Trickle Charging my Boat Battery

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fmueller87 asked Jan 25, '21

Trickle Charging my Boat Battery

Dear All,

We sometimes leave our boat out of the water for 1-3 months at a time (in the dry store), rather than heaving the heavy batteries out of the boat to store in small apartment, we would like to trickle charge them with solar.

Now the question is, can I leave a BlueSolar PWM-Light 10A connected permanently with a 20 Watt solar panel, to trickle charge the battery? (similar to the "maintenance/wintering" chargers that can be found for cars - these are 230 V / 12V)

As far as I know the PWM Light has a fixed charge regime, of Bulk, Absorption, Float. Would it be suitable for the 12V Deep Cycle (maintenance free / sealed and have 140 Ah) Lead Acid batteries on board the boat? It is two sets of batteries (which are not physically connected), so likely would need two chargers and two panels?

The charge cycle completes and then restarts and after two hours of Absorption, it switches to float.

In short, can this be done, or if not could somebody suggest a simple / affordable system that can be used for this purpose.

Many thanks and best regards,

Fabian

MultiPlus Quattro Inverter Charger battery charging BlueSolar PWM

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Answer 1 · 2021-01-25T18:22:20Z

randy-putnam answered · Jan 25, 2021 at 06:22 PM

Frankly, I think just 1-3 months of storage wont hurt you batteries, especially if you fully charge them before storage. I’ve left fully charged FLA engine and house bank batteries on the boat while stored indoors in upstate NY, from late October to early or mid April (5-6 months) with no adverse effects. Before launching I would bring my generator and charge them up just to be sure they were at or near capacity.

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Answer 2 · 2021-01-26T14:35:16Z

crankshaw answered · Jan 26, 2021 at 02:35 PM

I have 200 ah flooded batteries. I use a 10w solar panel directly wired to the battery for maintenance during storage. For a smaller battery bank, I’d suggest a 5w panel directly wired. Using the PWM controller and a 20-w panel will work fine tho.

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Answer 3 · 2021-01-27T10:42:47Z

fmueller87 answered · Jan 27, 2021 at 10:42 AM

@crankshaw Many thanks for the info. I have contemplated going that route. So there is no detrimental effect, and no overcharging of the battery, even long term?

Those 5-10 W panels are nominal 18 V, this is also not an issue for the batteries?

In regard to size i have 2 x starting batteries in parallel (2 x 140 Ah) and 1 utility battery (1 x 140 Ah). I reckon an approx. 10W panel should be fine directly hooked up.

Thanks again, best regards

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Answer 4 · 2021-01-27T14:51:13Z

crankshaw answered · Jan 27, 2021 at 02:51 PM

On my 200 aH flooded batteries directly wired with a 10w panel, I generally see 13v in full sun, occasionally 13.2v.

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