn't getting any use. Inverter is $625 including remote and second charger is $217. Second battery is $949. Transfer switch for the inverter already installed

This could not be a commercial system as switching through the both position I think needs to be momentary. Removing the both position means you get a break in power which is not acceptable.

I haven't allowed for ventilation yet so the dinette seat is removed while charging till I get some holes drilled and maybe a fan installed. If the lithium battery fails early I'm not gonna be happy. As noted in the referenced thread the original idea was not mine. A guy was trying to find a way to charge his large AGM bank to 100% (six hours) without sun.
Harry 2006RB
Re: Lead Acid Lithium hybrid battery system
Reply #7 –
"Everybody I know has ruined a set of AGM deep cycle batteries as they don't tolerate inadvertent abuse."
----
AGMs are very susceptible to overcharging; "inadvertent abuse" can very likely be translated as not matching the AGMs with a compatible charge controller and multi-stage converter. One can't just slap a couple AGMs into an inadequate component partner system and expect them to function properly.
2003 TK has a new home
Re: Lead Acid Lithium hybrid battery system
Reply #8 –
Quote from: hbn7hj  - 

I don't like AGM batteries. I'm using Trojan flooded. AGMs are fine under the hood. Everybody I know has ruined a set of AGM deep cycle batteries as they don't tolerate inadvertent abuse. Just a personal bias.


I haven't allowed for ventilation yet so the dinette seat is removed while charging till I get some holes drilled and maybe a fan installed. If the lithium battery fails early I'm not gonna be happy. As noted in the referenced thread the original idea was not mine. A guy was trying to find a way to charge his large AGM bank to 100% (six hours) without sun.

Yes, lithiums are very sensitive if not used with matched converters and solar chargers and I have changed several ruined sets for others.
They are too expensive, IMO,  for the limited benefits over conventional lead-acid batteries.
The primary benefit is not having to add water. They are very useful if adding batteries to the interior, then they are the only practical choice.

In our LD, I have always used lead-acid T-105s, mounting four of them in a tray under the floor.
Battery tray- new | Flickr
They charge fine, able to efficiently absorb more amperage than the stock two battery system.
Combined with a 70-amp converter and over 400-watts of solar, we rarely run low on battery power except for two or three winter months when a hour or two of generator time is needed, every couple of days.
It's relatively simple system and works without much input, other than determining if and when the generator needs to be run.
The battery capacity meter lets us know the generator is needed .

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lead Acid Lithium hybrid battery system
Reply #9 –
"...lithiums are very sensitive if not used with matched converters and solar chargers and I have changed several ruined sets for others."
---
Larry, did you mean to say "AGMs" instead of "lithiums"? 
2003 TK has a new home
Re: Lead Acid Lithium hybrid battery system
Reply #10 –
Quote from: JCT  - 
"...lithiums are very sensitive if not used with matched converters and solar chargers and I have changed several ruined sets for others."
---
Larry, did you mean to say "AGMs" instead of "lithiums"?

Yes, I meant to say AGMs. It has been corrected.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lead Acid Lithium hybrid battery system
Reply #11 –
I'm not tinkering. This is a full blown, so far successful, effort to increase the power capabilities of the RV without making changes beyond my capability. The rapidly increasing park space rental rate is the motivation. I could pay $50/day with no seasonal option but I refuse, so far.  Off grid in cold temps are a challange and, yes, I have a catalytic heater which uses no electrical power.

My friends here in Moab had an 8 day stay (Diesel pusher) at $75/day. The place was booked. Supply and demand run the show and if I owned a park I'd charge that, too.

Soon I expect the off grid locations to start charging or increase rates. The two week stay limit wasn't there or was ignored not too many years ago. Will the geezer rate go away? Eventually I expect I'll have to change my destinations. The good news to me is many new RVs are not capable of off grid operation with their compressor fridges and limited battery bank. For $1300 I'm still in the game though I will expand to $3000.
Harry 2006RB