Do you really need a $400 charger?

[lewisa]

I have been using a IOTA 55 amp charger for over 10 years (with the 3 stage plug in) without any problems. I have a 4 battery golf cart (6 Volt) bank (Trojan T-105's) that provides 450 AH of capacity. As long as the charger is protected from the weather, a "marine" unit is unnecessary. The main limitation is that it does not provide for independent charging of multiple banks.

[Sailmon]

When I was looking to replace my charger, the folks at Lifeline discouraged use of Iota charger. Not sure why. I went with ProMariner - so far (after 13 months of living aboard) it’s working well with shore power and generator.

[CGirvan]

Originally Posted by travellerw

First, let me say there are many ways to do the initial balancing. Yes, Mainsail talks about using a benchtop power supply and doing the pack as a parallel bank. There is nothing wrong with this, and its probably one of the "safest" options. However, it TAKES A VERY LONG TIME.

I didn't have access to a benchtop supply (nor could I ship one here), so I had to come up with a different way. Instead I used my standard onboard charger with the bank hooked up in series. I monitored each cell with my multimeter as the charging progressed. The first 3 hours was pretty boring as the cells pretty much stayed balanced the whole time I was puting in 65A. However, as the individual cells climbed past 3.4V I started to see some imbalance happening. At that point I used a 0.1 OHM 100W resistor ($15 at Digikey) to bleed the high cell. I would then recheck about every 1.5 minutes and bleed again. To push from 3.4V/cell to 3.8V/cell took about 1 hour (so it was a boring hour of repetative work). At that point the cells were within 0.01V of each other and slowly dropping. I reconfigured them in parallel and let them sit for about 18 hours.

In the morning each cell was reading 3.52V. So I reconfigured them back into series and let them sit another 24 hours. At 24 hours they were all still perfectly balanced. I have been using them ever since and they are all still within 0.01V of each other at 3.45V/cell.

P.S. There is no way that power supply you posted could run at its full rated 50A @ 13.8V. I guarntee you will let the smoke out if you do that even a couple of times. It would probably survive 25-30A though. Personally, I think I IOTA chargers are a better deal if you are willing to put in the work like I did.

Thanks for this.


I haven't purchased batteries or charger yet, still in the planning stage. Love to see different options on how to go about this as unfortunately the budget is tight.

[travellerw]

Originally Posted by CGirvan

Thanks for this.


I haven't purchased batteries or charger yet, still in the planning stage. Love to see different options on how to go about this as unfortunately the budget is tight.

No worries.. If you are looking for a "super budget" way, then this PDF details a homemade resistor from and old extension cord. Of course its only budget friendly if you have access to an old cord or 200ft of 16 gauge wire.

https://marazuladventures.files.word...batteries8.pdf

I hope you move forward with your project. LiFePO4 batteries are pretty magical.

[john61ct]

Originally Posted by lewisa

The main limitation is that it does not provide for independent charging of multiple banks.

Some chargers marketing materials may **claim** to do this, but I have yet to find one that does, at least any designed for deep cycling House banks at 12 or 24V.

Any that did, would be in effect X number of separate regulators that happen to be enclosed in one metal box. I suppose they could be fed by a common power supply.

[EngNate]

If you want performance and service life from your batteries the question should be, can you get it for only $400? Maybe, if the output doesn't need to be high. The 3 stage program is essential. The charger capacity should be at least 10% of bank AH rating. Don't exceed 20% except with a unit that has settings for bank AH.

I've got no personal interest in the following recommendation: Pro Mariner Pro Nautic P. I deal with this stuff and I've seen quite a few of these sold and installed over a number of years and they've performed well, been reliable, and are at the lower end of the price range.

[john61ct]

Originally Posted by EngNate

Don't exceed 20% except with a unit that has settings for bank AH.

True for GEL maybe.

FLA doesn't matter go high as you like long as voltage is well regulated and keep them watered, basically self regulating. But waste of money, since they don't accept much higher than .2C anyway, and that only for a short time.

But, some AGM .2C is a **minimum**, others it's .4C.

[Zil]

Originally Posted by mitiempo

Pronautic P chargers come with a temperature sense cable designed to go on a battery post.

Yes that is where my temperature sense wires are designed to be, on a negative battery post. The Pronautic still doesn't have a voltage sense wire.

[a64pilot]

I didn’t see the separate voltage sense wire for the Sterling?
Been a few years since install, but I only remember a temp sense wire

[mitiempo]

Originally Posted by a64pilot

I didn’t see the separate voltage sense wire for the Sterling?
Been a few years since install, but I only remember a temp sense wire

My mistake. It is a temp sensor that comes with the Pronautic P. They do not have an option for a voltage sensor.

But if the charger is installed fairly close to the batteries with the appropriate wire size a voltage sensor is not really necessary.

[SailFastTri]

Originally Posted by Bigjim

snip
I've got two banks of 2 100 ah batteries.

Snip

Sorry to shift topics but why are your battery banks divided that way? A boat the size of yours usually has a house bank and engine starting bank. The starting bank doesn’t need 200ah just to crank the engine, and most people would like to have more storage capacity in the house bank.
... Just thinking it might be to your advantage if you reconfigured your banks to use 1 starting battery and 3 batteries in the house bank.