Where to connect solar controller output

[noelex 77]

6v golf cart batteries are a great solution for many boats, but it is important to understand that when connected in series the capacity is not additive.

Two 6v 220 Ahr batteries add up to a 12v battery with a capacity of 220 Ahrs (not 440 Ahrs as is sometimes assumed).

So to have a lead acid battery with capacity of around 200 AHrs @ 12 v the overall volume of the battery or battery bank will be around twice the size of a typical large car staring battery.

The other tip when comparing capacity of various alternative lead acid battery options is to make sure you are comparing like with like. Most manufacturers quote the C20 rate, but some use C100, which will artifically elevate the specifications.

[flightlead404]

Originally Posted by thomm225

420 ahr AGM. Nice. What brand are they?

I couldn’t find any normal size 12 volt batteries with over 200ah so bought 220 ah 6 volt golf cart batteries

I have 2 x 210 ah Lifeline 4D. Now I've removed the subwoofer for the 5.1 surround sound in the salon (really?!?!?!?!) I have room for another. Since the batteries are less than 1 year old I feel ok putting another new one in there.

I'll probably add that in in a couple of months once I've moved back towards S FL from Hilton Head.

Planning to head south in a month so, of course, loads of last minute stuff to do

[thomm225]

Originally Posted by flightlead404

I have 2 x 210 ah Lifeline 4D. Now I've removed the subwoofer for the 5.1 surround sound in the salon (really?!?!?!?!) I have room for another. Since the batteries are less than 1 year old I feel ok putting another new one in there.

I'll probably add that in in a couple of months once I've moved back towards S FL from Hilton Head.

Planning to head south in a month so, of course, loads of last minute stuff to do

Okay, Lithium Batteries that explains it.
Thanks.

[thomm225]

Originally Posted by noelex 77

6v golf cart batteries are a great solution for many boats, but it is important to understand that when connected in series the capacity is not additive.

Two 6v 220 Ahr batteries add up to a 12v battery with a capacity of 220 Ahrs (not 440 Ahrs as is sometimes assumed).

So to have a lead acid battery with capacity of around 200 AHrs @ 12 v the overall volume of the battery or battery bank will be around twice the size of a typical large car staring battery.

The other tip when comparing capacity of various alternative lead acid battery options is to make sure you are comparing like with like. Most manufacturers quote the C20 rate, but some use C100, which will artifically elevate the specifications.

True enough which to be sure I verified with one of my old school techs when he dropped by recently (rather than look it up to be sure. Would have verified with one of my young techs but they are clueless about such things but experts on anything computer related from networks to IP, MAC Addresses to software to cyber security) BUT

The two 90 ah 12 volt batteries I had in parallel before for 180 ah were a lot smaller physically than these 6 Volt 220 AH Golf Cart Batteries so I'm hoping they will be more long lasting than just the 40 AH's implied.

They are longer and about three inches taller than the 12 volt batteries. So based on physical size alone and the fact that they are "real" deep cycle batteries not 12 volt so-called "Deep Cycle" Batteries from the auto parts store they will be significantly better.

I haven't tested them on a short cruise yet though where I have all sorts of things running and then leave the fan and depth finder on all night. When I did this with the 12 volt batteries many times I'd be under 12 volts in the am which could be due to running the computers and HDTV to much after dark. (on the inverter)

https://www.youtube.com/watch?v=-TOdSCDHb2s

[flightlead404]

Originally Posted by thomm225

Okay, Lithium Batteries that explains it.
Thanks.

No, they are AGM

Lifeline GPL-4DA AGM Deep Cycle

https://batteryguys.com/products/lifeline-gpl-4da

[thomm225]

Originally Posted by flightlead404

No, they are AGM

Lifeline GPL-4DA AGM Deep Cycle

https://batteryguys.com/products/lifeline-gpl-4da

The large ones.

Nice, Thanks.

I actually wanted two 12 volt batteries in parallel of the "normal" physical size with over 200 ah each, but I have a space problem and couldn't go with the larger size shown in the link.

So I went with the 6 volt Golf Cart True Deep Cycle Batteries this time for a change that just fit. Plus the Golf Cart Batteries were like $135 each.

I'm not running a fridge or anything so maybe these will work ............for my needs.

I have two 20 A PWM controllers hooked to them from two different panels while at the dock. One panel the Renogy is unplugged at this time. One side anyway. I may plug it in later if I want to run the voltage up a bit before I sail to maybe 14.2 -14.4, and when sailing both panels stay attached then I add a 20 watt panel (or two) straight to the batteries if necessary.

This switching, swapping, disconnecting, and adding controllers and panels doesn't seem to bother my PWM controllers, but it really messed with the Victron 75/15 MPPT Controller I had online for a while..

[thinwater]

Originally Posted by HankOnthewater

... Or is it that if the fuse blows, something is already awry in a big way? And a damaged controller is the least of the worries?...

Yes, this. If properly sized, the fuse or breaker should never pop. If it does, something was overheating in a major way and the boat could burn down.


So yes, the lesser of two evils. The controller might be damaged, but the boat won't burn.



No confusion, just an unavoidable compromise.