Expansion Battery

[IBTripping]

I have a Pecron model E2000LFP which is a 1920 watt hour solar charger. A Pecron 3,000 watt hour expansion battery is pricy at $699. As an alternative I purchased a 5,000 watt hour 51.2 volt lithium lifepro4 battery at $400. Thus, I have a total of 7,000 watts or 7 kw of storage. I can connect the 51.2v battery to one of the two Pecron solar inputs which require a minimum of 36v input to charge. It's a pretty cool setup. Below is a picture of the 51.2v battery I purchased. It advertises low temperature and high heat shutoffs. However, I plan to keep the battery inside my trailer to avoid 32 F temperatures.

I also had to purchase a $100 51.2v battery charger. Thus, I only saved $200 going this route. But, I increased expansion capacity from 3,000 watt hours to 5,000 watt hours. A better way to look at it is that the $699 Pecron expansion battery costs $0.23 per watt hour while the 51.2v lithium battery plus charger cost $0.08 per watt hour. Biggest problem was lifting that heavy thing into the travel trailer.

 

[whiteva]

Fantastic!

I got a new battery for the mower. $29.99

Funny how a simple battery will make us happy.

 

[Old_Crow]

Fantastic!

I got a new battery for the mower. $29.99
View attachment 2401193
Funny how a simple battery will make us happy.

No kidding. I had to buy a new battery for the motorcycle because after sitting for a year it was toast. The bike now starts better than it has since I picked it up in '22.

 

[RayIN]

I agree about batteries. I bought a new mower battery at RK and it has never performed as well as the previous WM battery.

 

[SteveSealey]

I have a question about connecting 2 house batteries to solar. Do I connect the negative on 1 and the positive on the other or connect the negative and the positive on just 1 battery since they are both connected parallel.

 

[Gary RV_Wizard]

With only two batteries it doesn't make much (if any) difference but as the number increases the balancing of the current flow begins to have some effect. With two, I'd do it the simple way, with the connections to one battery. Each terminal is directly connected to the other battery anyway. In effect, the solar controller is directly connected to both.

With 3 or more batteries, an argument can be made for optimizing the current path through the battery bank. I'll let battery aficionados explain how that can be of benefit, but it's my personal opinion that the benefit is negligible until you connect 6+.

 

[DonTom]

. I'll let battery aficionados explain how that can be of benefit, but it's my personal opinion that the benefit is negligible until you connect 6+.

Pretty simple, more current, more heat, more voltage loss, but only when there are so many actually needed batteries. Draw the same low current as the two batteries, and then it also makes no difference with a dozen batteries. IOW, it is not the number of batteries, but the current draw. And usually, more batteries means you have a higher current draw available, so the small stuff then becomes a bit more critical.

-Don- Douglas, AZ

 

[DonTom]

No kidding. I had to buy a new battery for the motorcycle because after sitting for a year it was toast. The bike now starts better than it has since I picked it up in '22.

For my 1971 BMW R75/5, they at Batteries Plus, they sell a small deep cycle battery (not supposed to be the best for a high current electric starter) that is the same size that they tell me the BMW riders are very happy with. I tried one, six years ago, it still starts my BMW instantly with the electric starter.

So much for deep cycle not being great for starting engines. This battery is half the price as the BMW battery and lasts twic as long.

-Don- Douglas, AZ

 

[John From Detroit]

So much for deep cycle not being great for starting engines. This battery is half the price as the BMW battery and lasts twic as long.

The smaller starter on the smaller engine does not draw what say an 8.1lVortec's starter draws.

Though I did hear of a motorcycle with that specific engine. I never saw it

 

[DonTom]

The smaller starter on the smaller engine does not draw what say an 8.1lVortec's starter draws.

But the ratio between the battery size and starter motor current draw should be around the same.

Motorcycle batteries are a lot smaller than you will find with an 8.1L engine.

-Don- Douglas, AZ

 

[John From Detroit]

But the ratio between the battery size and starter motor current draw should be around the same.

Motorcycle batteries are a lot smaller than you will find with an 8.1L engine.

-Don- Douglas, AZ

On that I agree Bigger starter = Bigger battery to run it.


Just beware of Wal-Mart battery ratings... The "Normal" rating standard if you can call it that that most everyone uses for amp hour capacity is the 20 hour rate. How many amps do you need to pull to go from Full to zero in 20 hours.
(20 times that = Amp hours so a 100 ah Battery you draw 5 amps for 20 hours it's zero)

Wal*Mart uses the how many hours does it take at ONE AMP method so that 100 AH battery I just tested at one amp lasts about 125 hours or a bit more so it magically gained 25% capacity.. Only it did not (and the difference is actually greater than I exampled)

 

[DonTom]

Wal*Mart uses the how many hours does it take at ONE AMP method so that 100 AH battery I just tested at one amp lasts about 125 hours or a bit more so it magically gained 25% capacity..

Yeah, the BS factor is in a lot of stuff.

-Don- Douglas, AZ

 

[John From Detroit]

Yeah, the BS factor is in a lot of stuff.

-Don- Douglas, AZ

Got that straight.