Battery isolater / charger for your BOV

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CrossCut
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Battery isolater / charger for your BOV

Post by CrossCut » Tue Mar 19, 2019 5:17 pm

I mentioned this in passing in the "What did you today for your BOV/how did you prepare your BOV" a few weeks back, didn't go into details because really wasn't sure it'd work. It took awhile to receive the solar charge controller, and then a foul weather delay, and finally troubleshooting (and replacing) a nearly broken 3rd brake light/truck cap dome light wire which produced some very weird symptoms.

Think it's finally almost compete now, and a success*

Backing up a bit, I received a free2me Stanley Power Station/Jump Starter that I wanted to keep in the BOV at all times, but it requires monthly (at least) recharging of the sealed lead-acid battery. Per the owner's manual the only safe charging method for continuous charging is plugging it into 115 VAC, it can be charged via it's cigarette lighter power socket but should not be left charging for over 6 hours when using that method. This suggested that it had smart battery charger circuitry for AC charging, but didn't when the cigarette lighter socket was used. This is still an assumption on my part, but seems reasonable.

So the goal was to add a battery charger that would run off the truck alternator to keep the Jump Starter battery charged, but not overcharge it, and not drain my truck battery when the engine was off, nor have the two batteries directly connected without isolation between them. I've hunted for battery isolaters in the past but good ones are expensive and ones with smart battery chargers even less common. The (few) details and specs for the $12.99 Solar Charge Controller seemed like the cheap problem solver for this - connect the trucks 12vdc system to the "solar" input for the charge controller and let the solar charge controller smartly charge the jump starter battery. The "load" connection from the solar charge controller not being used at all (for now anyway).

Before, with the Jump Starter in it's new home:

Image

Current (ugly, pre-soldered, pre-cleaned up) configuration:

Image

I did replace the 1A fuse in the cigarette lighter plug with a 5A fuse, which meets the specs for both the Jump Starter and the Solar Charge Controller. Also added a diode between the truck's battery/alternator and the solar charge controller as added protection against the jump starter battery discharging into the truck wiring.

Been testing this for the past few days and it appears to working. The only issue seen so far that I can't explain is on the battery charger side, the "Charge" led is constantly on solid, whether or not the truck is running. The solid lit led indicates "equalization", and in all tests it's never changed to blinking "bulk" or "float" patterns. I did confirm the battery is NOT being charged when the truck is not running, but is being charged at above the "float" 12.8v level when it is. The constant "equalization" led indication does have me a little perplexed, although maybe it's normal for a newly connected battery? Any thoughts on that appreciated.

Other than that, the only downside (or 'gotcha') that I see is the requirement to "connect battery first" before connecting the truck wiring to the "solar" side. The charge controller supports 6 or 12v batteries, so it needs to know if it's connected to a 6v or 12v battery first. It's not a problem now, but if disconnecting the cigarette lighter plug from the jump start battery from the solar charge controller in order to to use it, like to jump start the truck, then I need to disconnect the truck wiring first before plugging the jump starter back in to recharge it. Hope that makes sense... Anyway, thinking of adding a rocker switch so I can switch off the input from the truck instead of having to disconnect wires each time I remove it to use it.

So, hopefully, an inexpensive solution for anyone looking for a cheap battery isolater/smart charger for either one of these jump starters or even a spare battery for the bed of your truck. Of course any suggestions, improvements, cheaper or better solutions are appreciated.

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raptor
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Re: Battery isolater / charger for your BOV

Post by raptor » Tue Mar 19, 2019 11:06 pm

Good post. Thanks for sharing. I generally charge my boost battery monthly.

I have been looking at one of the batteryless ultracapacitor devices as well as the newer li-ion devices to replace current lead acid unit.

This seems like a neat alternative.

CrossCut
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Re: Battery isolater / charger for your BOV

Post by CrossCut » Sat Mar 23, 2019 4:33 pm

raptor wrote:
Tue Mar 19, 2019 11:06 pm
Good post. Thanks for sharing. I generally charge my boost battery monthly.

I have been looking at one of the batteryless ultracapacitor devices as well as the newer li-ion devices to replace current lead acid unit.

This seems like a neat alternative.
Thanks. So far, so good. Drained the jump start battery down to 12.5v and took the truck to town to pick up a rocker switch today, almost an hour there&back, battery was up to 12.72v after resting for a few minutes when I got home. More than a trickle charge it seems, and not bad considering this is charging through 18-20 gauge wire. Should have checked the amps it was charging with, but didn't before cleaning it up a little.

Image

Not much prettier, but finished projects that are held together with electrical tape and cable ties is almost my trademark. Didn't connect the ground on the rocker switch so it'd light up when on, but the charge LED on the controller goes out when the switch is off so it's easy to determine the switch position.

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Stercutus
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Re: Battery isolater / charger for your BOV

Post by Stercutus » Sat Mar 23, 2019 5:01 pm

raptor wrote:
Tue Mar 19, 2019 11:06 pm
Good post. Thanks for sharing. I generally charge my boost battery monthly.

I have been looking at one of the batteryless ultracapacitor devices as well as the newer li-ion devices to replace current lead acid unit.

This seems like a neat alternative.
The Li-Ion Jump Packs tend to be so cheaply made they will only crank a four cylinder or less. I keep one for my ATV and KLR but that is about all I will trust it with. It does work on those though.
These days of dust
Which we've known
Will blow away with this new Son

But I'll kneel down wait for now
And I'll kneel down
Know my ground

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