Garmin Gear and Lithium 24v Questions

[marto78]

Just found this video on another forum.



And this one

[Corry]

Build your own battery and save heaps,you could build a 304amp kit for $1800 and save heaps of space and weight only 24kg.

Very interested to know more about this, how does one start to build his own battery?

It’s basically the exact same set up that revolution is recommending except one large 300ah Power Paul Battery

I'm going to talk to Paul again, as I'm going to be limited with space and positioning of the batteries, I'm thinking 2 would be best, that way I can even weight over each side of the boat. The front cast deck has been built to fit a fridge underneath it, which will be in the middle, I'm picturing putting a battery either side of it, to even out the weight. Although one might work, as the start battery is mounted on one side at the rear... have to think about that.

Thats 9 kings batteries for 1 revolution battery

As you say marto, that's a very hard thing to go past.

Just found this video on another forum.

Very interesting marto.

I was pretty impressed all the way until seeing that the QR Codes had been removed, and not like they just weren't there, they had actually been removed. Maybe this explains why they are so cheap, maybe they are secondhand and repurposed. Maybe, even maybe it is all legit, but I would think if it was a case of changing resellers that they would put another QR Code on it at least.

Hmmmmm.... so got a bit more research to do, really want this boat to be ready to so I can actually see what room I've got where. I like the idea of making my own, could be made in specific sizes to fit, but need to know a lot more about that before I go committing to doing it.

Thanks all for your contributions, great info being shared.

[chris69]

By a kit 4x 3.2 v cells and bms build a box put it in it done there’s heaps of how to put it together vids on YouTube .

[marto78]

The Kings 200ah lithium is on sale today for $699.

[Lovey80]

Just found this video on another forum.



And this one

good vid. The removal of the QR code is a bit concerning but the cells passed the capacity tests with flying colours.

it did look like hose 10A wires got a little bit melts on that 120-130a discharge test. I wouldn’t be pushing one of those to it’s limits for long. The other thing is the BMS. No Bluetooth to the BMS would annoy me after having one. The cells were already 16ma out of balance following 9 full cycles, where all 9 times the BMS got to bleed off a bit of energy at the top. I’d expect that balance to drift a lot if there’s long periods when camping where it doesn’t get to 100%. It could become an issue and limit your capacity long term.

but for the money of these batteries they are a bargain.

[Dignity]

Lovely, I mostly understood what you said and I reckon there would be a lot of boaties who understand none of it and to be honest 16 milli amps in my mind is negligible. My brother who is quite technical and owns a boat didn't even know what an AGM battery was when I mentioned that I was replacing one the other week. He depends on the retailer/installer leading him, sometimes it's up the garden pat, and there are others I've spoken to about battery set ups in their boats and they are of a similar vein to my brothers so there is a huge market out there for shonky sales. You fellas that make your own, kudos to you but I wouldn't attempt it. too many unknowns and too testical for me.

[Lovey80]

Yeh totally get that Digs. That’s why I just bought the Power Paul battery as it has all the things I’d build into a battery for myself. But let me explain what I meant above and how it works out in practice.

if you want to retain full capacity out of your batteries then all the cells need to be balanced. The BMS has two over voltage protection parameters. Once for individual cells and one for the pack as a whole. If you have a high end BMS with blue tooth you can adjust these accordingly to your needs and how you charge them.

If just one of your cells get too far out of balance, then when you charge your battery to completely full, the BMS will shut down charging far too early because one cell has hit its high voltage limit (Over Voltage Protection). What that means is that one cell is full and potentially three others are not full. Most cheap BMS’ use a very small resistor or similar to bleed off about 20ma of the charge that is going into the highest voltage cell. If you are charging with 15a, then this 20ma being bled off is bugger all. Over time this problem can get worse and worse. If you use a really small charger and cycle your battery from 100% down and back to 100% every time this problem will be limited somewhat. But if you spend long periods cycling the battery with the battery below say 98% (and you charge with 10a+) the cells can drift quite a lot. If you can’t look at the individual cell voltages you’d never know what’s happening and effectively your 100ah battery may only provide you 90ah because your cells never get fully charged. The lowest charged cell will hit the low voltage disconnect before the other cells have been fully drained.

I had this issue with one of my batteries before I fitted an active balancer. When charging there was over 200ma deviation between highest and lowest cell when the BMS shut down. The shunt was telling me I was at only 95% state of charge but I couldn’t push any more charge into it because one cell was hitting 3.65v while the other 3 were around 3.30v each. The total battery voltage was around 13.5v but my charger was set to 14.2v. That was just one period of about 3 months where I didn’t fully charge the battery. Over time that could get significantly worse.

sorry for the side track.

[Dignity]

So much electrickery. Am active balancer, something I need to investigate, shunts have been mentioned once or twice here and looking them upot appears that it's not the same as a battery meter/monitor, another thing to investigate. My Green Marine 36v lifepo4 battery has a bms but it will not operate unless there is a load on ot i.e. leccy drawing power or being charged. I asked the guy who delivered it (one of the owners) why and he said it was because ot current draw while sitting idle, now I think I understand a bit better. My 12v one had a bms that failed after only 1 month, and I took it back. They replaced the bms and rebalanced the battery, they also gave me the optionof attaching a Victron bms externally which I have but not sure how to use it other than read what's been used etc and I disconnect it between chargi g and using. Lot's to learn here, thanks for your sidetrack.

[marto78]

Corry and Marto, how important is on board charging to you guys? I haven't done the install (or bought the 36v electric) for the offshore boat yet. But on board charging and simplicity of the system is important to me.

I have bought a 36v converter for the electric so that I can keep everything else 12v. I'll probably install a 300Ah 12v lithium battery as my house battery and run a DC-DC charger from each start battery (Cat) to the house. That will give me 40-50 amps in total of on board charging if I don't add solar. I've taken Nagg's extensive off shore use and 100ah (12v) as not being enough into account. @36v a 300ah battery (plus losses from the converter) is going to find myself in the same territory of not having enough for big days on the water. But with the dual motor charging and the way I fish it should be more than enough.

https://revolutionpoweraustralia.com...r-12v-36v-50a/

https://revolutionpoweraustralia.com...r-12v-24v-50a/

Lovey I've been seriously looking at these converters but 50a output isn't enough for any of the 24v or 36v electric motors on the market.

The Minn Kota 24v and 36v draws 60a at 100% power while the Kraken draws 57a at 24v and 54a at 36v. Plus if your drawing 50a at 36v you will be drawing 150a off the 12v battery.

I'm looking at buying another 12v 200ah battery and running the Kraken on a 24v system while running a 24v to 12v converter for the fridge.

[Lovey80]

Lovey I've been seriously looking at these converters but 50a output isn't enough for any of the 24v or 36v electric motors on the market.

The Minn Kota 24v and 36v draws 60a at 100% power while the Kraken draws 57a at 24v and 54a at 36v. Plus if your drawing 50a at 36v you will be drawing 150a off the 12v battery.

I'm looking at buying another 12v 200ah battery and running the Kraken on a 24v system while running a 24v to 12v converter for the fridge.

There are guys running them successfully out there at the moment. I haven’t had a chance to try mine yet. 150A -180A is no problem for the PowerPaul 300Ah batteries. I’ve just wired mine into the Ute. Quality piece of kit that takes up a lot less realestate than the competitors that must have a lot of empty space inside some of those boxes.

[Lovey80]

Lovey I've been seriously looking at these converters but 50a output isn't enough for any of the 24v or 36v electric motors on the market.

The Minn Kota 24v and 36v draws 60a at 100% power while the Kraken draws 57a at 24v and 54a at 36v. Plus if your drawing 50a at 36v you will be drawing 150a off the 12v battery.

I'm looking at buying another 12v 200ah battery and running the Kraken on a 24v system while running a 24v to 12v converter for the fridge.

Check out his vid. He’s gone down this path. I think this type of system is as good as it gets but possibly a bit low on capacity if he’s only using one of the 100Ah batteries for his leccy.

[rayken1938]

Just as an aside what does everyone do with their old lithiums? None of my local scrappies want them.

[marto78]

That's a nicely set up boat but I still don't understand how a dc converter rated to 50a will work with a electric motor that at 100% power will draw 56a?

It's easy to say you won't ever use 100% power but what's stopping the electric motor hitting max power when spot locking in a high wind/current? And what happens to the converter when this happens?

Does it reset straight away once the current draw is below 50a? Or if you use a 50a resettable breaker to limit current draw (as you should) that is going to be a big PITA if you have to go reset it when it trips out.

https://trollingmotorpro.com/trollin...mp-draw-chart/

I spoke to Trolltek about this last week and they told me to not use the converter and to go with a seperate 24v battery for the electric motor. They couldn't tell me what the over current limit was in their units.

Maybe I need to talk to Revolution or Victron to see if they can supply any more information on their converters and whether they are suitable.

[marto78]

Just as an aside what does everyone do with their old lithiums? None of my local scrappies want them.

Most council dumps will take old batteries

[marto78]

I just came across a Renogy 24v 100ah battery on sale for $1100 with free delivery.

https://au.renogy.com/24v-48v-100ah-...5&gad_source=1

I'm thinking of pairing this up with a Stirling 12v to 24v dcdc charger

https://www.theboatwarehouse.com.au/...-charger-ip68/

To me this seems like a fairly cost effective way to run an electric motor without the added worry of the 12v to 24v converter cutting out when you really need it.

To run other 12v accessories off the 24v battery a step down converter like this can be used

https://extremeoffgridaccessories.co...RoCor0QAvD_BwE

The only thing I don't like about this system is that I have already bought a 12v 200ah battery to use with a 12v to 24v converter but I'm sure I'll be able to find somewhere else to use it.