Probably asked before but using starter battery to supplement Hab battery (X2)

Sep 1, 2017
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Ok, so you can never have enough power - right?

I have x2 90A/Hr Vartas charged via a 150W panel.

This works fine (over our last 30 odd day stay in Spain in January).

However, when charigng the e bikes, the voltage dropped lower than I ideally would like. (approx 90 - 100w load via the inverter and bike 240v charger).

This leads to some 'micromanaging' on my behalf - monitoring battery voltage and switching off inverter etc .

I also used a 50w folding panel (with its own 3A controller) direct into the battery terminals to help stem the draw (so to speak) but still thought the battery voltage was dropping too much. (perhaps the two controllers argue with each other too much).

So, my question is:


I have a 100 A/Hr ish starter battery (also getting a trickle charge via the Electroblok and LRM solar charger) that is basically sittting there. (in this case for 21+ days doing nothing).

So why can't I link in the starter battery to supplment the (high) load when utilising an Inverter (for a relatively short period of time)? The using the LRM solar charger to gradually replace the current used?

To me it seems an easy, cost effective solution to short term, high load scenarios?

Of course you wouldnt use it if you thought you would need the starter motor to be used straight after.

But, is it not better than fitting and carrying a third hab battery for those 'sort term high drain' situations?

Ok, I am aware that a starter battery is designed for short term high load and not longer term low loading, but how much could 100W / 3 batteries = 33 = < 3 amps harm a starter battery - that's akin to having your sidelights and radio on in your car?

I couldnt find any previous posts on this and the question intrigues me.
 

funflair

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I guess if you know what you are doing, both in making the connection and managing the charge levels then no real reason why not, as you say starter batteries are different to leisure batteries but that depends on the leisure battery that you have as some as just starter batteries with a different label on anyway.

Martin
 

pappajohn

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And should the starter battery be incapable of turning over the engine due to it being flat........well, that's what breakdown cover is for.

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Lenny HB

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I wouldn't you can live with flat leisure batteries but you aren't going anywhere with a flat starter battery. The LRM will only trickle charger the starter battery at a max of 2 amps and the leisure battery takes priority.
Best to keep the bike batteries topped up rather than charging them from flat, that's what we do.
 
OP
D
Sep 1, 2017
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Evening Lenny
It's late, so just a quick one:

If I link up the lesiure batteries to the starter battery with an isolatable connection then I can recharge the starter battery at the full output of the solar panel ( divided by 3 if there are now three batteries linked together) and therefore pull up the voltage of the starter battery as quick as the leisure batteries?
 

Lenny HB

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Yes it would work but I don't see the point, safer to run the lesiure batteries lower and have solar recharge them quicker.
You are taking X amount of power out and have Y amount of charge going in, does not matter how many batteries if you can't recharge them.

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OP
D
Sep 1, 2017
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Yes it would work but I don't see the point, safer to run the leisure batteries lower and have solar recharge them quicker.
You are taking X amount of power out and have Y amount of charge going in, does not matter how many batteries if you can't recharge them.

But I am looking at a short term high load situation (like charging a E bike or running a hairdryer). Having a third battery online gives me 33% more capacity - ie more time to charge the E bike battery etc, without having to stop because the (2 battery setup) hits 12.2 V.

After the high load situation, all batteries would have days to recover, with the solar topping them up.

I suppose another advantage is that the leisure batteries would be less depleted (when supplemented by the starter battery) and this could be advantageous in ensuring there was sufficient power to run loads in the evening (for example, if the sun was hidden under heavy cloud after the E bike charging event.

Just my thoughts you understand, I am not trying to be argumentative.
 
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